bio 114 > exam 3 > Flashcards

exam 3 Flashcards

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1
Q

evolution

A

change in inherited characteristics of a group of organisms over generations
- populations evolve, individuals do not

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2
Q

six types of evidence for evolution

A
  1. direct observation of evolution through artificial selection
  2. fossil evidence
  3. shared characteristics among living organisms
  4. similarities and differences in DNA
  5. biogeographic evidence
  6. common patterns of embryo development
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3
Q

artificial selection

A

brought by selective breeding
selective breeding: humans allow only individuals with certain characteristics to mate

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4
Q

natural selection

A

individuals w advantageous inherited characteristics survive + reproduce more than those w less useful characteristics

  • environment chooses winners
  • characteristics of individuals that breed most successfully become more common in successive generations
  • overall changes seen across popuulation
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5
Q

homologous trait

A

similar features in species that have common descent
- features may begin to look different over time

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6
Q

vestigial trait

A

features that are inherited from a common ancestor but no longer used

may appear as reduced or degenerated parts whose function is hard to discern

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7
Q

theory of common descent

A

all species living and extinct are descended from ancient common ancestors

all life on earth shares a common genetic heritage

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8
Q

why do distantly related species have similar DNA

A

they share a common ancestor
- theory of common descent

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9
Q

adaptation

A

evolutionary process where population becomes better matched to environment over time via natural selection

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10
Q

fossils

A

mineralized remains or impressions of formerly living organisms

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11
Q

fossil record

A

enables biologists to reconstruct life’s history on earth

evidence for species evolution

depth from earth’s surface creates a timeline

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12
Q

transitional fossils

A

evidence of species w similarities to the ancestral group and similarities to descendent species

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13
Q

common ancestor

A

single organism from which many species have evolved

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14
Q

common descent

A

when a group of organisms share a common ancestor

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15
Q

biogeography of species

A

geographic locations where its fossils are found

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16
Q

embryonic development

A

how an embryo grows and develops
- may mirror early developmental stages of ancestral forms
- shared patterns among species caused by descent from common ancestor

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17
Q

why does evolution only occur in populations + not individuals

A

evolution corresponds to changes in a population’s allele frequency over time
- allele frequencies in a population change (become more or less common) -> phenotypes of population change
– population evolves

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18
Q

directional selection

A

individuals at one EXTREME of an inherited phenotypic trait have advantage over other individuals in population
- most common

ex. big, medium, small mice. big mice have advantage

ex. the peppered moth

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19
Q

stabilizing selection

A

individuals w intermediate values of an inherited phenotypic trait have an advantage

ex. big, middle, small mice. MIDDLE mice
ex. birth weight in humans

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20
Q

disruptive selection

A

individuals with either extreme of an inherited trait have an advantage

ex. big, middle, small mice. BIG and SMALL mice
- least commonly observed in nature

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21
Q

how natural selection results in increased reproductive success of population in its environment

A

natural selection makes more helpful trains more common, making the population better adapted to its environment

-> inc reproductive rate

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22
Q

how dna mutations create new alleles at random

A

dna mutation -> different sequence of genes -> new alleles

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23
Q

genetic drift

A

random changes in genetic makeup of population over time by chance
(not because some are better or worse)
- more likely to cause evolution in small populations

two main types:
- genetic bottleneck
- founder effect

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24
Q

genetic bottlenecks

A

drop in size of population for at least one generation
- causes loss in genetic variation–> severe inbreeding

