1
Q
where did life begin, how did it begin?
ur mom
A
- in water
- small volume of water + other substances enclosed in membrane and chemical reactions occurred
2
Q
how are hydrogen bonds formed in water
A
- covalent bond in water molecule has unequal sharing of electrons as oxygen is more EN
- partial charges creates attraction b/w molecules
3
Q
what is cohesion of water caused by
A
hydrogen bonds
4
Q
how is cohesion used in the transport of water under tension in the xylem
A
- continuous columns of water in xylem experience tension from root and leaves, but move up as tension is stronger in leaves
- water can withstand tension bcus of hydrogen bonds
- breaking of water column typically takes more energy than available
5
Q
how are water surfaces used as habitats
A
- water molecules are much more attracted to each other than air causing surface tension
- able to float much denser objects as cohesion b/w water molecules > water and floating object
- to break surface: many hydrogen bonds must be broken at once
6
Q
what does water adhere to
A
materials that are polar are charged
7
Q
capillary action in soil
A
- water is attracted to many chemical substances in soil
- porous soil: water drawn up by capillary action through dry soil, wetting it
- how water can rise from underground source
8
Q
capillary action in plant cell walls
A
- water adheres to cellulose in cell walls
- if water evaporates from cell walls in leaves, adhesive forces cause water to be drawn from nearest xylem vessel
- keeps walls moist to absorb CO2 for photosynthesis
9
Q
why is water used as medium of metabolism and transport in plants and animals
A
- solvent properties
- wide variety of hydrophilic molecules dissolve in water + most enzymes catalyse rxns in aq solutions
10
Q
how does buoyancy allow for organisms to use water as a habitat
A
- if density of object < density of fluid, buoyancy force will be greater than gravity force, causing it to float
- living organisms have overall density close to water, not much energy needed to float
- ex. bony fish have air-filled swim bladder to control their density
11
Q
viscosity as a property of water
A
- due to internal friction when one part of fluid moves relative to another
- pure water has higher viscosity than organic solvents bcus hydrogen bonds
- solutes increase viscosity
12
Q
specific heat capacity as a property of water
A
- heat needed to raise 1g of material by 1C
- water has high SHC because hydrogen bonds must be broken to raise temp, needs a lot of energy
- as result, aquatic habitats are quite thermally stable
13
Q
thermal conductivity of water
A
- rate in which heat passes material
- water has high thermal conductivity, useful to absorb and transfer heat
- ex. high water content of blood allow it to carry heat from parts of body where it is generated to ones that need it
14
Q
physical properties of air vs. water on individuals
A
- air less dense, less buoyant force on individual
- water more viscous, ind. needs more energy to move through it
- water more thermal conductivity, conducts heat away from ind’s body
- water higher SHC, more stable environment for ind
15
Q
_____ is the genetic material for all living organisms, how abt viruses?
A
DNA (deoxyribonucleic acid)
- viruses have RNA (ribonucleic acid), but cannot reproduce, therefore not living
16
Q
3 main parts of a nucleotide
A
- pentose sugar
- phosphate group
- base
17
Q
how does sugar-phosphate bonding work to link nucleotides tgt
A
- covalent bonds formed b/w phosphate of one nucleotide to pentose sugar of another to make continuous chain
- creates sugar-phosphate backbone
18
Q
what are the bases in DNA vs RNA
A
adenine, cytosine, guanine, thymine (uracil replaces thymine in RNA)
19
Q
what is RNA, how is it created
A
a polymer formed by condensation of nucleotide monomers
- OH on carbon 3 of sugar and OH on phosphate group have H2O removed, leaving a single O (sugar phosphate backbone)
- covalent bonds to this O links nucleotides (condensation reaction)
20
Q
structure of DNA
A
- double helix made of 2 antiparallel strands of nucleotides
- strands linked with hydrogen bonding
- bonds b/w complementary base pairs
21
Q
differences of DNA vs RNA
A
- DNA is double stranded (2 polymers of nucleotides), RNA is single stranded(1 polymer of nucleotides)
- bases are different (thymine vs. uracil)
- pentose sugar in DNA is deoxyribose (one less oxygen than ribose), sugar in RNA is ribose
22
Q
role of complimentary base pairing
A
- allows genetic information to be replicated and expressed
- based on hydrogen bonding
23
Q
semi-conservative replication
A
the process where DNA replication results in two new DNA molecules
- each contains one original strand and one newly synthesized strand
24
Q
possible DNA base sequences
A
- any length of DNA in any sequence is possible
- diameter of DNA is 2 nanometers, immense lengths of DNA can be stored in a small volume (small space, lots of info)
25
genetic code in living organisms and viruses
- all living organisms and viruses use same genetic code (64 codons)
- minor exceptions where stop codon codes for AA instead
- evidence of common ancestry
26
cell theory
- all living organisms are composed of cells
- cells are the basic unit of life
- all cells come from pre-existing cells
27
how to calculate real magnification of microscope lens
eyepiece lens x objective lens
28
advantages of electron microscopes
- good resolution, very high magnification
- allows scientists to investigate detailed structure of cells
29
advantages of freeze-fracture electron microscopy
- produces images of surface of cells
- allowed fundamental change in theories about membrane structure
- gives impression of 3D image through shadowing
30
advantages of cryogenic electron microscopy
- mostly used to research structure of proteins
- previous methods only produced images of protein in most stable form, but cryo-EM analyses proteins when water around them froze
- allows scientists to research proteins changing from one form to another as they carry out function
31
advantages of fluorescent stains and immunofluorescence
- locates chemicals that are difficult to find without stains
- generates bright images
32
how do fluorescent stains and immunofluorescence work
- stains (coloured substances) bind into some chemicals but not others allowing substances to be distinguished under microscope
33
how does freeze-fracture electron microscopy work
- sample plunged into liquified propane at -190C for rapid freeze
- frozen sample fractured at weakest points
- some ice at surface removed to enhance texture(etching)
- vapour of platinum or carbon fired on surface to create replica <- can be examined
34
how does cryogenic electron microscopy work
- thin layer of pure protein solution applied on grid <- flash frozen in liquid ethane
- place in electron microscope and patterns of electrons transmitted by individual protein molecules recorded
35
structures that are common to cells in all living organisms
1. plasma membrane (outer boundary of lipids that controls entry, exit of substances)
2. cytoplasm (mostly water w/ substances dissolved/suspended, allows metabolism in cell)
3. DNA (genetic materials w/ info needed for cell to carry out all functions)
36
plasma membrane + cell wall of prokaryotic cells
- all cells have plasma membrane
- vast majority of prokaryotic cells have cell walls
- cell wall thicker + stronger than membrane
- protects cell, maintains shape
- in prokaryotes, contains peptidoglycan
37
cytoplasm in prokaryotic cells
- no nucleus, entirely filled w cytoplasm
- not divided into compartments by membranes, one chamber
38
naked DNA in prokaryotic cells
- aka plasmid DNA
- part of cytoplasm looks lighter, contains DNA
- typically a single molecule of DNA that forms loop/circle
- unlike eukaryotic DNA, not associated with proteins ("naked")
39
ribosomes in prokaryotic cells
- only cytoplasmic organelle in prokaryotic cells
- smaller than eukaryote ribosomes (70S vs. 80S)
40
basic eukaryotic organelle structure
- plasma membrane enclosing compartmentalized cytoplasm with 80S ribosomes
- membrane bound cytoplasmic organelles
41
mitochondria in eukaryotic cells
- surrounded by double membrane
- inner membrane folded inwards to increase SA for energy production
- carry out aerobic respiration, in all cells that perform aerobic respiration
42
structure nucleus in eukaryotic cells
- containing chromosomes made of DNA bound to histones contained in a double membrane
- pores to transport nutrients
43
rough endoplasmic reticulum in eukaryotic cells
series of connected, flat, continuous single membranous sacs playing central role in synthesis and transport of polypeptides
44
smooth endoplasmic reticulum in eukaryotic cells
series of connected, flat, continuous membranous sacs NOT involved in protein synthesis
- synthesizes phospholipids and cholesterol for repair+formation of membrane
45
golgi apparatus in eukaryotic cells
modifies polypeptides and lipids + pack into vesicles
- packs dispatched for transport or to lysosomes/plasma membrane and secreted vis exocytosis
46
vesicles in eukaryotic cells
- transport: transports molecules by budding off one organ and fusing onto another
- secretory: secretes molecules via exocytosis + adds new phospholipids into cell membrane
47
lysosomes in eukaryotic cells
- single membrane
- contains enzymes that digest large molecules to recycle cells own organelles if old/damaged
- immune defense: digests pathogens engulfed by phagocytes
48
vacuoles in eukaryotic cells
- storage of water/nutrition/waste
- maintains tugor pressure against cell wall, allows plants to stay upright
49
cytoskeleton in eukaryotic cells
formed w microtubule, and microfilaments
- maintains cell shape, organizes parts, allows movements/division of cell
- NOT AN ORGANELLE
50
processes of life in unicellular organisms
homeostasis, metabolism, nutrition, excretion, growth, response to stimuli, reproduction
51
homeostasis as a process of life in unicellular organisms
maintenance of a "stable"/constant internal environment in an organism
52
metabolism as a process of life in unicellular organisms
sum of all biochemical reaction in a living organism
53
nutrition as a process of life in unicellular organisms
supplying nutrients required for energy/growth/repair in an organism
54
excretion as a process of life in unicellular organisms
removal of waste products of metabolism of organism
55
growth as a process of life in unicellular organisms
an increase in size/number of cells
56
response to stimuli as a process of life in unicellular organisms
perception of stimuli and carrying out action in response
57
reproduction as a process of life in unicellular organisms
production of offspring sexually or asexually
58
plastids definition then how it's present in animals vs. fungi vs. plants
- a family of organelles w two outer membranes and internal membrane sacs
a: none
f: none
p: varied types such as chloroplasts for photosynthesis and amyloplasts to store starch
59
cell wall definition then how it's present in animals vs. fungi vs. plants
- rigid layer outside plasma membrane to strengthen+protect
a: none
f: cell wall composed of chitin
p: cell wall composed of cellulose
60
vacuoles definition then how it's present in animals vs. fungi vs. plants
- flexible fluid-filled compartment w single membrane
a: small temporary vacuoles expel excess water/digest food or pathogens taken in by endocytosis
f+p: large permanent vacuole for storage + pressure in cell
61
centrioles definition then how it's present in animals vs. fungi vs. plants
- cylindrical organelles that organize assembly of structures composed of microtubules
a: used to construct spindle fibre used in mitosis and the 9+2 microtubules in cilia + flagella
f+c: none unless swimming male gametes that have centriole at base of flagellum
62
undulipodia definition then how it's present in animals vs. fungi vs. plants
- cilia + flagella used to generate movement of cell or fluid around it
a: present in many, including tail of male gametes
f+c: non except male gametes that swim using flagella
63
atypical number of nuclei in red blood cells
- do not have nucleus, removed during late stages of development
- smaller/more flexible but cannot repair itself therefore short lifespan of 100-120 days
64
atypical number of nuclei in skeletal muscle
- groups of cells fuse together, bcus each cells has own nucleus, creates large multinucleate structure forming long muscle fibres
65
how is variation between organisms a defining feature of life
- no two individuals are identical in all their traits as they will always adapt to slightly diff environments
- patterns of variations are complex, basis of naming and classifying organisms
66
how were species originally classified, by who?
- as groups of organisms with shared traits by Carl Linnaeus
- morphological species concept "morphology"
67
how does the binomial system for naming organisms work
- first part identifies genus (capitalized), species in same genus have similar traits
- second part identifies species
- always written in italics
- after used once, can be abbrev. to first letter of genus w full species name
68
what does the biological species concept state
species is a group of organisms that can successfully interbreed and create fertile offspring
69
what are some challenges with the biological species concept
- asexual organisms
- geographical separation and gradual divergence make it difficult to apply
- when migrations brings closely related but distinct species together
- ex. female ligers can sometimes be fertile, however saying lions and tigers are the same species is not acceptable
70
how do we currently classify species
- using the biological species concept
- however there are many competing definitions/classifications of species
71
define speciation
splitting/divergence of one species into two or more
- species separated and cannot interbreed, natural selection acts differently on each population and they evolve differently
72
how does speciation occur, how to differentiate b/w populations and species
- speciation happens gradually when interbreeding doesn't occur with populations getting more and more different w/ their traits as generations pass
- arbitrary decision whether two populations are the same species
73
number of chromosomes in humans vs chimpanzees, why is this the case?
46 in humans vs. 48 in chimps
- both are even numbers as all diploid cells have an even number of chromosomes
74
does chromosome number matter? does more make an organism more complex?
- not really as long as all members of the species have the same number of chromosomes
- no, lengths of chromosomes can still vary (some may have few large ones while others have many small ones)
75
where did human chromosome 2 arise from
fusion of chromosomes 12 and 13 of a shared primate ancestor
76
what can be looked for to classify chromosomes?
- banding patterns
- length
- centromere position
77
define genome
all the genetic information of an organism (entire base sequence of each DNA molecule)
78
what are single nucleotide polymorphisms (SNPs)
positions in a gene where more than one base may be present in diff individuals of population (when at least 1% if individuals have a diff base in a spot)
79
variation of genome in same species
- share most of genome, but mutations/variations like SNPs can give diversity
- alleles can be present in an individual, but very small number of bases are different or else gene can lose function
80
variation in genome size of eukaryotic organisms
- determined by total amount of DNA
- large genomes can contain a lot of non-functional DNA (junk DNA)
81
variation of genome size within species vs. b/w species
variation b/w species is much larger than within a species
82
how do base sequence change in diff populations of eukaryotic organisms
- two populations of species will have varied base sequence as variations accumulate
- infrequent changes in base sequence in genes with vital functions
83
current uses of whole genome sequencing
- research in evolutionary relationships to better conserve/protect biodiversity
- research into genomes of pathogenic bacteria and viruses to help prevent infectious disease
84
future uses of whole genome sequences
- personalized medicine <- sequences genomes of individuals to understand human origins and migration, genetic diseases
85
how has whole genome sequencing become more accessible
- speed is increasing and price is decreasing because of technological developments
86
define Darwinism evolution vs. Lamarckism
D: the change in heritable characteristics(genes) of a population (natural selection) <-- current definition
L: evolution as the inheritance of acquired characteristics <-- not true
87
base sequences as evidence of common ancestry/evolution
- bcus evolution is the change in heritable characteristics, genes should change whenever evolution occurs
- change occurs in DNA/RNA/AA
- the more closely related two species are morphologically/other traits, fewer differences in base sequence <- shows that species develop overtime thru divergence
88
selective breeding as evidence of evolution
- selectively bred animals/plants are drastically different from og ones
- artificial selection causes rapid evolution, suggests natural selection also caused major evolutions but in a longer period of time (billions of years)
89
homologous structures as evidence of evolution + define
- same structure but different function (divergence evolution)
- inherited from common ancestor, but have evolved in diff ways in diff organisms to adapt <- now look very different, but same bone structure
- difficult to explain w/o evolution
90
pentadactyl limb as an example of homologous structures
- shared by humans, moles, horse, bats
- very different functions, but same bones
- a common ancestor of all tetrapods (4 legged vertebrates) had pentadactyl limbs, all descendants retain same basic arrangement
91
define analogous structures
structures of an organism that have the same function but different structure/evolutionary origin
92
human eye vs. octopus eye as an analogous structure
- strikingly similar, both are used to see
- human eye has nerve fibres in front of retina, creating blind spot
- octopus has nerve fibres behind retina, no blind spot
- difference in structure suggests convergence evolution
93
how does number of species on earth change
- speciation is the only way in which new species occur, increasing # of speices
- extinction causes the number of species to decrease
94
the role of reproductive isolation and differential selection in speciation
- must have RI as it stops the mixing of gene pools and blending of traits
- natural selection will cause traits to change
- if natural selection remains same b/w 2 populations, will not become different, but if it changes, differential selection occurs
- leads to divergence evolution/divergence selection
95
how does geographical isolation lead to reproductive isolation
geographical isolation leads to reproductive isolation and allows for different selection pressures on population
96
chimpanzees and bonobos as example of divergence
- long ago, the congo river was dry and chimps could cross it however now it's deep, separating the 2 populations on either side as none can swim
- geographical isolation caused reproductive isolation and different traits developed due to diff selection pressures
97
define ecosystem diversity
variety in the combinations of species living together in communities due to varied adaptations to varied environments on earth
98
define species diversity
the many species in an area that have varied body plans, internal structure, life cycles etc.
