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Evolution Flashcards

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Biology 101 flashcards
1
Q

What is natural selection?

A

Natural selection is a mechanism for evolutionin which the individuals best adapted to theselection pressures in their environmentsurvive and pass on their alleles.

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2
Q

What is allele frequency?

A

How common an allele is in a population

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3
Q

What is a gene pool?

A

The combination of all the genes (and alleles) present in a reproducing population or species

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4
Q

What are mutations?

A

A change in the DNA sequence of an organism (can be inherited or acquired)

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5
Q

What are the four steps of natural selection?

A
  1. Variation in phenotypes
  2. Selection pressure
  3. Unfavorable and favorable phenotypes
  4. The fitter phenotypes will be passed onto offspring
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6
Q

Benefits of high genetic variation?

A
  • less likely to go extinct (higher chance of having more favorable traits)
  • low genetic variation increases likeliness of interbreeding
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7
Q

What is speciation?

A

formation of a new species (throughseparation of one species into two or more separate species)

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8
Q

What are the three stages of speciation?

A
  1. Variation
  2. Isolation
  3. Selection
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9
Q

What is genetic isolation for speciation?

A

Different groups must be prevented from interbreeding and gene flow, this stops any differences from one population reaching the other population

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10
Q

What are 5 types of selection pressures that lead to speciation?

A

Geographical: separation by physical barriers such as mountains, ocean
Ecological: different niches (ecosystems/habitats - forest, desert)
Temporal: different breeding cycles
Behavioral: Courtship behavior varies between species
Structural: differences in reproductive organs

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11
Q

What is the third step of speciation, and explain?

A

Natural selection affects the genotype and causes changes (mutations) that prevent the groups breeding even if they got back together. Differences in conditions of the two species would mean different characteristics are selected for in each population (predation, food availability).

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12
Q

What are homologous structures, and give example?

A

features of organisms with similar structure, closely related, but different functions
- human arm, bird wing, bat wing
- pentadactyl
- evolutionary relationship

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13
Q

What are analogous structures, and give example?

A

Features of organisms that look similar but genetically very different (no evolutionary relationship). - different structures but the same functions (because they share common environments), and not related
- sharks and dolphins fins
- bird wing, insect wing

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14
Q

What is divergent evolution?

A
  • When two or more species evolve from a common ancestor (formation of new species due to environmental change) - finches
  • Homologous structures
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15
Q

What is convergent evolution?

A
  • When two or more unrelated species adopt similar adaptations in response to common environmental conditions to have similar functions
  • analogous structures
  • sharks are a fish, dolphins are mammals, yet both need flippers to swim
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16
Q

How to determine if a new species is formed?

A

They are no longer capable of reproducing together

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17
Q

What the 5 steps to form a fossil?

A
  1. Organism dies
  2. Body is covered with sediment layers (rock). Soft tissues decompose and hard body structures become fossilized by permineralization
  3. Layers accumulate over time (due to pressure)
  4. Earth moves which moves layers of rocks to the surface
  5. Rock erodes, so fossil exposed
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18
Q

What are the best conditions for fossilization?

A

Sea is the best:
* Areas of rapid sediment accumulation
* Constant cool temperatures
* Low light availability
* Physical protection from scavengers and decomposers (fungi, bacteria)

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19
Q

What are transitional fossils?

A

Also called missing links. Darwin’s theory that life originated in sea, and crawled onto land + adapted (they are fossils with both sea, land and sky characteristics)

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20
Q

What is fossil dating?

A

Figuring out age of fossil by analyzing the atomic structure of fossils or by comparing their age to other fossils.

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21
Q

What is relative dating?

A

The location of a fossil in the strata gives indication of the time the animal lived. Can also provide information about which other species were living at the same time.

22
Q

What can index fossils do?

A

Index fossils within the strata can be used to determine the relative ages of fossils.

23
Q

What is absolute dating?

A

A method that uses the amount of radioactivity remaining in the rock surrounding the fossil to determine its age (date fossils up to 60,000 years old.) Most carbon in living things is carbon-12, but there is small amount of carbon-14. After death, unstable carbon-14 decays, but carbon-12 does not. The ratio between these can determine absolute age of fossil (looks at Carbon 14 half-life)

24
Q

What are the 6 forms of evidence of evolution?

