Chapter 20

Question 1

What is Evolution?

Answer 1

Process of genetic change through time

Question 2

Define Genetic Variation

Answer 2

Raw material for natural selection

Question 3

Darwin’s definition for evolution

Answer 3

1. All species arise from pre-existing species
2. Over time, species accumulate differences such that descendant and ancestral species are not identified

Question 4

Define Natural selection

Answer 4

Differential reproduction and survival under natural conditions

Question 5

Lamarck’s evolution theory

Answer 5

Inheritance of acquired characteristics

Question 6

What are Allele frequencies?

Answer 6

How many of a specific allele exists in the population

Question 7

What is the Hardy-Weinberg equilibrium?

Answer 7

1. No mutation takes place
2. No gene flow from other sources
3. Random mating is occurring
4. Population size is large
5. No natural selection occurs

Question 8

Numerically, allele frequencies can vary. What’s the variation?

Answer 8

0 to 1

Question 9

What causes change in allele frequency?

Answer 9

1. Mutation
2. Gene flow
3. Non random mating
   4.Genetic drift
4. Natural selection

Question 10

Define mutation

Answer 10

Changes in genetic sequence

Question 11

Define gene flow

Answer 11

Exchange of genes between populations.

Question 12

Define genetic drift

Answer 12

Random changes. Occurs more often in small populations. Also causes bottlenecks and founder effects

Question 13

Bottlenecks

Answer 13

When the population crashes and only a small % remains

Question 14

Founder effect

Answer 14

Small segment of larger population becomes isolated in a new area.

Question 15

Heterozygous advantage

Answer 15

Favored over homozygotes
Works to maintain both alleles in population
Sickle cell anemia

Question 16

Sickle cell anemia

Answer 16

Hereditary disease affecting hemoglobin
Allele is recessive

Question 17

What agents of evolutionary change affect allele frequency?

Answer 17

Natural selection
Genetic drift
Gene flow
Mutations

Question 18

How many methods are there to measure genetic variation?

Answer 18

2

Question 19

What are the two ways to measure genetic variation?

Answer 19

Enzyme polymorphism and DNA sequence polymorphism

Question 20

Study of changes in gene frequencies in populations

Answer 20

Population genetics

Question 21

Selection that favors the mean of the population

Answer 21

Stabilizing selection

Question 22

Those at one end of the phenotype are favored

Answer 22

Directional selection

Question 23

Those at both extremes being favored over the mean

Answer 23

Disruptive selection

Question 24

Selection that favors rare phyenotypes

Answer 24

Negative frequency dependent selection

Question 25

A group of organisms of the same species living in the same area

Answer 25

Population

Question 26

Having more than 2 copies of your genome

Answer 26

Polyploidy