- encompasses both species richness and eveness
99
define genetic diversity
variety of gene pool of each species b/w both geographically separated populations and within populations
100
current number of species on earth vs. biodiversity in the past
- currently 2M species discovered + named, however many more exist
- fossils suggest # of species now is higher than ever before
- cus 66M years since last mass extinction, biodiversity can develop
101
over harvesting as an anthropogenic cause of species extinction
- humans take plants/animals from natural ecosystem faster than they can reproduce, causing extinction
- ex. fishing rates
102
habitat destruction as an anthropogenic cause of species extinction
- 13B hectares of land are used for livestock and agriculture
- land used to build towns/cities
- leads to loss of species
103
invasive species as an anthropogenic cause of species extinction
- introduced to area by humans
- alien species can drive native species to extinction by predation.comp for resources
- endemic species can be lost in they hybridize w alien species
104
pollution as an anthropogenic cause of species extinction
- chemical industries produce many substances that enter environment
- no part of the world can be unaffected by pollution
105
global climate change as an anthropogenic cause of species extinction
- human changes causing very rapid changes in environment, animals cannot adapt as quickly
- can face extinction
106
what are examples of anthropogenic causes of ecosystem loss
land use/agricultural expansion, urbanization, overexploitation, mining, building dams, drainage, leaching of fertilizers, climate change
107
what can be used as evidence for a biodiversity crisis
population size, range of species, diversity of species, richness/evenness of biodiversity, area occupied, genetic diversity
108
what counts as good evidence for a biodiversity crisis
- reliable surveys from all around the world that's peer reviewed
- "citizen science" where individuals monitor population/ecosystem regularly
- surveys need to be repeated many times to ensure it's accurate
109
what is the main cause of the current biodiversity crisis
human population growth
- anthropogenic causes of species extinction and ecosystem loss
110
advantage of in situ conservation
- species lives in environments it’s adapted to
- retains natural habitat and prevents loss of other endangered species
- costs are low if wildlife reserve in good state, limited human intervention
111
examples of in situ conservation
- rewilding
- management of nature reserves
- reclamation of degraded ecosystems
112
advantages of ex situ conservation
- species may not be able to safely remain in natural habitats
- allows for control of conditions
- improve chances of successful breeding
- store living materials long term for future use
113
examples of ex situ conservation
- zoos
-
114
disadvantages of ex situ conservation
- doesn’t prevent destruction of natural habitats
- species raised in captivity are less likely to be successfully reintroduced into environment
- increases inbreeding
115
what two criteria determine species most need of conservation
1. does the species have few or no close relatives?
2. is the species in danger of extinction because all remain populations are theatened?
116
what does EDGE stand for
evolutionarily distinct and globally endangered
117
why is carbon so important for life
- can form 4 covalent bonds w other carbons or other non-metallic elements to create complex and stable structures
- can be linked by covalent bonds to form chain of any length (branched or unbranched)
- can form single or multiple rings
118
what are macromolecules, what are the main classes?
- molecules composed of a very large # of atoms
- main classes: polysaccharides, polypeptides, nucleic acids
119
what is a condensation reaction
- when two molecules are linked together and at the same time a smaller molecule is released
120
how are polysaccharides/polypeptides/nucleic acids constructed
- by removing a hydroxyl group from one of the molecules being linked and a hydrogen from the other
- creates water which is released, allows bond to be made
- requires ATP
121
what occurs during the synthesis of polysaccharides
- glucose is monosaccharide used to make glycogen (polysaccharide)
- glucose linked w glycosidic bonds (C-O-C linkages thru condensation)
- unbranched: C1 of glucose linked to C4 of another (1-->4 bond)
- branhces: C1 of glucose linked to C6 of another (1-->6 bond)
122
examples of polysaccharides, polypeptides and nucleic acids
polysaccharides: starch, glycogen, cellulose
polypeptides: insulin, glucagon, hemoglobin
nucleic acids: DNA, RNA
123
how are polymers broken/digested into monomers
- thru hydrolysis reactions
- polymers deconstructed so monomers can be reused for new polymers or source of energy
124
how does hydrolysis work
water molecules are split to provide hydrogen and hydroxyl groups
- used to make bonds on monomers that replace broken bond
125
forms of monosaccharides
- pentose (ribose) or hexose (fructose, glucose)
- one oxygen atom in ring and 4-5 carbon atoms in ring
126
how doe the properties of glucose affect how it's used
- soluble, small molecule so easy to transport (dissolved in blood)
- chemically stable, however would cause osmotic problems in stored in cells so typically converted into glycogen or starch
- yields energy when oxidized, can be used as substrate for respiration
127
why are polysaccharides good energy storage compounds
- large size, low solubility so doesn't really affect osmotic balance
- branched structure makes them relatively compact
- glucose can be removed from starch + glycogen when needed by hydrolysis (break 1-->4 glycosidic bond to separate 1 glucose) allowing it to be transported elsewhere
128
how is the structure of cellulose formed
- composed of beta-glucose
- condensation rxn link C1 of free b-glucose to C4 of b-glucose at end of chain (all 1-->4 bonds therefore unbranched chain)
- naturally OH group of C1 is diagonal to OH group of C4, so must be inverted so OH groups are horizontal for condensation rxn
129
how is cellulose's structure related to function as structural polysaccharide in plants
- straight chain of beta-glucose allows for bundles of molecules arranged in parallel, hydrogen bonds can form
- bundles are microfibril and are basis of plant cell walls
- high tensile strength because of the cross-linked hydrogen bonds, prevents plant cells from bursting
130
define oligosaccharide
a short chain of monosaccharides linked by glycosidic bonds
131
what are glycoproteins, what do they do
- polypeptides with carbohydrate attached (oligosaccharide)
- facing outwards of cell, allows other cells to recognize them
132
how are glycoproteins present in ABO blood
- no known function but affect blood transfusion
- oligosaccharides present are O, A, B
- affects how blood can be transfused from person to person
133
properties of lipids, what are some examples
- substances in living organisms that dissolved in non-polar solvents <- hydrophobic
- sparingly soluble in aqueous (water based) solvents
- not repelled by water, more attracted to non-polar substances
- ex. fats, oils, waxes, steroids
134
how are triglycerides (mainly oils/fats) created
- combine 3 fatty acids and one glycerol with 3 condensation rxns, producing 3 H2O molecules
- link b/w each fatty acid and glycerol is ester bond
135
how are ester bonds formed
when an acid reacts with the hydroxyl group (OH) in an alcohol
136
structure of phospholipds
- 2 fatty acids + phosphate group linked to glycerol
- because phosphate is hydrophilic, phospholipids are both hydrophilic and hydrophobic
137
differences in carbon bonds and H in saturated, monounsaturated, and polyunsaturated fatty acids
saturated: no double bonds in C (as many H as possible)
monounsaturated: 1 double bond in C (less that max # of H)
polyunsaturated: 1+ double bond in C (less that max # of H)
138
how does # of double bonds in fatty acids affect melting point
- presence of double bonds lower the melting points of fatty acids as they prevent tight packing leading to weaker intermolecular interactions
139
what properties of triglycerides make them good for long term energy storage
- very chemically stable, energy not lost
- don't affect osmotic balance
- release 2x energy compared to carbohydrates, more energy can be stored
- poor conductor of heat, insulator to conserve body heat
- liquid at room temp, shock absorber
140
define amphipathic
substances that consist of both hydrophilic and hydrophobic parts
141
how do phospholipids form phospholipid bilayer
- hydrophobic tails, hydrophilic head
- when mixed with water, phosphate heads attracted to water, hydrocarbon tails attracted to each other
- forms double layer w heads outside, tails inside
- basis of all cell membranes
142
how can steroids be identified, examples
- 4 fused rings of C atoms
- 3 cyclohexane rings, 1 cyclopentane ring
- 17 carbon atoms total
- ex. testosterone and oestradiol
143
how are non-polar steroids able to pass phospholipid bilayer
- mostly hydrocarbon-->hydrophobic
- allows to pass thru phospholipid bilayer to enter/leave cells
144
structure of an amino acid
- central carbon atom (alpha carbon) with single covalent bonds to N of amine group, C of carboxyl group
- covalent bond to H and R group
145
how are dipeptides formed
- two AA with condensation rxn to form peptide bond
- peptide bond: C-N bond formed b/w amine group and carboxyl group, catalyzed in cells by ribosomes
- H2O is removed
- peptide bond is same no matter R group
146
oligopeptides vs polypeptides vs dipeptides
dipeptides: 2 AA
oligo: 2-20 AA
poly: 20+ AA
147
essential AA vs. non-essential AA
essential: AA that cannot be synthesized by animal, must be obtained
non-essential: AA can be synthesized by animal using metabolic pathways
148
essential AA and non-essential AAs in plants and animals
- plants can synthesize all 20 AA (non-essential)
- animals have 9 essential and 11 non-essential AA, must obtain from diet
149
number of amino acids possible in a chain
- practically infinity as there are 20 which can be combined in any order to any length
- however, not all occur as ribosomes don't make random sequences, receives info from genetic code
150
examples of polypeptides
- beta-endorphin (natural painkiller)
- insulin
- alpha amylase (enzyme in saliva aiding in digestion of starch)
- titin (largest polypeptide)
151
define denaturation
when protein loses folded structure when bonds are broken resulting in change of conformation of protein, loses function
- often occurs in extreme environments and is not reversible
152
how can temp cause denaturation
- causes vibration within molecule that can break intermolecular bonds
- proteins vary in heat tolerance (ex. thermus aquaticus in hot springs->80C)
153
how can pH cause denaturation
- extreme pH cause pos/neg charges on R-groups to change, breaking ionic bonds or forming new ionic bonds
- proteins vary in pH tolerance (ex. pepsin in stomach ->1.5pH)
154
structure of cell membranes
- basic structure of all biological membranes is same -> bilayer of phospholipids/amphipathic molecules
155
how do lipid bilayers act as a barrier b/w aqueous solutions
- hydrocarbon tails interact w each other to form membrane that has low permeability to hydrophilic particles, ions, polar molecules
- solutes close to membrane surface may pass thru heads of phospholipds but are drawn back if they enter hydrophobic core
156
how does diffusion work
- more particles move from area of higher concentration to lower conc. than the other way
- passive process
157
how does oxygen diffuse through membranes
- non-polar particle so can diffuse easily
- if conc. inside cell is lower than outside cus aerobic respiration, oxygen will enter thru passive diffusion
158
integral proteins
- hydrophobic on some of surface so embedded into hydrocarbon chains in centre of membrane
- transmembrane proteins
159
peripheral proteins
- hydrophilic on surface, not embedded into membrane
- attached to inside and outside surface of plasma membrane and integral proteins, often reversible
- some have single hydrocarbon chain to insert into membrane as anchor to surface
160
define osmosis
when water (solvent) moves thru a semi-permeable membrane from a less concentrated solution to a higher concentrated solution to equalize their concentrations
161
how does osmosis work
- substances that dissolve in water do so by forming intermolecular bonds
- these bonds restrict movement of water
- regions of higher solute conc have less freely moving water molecules vv.
- bcus of this, net movement from low solute conc. to high solute conc.
162
what are aquaporins
- channel proteins that transport water across membrane in a single file
- positive charges in middle of aquaporins prevents protons (H+) from passing thru
163
what is a channel protein, what does it allow for
- an integral transmembrane protein with a pore that connects cytoplasm to outside
- allows for facilitated diffusion of ions and polar molecules
164
how do channel proteins support facilitated diffusion
- diameter of pore and chem properties ensure one type of particle passes thru
- allows particles to pass thru both ways but more go from high conc->low conc
- can close to prevent diffusion
165
differences in pump proteins vs. channel proteins
- pump proteins used energy (ATP) to carry out active transport, channel proteins is passive diffusion
- pump proteins move particles in one direction, channel moves both
- pump proteins usually move particles against conc. gradient while channel almost moves down conc. gradient
166
how do pump proteins work
- 2 different conformations
- transported particle enters from one side to reach the centre of pump protein
- pump protein changes to other conformation allowing particle to pass to other side of membrane before returning to og conformation
- energy is used change conformations
167
define selectively permeable vs semi-permeable membrane, what are cell membranes?
- selectively: allows for passage of particular particles but not others
- semi: allows for passage of certain small solutes and freely permeable to solvent
- have both (partially permeable)
168
what is selective permability membranes, what is not
- facilitated diffusion and active transport allow for selective permeability as they're specific to particular particles
- simple diffusion is not selective as it depends on size/polarity of particles
169
define glycoproteins, place in cell
- molecule comprised of protein and carb chain
- protein part embedded in membrane and carb part in exterior environment of cell
170
define glycolipids, place in cell
- molecule comprised of lipids and carb chain (1-4 sugar units)
- lipid part have 1-2 hydrocarbons which fit into hydrophobic core of phospholipid bilayer, carb chain on exterior
171
functions of glycoproteins and glycolipids
- cell recognition, helps immune system distinguish foreign cells
- creates carbon rich layer outside of cell (glycocalyx), allows for cell adhesion when fusion of glycocalyx
172
what are organelles
discrete structure in cells that are adapted to perform one or more vital functions
173
examples of organelles, examples of what are not organelles
organelles: nuclei, vesicles, ribosomes, plama membrane
not organelles: cell wall, cytoskeleton, cytoplasm
174
what are the advantages of separation of nucleus in cytoplasm
- safeguards DNA
- separation of transcription and translation as translation cannot occur until mRNA has left nuclear membrane, modification of mRNA can occur (eukaryotic cells)
- translation can happen right after transcription, mRNA cannot be modified (prokaryotic cells)
175
what are the advantages of compartmentalization in cells
- enzyme/substrates for particular process are more concentrated
- substances that could cause damage kept inside a membrane
- conditions can be mantained to ideal level for particular process
- organelles+content can be moved within cell
176
lysosomes ad advantage of compartmentalization in cells
- digestive enzymes of lysosome could digest+kill cell if not safely stored in lysosome membrane
177
how do gradients affect gene expression of early-stage embryo
- position of cell in embryo determines how it differentiates
- gradients cell's position in embryo and determines pathway of differentiation, regulating gene expression
178
define fertilization
fusion of male and female gamete to produce a single cell
179
how are embryos of multicellular organisms created
- cel produced by fertilization undergoes mitosis so all cells are genetically identical
- cells are unspecialized, develop along diff pathways as embryo grows
180
properties of stem cells
- can divide repeatedly and endlessly
- can differentiate along diff pathways (no longer stem cells)
181
what is a stem cell niche, what does it do
- precise location of stem cells within a tissue (stem cell niche)
- provides conditions needed for stem cells to remain inactive over long periods of time and differentiate when required
182
examples of stem cell niches
- bone marrow (produces replacement blood cells)
- hair follicles (generates new hair growth)
183
totipotent stem cells
can differentiate into any cell type (ex. early stage embryos)
184
pluripotent stem cells
capable of differentiating into all cells in adult human body but create a new organism
- (ex. late stage embryos)
185
multipotent stem cells
can differentiate into several types of cell in the same group (ex. haematopoietic stem cells in bone marrow can become many blood cells)
186
cell size of sperm as aspect of specialization
- 50micrometers, long but narrow
- smallest volumes of any human cell
- reduces resistance allowing it to reach egg easier
187
cell size of egg as aspect of specialization
- 110micrometers, spherical
- largest volume of any human cell
- allows for large quantities of food reserves to be stored in cytoplasm
188
cell size of RBC as aspect of specialization
- 6-8micrometers, disk shaped
- small size and shape allows to pass thru narrow capillaries and good SA:V ratio
189
cell size of WBC as aspect of specialization
- 10micrometers when inactive 30micrometers when active
- extra volume: cytoplasm, rER, golgi apparatuses for protein synthesis to secrete antibodies
190
cell size of motor neurons as aspect of specialization
- 20 micrometers in diameter, long
- large size allows enough proteins to be made to maintain very long axon
191
cell size of striated muscle fibre as aspect of specialization
- 20-100micrometres diameter w/ lengths >100mm (10cm)
- allow fibre to exert greater force and contract by greater length
192
how do SA:V ratios put constraints on cell size
- rate in which substances used and waste products enter/leave cell depends on SA
- ratio too small: waste products will accumulate, substance will not enter as quick and required, may overheat as metabolism produces heat faster than it can be lost
193
how can gas exchange be maximized
- large SA:V ratio means distance b/w centre and exterior environment is smaller vv.
