Exam 12: Inheritance, Genes, and Chromosomes

The blue sclera allele has 75 percent penetrance for producing blue sclera, 60 percent penetrance for fragile bones, and 40 percent penetrance for deafness.If these probabilities of penetrance are independent, _______ percent of individuals with the blue sclera allele will be unaffected.

You have discovered a new species of rodent in a remote forest.You manage to trap a handful of the animals and bring them back to your lab to establish a breeding program for study.All of the rodents have smooth cup-shaped ears, but as you breed successive generations, you also notice individuals with notched ears, ones with serrated ears, and ones with long floppy ears.Genetic tests establish that there is only one gene involved, so you infer that the genetic phenomenon responsible is _______.

Due to the phenomenon of dominance,

Linkage on a single chromosome violates Mendel's law of

Suppose a mutant phenotype was due to a mutation in a mitochondrial gene.Which pattern would you expect to see?

The most likely explanation for the observation that round is dominant to wrinkled in Mendel's peas is

A dihybrid cross for unlinked genes

An organism that produces both male gametes and female gametes is called

For a typical situation of incomplete dominance in which one parent is BB and the other is bb, _______ percent of the offspring would be expected to display the heterozygous phenotype in the F₂ generation.

Refer to the figure of chicken combs.In chickens, when the dominant alleles of the genes for rose comb (R) and pea comb (A) are present together (R_A_), the result is a bird with a walnut comb.Chickens that are homozygous recessive for both genes produce a single comb.A rose-combed bird is mated with a walnut-combed bird and produces offspring in the proportion 3 walnut : 3 rose : 1 pea : 1 single. What were the genotypes of the parents?

Suppose Mendel had an assistant who sometimes forgot to emasculate the short plants before placing pollen from the homozygous tall plants on the pistils of the short plant flowers.As a result, about 2/3 of the pollen that fertilized the short flowers came from short plants.What fraction of the progeny from this cross would have been tall? (Recall that the trait of tall is dominant to short.)

Suppose that in a hypothetical population of lizards, the probability of obtaining a male is 0.6.Assume that the sexes of each individual are independent.What is the probability of obtaining exactly two males in a clutch of three? (Note that there are three ways this can occur, depending on the order in which the probabilities are calculated.)

The X7 allele in a species of a plant has 75 percent penetrance for producing red spots and 60 percent penetrance for dwarfism.If these probabilities of penetrance are independent, _______ percent of individuals with the X7 allele will have neither red spots nor will be dwarfs.

One of the major contributions of Mendel to the study of genetics was

If both parents have AB blood type, _______ percent of their children would be expected to have type AB blood.

If two strains of true-breeding plants that have different alleles for a certain character are crossed, their progeny are called

Cleft chin is an X-linked dominant trait.Assume that a man with a cleft chin marries a woman with a round chin.What percent of their female progeny will show the cleft chin trait?

A bacterial cell's genotype can be altered by

A human female is heterozygous for a recessive X-linked trait.She has children with a male who does not have the trait.Their sons have a _______ probability of expressing the trait, whereas their daughters have a _______ probability of expressing the trait.

What do geneticists call stable inherited changes in genetic material?