chap 16&17

Question 1

• The study of diversity found within a population

- looks at diversity in terms of allele differences

Answer 1

population genetics

Question 2

• alternate forms
• each trait in an individual is controlled by these
• dominant _______’s are expressed by capital letters and mask the expression of recessive ________
• recessive ______ are always expressed in lower-case letters

Answer 2

alleles

Question 3

How do homozygous individuals differ from heterozygous individuals?

Answer 3

• homozygous have identical alleles for a trait

- heterozygous have different alleles for a trait

Question 4

How does phenotype differ from genotype?

Answer 4

• phenotype refers to the physical trait expressed

- genotype refers to alleles or genetic make-up

Question 5

the various alleles at all the gene loci in all individuals found in a population

Answer 5

the gene pool of a population

Question 6

assumes allele frequencies in a population will remain constant if there is no mutation, no gene flow random mating, no genetic drift, and no selection

Answer 6

Hardy-Weinberg Equilibrium

Question 7

What is the significance of deviations rom Hardy-Weinberg Equilibrium?

Answer 7

provides evidence that evolution has taken place

Question 8

Causes of microevolution

spontaneous change in DNA of an organism

Answer 8

genetic mutations

Question 9

Causes of microevolution

movement of alleles between populations which leads to more similarities between the population involved

Answer 9

gene flow

Question 10

Causes of microevolution

when individuals don’t choose mates randomly

Answer 10

nonrandom mating

Question 11

Causes of microevolution
occurs by disproportionate random sampling from a population; can cause some alleles to be lost and others to become fixed in the population

Answer 11

genetic drift

Question 12

Causes of microevolution
adaptation of a population to the biotic (living) and abiotic (non-living) environment; requires variation, inheritance, differential adaptiveness, differential reproduction; results in a change in allele frequencies of the gene pool and improved fitness of the population

Answer 12

natural selection

Question 13

Name and describe the three types of selection

Answer 13

directional- phenotypes are shifted to one side or the other of the normal bell curve

stabilizing- most phenotypes are found in middle range off the normal bell curve

disruptive- two curves representing two phenotypes replace the bell curve

Question 14

adaptive changes in males and females that lead to an increased ability to secure a mate

Answer 14

sexual selection

Question 15

• allelic differences within a population
• populations with limited variation may not be able to adapt to new conditions
• maintaining variability is good for a population since it helps to ensure that adaptions can take place

Answer 15

genetic variablity

Question 16

those that are subject to natural selection

Answer 16

exposed alleles

Question 17

What is the importance of recessive alleles?

Answer 17

• even lethal alleles can remain in a population at low frequencies virtually forever
• lethal recessive alleles may confer advantages to heterozygotes

Question 18

How do heterozygotes affect recessive alleles?

Answer 18

they shelter them from selection

Question 19

What is the heterozygote advantage?

Answer 19

• refers to advantage to having multiple alleles for a trait

- assists in the maintenance of genetic (and therefore phenotypic) variations

Question 20

How does the heterozygote advantage help people with sickle-cell disease?

Answer 20

they don’t die from either sickle-cell disease or from malaria if they are heterozygous for sickle-cell disease

Question 21

populations which breed only among themselves

Answer 21

species

Question 22

separate populations which have adaptions to their particular environments but can still interbreed

Answer 22

subspecies

Question 23

Differentiate between microevolution and macroevoltion

Answer 23

Micro-

• involves allelic frequency changes within the gene pool of a population
• can be observed within one’s lifetime

Macro-

• requires the origin of species
• observed best within the fossil record

Question 24

• populations which breed only among themselves
• a particular type of living thing
• has its own evolutionary history
• is identified by a two-part scientific name

Answer 24

species

Question 25

- states that members of a species share the same distinct evolutionary pathway - states that species can be recognized by morphological (structural) trait differences - assumes that members of a species are reproductively isolated (only mate with members of the same species)

Answer 25

evolutionary species concept

Question 26

Name an advantage and disadvantage of the evolutionary species concept.

Answer 26

Advantage: applies to both sexually and asexually reproducing organisms Disadvantage: morphological traits are used to distinguish among species

Question 27

- states that members of a species have a single gene pool | - relies on reproductive isolation rather than trait differences to define a species

Answer 27

biological species concept

Question 28

Name an advantage and disadvantage of the biological species concept

Answer 28

Advantage: -can designate species even when trait differences may be difficult to fin -is supported by molecular genetics Disadvantage: -can't be applied to asexually reproducing organisms -can't be applied to organisms known only by the fossil record

Question 29

Why is the biological species concept so important?

Answer 29

it gives us a way to know when speciation has occurred

Question 30

What is necessary for two species to remain separate?

Answer 30

gene flow can't occur between them

Question 31

Name and describe the two major types of reproductive isolation strategies

Answer 31

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