Inheritance

Albinism is a recessive trait. A man and woman both show normal pigmentation, but both have one parent who has albinism (without melanin pigmentation). What is the probability that their first child will have albinism?

• 0

• 1/2

• 1/4

• 1

Mendel crossed yellow-seeded and green-seeded pea plants and then allowed the offspring to self-pollinate to produce an F2 generation. The results were as follows: 6,022 yellow and 2,001 green (8,023 total). Which of the following statements correctly describes the relationship of the allele for green seeds to the allele for yellow seeds?

• The green allele is dominant to the yellow allele.

• The two alleles exhibit incomplete dominance.

• The green allele is recessive to the yellow allele.

• The two alleles are codominant.

Gray seed color in peas is dominant to white. Assume that Mendel conducted a series of experiments where plants with gray seeds were crossed among themselves, and the following progeny were produced: 302 gray and 98 white. What is the most probable genotype of each parent?

• GG × gg

• Gg × Gg

• GG × Gg

• gg × Gg

Black fur in mice (B) is dominant to brown fur (b). Short tails (T) are dominant to long tails(t). What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails?

• 1/16

• 3/8

• 1/2

• 9/16

Which of the following statements best describes the addition rule of probability?

• the probability that two or more independent events will occur simultaneously

• the probability that either one of two independent events will occur

• the probability of producing two or more heterozygous offspring

• the likelihood that a trait is due to two or more meiotic events

In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (RW) offspring of red (RR) and white (WW) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?

• red × white

• roan × roan

• white × roan

• red × roan

Which of the following inheritance patterns describes the ability of a single allele to have multiple phenotypic effects?

• incomplete dominance

• multiple alleles

• pleiotropy

• epistasis

Which of the following phenotypes is an example of polygenic inheritance?

• the ABO blood group in humans

• pink flowers in snapdragons

• skin pigmentation in humans

• white and purple flower color in peas

Which of the following scenarios describes an example of epistasis?

• Recessive genotypes for each of two genes (aabb) results in an albino corn snake.

• In rabbits and many other mammals, one genotype (ee) prevents any fur color from

  developing

• In Drosophila (fruit flies), white eyes can be due to an X-linked gene or to a combination of other genes.

• In cacti, there are several genes for the type of spines.

Gene S controls the sharpness of spines in a type of cactus. Cacti with the dominant allele, S,

have sharp spines, whereas homozygous recessive ss cacti have dull spines. At the same time, a

second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn

cactuses have no spines at all. A cross between a true-breeding sharp-spined cactus and a

spineless cactus would produce ________.

• all sharp-spined progeny

• 50% sharp-spined, 50% dull-spined progeny

• 25% sharp-spined, 50% dull-spined, 25% spineless progeny

• It is impossible to determine the phenotypes of the progeny.