chapter 20

Question 1

mutations in skin cells that are non-heritable are [blank] mutations, whereas mutations that can be passed on from parent to offspring are referred to as [blank] mutations.

Answer 1

somatic, germline

Question 2

• shifts the population mean
• one extreme trait is favored
  what type of selection is this?

Answer 2

directional

Question 3

when calculating the allele frequency of allele A in a population, why do we multiply the frequency of individuals who are homozygous for A by 2?

Answer 3

because each individual who is homozygous for A has two copies of the allele.

Question 4

in a population of mendel’s garden peas, the frequency of green-flowered plants (genotype aa) is 49%. The population is in Hardy Weinberg equilibrium. What are the frequencies of the AA and Aa genotypes?

Answer 4

9% AA, 42% Aa

Question 5

which type of selection decreases overall phenotypic variation in a specific trait?

Answer 5

stabilizing selection

Question 6

what does the term 2pq represent in the Hardy-Weinberg equilibrium?

Answer 6

the frequency of heterozygotes

Question 7

what does variation promote?

Answer 7

survivorship and/or reproduction

Question 8

what is one major mechanism of evolution?

Answer 8

natural selection

Question 9

define gene pool

Answer 9

consists of all the alleles that are present in all individuals in a species or population

Question 10

what causes variation?

Answer 10

it can be caused by genetic differences p, or due to environmental effects

Question 11

what’s the ultimate source of genetic variation?

Answer 11

mutation

Question 12

what type of mutation cannot be passed on to the next generation?

Answer 12

somatic cells

Question 13

what are germ cells?

Answer 13

sperm and egg

Question 14

which cell mutation is the only type that can impact evolution?

Answer 14

germ cells

Question 15

what is a deleterious mutation?

Answer 15

a negative impact on survival or reproduction

Question 16

what is an advantageous mutation?

Answer 16

they have a positive benefit on survival and reproduction or they might be neutral

Question 17

what is the other way of producing genetic variation?

Answer 17

recombination

Question 18

how do we get the allele frequency?

Answer 18

the number of copies of an allele divided by the total number of alleles

Question 19

what is the fixation of an allele?

Answer 19

all individuals in a population possess the same allele; it’s frequency is 1.0

Question 20

how do we calculate allele frequencies?

Answer 20

number of copies of an allele / total number of alleles in a population?

Question 21

the hardy-weinburg equilibrium is also known as a…?

Answer 21

null model (meaning a model of no change)

Question 22

what is the frequency of homozygous individuals?

Answer 22

p^2 and q^2

Question 23

what is the frequency of heterozygous individuals?

Answer 23

2pq

Question 24

what five key conditions need to be met in order for a population to be in Hardy-Weinburg equilibrium?

Answer 24

1. there can be no natural selection happening
2. no migration
3. no mutation
4. no genetic drift
5. individuals must mate at random

Question 25

no genetic variation means...

Answer 25

no natural selection

Question 26

an individual that is best adapted to survive due to advantageous alleles can do what?

Answer 26

- leave more offspring - can be passed on to the next generation

Question 27

when it asks you a question about an organism being the most fit, remember to choose the answer focused on reproduction.

Answer 27

!

Question 28

what are the three types of selection?

Answer 28

(1) positive (2) negative (3) balancing

Question 29

directional selection occurs when environmental pressures favor one phenotype more than another.

Answer 29

!

Question 30

which selection maintains the status quo and acts against extremes?

Answer 30

stabilizing (think of the black and white animal that can't survive in said environment, in a stabilizing environment the grey animal is likely to survive. another example is if a baby is too heavy or too light there may be complications, therefore the optimal birth weight would be in between these two extremes)

Question 31

which selections selects against the mean?

Answer 31

disruptive (it's basically a preference to the extremes over the intermediate traits)

Question 32

what is artificial selection?

Answer 32

it’s man made / manipulated

Question 33

sexual selection influences what and does not improve what?

Answer 33

it influences your ability to get a mate and does not improve survival or reproductive success

Question 34

whats the difference between intersexual and intrasexual?

Answer 34

intersexual is one sex has a preference for the opposite sex trait while intrasexual the same sex creates a competition to have access and win over the other sex

Question 35

the correlation between the time two species have been evolutionary separated and the amount of genetic divergence between them is known as…

Answer 35

the molecular clock

Question 36

distinct populations of an ancestral species separate and diverge through time, again and again, giving rise to multiple descendant species, this is the definition of…

Answer 36

phylogeny

Question 37

competition among members of one sex for access to the other sex results in (blank) selection A. disruptive B. sexual C. directional D. stabilizing

Answer 37

the answer is B. sexual

Question 38

in genetics, two individuals are part of the same population if : select al that apply A. they are the same species B. they are in the same geographic area C. they have the same phenotype D. they are from different gene pools

Answer 38

the answer is A and B

Question 39

if a populations is not in hardy-weinberg equilibrium, we can conclude that: A. nonrandom mating has occurred B. natural selection has occurred C. one of the assumptions of the hardy-weinberg equilibrium has been violated. D. evolution has occured because one or more of the assumptions of the hardy-weinberg equilibrium has been violated. E. all of these choices are correct

Answer 39

the answer is D