- often specialized gas-exchange surfaces are required to sufficient gas exchange (ex. alveoli)
194
define gas exchange
- all organisms absorb one gas and release another one into environment
- (ex. O2 and CO2 thru plasma membrane)
195
what are the properties of gas-exchange surfaces
- permeable - for easy diffusion
- large - for big SA:V ratio
- moist - so gases can dissolve
- thin - short distance for gas to diffuse
196
why are concentration gradients at exchange surfaces important in animals
- allows for diffusion which works to even out concentration gradients
- when even, gas exchange stops, so gradient must be maintained
197
how is a concentration gradient maintained in lungs/blood vessels
- continuous blood flow in capillaries of new low O2, high CO2 blood
- constant respiration in lungs allows for lung air to maintain high O2, low CO2
- diffusion of O2 and CO2 at fast rate bcus dense networks of blood vessels
198
adaptations of human lungs for gas exchange
- cells in walls secrete pulmonary surfactant (like phospholipid structure) to reduce surface tension and prevents collapse of lung
- many capillaries and alveoli making for a lot of SA
- many branched bronchioles for SA
199
how does breathing work
- gas will always move from areas of high pressure to lower pressure
- inhalation: pressure in thorax drops below atmospheric pressure, gas drawn in
- exhalation: pressure in thorax rises above atmospheric pressure, gas expelled
200
what does the diaphragm do during inspiration vs expiration?
i: contracts, moves downwards to push abdomen wall out
e: relaxes, pushed upwards into more domed shape
201
what does the abdomen wall muscles do during inspiration vs expiration?
i: relax allowing pressure from diaphragm to push it outwards
e: contract to push abdominal organs and diaphragm up (forced expiration)
202
what do external intercostal muscles do during inspiration vs expiration?
i: contract, pulls ribcage up and out
e: relax, pulled into elongated state
203
what do internal intercostal muscles do during inspiration vs expiration?
i: relax, pulled into elongated state
e: contract, pulls ribcage up and out
204
what is used to measure lung volumes
spirometers
205
waxy cuticle as adaptation for gas exchange and water conservation in leaves
- secreted by epidermis cells
- waterproof layer, particularly think in upper leaves of plants in dry habitats (prevents water loss)
206
epidermis as adaptation for gas exchange in leaves
- acts as barrier between external environment and internal environment
207
spongy mesophyll as adaptation for gas exchange and water conservation in leaves
- connected to outside air via stomata
- large SA for gas exchange, spaces b/w
- walls permanently moist (from xylem) to allow CO2 to dissolve and enter cells
208
guard cells (stoma) as adaptation for gas exchange and water conservation in leaves
- two guard cells cover pore called stoma
- close stoma at night when no photosynthesis and gas exchange and when plant is dehydrated
209
factors affecting transpiration rates
- temperature: at higher temps, more energy available for evaporation and can hold more water vapour
- humidity: higher humidity of air, smaller concentration gradient in and out of plant, lower rate of diffusion
210
how is transpiration a result of gas exchange
- walls in spongy mesophyll are moist, when stomata opens for gas exchange, water vapour will diffuse out
211
how to calculate stomatal density
mean # of stomata/area of field of view
212
what are the adaptations of capillaries for exchange of materials
- branching of capillary network, narrow diameters (10micromemters), thin walls (one layer of endothelium cells) to maximize SA
- some have fenestrations (large pores) that allow larger volumes of materials to be exchanged, speeding up exchange b/w blood and tissues
213
differences in structure of veins and arteries
a: thicker wall, narrower lumen, circular, corrugated inner surface, visible fibres in wall
v: thinner wall, wider lumen, circular or flattened, not corrugated inner surface, few visible fibres in wall
214
adaptation of arteries to successfully transport blood away from heart
- narrow lumens: help maintain high BP and high velocities of blood flow
- walls are thick/contain elastic fibres: helps arteries withstand BP w/o bulging and allows size of lumen to return to normal after pulse of blood
- smooth muscles to control rate of blood flow to tissues (vasoconstriction and vasodilation)
215
how to pulse oximeters measure pulse
- red LED and infrared light goes thru tissues of finger
- detection of variation in amount of blood in tissues each heartbeat
216
adaptation of veins to successfully transport blood towards heart
- contain pocket valves - if blood flows backwards, gets caught in flaps + closes it
- assisted by gravity and pressures exerted by adjacent tissues (skeletal muscles) -> contraction makes muscles shorter and wider, squeezing on veins like pump
217
what causes occlusion of coronary arteries
- fatty deposits (plaque) which build up on wall of artery and contain variety of lipids
- can be (impregnated?) w calcium salts which harden artery and makes inner surface rough, maybe triggering formation of blood clot
218
what are the consequences of occlusions in coronary arteries
- blood clots can form and block flow of blood to heart muscles (heart attack)
- tissue death in heart (myocardial infarction)
- all these conditions associated w coronary heart disease (CHD)
219
transport of water from roots to leaves during transpiration as explained by cohesion-tension theory
1. transpiration (evaporation), occurs in stomata and created tension (negative pressure)
2. tension from transpiration “pulls” water up xylem upwards
3. cohesion, water moves like a “chain” as water is pulled out of stomata
4. adhesion, water creates hydrogen bonds to xylem walls, allowing it to “crawl” up
220
adaptation of xylem vessel for water transport
- formed by column of cells end to end where material b/w adjacent cells is removed and contents break down to make one continuous tube
- lignified wall thickening which help xylem withstand tension
- pits to allow entry and exit of water
221
define habitat, what can it mean
- a place where the organism lives
- can be geographical location or the physical conditions or the type of ecosystem
222
adaptations of lyme grass to sand dunes
- adaptation to abiotic environment
- thick waxy cuticle on leaves to reduce transpiration
- stomata in furrows where humid air can remain even in windy conditions
- leaves roll up during droughts, humid chamber, reduces SA
- rhizomes (underground stems) that extend deep into dune for water
- accumulation of carbs in root and leaf cells, increasing osmotic potential (more H2O)
223
adaptations of mangrove trees to mangrove swamps
- secretion of excess salt from salt glands
- root epidermis coated in suberin (cork) reducing permeability to salt
- large buoyant seeds that can be carried by ocean
- cable roots grow close to soil surface (more O2)
- some roots grow vertical into air to absorb O2
224
abiotic variables that affect species distribution for plants and animals
plants: temp, water, light, soil pH+salinity
animals: water, temp
225
what is the range of tolerance of a species
the range of environmental conditions within which an organism has adapted to survive, grow, and reproduce
226
how is range of tolerance a limiting factor
- plants/animals can only grow/survive in environments that they are adapted to
227
what conditions are required for hard coral formation
- depth <50m so light penetrates (for coral and zooxanthellae)
- pH above 7.8 for deposition of calcium carbonate in skeleton
- salinity b/w 32-42 ppt of dissolved ions to maintain osmotic factors
- clear water for light
- temp 23-29C
228
what two abiotic factors determine biome of ecosystem
- temp
- rainfall
- for any given temp and rainfall pattern, one natural ecosystem is likely to develop
229
define biome
a group of ecosystems with similar communities due to similar abiotic conditions and convergent evolution
230
climate conditions of a tropical rainforest biome
- high temp
- high precipitation
- high light intensity
- minimal seasonal variation
231
climate conditions of a temperate forest biome
- medium temp
- high/medium precipitation
- medium light intensity
- warm summers, colder winters
232
climate conditions of a taiga (boreal forest) biome
- low temp
- high/medium precipitation
- medium/low light intensity
- short summers, long cold winters
233
climate conditions of a hot desert biome
- high/medium temp
- medium precipitation
- high/medium light intensity
- has dry season or cold season
234
climate conditions of a tundra biome
- very low temp
- medium/low precipitation
- low light intensity
- very short summer, very cold winter
235
how are saguaro (cactus) adapted to hot desert climates
- wide-spreading root system for water
- deep roots ~1m down
- fat stems w storage tissue to conserve water after rare rainfall
- pleated stems allow shrinkage in droughts, swelling after rains
- thick waxy cuticle on stem to reduce transpiration
- stomata opens at night, closes during day
236
how are fennec foxes adapted to hot desert climates
- nocturnal, avoid high temps of day
- underground den to stay cool
- long thick hair for insulation on cool nights and hot days
- pale fur to not absorb sunlight
- can ventilate at 600breaths/min for heat loss
237
how are the meranti trees adapted to the tropical rainforest climates
- can grow very high, higher than other trees to avoid comp for light
- hard dense wood trunk w extra support at base to provide support against wind
- smooth trunk+oval leaves to shed rainwater rapidly
- enzymes of photosynthesis adapted to temps as high as 35C
238
how are spider monkeys adapted to the tropical rainforest climates
- long arms+legs+flexible shoulders for climbing and swinging
- large hooklike hands and feet to grasp branches
- long tail acts like 5th hand
- developed larynx for wide range of sounds to communicate in dense rainforest
- breeds at any time of year bcus resources always abundant
239
define ecological niche
- central hypothesis in biology that states that every species in an ecosystem fulfils a unique role
240
what biotic and abiotic factors affect ecological niches
- zones of tolerance (where it lives in ecosystem)
- adaptations to obtain food efficiently (better than competitors)
241
obligate aerobes vs. obligate anaerobes vs facultative anaerobes
obligate aerobes: require continuous O2 supply, only live in oxic environments (ex. all animals and plants)
obligate anaerobes: inhibited or killed by oxygen, only live in anoxic environments (ex. clostridium tetani)
facultative anaerobes: use O2 if available (ex. e coli, yeast)
242
what organisms use photosynthesis as a mode of nutrition
- plants, eukaryotic algae, several groups of bacteria
- occurs in two of three domains of life, in eukaryotes and bacteria but not archaea
243
how do animals obtain nutrition
| method of consumption
- use holozoic nutrition meaning that pieces of food swallowed before being fully digested inside body
244
stages of holozoic nutrition
1. ingestion - taking food in
2. digestion - breaking large food molecules into smaller ones
3. absorption - transport of digested food into blood and tissues of body
4. assimilation - using digested foods to synthesize proteins, making them part of body
5. egestion - getting rid of undigested material from end of gut
245
define mixotrophic nutrition, what organisms use this?
- organism that uses methods of autotrophs and heterotrophs to obtain nutrition
- some unicellular eukaryotes (protists) use (ex. euglena)
246
obligate vs. facultative mixotrophs
obligate: must use both autotrophic and heterotrophic modes of nutrition
facultative: can be entirely autotrophic or heterotrophic or use both
247
define saprotrophic nutrition, what organisms use this?
- obtain nutrition by secreting digestive enzymes into dead organic matter and digesting it externally
- used by many bacteria and fungi (aka decomposers)
248
what are the 3 domain of life
archaea, bacteria, eukaryotes
249
3 types of nutrition in archaea
phototrophic: absorption of light by pigments other than chlorophyll
chemotrophic: oxidation of inorganic chemicals
heterotrophic: oxidation of carbon compounds obtained from other organisms
250
how can dentition be used to determine diet in the family of Hominidae
- hominidae: includes humans, orangutans, gorillas, chimps
- teeth of herbivores are large and flat to grind plant tissue
- omnivores have mix of sharp teeth for meats and flat molars for plants
251
adaptations of insect herbivores for feeding on plants
- beetles/others insects have jaw-like mouth parts for biting/chewing leaf
- aphids/other insects have tubular mouth parts for piercing leaves/stem to reach phloem and feed on sap
252
adaptations of plants to resist the feeding of herbivores
- tough, sharp spines
- stingers to cause pain
- synthesize substances that are toxic to herbivores
253
some physical adaptations of vampire bats as predators
- unique dentition to catch and kill prey
- razor sharp teeth to pierce prey and feed on blood
254
some physical adaptations of buff-tip moths as preys
- camouflage as they resemble birch twigs, so predators cannot spot them
255
some chemical adaptations of black mambas as predators
- produce venom containing neurotoxins
- paralyzes prey when injected via fangs so it can be eaten without resistance
256
some chemical adaptations of caterpillars of cinnabar moth as prey
- plant it feeds on contains toxic alkaloids, accumulates
- black and yellow stripes are warnings to predators that they have toxins
257
some behavioural adaptations of grizzly bears as predators
- ambush strategies to catch migrating salmon by trial and error/copying others
258
some behavioural adaptations of blue striped snappers as prey
- swim in tight group with sudden changes of direction "schooling"
- threats more likely to be detected and difficult for predator to catch
259
rank behavioural/chemical/physical adaptations from fastest changing to slowest
- behavioural
- physical: requires genetic change
- chemical: requires change in enzymes
260
adaptations of trees for harvesting light
- dominant leading shoot that grows rapidly to reach great height where they are unshaded by others
261
adaptations of lianas for harvesting light
- climb through other trees, using as support to reach light
262
adaptations of epiphytes for harvesting light
- grow on trunks and branches of trees, receive higher light than if growing on forest floor
263
adaptations of strangler epiphytes for harvesting light
- climb up trees, encircle them and outgrows their branches shading leaves of tree, killing tree
264
adaptations of shade-tolerant shrubs for harvesting light
- live off the light that reaches forest floor
265
fundamental niche vs. realized niche
fundamental: the potential of a species based on adaptations and
tolerance limits
realized: actual extent of a species niche when in competition with
other species.
266
define competitive exclusion
- when two fundamental niches of different species overlap, one species will exclude the other from that part of it's range thru competitions
267
why do ecological niches need to be unique
- if 2 species have overlapping fundamental niches and one outcompetes the other in all areas, they will be excluded from ecosystem
- w/o realized niche, cannot exist in ecosystem
- every species must have different realized niche to survive
268
what are enzymes, why are they important
- biological catalysts that increases the rate of a chemical reaction
- processes would be too slow to sustain life w/o enzymes
269
define metabolism
the complex network of interdependent and interacting
chemical reactions occurring in living organisms
270
specificity of enzymes in metabolism
- specificity means each enzyme catalyzes one specific reaction or group
- organisms must make large numbers of enzymes
271
benefits of enzymes role in metabolism
- enzymes can be made at different speeds to change rate of rxn
- enzyme production an be temp stopped in rxn not required
- gives organisms some control over metabolism
272
what are anabolic reactions
- build up smaller molecules into larger ones, formation of macromolecules from monomers by a condensation rxn
- rxn requires energy
273
examples of anabolic reaction
- photosynthesis
- protein synthesis
- DNA synthesis
- synthesis of complex carbs (starch, cellulose, glycogen)
274
what are catabolic reactions
- breaking down or larger molecules into smaller ones, hydrolysis of macromolecules into monomers
- releases energy
275
examples of catabolic reactions
- digestion of food
- oxidation of glucose/lipids in cell respiration
- digestion of complex carbon compounds
276
structure of enzymes
- globular proteins with precise 3D structure and chemical properties
277
how do active site of enzymes work for catalysis
- where substrate binds to enzyme
- shape and chemical properties of active site of substrate must match
- ensures specific substrate binds
278
structure of the active site
- vary in size depending on substrate
- just a few amino acids at active site needed to change substrates into products
- AAs brought together by folding of polypeptides so 3D structure of enzyme is crucial
279
what occurs during interaction bw substrate and active site
- substrate movement random until chemical properties of enzyme attract it
- both enzyme and substrate change shape to allow for binding
- substrate can bind
- changes in substrate molecules allow easier break/formation of bonds, converting into products
- product detach, enzyme reused
280
define induced fit binding
change of bond angles and bond lengths in substrate and active site in order to bind
281
how does molecular motion affect substrate-active site collision
- substrate must get very close to enzyme to bind, can be achieve thru molecular motion
- more movement means higher rate of substrate-active site collision
- sometimes large substrates or enzymes in membranes cannot move, other enzyme/substrate must move
282
define enzyme-substrate specificity
- shape/chemical properties of an enzyme's active site allows substrate to bind but not other substances
283
how does temp affect rate of enzyme activity
- at higher temps, enzymes and substrates move quickly higher chance to bind
- bonds in enzyme vibrate more, can break, changes structure, cannot bind to substrate (denatured)
- if temp gets too high, all enzymes will denature, no activity
284
how does pH affect rate of enzyme activity
- if pH changes from optimum, ionic bonds bw amino acids are altered
- changes structure of enzyme, active site cannot bind to substrates
- beyond certain pH, denaturation will be irreversible
285
how does substrate concentration affect rate of enzyme activity
- if higher substrate conc, substrate-active site collision will occur more, inc rate of rxn
- plateaus at optimum point as all enzymes are taken by substrates, rxn cannot occur any quicker
286
what is activation energy
- the energy required for substrates to pass thru transition state before conversion to products (breaks bonds in substrates)
287
what are the effect of enzymes on activation energy, why?
