Ch. 19

Question 1

What causes phenotypic variation?

Answer 1

genetic mutations

Question 2

Discrete genetic variation

Answer 2

traits with a limited amount of phenotypes, determined by a single gene locus

Question 3

Continuous variation

Answer 3

phenotypes produced by 2+ genes combined

Question 4

What is responsible for genetic diversity in offspring?

Answer 4

Sexual recombination

Question 5

What is sexual recombination

Answer 5

the exchange of DNA between homologous chromosomes from each parent to create variation

Question 6

Crossing over

Answer 6

homologous chromosomes from each parent cross over and exchange a gene at the same loci. each allele differs

Question 7

independent assortment

Answer 7

lining up of homologous chromosomes after crossing over, randomly assort into each 4 daughter cells

Question 8

random fertilization

Answer 8

random sperm and egg united

Question 9

What type of cell can new alleles arise in where there is a mutation in zDNA

Answer 9

sex cells

Question 10

point mutations

Answer 10

occurs in DNA when a single nucleotide is changed, deleted, or added, changes the amino acid which changes the protein. usually harmless

Question 11

deletion

Answer 11

deletion of a nucleotide

Question 12

duplications

Answer 12

duplicate nucleotides, expand genome size and can mutate into new alleles

Question 13

reciprocal translocations

Answer 13

nucleotides moving chromosomes, no frameshift. over time, the duplicated gene picks up more and more mutations

Question 14

why does most DNA variability not affect the phenotype?

Answer 14

coding DNA only = 1%
could code for the same amino acid
have regulatory regions that won’t turn on the gene if a mutation is present

Question 15

gene pool

Answer 15

all alleles of every gene in a population

Question 16

smallest fundamental unit of evolution

Answer 16

microevolution

Question 17

hardy Weinberg principle

Answer 17

evolution is not happening, large population, random sexual reproduction, frequencies do not change in the next generation

Question 18

5 conditions of the HW principle

Answer 18

1. large population
2. random sexual selection
3. no natural selection
4. no gene flow
5. no mutations

Question 19

natural selection

Answer 19

not random, changes allelic/genotypic frequencies, specific to environment

Question 20

genetic drit

Answer 20

founder effect and bottle neck effect, due to random chance, small populations, reduces genetic diversity

Question 21

gene flow

Answer 21

alleles move in and out of population, migration of adults, dispersion of gametes, seeds, larvae, adds diversity, makes populations less different

Question 22

relative fitness

Answer 22

best reproductive success

Question 23

disruptive (diversifying) selection

Answer 23

extremes are favored over intermediates, diversity is maintained

Question 24

stabilizing selection

Answer 24

intermediates are favored over extremes, less diversity

Question 25

sexual selection leads to

Answer 25

sexual dimorphism: sexes differ in appearance

Question 26

diploidy

Answer 26

less successive recessive alleles hidden in heterozygotes

Question 27

HETEROZYGOTE ADVANTAGE

Answer 27

heterozygote favored, maintains both alleles

Question 28

frequency dependent selection

Answer 28

higher frequency = less survival