Exam 12: Inheritance, Genes, and Chromosomes

What is the genetic significance of a hemizygous gene?

Suppose on the hypothetical planet Trantor, a plantlike creature called a zork exhibits the characteristics of blending inheritance.Red zorks that are crossed with other red zorks produce only red offspring.White zorks that are crossed with other white zorks produce only white offspring.White zorks that are crossed with red zorks yield pink offspring.If pink offspring were backcrossed to their white parents, which would be the most likely result?

In Drosophila, the genes for body coloration and eye size are on different chromosomes.Normal-colored bodies are dominant to ebony-colored (very dark) bodies, and normal-sized eyes are dominant to eyelessness.Line A is true breeding for normal body color and normal eyes, whereas line B is true breeding for ebony bodies and eyelessness.If 400 F₂ flies were produced, _______ would be expected to have both normal body color and normal eyes.

Penetrance and expressivity are related to

Refer to the figure showing a pedigree. What is the probability that individual A will pass on the trait to her offspring?

In tomatoes, tall is dominant to dwarf, and smooth fruits are dominant to hairy fruits.A plant homozygous for both dominant traits is crossed with a plant homozygous for both recessive traits.The F₁ progeny are crossed with a homozygous recessive, with the results shown in the table. These data indicate that the genes are

You are researching the effects of a dominant mutation that causes a particular rare phenotype.Your pedigree studies show you that not everyone who has the allele shows the phenotype.You conclude that the allele has low _______.

Assuming that the probability of a boy being born is 1/2, the probability that a family with four children will include 3 boys and 1 girl is _______.

In Drosophila, the genes for body coloration and eye size are on different chromosomes.Normal-colored bodies are dominant to ebony-colored (very dark) bodies, and normal-sized eyes are dominant to being eyeless.Line A is true breeding for normal body and normal eye, whereas line B is true breeding for ebony bodies and being eyeless.From a dihybrid cross between lines A and B, 480 flies are scored.How many F₂ flies are expected to have both ebony body color and to be eyeless?

True-breeding dark mice are crossed with true-breeding light mice.The resulting progeny are then crossed with one another.This is an example of a _______ cross.

Which observation would not support the hypothesis that the gene controlling maleness is located on the Y chromosome?

Agouti is a type of coat color pattern in mice that cannot be expressed in albinos (white mice).A nonalbino agouti mouse that is heterozygous at the albino (A) and agouti (B) loci (AaBb) is mated to an albino mouse that is heterozygous at the agouti locus (aaBb).Nonalbino mice without the dominant agouti allele (AAbb and Aabb) are black.What percent of the progeny would you expect to be agouti?

A man has a rare dominant autosomal trait.There is a _______ probability that one of his children will have the disease.

Mendel's laws of inheritance can be observed in human genetics through the study of _______.

Elongated and Five are two genes in a housefly that are 24 centiMorgans (cM; map units) apart.The E allele of Elongated produces elongated wings, and the e allele produces small wings (E is dominant).The F allele produces five stripes on the back of the fly, and the f allele produces four stripes (F is dominant).In a cross of EeFf  eeff, what proportion of the offspring should have elongated wings and five stripes?

Suppose that in a certain population of lizards, the probability of the birth of a male is 0.6.Assume that the sex of each individual is independently determined.What is the probability that a clutch of three will be all male?

Suppose a man is blood type O.From this, we can infer that

Allelic variation at the insulin growth factor-1 gene is one of several variables that affect body size in dogs.Based on this information, one can say that this gene

In Drosophila, production of eye color pigment requires a functional protein encoded by the white locus.Individuals with two copies of the w allele lack any eye color pigment; individuals with at least one wild-type allele have pigment.The bw allele at the brown locus produces a defective enzyme responsible for converting one type of pigment to another.Individuals with two bw alleles have brown eyes; individuals with at least one wild-type allele at the brown locus have normal red eyes (assuming that they have eye pigment).Which statement is true?

Classical albinism results from a recessive allele.What is the expected ratio for the progeny when a fully pigmented male with an albino father has children with a fully pigmented female with no history of albinism in her family?