- bonds in substrate are weaker when binded to active site, less activation energy needed to break them
- release of energy is unchanged as new bonds are made, but activation energy smaller
- rate of reaction increases
288
what does ATP stand for, what kind of molecule is it
adenosine triphosphate
- a nucleotide
289
structure of ATP
- 3 phosphate groups
- ribose (5 carbon sugar)
- adenine (nitrogen-containing base)
290
what properties of ATP make it suitable as energy currency in cells
- third phosphate group can be easily removed and added by hydrolysis and condensation rxns
- hydrolysis releases small amount of energy enough for processes in cell
291
hydrolysis/condensation of ATP equation
ATP+H2O -->ADP + phosphate + energy
- or other way around for condensation
292
what life processes in cells need ATP
- synthesizing of macromolecules
- active transport
- movements
293
how is ATP used to synthesize macromolecules
- endothermic process, needs ATP
- one or more ATP molecules used to link a monomer to polymer
- ex. synthesis of DNA during replication, RNA in transcription
294
how is ATP used for active transport
- used to cause reversible changes in conformation of pump protein (more stable--> less stable shape)
295
how is ATP used for movements in cell during mitosis
- ATP is needed to move chromosomes to poles and pinch cytoplasm during mitosis
296
what does conversion from ADP to ATP require
- requires energy that can come from cell respiration, photosynthesis, chemosynthesis
297
how does cell respiration produce ATP
- uses energy released from oxidization of carbon compounds
- wide range of carbon compounds can be used, glucose and fatty acids are main ones
298
relationship between gas exchange and cell respiration
- cell respiration cannot continue w/o gas exchange cus of excess of CO2, lack of O2
- gas exchange cannot continue w/o cell respiration cus there will be no concentration gradient
- interdependent
299
formula of aerobic respiration in humans/animals/plants
glucose + oxygen --> CO2 + H2O
300
formula of anaerobic respiration in humans/animals/plants
glucose --> lactate
301
formula of anaerobic respiration in yeast (fermentation)
glucose --> ethanol + CO2
302
oxygen in aerobic vs. anaerobic cell respiration
aer: oxygen used
anaer: oxygen not used
303
yield in aerobic vs. anaerobic cell respiration
aer: higher yield (30 ATP per glucose)
anaer: lower yield (2 ATP per glucose)
304
waste products in aerobic vs. anaerobic cell respiration
aer: CO2 and water
anaer: CO2 + lactate or ethanol, NO water
305
possible substrates in aerobic vs. anaerobic cell respiration
aer: carbs like glucose, lipids (fats, oils)
anaer: only carbs
306
location of occurrence of aerobic vs. anaerobic cell respiration
aer: initial rxns in cytoplasm, more in mitochondria
anaer: all rxns in cytoplasm, none in mitochondria
307
what is photosynthesis
- transformation of light energy into carbon compounds (chemical energy)
308
equation for photosynthesis
CO2 + water+(sunlight) --> glucose + oxygen
309
how is carbon converted into glucose in photosynthesis
- hydrogen needed, obtained from photolysis (splitting molecules of water)
- rxn only occurs when light is available
- splitting leaves oxygen as the waste product
310
why do plants appear green
- chlorophyll (main pigment in photosynthesis) as red and blue wavelengths can excite it but green cannot <- reflected
311
absorption spectrum vs action spectrum
absorption: graph showing % of light absorbed at each wavelength by pigment/group of pigments
action: graph showing rate of photosynthesis at each wavelength of light
312
correlation b/w absorption spectrum and action spectrum
photosynthesis occurs at a higher rate when a greater percent of light is being absorbed
313
what does FACE stand for, what is it
- “free air carbon dioxide enrichment experiments”
- tests if pollution could increase plant growth bcus when temp + light intensity are at optimal levels, increase in CO2 leads to a higher rate of photosynthesis
- circle towers that release CO2 and air are built into semi natural vegetation to increase CO2 conc.
314
structure of neurons
- cytoplasm+nucleus make up cell body
- dendrites are many short branched nerve fibres
- axons are one very long nerve fibre
315
why is the resting potential in neurons negative
- sodium-potassium pumps use ATP to pump 3 Na molecules out and 2 K molecules in
- generates charge imbalance and concentration gradients
- pumped ions leak back thru membrane by diffusion, membrane is 50x more permeable to K+, so leakage is faster, increasing overall charge imbalance
- neg charged proteins in nerve fibre
316
define depolarization and repolarization
depolarization: change in membrane potential from negative to positive
repolarization: change back from positive to negative membrane potential
317
what are depolarization and repolarization caused by
- movement of positively charged ions across the membrane
318
what occurs during depolarization
- Na channels open, Na diffuses into neuron
- when threshold potential reached, depolarization reaches critical level where Na channels open, Na rushes in, full depolarization occurs
- reverses charge imbalance across membrane from -70mV to +30mV
319
what occurs during repolarization
- K channels open, K diffuses into neuron so that the inside of neuron is neg again
- k channels remain open until membrane potential is -70mV
320
how does the diameter of the axon affect the speed of an impulse
- humans: diameter of one nerve is ~1um and impulses travel ~1m/s
- some animals have larger diameters allowing for faster impulses bcus less resistance
- larger axons used to coordinate rapid rxns for survival
- ex. giant axons in squids have: d=500um, impulses are up to 25m/s
321
what is myelination and how does it affect the speed of a nerve impulse
- coating of fatty substance (myelin) forming myelin sheath, acts as insulator
- coating consists of Schwann cells with gaps called nodes of ranvier
- allows nerve impulses to jump from node of raniver to node of ranvier <- faster, up to 100m/s
322
what are synapses, 3 main types
- a junction b/w two cells in the nervous system
- b/w sensory receptors and neurons, b/w neurons in brain and spinal cord, neurons and muscle fibres/glands
323
movement of signals in a synapse
- can only pass in one direction
- presynaptic neurons brings signal to synapse in AP
- postsynaptic neurons carries signa; away from synapse in AP
324
what occurs in the presynaptic neuron during synaptic transmission
- AP propagated along presynaptic nerve
- depolarization of presynaptic membrane causes Ca to diffuse in thru membrane channels
- influx in Ca-> vesicles containing NTs fuse w/ presynaptic membrane
- NT release into synaptic cleft via exocytosis
325
what occurs in the postsynaptic neuron during synaptic transmission
- NTs diffuse across synapse
- NTs bind to receptors in postsynaptic membrane, ion channels open
- Ions diffuse into postsynaptic neuron -> membrane potential less neg
- if excitatory postsynaptic potential strong enough, triggers AP
- NTs rapidly broken down and removed from synapse
326
how is acetylocholine used when signalling b/w neurons
- binds to receptor in postsynaptic membrane (open Na channel)
- Na diffuses in -> excitatory postsynaptic potential
- ACh binds to receptor for short time, generates one AP
- acetylcholinesterase in synapse breaks down ACh back into choline and acetyl group
- choline reabsorbed and turned back into ACh
327
what is system integration, what is its importance
- coordination b/w different systems to perform various functions of life
- necessary for organism to function
328
what is the hierarchy of subsystems integrated in a multicellular organism
cells, tissues, organs, organ systems, and organisms
329
what are tissues, what are the structures
- group of cells adapted to specific function, larger organisms have more cells in tissue rather than larger cells
- cells in tissue stick to each other
- cells within a tissue can communicate with each other
330
what are organs, what are the structures
- a group of tissues that work together to carry out a specific function of life
- tissues in organ are interdependent
331
what are emergent properties
properties that are not evident in the individual components of a system, but show up when combining those components
332
type of signal in hormone vs. nervous signalling
chemical vs. electrical (passing of cations)
333
transmission of signal in hormone vs. nervous signalling
in bloodstream. vs in neurons
334
destination of signal in hormone vs. nervous signalling
widespread throughout body but only certain cells respond vs. highly focused to one specific effector cells
335
effectors in hormone vs. nervous signalling
target cells in any type of tissue vs. muscles or glands
336
speed of response in hormone vs. nervous signalling
slower vs. very rapid
337
duration of response in hormone vs. nervous signalling
long (until hormone broken down) vs. short (unless nerve impulses sent repeatedly)
338
types of response in hormonal signalling
growth, development (puberty), reproduction, metabolic rate, solute conc. in blood, mood
339
types of response in nervous signalling
striated muscle, smooth muscle, cardiac muscle, exocrine glands, endocrine glands
340
how are materials transported b/w organs
- thru circulatory system as blood circulates thru all tissues
341
how does the brain help integrate organs
- receives info from many inputs, processes it, stores some, and sends to parts of body
- stored info can be short or long term, crucial for learning
342
unconscious vs. conscious processes
unconscious: performed when awake or asleep, involuntary and coordinated by brain+ spinal cord (ex. secretion of glands)
conscious: performed when awake, voluntary and only coordinated by cerebral hemispheres of brain (ex. movement of striated muscle)
343
how does the spinal cord help integrate organs
- only coordinates unconscious processes
- in some cases quicker than if signals were conveyed to and from the brain
344
white matter vs. grey matter in spinal cord
white: contains myelinated axons + other nerve fibres which convey signals from sensory receptors->brain->organs
grey: contains cell body of motor neurons and interneurons w/ many synapses which processes info and decision making in spinal cord
345
how do sensory neurons convey messages to CNS
- external and internal stimuli perceived by receptor cells
- signals from receptor cells conveyed to CNS using sensory neurons
- brain receives signals from organs in head, spine receives from body
346
how are messages conveyed from CNS to target cells (using muscle contraction as example)
- primary motor cortex sends signal via motor neuron to striated muscle
- signals in motor neurons are nerve impulses
- when nerve impulse reaches end of axon, stimulates muscle fibres to contract
347
what is a nerve, structure?
- a bundle of nerve fibres enclosed in a protective sheath that can vary in size
- most contain nerve fibres of sensory and motor neurons
- all organ served by >1 nerve
348
outline the process of a pain reflex arc
- receptor cells sense a stimulus
- sensory neurons receive signals from receptor cells or own nerve endings, long axons carry nerve impulse to interneurons in CNS
- interneurons receive signal, make decisions and decide response
- motor neurons receive signal from interneurons, if threshold potential reached, impulse passed along axon to effector
- effector carries out response to stimulus
349
what is the role of the cerebellum
- control skeletal muscle and balance
- does NOT make decisions about what muscles to contract but will fine-tune timing of contraction
350
what are circadian rhythms, what are they dependent on
- the 24 hour sleep wake pattern (rhythms in behaviour)
- depend on superchiasmatic nuclei or SCN cells in hypothalamus
351
how does melatonin secretion support the circadian rhythms
- secretion increases in evening for drowsiness and drops to low level at dawn for waking to control sleep-wake cycle
- contributes to nighttime drop in temp, and less urine production
352
what is melatonin, where is it secreted
- hormone that plays role in sleep
- secreted from pineal gland
353
what is epinephrine, where is it secreted
- aka adrenaline, hormone that prepares body for vigorous physical activity
- secreted by adrenal glands
354
how does epinephrine (adrenaline) prepare body for physical activity
- muscle cells break glycogen to glucose to be used in aerobic or anaerobic respiration
- liver cells break glycogen to glucose releasing it into bloodstream
- bronchi and bronchioles dilate, easier ventilation
- ventilation rate increases, sinoatrial node speeds up HR
- arterioles to liver and muscles widen while ones to gut, kidney etc. are narrower
355
why is epinephrine useful for preparing for physical activity
- increases supply of O2 and glucose to muscles maximizing production of ATP
356
role of the hypothalamus
to link the nervous system to the endocrine system via pituitary gland
- directs secretion in pituitary gland
357
parts of the pituitary gland
- anterior and posterior lobe
- operate in different ways however both secrete hormones into capillaries under direction of nuclei in hypothalamus
358
what is the sinoatrial node, how does it work
- special group of cardiac muscle cells in wall of right atrium
- accts as pacemaker for heartbeat
- signal from medulla: sympathetic nerve causes inc in HR, vagus nerve causes dec. in HR
359
what do baroreceptors do, wherea re they found
monitor BP, found in carotid arteries, and lungs
360
what do chemoreceptors do, where are they found
monitor blood pH, O2 and CO2 concentration
- medulla of brain, carotid arteries
361
how is heart rate controlled
- cardiovascular centre (in medulla) receives sensory input from baroreceptors and chemoreceptors
- low BP = inc in HR vv.
- low O2 or pH = inc in HR vv.
