Ib bio > unit 12 > Flashcards

unit 12 Flashcards

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1
Q

what were the conditions of pre biotic earth

A

atmosphere was mainly methan and CO2-very hot
No ozone layer-high UV exposure
very unstable- no protection- many storms and meteorites

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2
Q

how did Earth’s early atmosphere lead to life

A

molecules and processes were unstable- and constantly changing which lead to 1st organic molecules

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3
Q

what did life do to earth

A

changed inorganic molecules
increased its stability

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4
Q

why is it hard to pinpoint beginning of life

A

the processes are so complex. living things cant just come from nothing
removing one process in a living thing means it cant live

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5
Q

what is life defined as

A

the ability to remain stable and pass that stability on over and over

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6
Q

why is there debate if viruses are living

A

they carry many processes of life except they cannot reproduce- maybe couldve at one point

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7
Q

what is considered smallest living things

A

cells

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8
Q

cells evolutionary path

A

cells-parent cells-primates-mammals-vertebrates-eukaryotes-prokaryotes-original prokaryote

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9
Q

ideas of progressive change in cells

A
  1. had to have control over chemical reactions-using original enzyme
  2. some way to self assemble own molecules to build up
  3. compartmentalization of processes
  4. controlled self replication
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10
Q

best way to estimate time

A

carbon dating: based off carbon isotopes in rock

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11
Q

why is carbon dating difficult to find how old life is

A

rocks change
hard to find rocks that old especially ones with life
used to be just single celled organisms-no fossils

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12
Q

What is the strelley pool formation of australia

A

-made of calcium carbonate deposits-make coral reefs
-best guess of oldest evidence of life

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13
Q

how are rate of mutations used to estimate time

A

-how often mistakes made, transcribed, harmful,beneficial, passed down
-how much DNA is different and how long it took for differences to form show how old life is
-mathematical models used

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14
Q

what genes passed on from LUCA to all living things

A

anaerobic respiration genes-some use nitrogen or other chemicals

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15
Q

what are hydrothermal vents

A

cracks in Earth’s surface-heat and chemicals coming out

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16
Q

how does the idea of hydrothermal vents suggest age of life

A

original organism could turn chemicals into energy-fits with Miller and Urey because it was probably underwater not exposed to atmosphere
fossilized biochemicals 4.5 bill years old found near vents

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17
Q

what was the miller-urey experiment

A

2 scientists set up experiment to recreate early atmosphere gases including ammonia
-used boiled water to make it hot
-storms with electrodes attached
-cold water pumped in to cause condensation of molecules
amino acids formed- organic molecules from inorganic

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18
Q

problem with Miller Urey experiment

A

there was to much control
probably wrong combination of gases-ammonia probably didn’t exist-has nitrogen which amino acids use

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19
Q

how did the first vesicle form

A

automatic formation of sphere because of phospholipids placed in water- ampipathic membrane
-water had to be liquid form

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20
Q

significance of first vesicles

A

high probability more organic molecules formed inside
could have started compartmentalization

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21
Q

what is the contradiction with where first genetic information came from

A

we need enzymes to make copies of DNA but DNA makes enzymes

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22
Q

likely answer to where 1st genetic information came from

A

RNA-less complex, 1 strand, easier to copy
-some viruses use RNA as genetic material
-ribosomes made of rRNA
-translation is similar to enzymatic reactions
-active sites similar to binding sites(ribozymes)
-RNA can act as genetic material and enzyme to pass along traits

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23
Q

best evidence that we probably have common ancestor

A

-all living things have same genetic code(codons code for same things, unlikely coincidental)

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24
Q

explanation to why the genetic code can be evidence for UCA even with mitochondria and chloroplast

A

those prokaryotes the organelles came from were out competed by organisms with our genetic code

