Chapter 17

Question 1

Members of a population share a common group of genes called

Answer 1

gene pool

Question 2

The number of times an allele occurs in a gene pool compared with the number of times other alleles for the same gene occur

Answer 2

allele frequency

Question 3

Three main sources of genetic variations are

Answer 3

mutations
genetic recombination during sexual reproduction
horizontal gene transfer

Question 4

A ________ is any change in a sequence of DNA

Answer 4

mutation

Question 5

Most hereditable differences are due to ____________ _________

Answer 5

genetic recombination

Question 6

__________ __________ ________ is the passing of genes from one organism to another that is not its offspring

Answer 6

lateral gene transfer

Question 7

____ _____ _____ is controlled by one gene. AN example in snails is the presence or absence of dark bands on their shells.

Answer 7

single-gene trait

Question 8

_______ _________ is controlled by two or more genes, and each gene often has two or more alleles.

Answer 8

polygenetic gene

Question 9

The combination of different alleles is an individuals ________.

Answer 9

genotype

Question 10

Natural selection acts on _________, not _________.

Answer 10

phenotype
genotype

Question 11

___________ ______ takes place when individuals at one end of the bell curve have higher fitness that those near the middle or at the other end of the curve.

Answer 11

Directional selection

Question 12

_________ ________takes place when individuals near the middle of the curve have higher fitness than individuals at either end

Answer 12

Stabilizing selection

Question 13

_________ ___________ takes place when individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle.

Answer 13

Disruptive selection

Question 14

3 types of selection

Answer 14

directional selection
stabilizing selection
disruptive selection

Question 15

Allele frequencies in a population gene pool does not change thus no evolution occurs (stays constant)

Answer 15

genetic equilibrium

Question 16

Allele frequency in a population should remain constant unless 1 or more factors cause frequencies to change

Answer 16

Hardy-Weinberg Principle

Question 17

Random change in frequency of alleles in a gene pool is called _________ __________.

Answer 17

genetic drift

Question 18

Change in allele frequency following a dramatic loss of population is call __________

Answer 18

bottleneck effect

Question 19

Change in allele frequency that results from a small group starting a new population

Answer 19

founder effect

Question 20

disruption of genetic equilibrium

Answer 20

gene flow

Question 21

list 5 conditions that disturb genetic equilibrium and cause evolution to occur

Answer 21

non-random mating
small population size
immigration/emmigration
mutations
natural selection

Question 22

Formation of a new species is called

Answer 22

speciation

Question 23

When two populations can no longer mate and produce offspring, __________ _________ has occured

Answer 23

reproductive isolation

Question 24

When populations are separated by a barrier such as a river, mountains, or ocean, __________ _________ can occur.

Answer 24

geographic isolation

Question 25

If two interbreeding populations develop different behaviors, such as different mating dances, then __________ _____________

Answer 25

behavioral isolation

Question 26

____________ _____________ happens when populations that live in the same habitat reproduce at different times`

Answer 26

Temporal isolation

Question 27

A _________ ______________ uses mutation rates in DNA to estimate how long ago two organisms shared a common ancestor. ( few mutations shared ancestor recently, many mutations shared an ancestor long ago)

Answer 27

molecular clock