A
  1. Biogeographical distribution
  2. Vestigial structures
  3. Embryology
  4. Fossils
  5. Comparative anatomy (bone structure)
  6. DNA and protein structure
25
Q

Explain biogeographical distribution

A

when a barrier splits a population, the species on each side of the barrier gradually become more different
- continental drift

26
Q

What are vestigial structures, and give examples?

A
  • structures that no longer perform the same function as in other organisms
  • organs were presumably important in ancestral species, but became redundant
    ▪ Appendix
    ▪ Coccyx bone
    ▪ Tonsils
    ▪ Wisdom teeth
27
Q

What is embryology?

A
  • all vertebrates have common features → some of these features can only be seen in the embryo stage
  • For example, turtle and human embryo are the same but each develops differently
  • notochord
  • dorsal, hollow, nerve cord
  • pharyngeal gills
28
Q

What is evolution?

A

The permanent change in the frequency of alleles in a population due to natural selection

29
Q

How are new alleles introduced into the gene pool?

A

Mutations

30
Q

What is gene flow?

A

Transfer of genetic material from one population to another

31
Q

What is allopatric speciation?

A

When geographical barriers isolate a population

32
Q

What is the study of fossils?

A

Palaeontology

33
Q

What are living fossils?

A

Existing species of ancient lineages that have not changed in form for a very long time (no change in selection pressures)

34
Q

What is half-life?

A

The time taken for radioactivity to decrease to half

35
Q

Some processes that will eventually expose fossils?

A

Erosion
Weathering
Mining

36
Q

Explain how a lack of genetic variation could ultimately lead to extinction unless the environment remains the same.

A

Variation is vital for natural selection to occur. If the environment changes, new selection pressures acting on the population will not be favorable to any individuals if they are all identical.

37
Q

2 pieces of evidence that support continental drift

A
  • Same species around whole world
  • Jigsaw puzzle
38
Q

What is continental drift?

A

The gradual movement of continents due to tectonic plates over millenia

39
Q

Explain relationship between amino acid, protein, and polypeptide

A

Amino acids are building blocks of proteins. They form a polypeptide chain, which are folded to form a protein.

40
Q

What is a protein?

A

The product of gene expression

41
Q

What is a sub-species?

A

A sub division of a species (some sub-species can still interbreed, such as dogs)

42
Q

Why do human embryos temporarily develop gill-like structures?

A

They have the genes for these structures, because they evolved from species that needed these gills. However, these genes are turned off during later embryo development stages

43
Q

Names types of selection pressures?

A
  1. Resource competition
  2. Predators
  3. Competition for mates
44
Q

What was Darwin’s and Wallace’s theory of evolution?

A

Natural selection

45
Q

What was Lamarck’s theory of evolution?

A

Organisms change over time due to changing environmental conditions. He stated that changes acquired in a lifetime could be passed on to their offspring, causing a gradual change in the species.

46
Q

How does DNA sequencing determine relatedness?

A

An analysis of the differences between the same protein in different taxa (levels of classification) gives an indication of species relatedness (the more similar the amino acids are, the more related they are)

47
Q

What is selective breeding?

A

Humans can select or remove particular traits from a population by directly controlling the breeding of animals and plants (they are the selection pressure)

48
Q

What are the 3 requirements for selective breeding?

A
  1. Variation
  2. Selection pressure
  3. Heritability (needs to be able to be passed on)
49
Q

What is the difference between selective breeding and natural selection?

A

Selective breeding is artificial selection pressure (humans)
Natural selection is environmental selection pressure (predation, climate change, disease)

50
Q

What does survival of the fittest mean?

A

Refers to individuals with the best suited physical features for a given environment to survive, reach sexual maturity, and reproduce.

51
Q

What is genetic drift?

A

the change in gene frequency in a population due to random chance

52
Q

What is directional selection?

A

Mode of natural selection in which an extreme phenotype is favored over other phenotypes

Science (5 decks)

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