ex. florida panther

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25
founder effect
occurs when small group breaks off from larger population and starts a new population somewhere else ex. dutch colonists in south africa
26
alleles
different version of same gene (sequence of DNA) produced by random mutation
27
allele frequencies
proportions of specific alleles in a population
28
four mechanisms of evolution
1. natural selection 2. mutation 3. gene flow 4. genetic drift | NEVER MAKE GRANDMA GRUMBLE
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three common patterns of natural selection
1. directional selection 2. stabilizing selection 3. disruptive selection
30
convergent evolution
when distantly related organisms evolve similar structures because they survive and reproduce under similar environmental pressures - organisms appear vastly similar despite vastly dissimilar genetics ex. streamlined bodies of sharks and dolphins
31
analogous traits
features that look similar / work in similar ways in diff species BUT not because the species shares a close ancestor - usually because they share similar environment result of convergent evolution
32
mutation
change in sequence of any segment of DNA in an organism - only way new alleles are generated in a species - new genetic variation
33
horizontal gene transfer
process by which bacteria pass genes to one another
34
conjugation
process where bacteria send small circular pieces of DNA called plasmids to each other through small tubes
35
gene flow
exchange of alleles between populations ex. horizontal gene transfer in bacteria
36
adaptive traits
lead to higher biological fitness - structural traits, biochemical traits, behaviors - enable a species to survive and reproduce in their unique environment
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biological fitness
survival and successful reproduction
38
biological species concept
a species is a group of natural populations that can be interbreed to produce fertile offspring and cannot breed with other such groups - does not always apply - often impractical to test
39
speciation
process by which one species splits to form two or more species occurs bc of genetic divergence
40
genetic divergence
accumulation of differences in DNA sequences of genes in 2 or more population - results in populations becoming more and more genetically dissimilar
41
allopatric speciation
formation of new species from geographically isolated populations
42
sympatric speciation
formation of new species in the absence of geographic isolation - common in plants and in the ocean and other large bodies of water
43
reproductive isolating mechanisms
prezygotic: ecological isolation, behavioral isolation, mechanical isolation, gametic isolation postzygotic: zygote death, hybrid sterility, hybrid performance
44
coevolution
when two species strongly rely on each other for survival to the point where they evolve in tandem
45
adaptation
trait that helps an organism survive and reproduce better in an environment process by which those helpful traits become more common in a population over time - can be advantageous to an individual or a population - can be evolutionary process of natural selection that enables good match between population and environment
46
generation time
average age difference between parent of offspring-- time it takes to produce a new generation
47
species
members of a group that can mate with one another to produce fertile offspring
48
species are identified and distinguished by
biogeographical info dna sequence similarity morphology (physical characteristics) ability to interbreed
49
geographic isolation
physical separation between populations - one of the most common ways new species form - little or no gene glow between populations - can occur when few members of a species colonize a region that is difficult to reach
50
ecological isolation
idea that two closely related species in the same area are reproductively isolated by minor differences in habitat
51
reproductive barrier
exists between two species when they are prevented from reproducing with each other divided into 2 categories: 1. prezygotic 2. postzygotic
52
prezygotic barriers
prevent a male gamete and a female gamete from fusing to form a zygote - act before zygote exists
53
postzygotic barriers
prevent zygotes from developing into fertile offspring - act after zygote is formed
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polyploidy
a condition in which an individual gains an extra full set of two or three chromosomes - can result in formation of a new species in a single generation - common in plants, also found in some animals - invariably fatal in people
55
critical events on timeline of life on Earth
earliest forms of life from water cambrian explosion: great inc in biodiversity devonian period: earth covered in plants
56
evolutionary tree
shows how diff plants, animals, etc. are related to each other make these trees by comparing DNA, body features and chemistry to see which organisms share common ancestors + how they change over time
57
linnaean system
system of biological classification
58
classify given species at each level of the linnaean system
species genus family order class phylum kingdom Silly Goats Fight Over Cold Plastic Kites
59
impact of prehistoric mass extinctions on earth's biodiversity
- entire groups of organisms perish - alters course of evolution if it wipes out dominant group
60
universal ancestor
ancestral cell placed at the base of the tree of life
61
biodiversity
variety of all the world's living things interactions w each other ecosystems they inhabit
62
domains
highest, most inclusive hierarchical level in the organization of life 3 domains: - bacteria - archaea - eukarya
63
prokaryotes
bacteria and archae - rapid reproduction - single celled organisms - no membrane closed organelles - make up more than 2/3 of life on earth - reproduce through binary fission
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eukaryotes
all plants, animals, fungi and many single celled organisms -
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lineage
line of descent
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clade
branch on evolutionary tree includes given ancestor and all its descendents
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nodes
marks the movement in time when an ancestral group split / diverge into two separate lineages represents most recent common ancestor
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three kingdoms of eukarya
fungi: mushroom, mold, yeast animalia: all animals protists: amoebas and algae
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causes of mass extinctions
climate change massive volcano erruptions changes in composition of marine and atmospheric gasses sea level changes
70
adaptive radiation
when group of organisms expands to take on new ecological roles and to form new species and higher taxonomic groups - great adaptive radiations in history of life occurred after mass extinctions
71
archaea environments
extremely hot, extremely cold, extremely salty, no oxygen, etc.
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microbes
microscopic organisms, primarily bacteria
73
human microbiome
complete collection of microbes that live in and on our cells and bodies affects - human gut health - brains - body odor - risk of infection - how attractive you are to other people - how attractive you are to mosquitos
74
citizen science
public plays a part in research in cooperation w professional scientists by: - contributing data - collecting data - analyzing data
75
basic structural plan of bacteria and archaea
- protective cell wall that surrounds plasma membrane - some have capsule around cell wall - short hairlike pili (links together and attaches to surfaces) - flagella propels bacterium through liquid
76
quorum sensing
system of cell to cell communication enables them to sense and respond to other bacteria in the area
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bacterial conjugation
bacterium can directly trade dna with another bacterium
78
sporulation
some types of bacteria undergo this - formation of thick walled dormant structures (spores) - survive boiling and freezing - allow microbes to hang out for a long period until conditions are favorable to reproduce - antibiotics cant kill this
79
two metabolic types of prokaryotes
aerobes: need oxygen to survive anaerobes: - don't use oxygen and survive without it - some are methanogens (feed on hydrogen to produce methane gas) - some perform fermentation
80
types of prokaryotes
1. heterotrophs 2. autotrophs
81
heterotrophs
type of prokaryotes - consumers (obtains energy by taking it from other sources) divided into chemoheterotrophs photoheterotrophs
82
autotrophs
type of prokaryote - producers, make food on their own 2 types: chemoautotrophs photoautotrophs
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chemoheterotrophs
type of heterotroph consume organic molecules to get energy and carbon
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photoautotrophs
type of heterotroph acquire carbon from organic sources but their energy from sunlight
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chemoautotroph
type of autotroph acquire carbon from carbon dioxide and energy from inorganic chemicals in their environment
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photoautotroph
type of autotroph absorb the energy of sunlight and take in carbon dioxide to conduct photosynthesis
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nitrogen fixation
process by which bacteria can take nitrogen gas from the air and convert it to ammonia
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decomposers
consumers that extract nutrients from the remains of dead or dying organisms and from waste products (urine and feces) - play crucial role in nutrient cycling
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nutrient cycling
breakdown of dead organisms - releases important elements back into soil, water and air - autotrophs use elements to make food, heterotrophs eat plants to get nutrients a cycle.
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dysbiosis
when the human microbiome shifts out of balance - may cause illness
91
cellular structures unique to prokaryotes
plasmid: small circular piece of DNA separate from main chromosome - carries extra genes capsule: sticky outer coating made of sugars or proteins, found outside cell wall - protects cell from dying out - helps bacteria stick to surfaces
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