AP Biology: Chapter 14 Review Questions

a couple has 5 children, all sons. if the woman gives birth to a sixth child, what is the probability that the sixth child will be a son?

1/2

assume that genes A and B are not linked. if the probability of allele A in a gamete in 1/2 and the probability of allele B in a gamete is 1/2, then the probability that BOTH A and B are in the same gamete is

1/2 X 1/2

a woman and her spouse both show the normal phenotype for pigmentation, but both had one parent who was an albino. albinism is an autosomal recessive trait. what is the probability that their first child will be an albino?

1/4

albinism (lack of skin pigmentation) is caused by a recessive autosomal allele. a man and a woman, both normally pigmented, have an albino child together. the couple decides to have a second child. what is the probability that this child will be albino?

1/4

in a cross AaBbCc x AaBbCc, what is the probability of producing the genotype AABBCC?

1/64

in snapdragons, heterozygotes have pink flowers, whereas the two homozygotes have red flowers or white flowers. when plants with red flowers are crossed with plants with white flowers, what proportion of the offspring will have pink flowers?

100%

in sheep, eye color is controlled by a single gene with two alleles. when a homozygous brown-eyed sheep is crossed with a homozygous green-eyed sheep, blue-eyed offspring are produced. if two blue-eyed sheep are mated with each other, what percent of the offspring will most likely have brown eyes?

25%

in crossing a homozygous recessive with a heterozygote, what is the chance of getting an offspring with the homozygous recessive phenotype?

50%

a child with blood type A is born to a mother with blood type B. the father must have which of the following blood types?

AB only

in peas the trait for tall plants is dominant (T) and the trait for short peas is recessive (t). the trait for yellow seed color is dominant (Y) and the trait for green seed color is recessive (y). a cross between two plants result in 296 tall yellow plants and 104 tall green plants. which of the following are most likely to be the genotypes of the parents?

TtYy x TTYy

a 9:3:3:1 phenotype ratio is characteristic of

a dihybrid cross

what is a genetic cross called between an individual of unknown genotype and a homozygous recessive?

a test cross

alleles

are alternative forms of a gene

a cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. this demonstrates

complete dominance

hydrangea plants of the same genotype are planted in a large flower garden. some of the plants produce blue flowers and others pink flowers. this can be best explained by

environmental factors such as soil pH

one gene masks the expression of another. what kind of inheritance is this?

epistasis

in a small group of people living in a remote area, there is a high incidence of "blue skin," a condition that results from a variation in the structure of hemoglobin. all of the "blue-skinned" residents can trace their ancestry to one couple, who were among the original settlers of this region. the unusually high frequency of "blue skin" in the area is an example of

genetic drift

albinism (lack of skin pigmentation) is caused by a recessive autosomal allele. a man and a woman, both normally pigmented, have an albino child together. for this trait, what is the genotype of the albino child?

homozygous recessive

the phenotype of the heterozygote differs from the phenotypes of both homozygotes. what kind of inheritance is this?

incomplete dominance

roan color in cattle is the result of codominance between red and white color alleles (Rr). how would one produce a herd of pure-breeding roan-colored cattle?

it cannot be done

Mendel's law of segregation was nearly impossible for most biologists to understand until there was a general understanding of

meiosis

one example is the ABO blood group system. what kind of inheritance is this?

multiple alleles

which of the following best describes the parents in a test cross?

one individual has the dominant phenotype and the other has the recessive phenotype

the ability of a single gene to have multiple phenotype effects. what kind of inheritance is this?

pleiotropy

roan color in cattle is the result of codominance between red and white color alleles (Rr). when two roan cattle are crossed, the phenotypes of the progeny are found to be in the ratio of 1:2:1 (red: roan: white) which of the following crosses could produce the highest percentage of roan cattle?

red X white

a child with blood type A is born to a mother with blood type B. if the father has blood type AB, which of the following statements is correct about the mother?

she contributed an i allele, which is recessive to the father's IA allele

what was the most significant result Gregor Mendel drew from his experiments with pea plants?

traits are inherited in discrete units and are not the results of "blending"

a plant with purple flowers is allowed to self-pollinate. generation after generation, it produces purple flowers. this is an example of

true breeding