- negative feedback loop
362
how is ventilation rate controlled
- chemoreceptors monitor blood pH in aorta/carotid arteries
- low pH (high CO2) triggers inc in VR which will dec CO2 conc in alveoli
- allows for more diffusion of CO2 from capillaries to lungs, increasing pH
363
how does the ENS play a role in peristalsis in the digestive system
| examples
- muscles can exert continuous moderate force for short periods
- circular muscles: contract behind food, pushing it forward
- longitudinal muscles: contracts along food
- esophagus: peristalsis occurs only downwards in one continuous wave
364
what is the ENS
- enteric nervous system
- part of the PNS
- extensive and complex, basically allows control of stomach and intestine w/o inputs from CNS
365
examples of voluntary movements of digestive system controlled by CNS
- initiation of swallowing as tongue is composed of striated muscles
- defecation
366
what is a disease, what is it caused by
- particular kind of illness with characteristic symptoms
- main types of causes are genetic, environmental, infection w/ a pathogen
367
what are pathogens, how do they work
- organisms that cause disease
- passed from one infected organism to another, enter organism and multiply
368
skin as primary defence against pathogens
- outermost layer, provides physical barrier
- tough layer of dead cells containing a lot of keratin (protein)
- sebaceous glands release sebum to maintain low pH on skin, inhibits bacterial/fungal growth
369
mucous membrane as primary defence against pathogens
- thin, softer skin that secretes mucous (sticky solution of glycoproteins)
- traps pathogens and harmful particles (swallowed or expelled)
- antiseptic properties
370
outline how cuts on skin are sealed by blood clotting
1. platelets cluster at site, release clotting factors, triggers clotting process
2. clotting factors produce enzyme thrombin
3. thrombin rapidly converts fibrinogen in blood to insoluble fibrin
4. fibrin forms mesh in cuts, traps more platelets and blood cells to form clot
371
innate immune system vs. adaptive immune system
innate: responds to broad categories of pathogen, doesn't change during life of organism (ex. phagocytes)
adaptive: responds a certain way to certain pathogens, builds memory of pathogens that have been encountered, immune system becomes more effective (ex. antibody-producing lymphocytes)
372
how do phagocytes control infections
- squeeze thru pores in capillaries to move to site of infection where they recognize pathogens
- engulf thru endocytosis, digest using enzymes from lysosomes
- forms pus
373
what are lymphocytes, where are they found
- cells in adaptive immune system that work together to rpoduce antibodies
- circulates in blood and lymph nodes
374
how do lymphocytes work to fight infection
- we have large amounts of B-lymphocytes that each make specific antibody
- little bit of each lymphocytes for each antibody
- when pathogen infects body, needed lymphocytes multiply and create large volumes
375
antibody structure
hypervariable region: recognizes+binds to specific molecules on pathogen
constant region: helps body fight pathogen by making it more recognizable to phagocytes to engulf them
376
structure of antigens
- glycoproteins or other proteins or some large polysaccharides
- usually located on surface of pathogen
377
what happens when someone is transfused the wrong blood type
- antibodies are produced to respond to foreign molecules (ex. transplanted organs or blood)
- antigens on wrong blood type trigger antibody production
378
how do we fight off pathogens (general process)
1. macrophage ingests pathogen and displays its antigens
2. helper T-cell specific to antigen activated by macrophage
3. B-cell specific to antigen activated by proteins from helper T-cell
4. B-cell divides repeatedly to produce antibody-secreting plasma cells
5. antibodies produced by clones of plasma cell are specific to antigen of pathogen, helps destroy it
379
what does activation of a B-cell require
- direct interaction with specific antigen and contact w helper T-cell that has been activated by same antigen
380
what occurs after B-cells have been activated
- don't immediately start producing antibody, too few of them and may not have needed organelles yet
- instead, divide repeatedly thru mitosis to form many clones
- golgi apparatus, ER develops allowing for rapid production of antibodies by protein synthesis
- B-cells that have grown+differentiated are plasma B-cells
381
how are helper T-lymphocytes/cells activated
- have antibody-like receptor in plasma membrane to help it bind to macrophage
- helper T-cells are specific to 1 antigen and bind w/ + activated by macrophage
382
what do activated helper T-cells do
- bind to B-lymphocytes
- B-cells are specific to one antigen and are activated by helper T-cells via binding + signalling protein
383
immunity from retaining memory cells
- most B-cells produced by mitosis become active B-cells but some become memory B-cells
- remain inactive until same pathogen infects body again -> activates+ responds rapidly
384
how is HIV transmitted
- thru blood and body fluid
- sex w/o condom where abrasions to mucous membrane can cause minor bleeding
- sharing of hypodermic needles
- transfusion of infected blood
- childbirth and breastfeeding
385
how does HIV work in the body
- invades and destroys helper T-cells leading to progressive loss of capacity to produce antibodies
- retrovirus w genes made of RNA
- uses reverse transcriptase to produce DNA copies of its genes in host
386
when does HIV become AIDS
- when conditions cause by HIV are combined in a person, its called AIDS
387
how can HIV be combatted
- using antiretroviral drugs that inhibit reverse transcriptase
388
what are antibiotics
- chemicals that inhibit growth of microorganisms
- block processes that occur in prokaryotes (bacteria) but not eukaryotes
389
when are antibiotics ineffective
- control bacterial infections but not viruses
- using it on viral infections will not work and will contributes to antibiotic resistance
390
antibiotic resistance
- since antibiotic discovery, more bacteria have become resistant
- more resistance = more antibiotics needed
- when antibiotic has multiple resistances, can lead to widespread strains <- public health concern
391
ways to avoid antibiotic resistance
- only prescribe antibiotics for serious bacterial infections and for min period
- hospitals maintain high standards of hygiene to prevent cross infection
- farmers avoid use of antibiotics in animals feeds
- pharm companies must develop new classes of antibiotics
392
what is zoonoses
an infection disease that can transfer from other species to humans or vv
393
what can a vaccine contain
- weakened, live version of pathogen
- killed pathogen
- subunits (proteins) of pathogen that acts as antigens
- mRNA coding protein that acts as antigen then humans can translate to make protein
394
how do vaccines work
- al vaccines contain antigens that allow pathogen to be recognized
- antigens stimulate primary immune response by activation of T-cells, B-cells and plasma cells
- pathogen will be destroyed by secondary immune response if enters body in future
395
how is herd immunity achieved, how does it prevent epidemics
- when significant proportion of population have contracted disease or been vaccinated
- spread of pathogen is impeded as it mostly encounters immune people
396
what is a population
group of individual organisms of the same species living in a given area
397
characteristics of a population
- normally interbreeds with each other
- diff populations often separated by a geographical barrier
- can be distinguished thru reproductive isolation
398
importance of random sampling
- not possible to determine exact size of population, random sampling is a good estimate
- every individual in population should have equal chance of being included in sample to limit bias, more accurate rep
399
what can random quadrant sampling be used for, how does it work
- estimates population size of sessile organisms
- repeatedly places quadrant frame in random positions in habitat and recording # organisms present each time
- randomly generated #s to represent location of quadrant (x and y axis)
400
assumptions made for capture-mark-release-recapture method of estimating population size
- no migration occurs in or out of population
- no deaths or births
- marked individuals have same chance of being captured as unmarked ones
- marks remain visible
- marks don't threaten survival
401
what is carrying capacity
the maximum size of a population that an environment can support
402
what factor limits carrying capacity
- competition for limited resources
plants: water, light, soil nitrogen
animals: water, breeding space, food, dissolved O2
403
what factors impact size of populations
density-independent factors (having same effect however large population is)
density-dependent factors (having increasing effect as population increases)
- population usually remains relatively stable due to negative feedback loops
404
the 3 groups of density dependent factors
competition: for limited resources
predation: becomes more intense as prey becomes denser and vv
infectious disease/parasitism: increase with population density as pathogens spread easier
| more predation as denser prey? is it cus theres more predators?
405
why does exponential phase of population growth curve occur
- when species have spread to new area, found new ecological niche
- resources are abundant
- initially, no predators, pathogens, pasts that target population
406
what is a community
groups of populations living together in an area and interacting with each other
407
competition as an intraspecific relationship
- individuals of population are likely same species, need same resources
- unless abundant, competition will occur
- causes natural selection
- ex. for light in plants, for pollinators in flowering plants, for food+breeding sites in animals
408
cooperation as an intraspecific relationship
- occurs more in social animals rather than plants
- strong advantages as all individuals benefit
- ex. communal roosting+feeding+defense against predation+parental care in animals
409
herbivory as an interspecific relationship within communities
- primary consumer feeding on producers which may or may not be killed
- ex. bison grazing on grass
410
predation as an interspecific relationship within communities
- one consumer species kills and eats another consumer species
-ex. anteaters feeding on ants
411
interspecific competition as an interspecific relationship within communities
- two or more species using the same resource with amount taken by one reducing amount available to other
- ex. ivy climbing up oak tree and competing for light
412
mutualism as an interspecific relationship within communities
- two species living in close association, both benefiting
- ex. zooxanthellae living on cells of hard corals and exchanging materials
413
parasitism as an interspecific relationship within communities
- one species (parasite) living inside/outside of host and obtaining food from them, harms host benefits parasite
- ex. ticks living on deer, sucking their blood
414
pathogenicity as an interspecific relationship within communities
- one species (pathogen) living inside host and causing disease
- ex. tuberculosis bacterium infecting badgers
415
mutualism b/w fabaceae family (pea/bean plants) and rhizobium bacteria
f->r: growing root nodules where bacteria can live and be protected, maintains low O2 for rhizobium, supplies sugar
r->f: produces and supplies ammonium, prevents nitrogen deficiency giving plant advantage
416
mutualism b/w zooxanthellae and hard corals
z->c: supplied carbon compounds and oxygen
c->z: provides safe environment, gives algae reliable source of light as coral grows near water surface, supplied CO2
417
how do invasive species affect endemic species
- invasive species not effectively regulated by density-dependent factors
- if alien and endemic species have same ecological niche-> competition for resources, endemic species can result in smaller realized niche, population decline
418
how can one test for interspecific competition
- presence/absence of species can show association b/w them
- chi-squared test, field manipulation (see effects of having 1 species removed), lab experiments (species growth tgt vs. apart)
419
predator-prey relationships as density-dependent control of population size
- overall predator population should remain stable if prey population is stable
- could have cyclical oscillation patterns
- prey # inc = more food for predators = more predators=more predation=less prey= no food for predators = less predators = les predation = more prey
420
how are top-down and bottom-up control present in populations of communities
- top down: acts from higher trophic level to lower one
- bottom up: acts from lower trophic level to higher one
- communities can experience both types of control, but typically one is more dominant than the other
421
what is allelopathy
- allelopathy: when allopathic agents are secreted into soil by plants to kill/deter growth of neighbouring plants
- a secondary metabolite, like antibiotics
422
what is an ecosystem
composed of all organisms in an area and their abiotic environment
423
open vs closed ecosystem
open: resources and enter or exit, includes both chemical substances and energy
closed: energy can enter or exit, chemical resources cannot
424
what is the principle source of energy that sustains most ecosystems
- sunlight as producers can harvest energy by photosynthesis
- percentage of light harvested is different depending on ecosystem (ex. sahara desert has high intensity of light, but little producers to harvest)
425
flow of chemical energy thru food chains
- producers convert sunlight into chemical energy used to make carbs, lipids (other carbon compounds)
- consumers obtain energy from the carbon compounds in the organisms which they feed on
426
why are food chains part of webs
- many consumers feed on more that one species and fed upon by 1+ species
- represents complex relationships b/w organisms
427
how to decomposers (saprotrophs) obtain energy
- secrete digestive enzymes into dead matter (faeces, dead organisms) and digest externally
- absorbs products of digestion
428
why are decomposers so important
- helps to break complex insoluble carbon compounds into simple soluble ones, causing breakdown of solid structures
- prevents build up of dead organic matter
- recycles energy
429
what are autotrophs
organisms that use external energy sources to synthesize carbon compounds from simple inorganic substances
430
what do autotrophs need to make carbon compounds
- need carbon source and a simple inorganic substance (nitrate, phosphate etc)
- need energy source to perform anabolic rxns to build carbon compounds
431
external energy source of chemoautotrophs
- exothermic inorganic chemical rxns
- thru oxidation of a substrate, energy released which synthesizes carbon compounds
- used by many prokaryotes
432
how do heterotrophs obtain carbon compounds
- digest carbon compounds (proteins, AA) of other organisms so it can pass thru cell membrane
- use products of digestion to build the carbon compounds they need
- digestion can occur internally or externally
433
what is assimilation
- absorbing carbon compounds into cells and making them part of body
434
how is ATP produced in autotrophs and heterotrophs
- by cell respiration
- carbon compounds are oxidized to release energy which is used to phosphorylate ADP, producing ATP
435
what is there less energy available higher up in food chain
- large energy losses b/w trophic levels cause by incomplete consumption, incomplete digestion and cell respiration
436
incomplete consumption as a source of energy loss
- organisms are usually not entirely consumed by organisms in next trophic level
- energy is then passed to saprotrophs instead of next trophic level, leaving the food chain
437
incomplete digestion as a source of energy loss
- not all food ingested in digested and absorbed, egested in faeces and passes to saprotrophs and detritus feeders
- ex. some animals don't digest tough plant matter
438
cell respiration as a source of energy loss
- substrates are oxidized to CO2 and water which are waste products and cannot supply energy for next trophic level
- only unoxidized compounds can be passed
- smaller amount of energy to each trophic level as # of energy-containing substances dec.
439
heat loss as a source of energy loss
- energy transformations are never 100% efficient
- not all energy from oxidation of carbon compounds in cell respiration is transferred into ATP, some converted to heat
- heat released in production of ATP in cell respiration, and when it's used
440
why are number of trophic levels in food chain restricted
- energy losses bw levels
- animals in higher trophic levels don't need to eat more food as prey contains large energy per unit mass, just not much prey available (less biomass)
441
how does biomass accumulate
- when living organisms grow and reproduction as it inc. # of growing organisms
- biomes vary in capacity to accumulate biomass depending on rates of photosynthesis
442
gross primary production vs. net primary production
GPP: total biomass of carbon compounds made by plants in photosynthesis
NPP: GPP minus biomass lost due to respiration of plant (aka amount of biomass available to consumers)
443
secondary production vs. primary production
- sp: accumulation of carbon compounds in biomass of animals and heterotrophs
- pp: accumulation of carbon compounds in biomass of autotrophs
- will always be lower per unit area than primary production as loss of biomass in every trophic level
- declines w each successive trophic level
444
pool vs. flux in the carbon cycle
pool: reserve of an organic or inorganic element
flux: transfer of an element from one pool to another
445
what are the 3 main types of carbon flux due to living organisms in ecosystems
- photosynthesis
- feeding
- respiration
446
when is an ecosystem a carbon sink or source
- if photosynthesis exceeds respiration, ecosystem acts as carbon sink
- if respiration exceeds photosynthesis, ecosystem acts as carbon source
447
what is sequestration
when carbon is stored in the natural environment and removed from the carbon cycle
448
what is natural gas and oil
- formed 550M years ago
- deep burial of partially decomposed organic matter where high temps caused chem changes and oil + gas production
449
what is coal
- formed 325-250M years ago
- wood+ other plant matter in swamps buried under other sediments
450
what is peat
- formed 10,000 years ago
- incomplete decomposition of dead plant matter cus acidic and anaerobic conditions
451
how is CO2 released in combustion of biomass, peat, coal and oil
- carbon can be sequestered in them for indefinite amounts of time
- can be combusted naturally (volcanic activity or lightning strikes)
- human activity has increased rate (burning)
452
what causes the annual fluctuations of keeling curves
- CO2 inc. b/w october and may then falls from may to october
- due to global imbalances in rates of CO2 fixation by photosynthesis and cell respiration (ex. photosynthesis higher in northern hemisphere during summer, less CO2)
453
what causes the long-term trend in keeling curves
- CO2 conc for one year shows that inc in not completely reversed by dec so overall inc in CO2
- from 1959 onwards in keeling curve, steady inc in conc of CO2 in atmosphere
- largly due to burning fossil fuels and anthropogenic factors (deforestation)
454
how do autotrophs and heterotrophs depend on each other for O2 and CO2
- CO2 conc. limit rate of photosynthesis so autotrophs rely on heterotrophs to supply
- oxygen only exists in atmosphere because it's produced by photosynthesis so respiring heterotrophs depend on photosynthesizing autotrophs
- huge fluxes, shows major interaction bw auto and hetero
455
recycling of chemical elements in ecosystem
- limited quantities of each chemical element on earth, can be recycled endlessly hence why we havent run out
- key role: decomposers break carbon compounds containing chemical elements to be reused
456
what is DNA replication, what is it needed for
- production of new strands of DNA with base sequences identical to existing strands
- need: reproduction and growth+tissue replacement in multicellular organisms
457
what is the semi-conservative nature of DNA replication
- 2 strands of double helix separate, both og strands used as templates
- new strands formed on og strands
- new DNA molecule has one og strand and one new strand
458
how does complementary base paring allow high degree of accuracy in copying base sequences
- only nucleotide carrying base complementary to template strand can be hydrogen bonded to each other
- ensures two DNA molecules from replication are identical to parent
- makes checking for mispairing and fixing it possible in DNA
459
role of helicase in DNA replication
- ring-shaped protein
- separates two strands of DNA by unwinding and breaking hydrogen bonds b/w bases
460
role of DNA polymerase in DNA replication
- moves along template strands adding one nucleotide to assemble new strands of DNA
- brings nucleotide to position where hydrogen bonds can form
461
what does PCR need
thermal cycler, primers, free DNA nucleotides, taq DNA polymerase
462
steps of PCR
1. denaturation at 95C, DNA is heated to separate into two strands –> all H bonds broken
2. annealing at 45C, small DNA primers attach to opposite ends of target sequence –> DNA cooled
3. elongation at 72C, heat-tolerant taq DNA polymerase copies strands
463
steps of gel electrophoresis
1. DNA samples amplified w PCR
2. DNA cut at specific base sequences
3. fluorescent marker binds to DNA fragments
4. samples added to gel electrophoresis chamber where electric current is passed through, separating DNA molecules by length (longer = moves less)
5. DNA is dyed to be more visible
6. banding pattern shows up that can be analyzed and compared
464
how is used DNA to analyze DNA in paternity testing/forensic analysis
- 13 short tandem repeats (STRs) (2-7 bases repeated each) that is unique to individual
- use PCR to amplify and gel electrophoresis to separate fragments of DNA
- band will be unique to person
465
how is PCR and gel electrophoresis used in testing of COVID 19
1. acquire DNA sample from nose/throat
2. use reverse transcriptase to convert viral RNA to DNA
3. use PCR to amplify specific viral sequence that are markers of COVID
4. fluorescent markers attach to target DNA, if threshold is met, positive test reuslt
466
pros and cons of PCR test for covid
pros: sensitive, and specific
cons: expensive, delayed results
467
how can DNA profiling be make more reliable
- by increasing number of measurements in experiment (ex. increasing # of markers used reduces probability of false match)
468
what is transcription
- synthesis of RNA using DNA template
469
what does RNA polymerase do during transcription
- binds to site on DNA at start of gene that is being transcribed
- unwinds DNA double helix separating it into 2 single strands, moving along it
- positions correct RNA nucleotides on template strand
- links RNA nucleotides by covalent sugar-phosphate bonds
- detaches RNA from template, allowing DNA to reform
470
differences of RNA and DNA
| in terms of transcription and translation
DNA: has thymine, double stranded
RNA: has uracil, single stranded
471
sense vs antisense strands
sense: DNA strand w base sequence to be copied into RNA (coding strand)
antisense: has complementary base sequence to sense strand (template strand)
472
what strand of DNA is RNA transcribed from
- the antisense (template) strand
- results in a strand of RNA with same base sequence as sense strand of DNA but RNA has uracil not thymine
473
what is stability of DNA templates, importance?
