Exam Review 4

Question 1

What are mutations?

Answer 1

Mutations are changes in the nucleotide sequence of DNA &; the ultimate source of new alleles.

Question 2

Sexual reproduction shuffles alleles to produce new combinations in what 3 ways?

Answer 2

1. Homologous chromosomes sort independently as they separate during anaphase 1 of meiosis.
2. During Prophase 1 of meiosis, pairs of homologous chromosomes cross over and exchange genes
3. Further variation arises when sperm randomly unite with eggs in fertilization

Question 3

What are the 3 main causes of evolutionary change?

Answer 3

1. Natural selection
2. Genetic drift
3. Gene flow

Question 4

What is genetic drift?

Answer 4

A change in the gene pod of a population due to chance.

Question 5

What is gene flow?

Answer 5

Results from the founder effect, when a few individuals colonize a new habitat.

Question 6

Can a small group adequately represent the genetic diversity in the ancestral population?

Answer 6

No it cannot!

Question 7

What does natural selection do?

Answer 7

Natural selection leads adaptive evolution and also is a blend of chance and sorting.

Question 8

Finish the sentence: an individuals relative fitness is the contribution it makes to the…

Answer 8

Gene pool of the next generation relative to the contribution of other individuals.

Question 9

Can everyone reproduce?

Answer 9

Not everyone gets to reproduce only the fittest individuals are those that produce the largest numbers of offspring.

Question 10

What does stabilizing selection favor?

Answer 10

Stabilizing selection favors immediate phenotypes acting against extreme phenotypes

Question 11

What does directional selection do?

Answer 11

It acts against individuals at one of the phenotypic extremes.

Question 12

What does disruptive selection favor?

Answer 12

Disruptive selection favors individuals at both extremes of the phenotypic range.

Question 13

Sexual selection is a form of?

Answer 13

Natural selection.

Question 14

What is sexual dimorphism?

Answer 14

In animal species, males and females show distinctly different appearances.

Question 15

What does sexual selection mean?

Answer 15

Individuals with certain characteristics are more likely than other individuals to obtain mates.

Question 16

What does Intrasexual selection (within the same sex) involve?

Answer 16

It involves competition for males, usually by males. “Fighting males”

Question 17

What is intersexual selection (between sexes) or mate choice, individuals of one sex (usually females)?

Answer 17

-that they are choosy picking their mates and often select flashy colorful mates. “Females pick”

Question 18

What prevents natural selection from eliminating unfavorable genotypes?

Answer 18

• in diploid organisms, recessive alleles are usually not subject to natural selection heterozygotes.

Also balancing selection.

Question 19

What is balancing selection?

Answer 19

Maintains stable frequencies cies of two or more phenotypes in a population.

Question 20

What is heterozygote advantage?

Answer 20

Heterozygotes have greater reproductive success than homozygotes.

Question 21

What is frequency dependent selection?

Answer 21

A type of balancing selection that maintains two different phenotypes in a population.

Question 22

The evolution of organisms constrained:

Answer 22

1. Selection can only act on existing variation. New, advantageous alleles do not arise on demand.
2. Evolution is limited by historical constraints. Evolution co opts existing structures and adapts them to new situations.
3. Adaptions are often compromises. The same structure often performs many functions.
4. Chance, natural selection, and the environment interact. Environments often change unpredictability.

Question 23

What are fossils?

Answer 23

Fossils are imprints or remains of organisms that lived in the past.

Question 24

What do fossils suggest?

Answer 24

That species changed over time.

Question 25

What is artificial selection?

Answer 25

When humans have modified species through selection and breeding.

Question 26

What is fossil record?

Answer 26

The sequence in which fossils appear within strata (layers) of sedimentary rocks.