Science Answers

Section 16-1
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VOCABULARY REVIEW
1. Population genetics is the study of evolution from
a genetic point of view.
2. A gene pool is the total genetic information available
in a population.
3. Allele frequency is the frequency of a certain allele
among all alleles of the same gene in a population.
4. Phenotype frequency is the frequency of individuals
with a particular phenotype in a population.
5. Hardy-Weinberg genetic equilibrium is a condition
in which the allele frequencies in a population
remain the same from generation to generation.
MULTIPLE CHOICE
1. b 2. c 3. b 4. d 5. a
SHORT ANSWER
1. Individuals represented by the two ends are those
with extreme variations of a specific trait.
2. Variations arise through mutation, recombination
during meiosis, and the random pairing of gametes
during fertilization.
3. (1) No net mutations occur; (2) individuals neither
enter nor leave the population; (3) the population
is large; (4) individuals mate randomly; and (5)
selection does not occur.
4. no, because those genes are not available for the
next generation
STRUCTURES AND FUNCTIONS
Phenotype frequencies: red = 0.625 ⋅ 0.625 = 0.391;
white = 0.375 ⋅ 0.375 = 0.141; pink = 1 – 0.391 – 0.141 =
0.468. Allele frequencies: R = 0.391 + (0.468 ⎟ 2) =
0.625; r = 0.141 + (0.468 ⎟ 2) = 0.375.
Section 16-2
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VOCABULARY REVIEW
1. Immigration is the movement of individuals into a
population. Emigration is the movement of individuals
out of a population.
2. Gene flow is the movement of genes from one population
to another. Genetic drift is a change in allele
frequencies in a population due to random events.
3. Random mating is mating that occurs without
regard to genetic makeup. Assortative mating is
mating based on similarity of characteristics.
4. In stabilizing selection, individuals with the average
form of a trait have the highest fitness. In
directional selection, individuals with one extreme
form of a trait have the highest fitness.
MULTIPLE CHOICE
1. c 2. d 3. a 4. c 5. b
SHORT ANSWER
1. mutations, gene flow, genetic drift, nonrandom
mating, and natural selection
2. By producing totally new alleles for a trait, mutations
can change allele frequencies.
3. Matings with some degree of kinship may occur,
increasing the chance of offspring with disorders
caused by recessive genes.
4. The bright coloration may increase a male’s
chances of being selected for mating by a female.
5. Genetic homozygosity leaves no variation for natural
selection to act on. Therefore, a new disease
could wipe out the entire population.
6. directional selection; the cow would not eliminate all
white flowers because the allele for white flowers is
also carried by plants with pink flowers, which are
not eaten. Crosses between plants with pink flowers
would continue to produce some plants with white
flowers.
STRUCTURES AND FUNCTIONS
a, disruptive; b, directional; c, stabilizing
Section 16-3
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VOCABULARY REVIEW
1. Morphology is the internal and external structure
and appearance of an organism.
2. Geographic isolation is the physical separation of
members of a population.
3. Punctuated equilibrium is a pattern of species
formation in which periods of sudden speciation
are preceded and followed by long periods with
little speciation.
MULTIPLE CHOICE
1. d 2. a 3. b