- refers to how DNA base sequence doesn't change after transcription
- DNA strands link up again after transcription to prevent any mutation
- DNA may be transcribed many times throughout life, instability would mean RNA would accumulate many mutations over time, translated proteins would work less
474
importance of transcription in the expression of genes
- first stage of gene expression
- not all genes in cell are always expressed, transcription is key stage where genes are turned on and off
- controls proteins produced from transcription to determine observable characteristics of individuals
475
what is translation
process of polypeptide synthesis from mRNA
476
roles of mRNA in translation
- hold information in form of genetic code
- single stranded
- has site which ribosome can bind
- sequence of codons that specifies AA sequence with start and stop codon
- mRNA can be translated many time until it is damaged or polypeptide not required
477
roles of tRNA in translation
- translates base sequence of mRA into AA sequence of polypeptide
- has anticodon consisting of 3 bases on one end and attachment point for wanted AA on other end
- each tRNA molecule has distinctive shape recognized by dedicated activating enzyme to attaches right AA to tRNA
478
roles of ribosomes in translation
- consists of small and large subunits
- small: binding site for mRNA
- large: three binding sites for tRNA, however only 2 tRNA can bind at any given time
- large subunit has catalytic site that makes peptide bonds bw AA to assemble polypeptide
479
relationship bw anticodon vs. codon
anti: the 3 nucleotides forming unit of genetic code on tRNA
codon: sequence of 3 nucleotides forming unit of genetic code on mRNA
- bases of anticodon must be complementary to codon for tRNA to bind to ribosome and deliver AA
480
why do living organisms used triplet code
- two bases would only form 16 combos, not enough for 20 AA
- three bases form 64 combos, enough for 20 AA
481
what does it mean by the genetic code is degenerate
- different codons can code for the same amino acid
482
what does it mean by the genetic code is universal
- genetic code used by all living organisms and viruses, with rare minor changes
483
process of translation
1. activating enzyme that fits tRNA binds to it, attaches specific AA corresponding to anticodon
2. tRNA carrying AA bind to A site on ribosome, complementary base pairing of anticodon to next codon
3. AA of tRNA linked to growing polypeptide with peptide bond, tRNA now holding whole chain
4. tRNA moves from A to P site as result of ribosome moving along mRA by 1 codon
5. polypeptide transferred to new tRNA in A site
6. tRNA moves to E site causing anticodon and codon + tRNA and ribosome to separate
7: cycle repeats
484
affects of gene mutation
- a change to the base sequence of gene
- even a single base substitution can change codon to different one
- may not affect structure of protein or may affect a lot
485
how is gene mutation present in sickle cell disease
- example of radical change due to single base substitution
- mutated gene codes for beta-globin polypeptide in hemoglobin
- mutation converts 6th codon of gene from GAG to GTG and allele goes from HbA to HbS
486
consequences of the gene mutation in sickle cell disease
- affects hemoglobin molecules when they are in tissues w low O2 conc
- hemoglobin link into chains and distort blood cells into sickle shape
- can get trapped in capillaries and damaging tissues, shorter lifespan of RBCs (4 days)
- body cannot replace RBC fast enough, leads to anemia
487
what are gene mutations
- random structural changes to genes at the molecular level
- should be distinguished from gene editing done by humans
488
what is substitution, how does it occur?
substitution: one base in coding sequence is replace by another
- can happen by chemical changes or mispairing during DNA replication
489
what is insertion, how does it occur?
insertion: a nucleotide is inserted, extra base in sequence
- requires a break in the sugar-phosphate backbone of DNA
490
what is deletion, how does it occur?
deletion: a nucleotide is removed, one less base in sequence
- requires two breaks in sugar-phosphate backbone
491
same sense vs. nonsense vs. mis-sense mutations
same sense: change one codon for an AA to another codon of the same AA
nonsense: changes a codon that codes for AA into stop codon
mis-sense: changes a codon into one that codes for a different AA
492
are base substitution mutations beneficial or dangerous
- beneficial mutations are outnumbered by deleterious mutations, but more significant
- beneficial mutations create new alleles that can be inherited by offspring and inc. genetic diversity
493
what are SNPs
- single nucleotide polymorphisms
- position in gene where one base is altered, can lead to new allele
- each person has 4000-5000, makes us unique
- can be associated with diseases
494
are insertions/deletion mutations beneficial or dangerous
- less likely to be beneficial compared to substitutions
- insertions/deletions almost always results in non-functioning polypeptide
- result of frameshift mutation
495
what is a frameshift mutation
when a mutation (insertion/deletion) changes the reading frame for every codon onwards in direction of transcription and translation
496
what causes and increases likelihood of gene mutations?
- errors in DNA replication and DNA repair also mutagens
- radiation if it has enough energy to chemically change DNA
- chemical substances like mustard gas
497
randomness in mutations
- cannot be directed in organism to achieve an intended outcome
- no natural mechanisms have been found to change a particular base to a certain trait
498
where can gene mutations occur
- anywhere in base sequences of genome
- some bases and positions in genome have higher probability of mutating
499
mutations in somatic cells vs. germ-line cells
somatic: mutations that occur in body cell of someone, cannot be passed to offspring, even if its beneficial
germ-line: mutations that occur in testes/ovaries can be passed to offspring, create new allele and may cause genetic disease
- determines what the consequences of mutation are
500
what is an allele
a variant of a gene, differing in one or more bases from other alleles
501
how does mutation create genetic variation
- increases # of alleles in gene in population, inc. genetic variation
- although most mutations are harmful/neutral it's needed for natural selection
502
how are new cells generated
- a mother cell divides and produces 2 daughter cells thru process of cell division
- all cells come from pre-existing cells
503
how does cytokinesis occur in animal cells
- plasma membrane pulled inwards->cleavage furrow
- done using ring of contractile proteins (actin and myosin)
- when cleavage furrows reaches middle, cell pinched apart
504
how does cytokinesis occur in plant cells
- microtubules at equator assemble vesicles which ruse to from plate-shaped structures
- creates 2 layers of membrane at equator which connect to pre-existing plasma membrane to divide cytoplasm
- cellulose+pectins+others brought in vesicles and exocytosis bw two new membranes forming cell walls
505
division of organelles in cytokinesis
- all daughter cells must receive one mitochondrion and one of every organelle that can only be made by dividing a pre-existing structure
506
budding of yeast as unequal cytokinesis
- nucleus divides, small outgrowth of mother cell receives one nucleus but only a small bit of cytoplasm
- dividing wall constructed, separating cells, leaving scar on mother cell
- repeats, do not need to double in size bw each division
507
oogenesis in humans as unequal cytokinesis
- development of female gamete (egg)
- meiosis first division produces one large cell w almost all the cytoplasm and a small polar body
- second division, results in one large cell and 3 small polar body
- large cell develops into oocyte
508
what is the main goal of mitosis and meiosis
- nuclear division to ensure that both daughter cells have a nucleus
- anucleate cells cannot synthesize polypeptides, cannot grow/maintain selves
509
role of mitosis in eukaryotes
- produce genetically identical cells (promotes continuity)
- daughter cells have same # chromosomes as parent cell
- daughter cells have same gene as parent, ensures all cells in organism has all required genes
- allows successful genome to be inherited by offspring in asexual reproduction
510
role of meiosis in eukaryotes
- to generate genetic diversity (promotes change)
- daughter cells have half as many chromosomes as parent (diploid become haploid)
- pairs of genes in diploid mother dealt randomly to daughter cells, variation in genes
511
importance of nuclear division
to prevent the production of anucleate cells
512
what needs to occur before mitosis and meiosis
- DNA replication to ensure each daughter cell receives all gene
513
structure of DNA before and after DNA replication
| in relation to cell division
before: DNA exists in nucleus as long single molecules call chromosomes
after: pair of identical DNA molecules (chromatids) held together by cohesin loops (still considered same chromosome)
514
condensation of chromosomes
- condensing occurs by wrapping double helix of DNA around histone proteins to form nucleosomes
- nucleosomes are linked together
- process still not fully understood
515
movement of chromosomes
- kinetochores assembled at centromere of each chromatid
- microtubules link with kinetochores at equator of cell and poles at opposite ends
- as cohesin loops cut, shortening of spindle microtubules by kinetochores cause sister chromatids to move to opposite poles
516
phases of mitosis
G1, S, G2, PMAT, C
517
interphase before mitosis
- all DNA is replicated and each chromosome consist of two elongated chromatids containing identical DNA held together by cohesin loops
518
prophase of mitosis
- chromosomes condense by packing DNA thicker and shorter
- microtubules grow from structure at poles (MTOCs)
- nuclear membrane breaks down
- kinetochore attached to centromere of chromatid
519
metaphase of mitosis
- microtubules grow from poles, attach to centromere of each chromatid
- chromosomes align at equator of cells
520
anaphase of mitosis
- cohesin loops cut, chromatids become separate chromosomes
- microtubules and kinetochores work together to bring chromosome to pole
- chromosomes reach pole at end of anaphase
521
telophase/cytokinesis of mitosis
- nuclear membrane forms around chromosomes
- chromosomes decondense into chromatin
- cell divides its cytoplasm (cytokinesis)
522
interphase after mitosis
- gene in decondensed chromosome can be transcribed and mRNA translated to synthesize proteins
- cell grows
523
meiosis results in cells that have half the number of chromosomes as its parent, this is called….
reduction division
524
what occurs during interphase in meiosis
- diploid cell
- DNA = chromatin
G1: synthesis of cell components + growth
S phase: DNA replication–> 2 identical strands w centromere held tgt until anaphase II
G2: cell prepares for meiosis
525
what occurs during prophase I of meiosis
- nuclear membrane breaks down
- spindle fibres form
- DNA condenses into chromosomes
- synapsis
- crossing over
526
what occurs during synapsis of meiosis
where homologous chromosomes pair up into tetrads
- genes of chromatids of homologous chromosomes align and attach with each other
527
what occurs during crossing over in meiosis
sections of chromosomes(chiasma) cut + exchanged b/w homologous chromosomes
- new combos of alleles created–> combos different from parent
528
what occurs during metaphase I in meiosis
- homologous chromosomes align at cell equator
- independent assortment: orientation of each homologous pair is random
529
what occurs during anaphase I in meiosis
- tetreds separate into homologous chromosomes and moves towards opposite side of cell
- kinetochores attach chromosomes to spindle fibre
*sister chromatids NOT separated
530
what occurs during telophase I and cytokinesis in meiosis
- occurs simultaneously
- new nuclei forms around chromosomes
DNA uncoils: chromosomes–>chromatin
- spindle fibres break apart
- left with 2 unique haploid cells
531
what occurs during prophase II in meiosis
- cells are haploid
- DNA condenses
- nuclear membrane breaks apart
- spindle fibres form
532
what occurs during metaphase II in meiosis
- chromosomes align at equator in single file
533
what occurs during anaphase II in meiosis
- sister chromatids pull apart from each other and move to opposite pole of the cell
- moved by microtubules
534
what occurs during telophase II and cytokinesis in meiosis
- occurs simultaneously
- spindle fibres break apart
DNA uncoils: chromosomes–> chromatin
END with 4 unique haploid gamete
cells
535
what are homologous chromosomes
chromosomes in pairs: one maternal one paternal
- Two chromosomes with the same set of genes, in the same sequence, sometimes with different alleles
536
what are tetrads
- aka bivalent chromosomes
- pair of homologous chromosomes
537
what do homologous chromosomes have in common
size, centromere location, order of genes
538
what is non-disjunction
errors in chromosome separation during anaphase I or II
- results in wrong # of chromosomes
539
what happens if nondisjunction occurs in anaphase I
- one gamete receives 2 copies of chromosome while other gamete receives none
-all resulting gametes after meiosis will have incorrect # of chromosomes
540
what happens if nondisjunction occurs in anaphase II
- half of the final 4 gametes will have an incorrect # of chromosomes
- other half will be unaffected
541
non-disjunction causing down syndrome
- when someone have 3 copies of chromosome 21instead of 2
- rare case where non-disjunction isn't lethal
542
how does meiosis promote genetic diversity using independent assortment
- bivalents (tetrads) are oriented in random directions (independent assortment) during metaphase I and II
- orientation of one bivalent doesn't affect others
- allows daughter cells to have variety of genes
543
how does meiosis promote genetic diversity by crossing over
- two non-sister chromatids brought together at same point along gene sequences and parts of DNA are swapped
- at least one crossover occurs in each bivalent
- creates chromatids with new combos of alleles
544
what is solvation
combination of a solvent with molecules/ions of a solute
545
how does solvation in water occur
- polar solutes dissolve as + charged ions attracted to -O pole and - charges ions attracted to +H2 pole
- attractions cause hydrogen bonds where water forms shells around ions, preventing them from precipitating (now dissolved)
546
water movement bw solutions of different concentrations
- attraction b/w solute and water is stronger than water-water, restricts movement of water molecules
- water always moves in both directions however net movement from less concentrated (hypotonic) solutions to more concentrated (hypertonic) solutions
547
hypotonic vs. hypertonic vs. isotonic solutions
hypo: less concentrated
hyper: more concentrated
iso: equally concentrated
548
water movement bw solutions of same concentration
- moves both ways equally rather than not move at all
549
properties of plasma membranes
- made of phospholipids
- thin (5nm or less)
- liquid state, allows changes of position
- very low tensile strength
- semi-permeable
550
properties of cell walls
- made of cellulose
- thick (250nm-5μm)
- solid state, changes in position limited
- high tensile strength, stronger than steel
- freely permeable unless impregnated w waterproof material
551
what happens to cells that lack a cell wall in isotonic, hypertonic, and hypotonic solutions
iso: stays normal
hyper: water leave thru osmosis, cell shrinks and develops crenations (indentations) from water loss
hypo: water enters thru osmosis, cell swells, easily can burst
552
how do freshwater unicellular organisms perform osmoregulation
- water moves from freshwater->cell
- use contractile vacuoles to remove excess water from cytoplasm to prevent cell from bursting
553
what happens to cells with a cell wall in isotonic, hypertonic, and hypotonic solutions
iso: stays normal
hyper: pressure in cell decreases, no longer pushes against cell wall, plasma membrane pulls away from cell wall (plasmolysis)
hypo: high pressures of water can build up and cell can become turgid<- normal state of plant cells as it provides support to plant
554
importance of isotonic solutions in medical environments
- allows water molecules to pass in and out thru plasma membrane at same rate, preventing dehydration and swelling of human cells
555
when are isotonic solutions used in medical environments
- intravenous drip
- rinse off wounds
- keep areas of damaged skin moist before skin grafts
- basis for eyedrops
- stores donor organs
556
features of asexual reproduction
- one parent needed
- mitosis to make genetically identical offspring
- existing gene combos maintained
- no genetic variation generated
- organisms adapted to unchanging environment produced adapted offspring
557
features of sexual reproduction
- tow parents needed
- meiosis to made genetically different offspring
- new gene combos produces
- genetic variation created
- offspring may be better adapted to changing environment
558
role of meiosis and fusion of gamete in sexual lifecycle
- fusion of gametes = fertilization
- fertilization doubles # of chromosomes, meiosis halves it to maintain correct #
- meiosis makes parental combos of genes break and form new combos
559
male gametes vs. female gamtes
male: travel to female, smaller, small food reserves, produced in a large #
female: sessile, larger, big food reserves to develop embryo, few produced
560
follicular phase of menstrual cycle
- first half of ovarian cycle
- group of follicles develops on ovary, egg stimulated to grow in each
- most developed follicle breaks open, releasing egg into oviduct (ovulation)
- other follicles degenerate
561
luteal phase of menstrual cycle
- second half of ovarian cycle
- wall of follicle that released egg develops into corpus luteum
- if fertilization doesn't occur, corpus luteum breaks down and ovary returns to follicular phase
562
uterine cycle of menstrual cycle
- changes that occur to endometrium (lining of uterus) during menstrual cycle
- menstruation marks beginning of uterine cycle
- from there, endometrium becomes thicker in prep for embryo
- no embryo, endometrium starts breaking down and shed
563
where are the hormones that regulate the menstrual cycle produced
pituitary gland: FSH (follicle stimulating hormone), and LH (luteinizing hormone)
wall of follicle (ovarian steroid hormones): oestradiol, progesterone
564
when does hormone FSH peak
- towards the beginning and middle of the cycle
- stimulates development of follicles, each containing oocyte and follicular fluid
- stimulates secretion of oestradiol
565
when does hormone oestradiol peak
- near end of follicular phase (day 14)
- stimulates repair and thickening of endometrium
- increases FSH receptors, making follicles more receptive to FSH, boosting oestradiol production (pos. feedback loop)
- at high levels, oestradiol inhibits secretion of FSH (neg. feedback loop), stimulates LH secretion
566
when does hormone LH peak
- sharp peak at end of follicular phase (day 14)
- stimulates completion of meiosis in oocyte, makes follicle wall burst open at ovulation
- promotes development of follicle wall into corpus luteum which secretes oestradiol and progesterone causing them to peak (day 21)
567
when does hormone progesterone peak
- rise at start of luteal phase, peak at day 21, drop by end of luteal phase
- promotes thickening and maintenance of endometrium
- inhibits FSH and LH secretion by pituitary gland (neg. feedback loop_
568
how does sperm reach egg in fertilization
- plasma membrane of sperm have receptors to detect chemical released by egg
- directional swimming towards egg
569
how do sperm and egg fuse
- sperm binds to egg plasma membrane, sperm nucleus enters egg cell <- moment of fertilization
- immediately after, glycoprotein around egg hardens, preventing entry of more sperm
- sperm tail +mitochondria doesn't penetrate or broken down in zygote
570
what happens after sperm and egg fuse
- nuclei kept separate until zygote's first mitosis when nuclear membranes break down
- participate jointly in mitosis, results in 2 genetically identical diploid nuclei each w 46 chromosomes
571
how are hormones used in IVF
- normal secretion of hormones suspended, artificial doses of FSH given to stimulate superovulation <- allows control over timing of egg production
- eggs can be harvested and fertilized in petri dish
572
production of pollen (male gametes)
- in anther, diploid cells go thru meiosis to produce haploid pollen grains
in each pollen grain, the haploid nucleus creates 3 copies of self
- 2 are male pollen gametes
- 1 used for gene expression during pollen development and fertilization
573
production of plant eggs (female gametes)
- in carpel (pistil) ovary and stigma connected by style (hollow tube)
- ovary has 1+ ovules, and cell in center of ovule goes thru meiosis to produce 4 haploid nuclei
- each one divides 3 times by mitosis = 8 total
- 1 becomes egg
- others help embryonic development + fertilization
574
pollination vs. fertilization in plant
p: transfer of pollen from anther to stigma by wind/animals etc.