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25
what is LUCA
last universal common ancestor
26
what does the biological species concept state
if 2 organisms can produce fertile offspring, they are the same species -share gene pool: all genes available to population to pass on
27
exception to biological species concept
separated organisms that cant mate different mating times/habits -fertile hybrids -asexual organisms -horizontal gene transfer
28
what is horizontal gene transfer
different species passing genes back and forth- sharing gene pool -spreads antibiotic resistance more than natural selection
29
why are horses and donkey different species
they have different chromosome numbers horse(64, n=32) + donkey(62, n=31)= mule(63, odd number)
30
why do organisms need to have same chromosome number to be same species
-to inherit same amount from each parent during meiosis-each gamete has 1/2 of resulting offspring after fertilization -have to have homologous chromosome pairs -prevent 2 species from mating together because there would be overlapping niches/competitive exclusion and evolution couldn't happen
31
what are homologous chromosomes
same zsize but not identical. we have 2 chromosome 1s-one from each parent 1 is biggest, 2 is second biggest and so on
32
difference in chromosomes across species
different masses
33
how can environmental DNA be used to identify species
scanning DNA by looking for specific genes, sequencing them, using database to say that certain gene would only be from certain species -sometimes fragments left behind can be used to identify general category of organism -helpful to see how we are affecting the amounts of these organisms
34
how can water samples help with identifying species
have a lot of DNA for many organisms even microscopic ones
35
what are dichotomous keys
easiest used for looks/ physical traits start with general, then grouped more and more specific until original organism reached- 2 choices ex: wings/ no wings
36
what is the need for classification
there are trillions of organisms can be used to infer that an organism has same trait ex: daffodil having chemicals used in medicine
37
why are organisms classified broad to specific
common ancestor gives broadly shared traits- ex: backbone can identify new organisms using ones we know about a lot organism probably has new trait that makes it unique
38
difficulties with classifying organisms
its a made up thing evolution is random and unpredictable-doesnt follow patterns mating is random
39
what is taxonomy
study of grouping organisms -breaks down prettyfast- can be made more complicated by DNA
40
what is a clade
group of organisms that all come from common ancestor all organisms must be listed to call it a clade
41
size of clade
larger: more ancient or more successful
42
example of organism with small clade but ancient
Ginko trees: evolved 100s of millions of years ago and haven't change own entire phylum- not closely related to other trees
43
how can common ancestors be found
DNA helps the most Comparing physiological traits using fossils- slim chance same traite came from diff ancestor- main way to determine extinction
44
difficulties with seeing when clades diverged
we don't have every fossil so its hard to see how organism evolved hard to see how old fossil is
45
how can we estimate when clades diverged
molecular clock: looking at differences in DNA and finding rate of mutations-looking at genome vs transcriptome vs proteome- 1 billionth of DNA molecules changes per year
46
uncertainties with using molecular clock
differences in organisms -bacteria reproduce- really fast- more mutations -how many are reproducing-flucuates because of environment
47
when did chimps and banobos diverge vs chimps and humans
chimps and banobos: 1 mill years ago chimps and humans: 4.5 bill- look more different
48
what is a cladogram
shows how clades are connected to each other -constructed using molecular clock -uses probability- how much DNA/traits in common -dont show exctinction/not extinct -software can be used to create
49
what is the principle of parsimony
simplest answer=probably correct answer
50
what do branches of cladograms show
divergence from common ancestor
51
how to analyze cladogram
which ones more/less related, where common ancestor is
52
end of cladogram branches
terminal branches
53
divergence in cladograms
nodes
54
bottom/beginning of cladogram
root- Luca for that group
55
what is cladistics
using cladograms to figure out what group organisms should be put in -groups not classes led to many reclassification of organisms
56
how can cladistics lead to reclassification
Domain being added, groups added, deleted and rearranged
57
example of organism being reclassified because of cladistics
Figwarts: type of plant -used to be 1 family, cladistics made us realize they don't have as much in common as we though -split into multiple families
58
what was the original top group
