Unit 7: Chapter 23

Question 1

natural selection acts on ______, whereas only ______ evolve

Answer 1

individuals

populations

Question 2

population genetics

Answer 2

the study of how populations change genetically over time

Question 3

population

Answer 3

localized group of individuals capable of interbreeding and producing fertile offspring

Question 4

gene pool

Answer 4

all of the genes in a population at any one time

Question 5

hardy Weinberg theorem use

Answer 5

used as a benchmark to measure evolution against

Question 6

the hardy Weinberg theorem states that frequencies of alleles and genotypes in a population’s gene pool ________

Answer 6

remain constant from generation to generation

Question 7

five conditions for hardy Weinberg equilibrium

Answer 7

large population
no gene flow
no mutations
random mating
no natural selection

Question 8

p

Answer 8

frequency of the dominant allele

Question 9

q

Answer 9

frequency of the recessive allele

Question 10

p^2

Answer 10

percent of individuals with the homozygous dominant genotype

Question 11

q^2

Answer 11

percent of individuals with the homozygous recessive genotype

Question 12

2pq

Answer 12

percent of individuals with the heterozygous genotype

Question 13

the two hardy Weinberg equations

Answer 13

p + q = 1

p^2 + 2pq + q^2 = 1

Question 14

mutations

Answer 14

changes in the nucleotide sequence of DNA that cause new genes and alleles to arise

Question 15

point mutation

Answer 15

change of one base in a gene

usually harmless

can have a significant impact on phenotype

Question 16

______ and ______ produce the variation that makes evolution possible

Answer 16

mutations and sexual recombination

Question 17

three major factors the alter allele frequencies and bring about the most evolutionary change

Answer 17

natural selection

genetic drift

gene flow

Question 18

genetic drift

Answer 18

describes how allele frequencies fluctuate unpredictably from one generation to the next

tends to reduce genetic variation trough a loss of alleles

the smaller the sample, the greater chance of deviation from a predicted result

Question 19

genetic drift: bottleneck effect

Answer 19

sudden change in the environment that may drastically reduce the size of a population

resulting gene pool may no longer resemble the original population’s gene pool

Question 20

genetic drift: founder effect

Answer 20

a few individuals become isolated from a larger population

can affect allele frequencies in the population

Question 21

gene flow

Answer 21

genetic additions or subtractions from a population resulting from the movement of fertile individuals or gametes

causes a population to gain or lose alleles

tends to reduce differences between populations

Question 22

discrete characters

Answer 22

variation that can be classified on an either-or basis

punk or white or red flowers

Question 23

quantitative characters

Answer 23

variations that vary along a continuum within a population

race
IQ

Question 24

phenotypic polymorphism

Answer 24

a population in which two or more distinct forms of a character are represented phenotypically

discrete characters

Question 25

genetic polymorphisms

Answer 25

heritable components of characters that occur along a continuum in a population

quantitative characters

Question 26

geographic variation

Answer 26

a difference between gene pools of separate populations

Question 27

fitness

Answer 27

the contribution an individual makes to the gene pool of the next generation compared to the contributions of other individuals

Question 28

relative fitness

Answer 28

the contribution of a genotype to the next generation compared with the contributions of other genotypes

Question 29

directional selection

Answer 29

favors individuals at one end of the phenotypic range

only shades of dark fur OR only shades of light fur

Question 30

disruptive selection

Answer 30

favors individuals at both extremes of the phenotypic range

only very light fur AND very dark fur

Question 31

stabilizing selection

Answer 31

favors intermediate variation and acts against extreme phenotypes

medium colored fur

Question 32

diploidy

Answer 32

maintains genetic variation in the form of hidden recessive alleles that can appear again

Question 33

balancing selection

Answer 33

when natural selection maintains stable frequencies of two or more phenotypic forms in a population

also called balanced polymorphism

Question 34

heterozygous advantage

Answer 34

some heterozygous individuals have a greater fitness than homozygous individuals

this maintains the passing on of both the dominant and recessive alleles

Question 35

sexual selection

Answer 35

natural selection for mating success

can result in sexual dimorphism

Question 36

sexual dimorphism

Answer 36

differences between sexes in secondary sexual characteristics

Question 37

INTRAsexual selection

Answer 37

direct competition amongst individuals of one sex for mating rights to the other

Question 38

INTERsexual selection

Answer 38

also called mate choice

individuals of one sex (usually females) are picky in selecting their mates from the other sex

Question 39

microevolution

Answer 39

change in the genetic makeup of a population from generation to generation