f: pollen grains go thru tube to an ovule in ovary where pollen grains are released to fertilize egg
575
what does it mean if a flower is hermaphrodite
- aka "perfect flowers"
- it contains both male and female parts
- still sexual reproduction
576
what is a cotyledon
an embryonic seed leaf
- typically first leaves to appear from germinating seed
- can be one (monocotyledon) or 2 (dicotyledon)
577
features of insect-pollinated flowers
- large, bright petals +scent to appeal and to be landing stage
- large, spiky pollen grains to stick onto insects
- stick stigma to collect pollen
- glands secrete nectar to attract insects as fuel<- deep in flower so insect must brush past anthers and stigma
578
what is cross-pollination, importance
transfer of pollen from an anther on one plant to the stigma of another plant
- promotes genetic variation and evolution
579
strategies of plants to promote cross pollination
- separation of anthers and stigma on same plant (ex. diff heights)
- separation of anthers and stigma on different plants (only male parts or female)
- anthers and stigmas maturing at different times
- use of outside agents to transfer pollen to different plants
580
why could self pollination be a problem
- no genetic diversity
- recessive traits are amplified
- inbreeding depression (rare recessive genes paired together)
- heritable characteristics are amplified, less healthy
581
self-incompatibility mechanism
- pollen can fail to germinate or pollen tube stops growing before reaching ovary due to rejection of self-proteins or cells (opposite of human immune system)
582
what is protandry vs. protogyny
protandry: when anthers of plant mature first
protogyny: when stigma of plant matures first
583
seed dispersal vs. pollination
sd: seeds transferred from female parent to germination site by wind/animals/explosion
p: pollen transferred from anther to stigma by wind/animals
584
common ways of seed dispersal
- dry and explosive
- fleshy+attractive for animals to eat
- feathery+winged to catch wind
- covered in hook to catch coats of animals
585
how does seed germination work, what does it require
- requires: oxygen, water, warmth
- food reserves (starch) are mobilized, digested then transferred to the growing embryo
586
inheritance in eukaryotes with a sexual life cycles
| gametes -> zygotes
- haploid gamete produced in parents and fused to form a diploid zygote
- zygote has two copies of each autosomal gene (one from each parent)
587
method of creating genetic crosses in flower plants
- paint brush can brush anther to get pollen then dabbed onto stigma
- anthers must be cut off, and flower in an enclosed area to prevent other pollen from reaching it
588
P vs. F1 vs. F2 generation
P: parents
F1: offspring in seeds inside of parent
F2: offspring of F1
589
what is a genotype
combination of alleles inherited by an organism
590
homozygous vs. heterozygous genotypes
homo: ex. DD, dd, as all gametes that can be produced will have this allele of the gene
hetero: ex. Dd, as all gametes will have different alleles of the gene
591
what is a phenotype
- observable traits of an organism resulting from genotype and environmental factors
592
traits affected by genotype/phenotype and both
genotype only: eye colour, haemophilia, ABO blood groups
phenotype only: languages, scars, body art
both: skin colour, height, diabetes
593
what is phenotypic plasticity
- capacity to develop traits suited to the environment experienced by an organism
- occurs by varying patterns of gene expression
594
how does phenotypic plasticity work
- genes are switched on and off, not changed to new alleles
- typically is reversible
595
normal vs. diseased allele in phenylketonuria
normal: codes for functioning phenylalanine hydroxylase, an enzyme that converts AA phenylalanine to another AA called tyrosine
diseased: codes for non-functioning phenylalanine hydoxylase so phenylalanine from diet is not processed efficiently
596
what occurs in phenylketonuria
- phenylalanine isnt processed, accumulates, tyrosine is deficient
- nerve cells in developing brain are very sensitive to phenylalanine levels so excessive amounts lead to brain damage
597
current treatment for phenylketonuria
- prevent foods with high phenylalanine content from entering diet from birth
- PKU no longer causes intellectual and developmental disabilities in infants
598
what is a gene pool, how does it relate to evolution
- all the genes of all the individuals in a sexually reproducing population
- every individuals gets max of 2 genes from gene pool
- changes in gene pool = evolution
599
how is the S-gene an examples of multiple alleles
- system that prevents inbreeding in apples
- 32 different S-alleles discovered
- each apple tree has 2 copies of S-gene and pollen grains each contain one of these (ex. if S2S3 genotype, 50% of pollen will be S2 and 50% S3)
- when pollen germinates stigma of another flower/tree, rejected if S-alleles are the same
600
6 genotypes of 4 phenotypes of blood type
type A: IAIA, IAi
type B: IBIB, IBi
type O: ii
type AB: IAIB
601
how do IA, IB, i alter the blood cell
IA: adds acetylgalactosamine into glycoprotein
IB: adds galactose onto glycoprotein
i: doesn't cause any alteration to basic glycoproteins
602
what antibodies will type A, type B, type AB and type O blood have
A: anti-B
B: anti-A
AB: none
O: anti-A and anti-B
603
what is the rhesus factor
- a protein on RBC that creates positive and negative blood types
controlled by D+ or D- alleles
pos: have rh antigens
neg: do not have rh antigens
604
what is incomplete dominance
- when heterozygous alleles blend and offspring has a combo/mixture of both alleles (intermediate phenotype)
- ex. 4 o'clock flower can be red or white when homozygous and pink when heterozygous
605
what is codominance
- when heterozygous alleles exist independently but with each other (dual phenotype)
- ex. AB blood type will have blood cells with A structure and some with B structure
606
sex in humans
- by 23rd pair of chromosomes (X and Y)
- all humans have an X chromosome which has 900 genes, needed for female and male development
- males have Y chromosome which has genes only needed for male development
607
how is the sex of a baby determined
- all females will pass down an X chromosome, doesnt affect sex of offspring
- males will pass down either X (female offspring) or Y (male offspring) chromosome in sperm
608
how do males develop in the womb
- SRY gene (testis determining factor, TDF) on Y chromosome causes embryonic gonads to develop into testes
- tests start secreting testosterone, develops other male organs
609
how doe females develop in womb
- gonads develop into ovaries by default
- ovaries start secreting oestradiol, causes female reproductive system to develop
610
sex linkage as an inheritance pattern
- where a trait/disorder is linked to genes located on X or Y chromosomes
- more commonly linked onto X chromosome as its larger
- leads to males more likely to get sex linked recessive traits as they only have 1 X chromosome
611
sex linkage vs gene linkage
sex: trait/disorder linked to gene located on sex chromosomes
gene: two or more genes being located close together and tend to be inherited together
- two genes can be gene-linked and sex-linked if located close together on X chromosome
612
how are alleles carried on X chromosomes shown
as a superscript on the X
613
haemophilia as a sex-linked genetic disorder
| what is the mutation
haemophilia - where blood doesn't clot properly
- has defective form of factor VIII, located on X chromosome
- females may be carrier of allele but don't show symptoms as they have another X chromosome
614
why is inbreeding in humans harmful
- many genetic disorders are caused by rare recessive alleles, both parents must have allele to pass onto offspring
- chances of this are much higher during incest
615
continuous vs. discrete variation
cont: range is possible, no distinct categories, influenced by environment and multiple genes if there's genetic cause
dis: separate categories of variation, no intermediates, influenced by 1 or few genes if there's genetic cause, usually not affected by environment
616
how is skin colour an example of continuous variation
- partly due to environment/sunlight which affect amount of melanin produced
- shows evolution in humans, ancestors had developed skin colours based on how much sunlight they were exposed to + in order to get vitamin D
617
what is polygenic inheritance
traits determined by multiple genes, leading to continuous phenotypes
618
what is homeostasis
the maintenance of the internal environment of an organisms to keep variables as close to optimal as possible
619
feedback loops in homeostasis
- positive feedback loops create change rather than stability, not used for homeostasis
- negative feedback loops maintains gap bw original and new levels
- uses a lot of energy but keeps internal environment in narrow limits, allowing organisms to survive
620
what is involved in blood glucose regulation
- kept within narrow limits, must balance glucose removed/added to blood
- set point ~5mmol/L
- regulated by insulin and glucagon <- secreted by cells in pancreas “isle of langerhans”
621
what must happen when blood glucose levels drop in order to maintain homeostasis
- pancreas detects it
- alpha cells make+secrete glucagon hormone which signals liver to convert stored glycogen into glucose which is then released into blood
- blood glucose levels increase
622
what must happen when blood glucose levels rise in order to maintain homeostasis
- pancreas detects it
- beta cells make+secrete insulin which allow skeletal muscle cells + liver to store glucose and convert it to glycogen
- blood glucose levels decrease
- insulin broken down by target cells which means secretion must be ongoing
623
what occurs when someone has type 1 diabetes
- body cannot produce enough insulin because of destructions of beta cells in isle of Langerhans by immune system
- autoimmune disease
- sudden onset
624
treatments for type 1 diabetes
- test blood glucose level regularly
- inject insulin when too high/before eating
- implant devices to release insulin
- stem cell treatment to create new beta cells (in development!)
625
what occurs when someone has type 2 diabetes
- cannot respond to insulin bcus lack of insulin receptors or glucose transporters on target cells
- slow onset
risk factors: unhealthy diets, prolonged obesity, genetic factors
626
treatments for type 2 diabetes
frequent, smaller meals to avoid peaks of glucose
avoid sugary foods
eat food w/ low glycemic index and high fibre (slower digestion)
exercise and weight loss to improve insulin uptake
627
what is diabetes, what does it do, what are the symptoms?
- consistently elevation blood glucose levels
- damages tissues+proteins
- prevents water reabsorption in kidneys
symptoms: constant thirst/urination/tiredness/sugar cravings/glucose in urine
628
how is body temp monitored
- by thermoreceptors which are free nerve endings of specialized sensory neurons
- sensory inputs from peripheral/central thermoreceptors to hypothalamus
- initiates response if hypothermia or hyperthermia
629
tissues as effectors of temperature change
- muscles contract to release heat
- subcutaneous adipose tissue (insulation) prevents heat loss
- brown adipose tissue generated heat at rapid rate
630
how is heat generated by cells for thermoregulation
- by metabolism
- hypothalamus secretes thyrotropin releasing hormone (TRH)
- goes to pituitary gland which releases thyroid stimulating hormone (TSH)
- TSH is a glycoprotein that stimulates thyroxin secretion in thyroid gland
- thyroxin increases metabolic rate of cells
631
vasoconstriction as a bodily response to cold
- constriction of arterioles in skin
- less blood flow to skin preventing heat loss
632
shivering as a bodily response to cold
muscles contract involuntarily to cause movement to generate heat
633
uncoupled respiration as a bodily response to cold
- when energy from mitochondria doesn’t produce ATP but rather heat
- brown adipose tissue has a lot of mitochondria (gives it the brown colour)
- mitochondria oxidizes fat and converts all energy to heat
634
hair erection as a bodily response to cold
- thick coat allows air b/w hairs which acts like thermal insulator
- erector muscles move hairs to increase insulating effect
635
vasodilation as a bodily response to heat
- circular muscles relax, arterioles dilate
- more blood flow to skin encouraging heat loss
636
sweating as a bodily response to heat
- sweat secreted by glands in skin <- controlled by hypothalamus
- water is evaporated, solutes remain, giving salty taste
- water has high latent heat of vapourization, cooling effect
637
types of thermoreceptors
- there are cold and warm receptors
- peripheral thermrec. are located near skin to sense outside temp
- central thermrec. located in body to sense core temp
638
how is natural selection achieved
- organisms produce more offspring then environment can support
- offspring are variated, ones better suited for environment will live "survival of the fittest"
- successful offspring will produce more offspring
- occurs over many years
639
what is a paradigm shift, ex
- when observations accumulate and are more easily explained by a new paradigm/theory than an existing one
- ex. lamarkism -> darwinism
640
role of mutations in natural selection
- creates new alleles, enlarging gene pool
- original source of variation
- only source of variation in non-sexual reproducing organisms
641
role of sexual reproduction in natural selection/variation
- meiosis produces new combos of alleles thru crossing over and independent orientation of bivalents
- fusion of male and female gametes creates new combos of alleles, bringing mutations of diff individuals tgt
642
how does overproduction of offspring and competition for resources promote natural selection
- breeding rate higher than available resources to support
- only the organisms that have the most successful adaptations will survive and reproduce, allows more offspring to inherit the adaptation
643
how are abiotic factors selection pressures
- differences in tolerance to abiotic factors is basis of selection
- ex. cold temps affects all organisms in area, but only ones tolerant to it will remain/live in area
644
how does intraspecific competition affect natural selection
- fitness: how well-adapted individual is
- fitness influences lifespan, if they're able to reproduce, number of offspring
- fitter individuals live long enough to have offspring, and have many allowing them to contribute more to gene pool of next generation
645
what kind of traits are not heritable
- traits developed during lifetime (acquired traits) bcus they don't alter genes
- typically genes inherited from environment are not heritable as they don't change base sequence
- doesn't support evolution
646
how is sexual selection a selection pressure
- if both mates are well adapted, offspring is likely to survive, if one mate is not well adapted, offspring more likely to die
- differences in physical/behavioural traits can be used as signs of fitness of mate, attracts mate, driving evolution
- ex. thru courtship
647
sexual selection in birds of paradise, why do females like exaggerated traits?
