Term test Ch.20

Question 1

Gene pool

Answer 1

Consists of all alleles present in all of the individuals in the species

Question 2

Two sources of genetic variation

Answer 2

1. Mutation
2. Recombination followed by segregation of homologous chromosomes during meiotic cell division(shuffling of genes basically)

Question 3

Somatic mutations

Answer 3

Occur in non-reproductive cells

Question 4

Germ-line mutations

Answer 4

Occur in reproductive cells

Question 5

What are allele frequencies

Answer 5

% of the population which has a certain allele

Question 6

When a population is fixed for an allele

Answer 6

We mean population exhibits only one allele for a particular gene

Question 7

Why can’t we observe traits

Answer 7

They are usually encoded by a large number of genes

Question 8

Can evolution occur without allele frequencies changing

Answer 8

No, it cannot occur without allele frequencies changing

Question 9

For a population to be in Hardy-Weinberg equilibrium

Answer 9

1. No difference in survival and reproductive success of individuals
2. The population is large enough to prevent sampling errors
3. The population are not added to or subtracted from by migration
4. There is no mutation
5. Individuals mate at random

Question 10

Are neutral mutations affected by natural selections

Answer 10

Neutral mutations aren’t affected by natural selection

Question 11

Sexual selection

Answer 11

Evolution of traits that increase individuals mating options

Question 12

Intrasexual Selection

Answer 12

Individuals of same-sex compete with each other

Question 13

Intersexual selection

Answer 13

male/female interactions that result in traits such as elaborate plumage in male birds

Question 14

Fitness

Answer 14

How adapted an organism is to its environment

Question 15

Positive Selection

Answer 15

Natural selection increasing frequency of an advantageous allele

Question 16

Negative Selection

Answer 16

Natural selection decreasing frequency of a deleterious allele, and are usually recessive

Question 17

Balancing Selection

Answer 17

Natural selection acting to maintain two or more alleles in a population

Question 18

Heterozygote advantage

Answer 18

Heterozygote’s fitness is higher than that of either of the homozygotes, resulting in selection that ensures both alleles remain in the population at intermediate frequencies

Question 19

Stabilizing selection

Answer 19

Maintains status quo and acts against extremes such as baby birth weight, too low or too high and it’s dead

Question 20

Directional selection

Answer 20

Leads to change in trait over time such as Darwin’s finches

Question 21

Genetic drift

Answer 21

Random change in allele frequencies by chance from generation to generation

Question 22

Population bottleneck

Answer 22

Originally a large population reduced to a few individuals

Question 23

Founders event

Answer 23

Few individuals starting a new population

Question 24

Gene flow

Answer 24

Movement of alleles from one population to another

Question 25

Molecular evolution

Answer 25

When 2 species have diverged genetically

Question 26

Molecular clock

Answer 26

Correlation between the sequence differences among species and the time since common ancestry of those species