kingdom-was only plants and animals until we added fungus, protista, and prokaryotes
59
why prokaryotes had to be split into two groups
prokaryotes can be very different from each other-fundamentally different
60
what domains are there now
bacteria and Archaea and eukaryotes
61
differences between Archaea and bacteria
-rRNA sequences- some similar to eukaryotes -archaea have introns(like humans), bacteria only exons -archaea has proteins around DNA -different molecules in outer layer -hypothesis is that we diverged from archaea
62
what is speciation
when a new species is created-cannot interbreed with organism it just evolved from anymore -separated gene pools
63
2 kinds of speciation
allopatric: geographic separation that causes accumulation of changes ex: Galapagos lava lizards, chimps and banobos Sympatric speciation: behavior speciation like mating habits change-gene pools change
64
2 speciation examples
cichlid fish- sexual selection winter pine moths- allopatric
65
what is adaptive radiation
small changes in organisms to fit into unique niches in an area to limit competition -not based on geography -galapagos finches, bromeliads
66
hybridization
-2 diff species mate- usually results in infertile offspring -waste of resources, cant fill niche because it cant reproduce - could cause extinction or speciation
67
how have organisms evolved to avoid hybridization
-different mating behaviors -differently shaped reproductive parts -gametes cant fertilize more apparent as environment changes
68
what is abrupt speciation
making new species in 1 generation
69
why are plants more likely to hybridize
-all have same form of pollen-similar sexually reproducing cells - most make seeds- grow same way
70
what is stem cutting and grafting
cutting piece of plant and glueing to another-creates hybrid
71
what does polyploidy mean
too many sets of chromosomes pollen is supposed to be haploid but can be diploid- results in triploid cell- uneven # diploid-+diploid-=tetraploid ex: knotweeds and smartweeds
72
what is a gene pool
all available alles to a population that can be passed on- only coding DNA has to be breeding unique to each population
73
what is allele frequency
amount of alleles- dominant vs recessive -different for each gene pool
74
how can we track our original gene pool
because they used to be separated. genes put in database to figure out where we are from because some genes can only come from certain race
75
how can allele frequency lead to evolution
it can create new traits and if it helps the organism the allele will get passed on and the frequency will increase. if 2 populations change enough and cant breed anymore, evolution has occurred evolution: change in allele frequency
76
what is neo darwinism
how DNA and alleles are connected to evolution DNA creates trait, trait is favorable, DNA is passed on
77
types of selection
stabilizing selection: when average trait becomes most common- most common- type disruptive selection: both extremes more common, average becomes much less directional selection: 1 extreme becomes more common- also common -usually due to change in environment
78
stabilizing selection example
birthweight too big, mother in danger and cant provide nutrients too small, child in danger
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disruptive selection example
crossbill bird- bill crossed more in either direction. if bills are linked up(average) it cant cut its seeds
80
directional selection example
height- average is much taller now
81
what is artificial selection
humans selecting traits to create new phenotype what traits taste better, survive better etc
82
artificial selection examples
dog breeds race horse crops- corn used to be all different, now all same
83
what has artificial selection done to genetic variation
drastically decreased, concerning if something wipes them all out
84
what is genetic equilibrium
idea that all alleles in a population have an equal chance of being inherited -means natural selection isnt happening-1 alleleisnt more beneficial -gene pool not changing
85
what conditions create equlibrium
1. nothing automatically changes allele frequency(mutations) 2. no sexual selection-no preferred traits for mating 3. no immigration or emigration 4. large population-randomness has lower effect, more likely same alleles passed on 5. no environmental changes
86
what is genetic drift
alleles increase or decrease because they just happened to be passed down -affects small populations more
87
how to estimate quilibrium
hardy-weinberg equation
88
what are the 2 Hardy Weinberg equations
p+q=1 p^2+2pq+q^2=1
89
Hardy Weinberg variables
p=frequency of dominant allele q=freq of recessive allele p^2=freq of homozygous dominant genotype q^2=freq of homozygous recessive 2pq=freq of heterozygous
90
what if equilibrium isn't found
natural selection has occured
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