- males have elaborate plumage and carry out vigorous dances, indicating it can obtain enough nutrition to grow and make energy
- males being able to survive in rainforest with elaborate plumage shows it's survival skills and how well it's adapted
- females are more likely to choose males w these traits, more offspring will have these traits too
648
conclusions from endler's guppy experiment
- investigated effect of predation on physical traits of guppies
colouration: more attractive to females but more visible to predator
- therefore, fewer predators = more colourful guppies, more predators = less colourful guppies
649
what does an ecosystem being stable mean
- that it can continue indefinitely because of the sustainable mechanisms within
- ex. daintree rainforest in australia has lasted 180M years <- contains ancient plant famillies
650
requirements for stability in an ecosystem
- steady supply of energy
- nutrient cycling with no leakages
- individual species must have high genetic diversity to survive selection pressures (high biodiversity typically means stable ecosystem)
651
what interferes with ecosystem stability
- harvesting/removal of materials from environment
- erosion (results in loss of nutrients)
- eutrophication can cause population inbalances
- removal of species by epidemics/poaching, especially if keystone
652
what is eutrophication
- nutrient enrichment in a body of water due to run off from land
- causes overgrowth of algae and plants, disrupting ecosystem
653
what is a tipping point
- an ecological threshold that's difficult to reverse
- creates abrupt change in ecosystem if reached
654
how is deforestation of amazon rainforest a potential tipping point in ecosystem stability
- deforestation-> decrease in forest cover -> reduces amount of transpiration from plants ->decrease in cloud formation -> reduces rainfall
- can leads to droughts which can lead to fires and more loss of ecosystem
- unsure when the ecosystem will stop being able to sustain itself and pass tipping point
655
what are mesocosms
- small experimental areas set up as ecological experiments
- can vary one or more variables to examine outcome
656
what is required for a mesocosm to work
- clear jars so that energy(sunlight) and enter
- decomposers to recycle energy from dead matter
- autotrophs to create carbon compounds and oxygen
657
what is a keystone species
- when one species has a disproportionate effect of the structure of an ecological community
- risk ecosystem collapse if removed
658
requirements for sustainability in an ecosystem
- nutrient availability-> nutrients recycled and never a lack of chemical elements in which life is based
- detoxification of waste products -> used up by another organisms before they become toxic in environment
- energy availability -> energy cannot be recycled, needs energy supply (sun)
659
sustainable harvesting of brazil nuts
- grow in trees of amazon <- over harvesting will lead to no new young trees
- in order to be sustainable, some nuts are left behind in order to germinate and grow into new trees
660
sustainable harvesting of atlantic cod
- overfished in 1990s <- population almost went extinct
- fish are open access resource so conservation was limited
- in order to be sustainable now, fish must stay in range of max. sustainable yield (fishing must occur slower that rate of population growth)
661
tillage as an example of unsustainable agricultural practices
- the process of preparing soil for a crop
- soil becomes degraded and erodes quickly
662
nutrient depletion as an example of unsustainable agricultural practices
- when crops are removed, nutrients are depleted (desertification)
- when there are no nutrients, farmers use chemical fertilizers which leach into water sources and cause eutrophication
663
monocultures as an example of unsustainable agricultural practices
- same crop grown year after year in large areas
- increases pests, weeds and causes nutrient loss in soil
664
mechanical tillage as an example of unsustainable agricultural practices
use of diesel oil in tractors/heating greenhouses
- high carbon footprint
665
what happens to a body of water when eutrophication occurs
1. nutrients (nitrate and phosphate fertilizers) go from land to water
2. aquatic plants grow rapidly
3. algae grows rapidly
4. algae bloom blocks sunlight from aquatic plants = water O2 levels fall
5. decomposition rate increases, aerobic respiration of decomposers reduce O2 further
6. greater biochemical oxygen demand (BOD)
7. death of organisms that require oxygen
666
what is bioaccumulation
- build up of toxins in tissue of organisms over time (ex. mercury)
- toxins that are fat soluble are not easily excreted, stay in adipose tissue
667
what is biomagnification
increase in chemical concentration in individual organisms going up the food chain
- predators consume large quantities of prey which have bioaccumulation in their tissues
668
why are macroplastics and microplastics dangerous to the oceans
- can cause entanglement, accidental ingestion, accumulation of toxins
- degrade very slowly, releasing toxic carbon compounds into ocean
669
what is rewilding, what is done during this process
practice of returning natural ecosystems to their original state
- stop human resource harvesting in area
- allow natural processes to restore habitat
- interventions may be taken to speed up restoration
670
what are some possible rewilding interventions
- distribute seeds of missing plants
- reintroduce apex predators and keystone species
- connect ecosystems broken by fragmentation
- control invasive species
671
hinewai reserve as successful example of rewilding
- 1250 hectors of farmland returned to natural forest
- alien mammals controlled w/ little interference by humans
- invasive species eliminated by better adapted native species
- however climate change and extreme weather are still threats
672
how do humans contribute to CO2 and methane production, causing climate change?
- CO2: combustion and biomass and fossil fuels, cell respiration
- methane: emitted from marches/waterlogged habitats, landfill sites
673
snow/ice melting as positive feedback cycle in global warming
- snow/ice = high albedo<- reflects solar radiation
- water = low albedo
- as polar/sea ice melts, more water exposed, darker and absorbs more radiation, further accelerates polar ice cap melting
674
melting of permafrost as positive feedback cycle in global warming
- permafrost: ground that remains frozen year round
- contains frozen detritus when begins to decay as permafrost melts (cus global warming)
- decay releases more methane, contributing to GHG, accelerating global warming
675
rising ocean temps as positive feedback cycle in global warming
- solubility of gas in water decreases as temp increases
- as temp of ocean rises, more CO2 released into atmosphere, raising global temp
676
melting of frozen hydrated methane cap as positive feedback cycle in global warming
- stores of methane can have frozen cap so methane can’t escape
- as ocean warms, cap may dissolve, releasing large amounts of methane which leads to more warming
677
increase in forest fires/droughts as positive feedback cycle in global warming
- higher temps -> decreased humidity -> dry plants
- increases risk of forest fires which emit a lot of CO2 and kill trees
- reduced carbon capture in trees leads to more warming
678
why do boreal forests act as carbon sinks how may it reach its tipping point and shift to a carbon source
colder temps reduce cellular respiration and decay rate
- may shift into carbon source when tipping point is reached
- with increasing temps, forest fires increase <- after fires, boreal forests may be replace w more temperate forests with less trees
679
pack ice vs landfast ice
moves with the wind and ocean currents vs. "fastened" to the shore and doesn't move
680
how does a loss of ice affect emperor penguins
- breeds on landfast ice away from the shore (flatter, easier to move on)
- landfast ice becoming unpredictable-> breeding locations cannot be safely found
- breeding too close to shore=more predation, breeding too far from shore = difficult to return to shore for feeding
681
how does a loss of ice affect walruses
- uses pack ice to rest b/w feeding and shelter from sea and predators
- sea ice of preferred for breeding becus of space and feeding range
pack ice is melting = walruses now must travel further from land to feed/expend more energy keeping warm in cold waters
682
what does it mean that ocean is stratified
- made up of layers
- warmer less salty water floats on top of cooler saltier water
683
how does climate change affect ocean stratification
- warmer climate = surface of ocean warms and expands volume <- causes ice to melt adding freshwater and decreasing salinity
- creates larger diff in density=slower mixing = inhibits transport of heat, oxygen, CO2 throughout ocean
684
how is ocean stratification and climate change a positive feedback loop
- warm water on top cannot absorb as much CO2-> more CO2 in atmosphere->more warming
- warm water cant absorb as much O2 and it’s harder to mix with deeper cooler layers
685
how does climate change affect nutrient upwelling
- most active biological zone at top 100m of ocean, where sunlight penetrates and photosynthesis occurs
- warmer surface water can prevent nutrient upwelling to surface decreasing ocean primary production and energy flow thru marine food chains
686
how does climate change affect ocean currents
- deep water currents approach continental shelves and are forced upwards carrying nutrients (upwelling of nutrients) providing important nutrient cycling
- warming of ocean=more stratification=decreased currents=reduces upwelling-> disrupts ecosystems
687
upslope range shifts as result of climate change
- as temps rise, species migrate upslope to cooler temps that match their optimal temp
- species at highest points cannot move higher can become threatened and extinct
- competitive exclusion occurs as new competition arrives
688
poleward range shifts as result of climate change
- warmer temps lead to shift of latitude range of populations
- not migration, due to relative deaths and colonizations at northern and southern boundaries of range (ex. net extinction @ S boundary and net colonization @ N boundary will make shift up)
689
how does ocean acidification affect corals
- increased CO2 conc. cause ocean acidification which suppresses calcification in corals as inc. CO2 levels make Ca levels very low due to interrelated chemical reactions
- coral bleaching (expelling zooxanthallae) as result of rising ocean temps
- keystone species, extinction could collapse ecosystem
690
how does climate change affect coral-zooxanthellae relationship
- algae benefits from access to sunlight from coral, coral benefit from carbs from algae
- loss of mutualistic symbiosis with zooxanthellae (algae) due to temp increase<- water too warm = algae ejected from coral leading to coral bleaching and death
691
what is carbon sequestration
the storage of carbon dioxide from the atmosphere and removal of CO2 from carbon cycle
692
what is afforestation as an approach to carbon sequestration
planting trees in an area where they currently don't exist
- approach to address climate change
- trees naturally store carbon for photosynthesis
693
peat-forming wetlands as an approach to carbon sequestration
- wetlands are the world's largest carbon sink
- dry peat is major fire hazard, must be monitored well
- monitoring includes restoration of water levels, blocking drainage, re-establishing native species
694
structure of polysaccharides (cellulose)
- 710,000 beta glucose monomer
- 1,4 glycosidic bonds oriented n alternating directions
- straight, unbranched chains (can be packed tightly)
- not soluble in water
695
properties/function of polysaccharides (cellulose)
- high tensile strength (ability to be stretched)
- bundles of microfibrils (often made of cellulose) compose cell wall, preventing it from bursting
696
structure of polysaccharides (amylose)
- thousands of alpha glucose
- 1,4 glycosidic bonds oriented in same direction
- curved, unbranched chains
- hydrophilic, however too large to be soluble in water (doesn’t affect osmotic balance)
697
properties/function of polysaccharides (amylose+amylopectin)
- only made by plant cells
- molecules vary in size, easy to add/remove glucose units
- useful for glucose/energy storage, glucose can be converted to starch for storage then hydrolyzed when needed (amylopectin more ideal, more free ends)
698
structure of polysaccharides (glycogen)
- 10,000 alpha glucose
- chain of 1,4 glycosidic bonds w 1,6 bonded branches
- curved and branched chains
- lower solubility than glucose, doesn’t affect osmotic balance
699
properties/functions of polysaccharides (glycogen)
- compact, easy to add/remove
- good for storage since doesn’t affect osmotic balance (insoluble)
- stored in liver and muscles of human
700
structure of polysaccharides (amylopectin)
- 100,000 alpha glucose
- 1,4 chain, 1,6 branches
- oriented in same way throughout
curved + branched chains
- hydrophilic, but too big to be soluble in water (doesn’t affect osmotic balance)
701
function of testes
to produce sperm and testosterone
702
function of scrotum
holds testes at lower than core body temp
703
function of epididymis
stores sperm until ejaculation
704
function of sperm duct
transfers sperm during ejaculation
705
function of seminal vesicle and prostate gland
secrete fluid containing alkali, proteins and fructose that is added to sperm to make semen
706
function of urethra
transfers semen during ejaculation and urine during urination
707
function of penis
penetrates the vagina for ejaculation of semen near the cervix
708
function of ovary
produces eggs, oestradiol and progesterone
709
function of oviduct
collects eggs at ovulation, provides a site for fertilization then moves the embryo to uterus
710
function of uterus
provides for the needs of the embryo and foetus during pregnancy
711
function of cervix
protects foetus during pregnancy and then dilates to provide birth canal
712
function of vagina
stimulates penis to cause ejaculation and provides birth canal
713
function of vulva
protects internal parts of female reproductive system
714
what is tidal volume (TV)
amount of air that can be inhaled or exhaled during one respiratory cycle
715
what is vital capacity (VC)
total air exhaled after max. inhalation and vice versa
716
what is residual volume (RV)
volume of air remaining in lungs after max. exhalation
717
what is total lung capacity (TLC)
max volume of air lungs can accommodate
TLC = VC +RV
718
what is inspiratory reserve volume (IRV)
air forcibly inhaled after normal tidal volume (after normal inhale)
719
what is expiratory reserve volume (ERV)
air forcibly exhaled after exhalation of normal tidal volume
720
what is inspiratory capacity (IC)
max volume of air inhaled following resting state (normal exhale)
721
what is functional residual capacity (FRC)
amount of air remaining in lungs after normal exhalation
722
structure of transverse section of dicot root
- star in middle (xylem) with circles around it (phloem) surrounded by a thin layer of cells (endodermis)
- layer of unspecialized cell to bulk out root (cortex) surrounded by another layer of cells (epidermis)
723
plant plan diagram of stem
- has area in middle (pith) with a ring (cambium)
- on the inside of the ring, protrudes (xylem) and on the outside protrudes (phloem)
- surrounding the phloem is the (cortex) surrounded by the (epidermis)
724
plant plan diagram of a leaf
- from up to down: upper epidermis, palisade mesophyll, spongy mesophyll, lower epidermis
- vascular bundle b/w mesophyll with xylem on top and phloem under it
- guard cells/stomata in lower upidermis
725
positive vs negative vs no association in chi-squared test
pos: species are found in same habitat
neg: species occur separately in different habitats
no: species occur as frequently apart as together
726
what is the BRCA1 gene
- a proto-oncogene that codes for BRCA1 in humans
- tumor suppressor gene-> works in DNA repair, mends double strand breaks+fixes mispairings
727
consequences of mutation in BRCA1 gene
- increased risk of other mutations bcus lack of DNA repairs
- increases risk of breast/ovarian/prostate cancers
- >20,000 variants, some benign (same-sense) some inc. risk of cancer by +80% in women
728
how can cancer develop
- proto-oncogenes are normal genes involved in cell growth and division
- mutations in proto-oncogenes can convert them to oncogenes
- oncogenes are genes that can cause uncontrolled division of cells -> can develop into cancer
729
chromosomes in eukaryotes vs. prokaryotes
euk: linear (straight) structure, multiple, tightly bound to histone proteins, located in nucleus
prok: circular, usually only one, found within the nucleoid
730
purine vs. pyramidines
purine: double ring structure (adenine, guanine)
pyramidine: single ring structure (cytosine, thymine)
731
endothermic vs. exothermic
endo: absorb energy, typically heat, from their surroundings->decrease in the temperature of the surroundings
exo: release energy, typically heat, into the surroundings ->temperature of the surroundings increases
732
endocrine vs. exocrine glands (+examples)
endocrine: secretes hormones into bloodstream influencing organs (ex. pituitary, thyroid)
exocrine: secretes substances thru ducts on body's surface or into organs (ex. sweat, salivary)
733
what does plasmolysis mean
- water leaving plant cells, allowing the cytoplasm and plasma membrane to shrink away from the cell wall
734
what is biochemical oxygen demand
- amount of oxygen consumed by bacteria and other microorganisms while they decompose excess organic matter under aerobic conditions
- depletes O2 levels
735
what is leptin
- hormone produced by fat cells playing crucial role in regulating energy balance and signalling to brain abt appetite
- satiety signal helping to regulate hunger and food intake
736
what is leptin resistance
- leptin constantly stimulates brain, dont get sensation of being full
- causes body to enter starvation mode, using less calories, but consuming more
- leads to obesity
