Exam 14: Mendel and the Gene Idea

When Mendel crossed yellow-seeded and green-seeded pea plants, all the offspring were yellow-seeded. When he took these F1 yellow-seeded plants and crossed them to green-seeded plants, what genotypic ratio was expected?

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?

The individual with genotype AaBbCCDdEE can make many kinds of gametes. Which of the following correctly describes why this situation is possible?

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?

Which of the following scenarios describes an example of epistasis?

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

A man has extra digits (six fingers on each hand and six toes on each foot). His wife and their daughter have the normal number of digits (five fingers on each hand and five toes on each foot.) Having extra digits is a dominant trait. The couple's second child has extra digits. What is the probability that their next (third) child will have extra digits?

Skin colour in a certain species of fish is inherited by a single gene with four different alleles. How many different types of gametes would be possible in this organism?

The pattern of inheritance can be predicted from data if one is given the parent or offspring genotypes or phenotypes. Two organisms, with genotypes BbDD and BBDd, are mated. Assuming independent assortment of the B/b and D/d genes, determine the genotypic ratios in offspring that would occur.

In human blood types, Rh positive is a trait that shows simple dominance over Rh negative. A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Which of the following phenotypes is possible for the father?

Skin colour in a certain species of fish is inherited via a single gene with four different alleles. One fish of this type has alleles 1 and 3 (S1S3), and its mate has alleles 2 and 4 (S2S4). If each allele confers a unit of colour darkness such that S1 has one unit, S2 has two units, and so on, then what proportion of their offspring would be expected to have five units of colour?

Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F1 individuals have red, axial flowers. The genes for flower colour and location assort independently. Among the F2 offspring, what is the probability of producing plants with white axial flowers?

Hutchinson-Gilford progeria is an exceedingly rare human genetic disorder in which there is very early senility and death, usually from coronary artery disease, at an average age of 13 years. Patients, who look very old even as children, do not live to reproduce. Which of the following statements represents the most likely assumption regarding this disorder?

Which of the following statements is correct in describing the terms monohybrid cross and dihybrid cross?

What was the most significant conclusion that Gregor Mendel (1822-84) drew from his experiments with pea plants?

Which of the following statements is a correct explanation for the observation that all offspring exhibit a phenotype for a particular trait that appears to be a blend of the two parental varieties?

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

One of two major forms of a human condition called neurofibromatosis (NF1) is inherited as a dominant gene, although it may range from mildly to very severely expressed. Which of the following is the best explanation for why a young, affected child is the first in her family to be diagnosed?

W. Affected individuals are indicated by a dark square or circle. - What is the probability that individual III-1 is Ww?

In a particular plant, leaf colour is controlled by gene locus D. Plants with at least one allele D have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding, dark-leafed plant is crossed with a light-leafed one, and the F₁ offspring is allowed to self-pollinate. The predicted outcome of the F₂ is diagrammed in the Punnett square shown in the figure, where 1, 2, 3 and 4 represent the genotypes corresponding to each box within the square. - Which of the boxes marked 1-4 correspond to plants with dark leaves?