Exam 12: Inheritance, Genes, and Chromosomes

In garden peas, the allele for tall plants is dominant over the allele for short plants.Suppose that a true-breeding tall plant is crossed with a short plant, and one of their offspring is crossed with a short plant.Out of 20 offspring resulting from the cross, about _______ should be tall.

Which phenomenon is the best evidence against genetic determinism?

The AB blood phenotype found in individuals with an I^AI^B genotype is an example of _______.

Many antibiotic resistance genes are located on plasmids.Antibiotics are routinely given to livestock by many farmers to improve productivity and prevent illness.Why are many individuals concerned about this practice as it relates to human health?

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 have deafness, blue sclera, and fragile bones.

In Drosophila, three autosomal genes have alleles as follows: Straight bristles (Hk) is dominant over hooked bristles (hk); straight wings (A) is dominant over arc wings (a); and red eye (Bw) is dominant over brown eye (bw).Two test crosses were performed, with the results shown in the table. What linkage can you determine from these crosses?

Unattached earlobes are a dominant trait in humans.Finn and Maggie both have unattached earlobes but their daughter, Celia, does not.If Finn and Maggie have a second child, what is the probability that this child will have attached earlobes?

What is another term for hybrid vigor?

One true-breeding line of mice is obese and dark, and the other true-breeding line is lean and light.Dark is dominant to light, but obese and lean exhibit incomplete dominance.The two genes involved are on separate chromosomes.What proportion of offspring from a dihybrid cross should be dark and be intermediate between obese and lean?

White eyes are a recessive sex-linked trait in Drosophila.If a white-eyed female fly is mated to a red-eyed male, their offspring should be

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, 400 flies are scored.How many F₂ flies are expected to have ebony-colored bodies and normal eyes?

Which statement about pleiotropy is true?

In a particular plant species, two alleles control flower color, which can be yellow, blue, or white.Crosses of these plants produce the offspring shown in the table. What will be the phenotype, and ratio, of the offspring of a cross of blue  blue?

Draw a Punnett square that shows a dihybrid cross with independent assortment.One gene affects whether mice have tails or are tailless, with tails being dominant.The other affects whether the mice have black or gray color, with black dominant.Write out the ratio of expected phenotypes from the cross.

When two loci are on the same chromosome, progeny sometimes do not exhibit the phenotypes that would be predicted by the law of independent assortment.This outcome can be explained by the phenomenon of

A human male carrying an allele for a trait on the X chromosome is

What is another word for "family tree"?

Mendel performed a cross between two individuals, each heterozygous for three different traits that are unlinked: Round versus wrinkled seeds (round is dominant), purple versus white flowers (purple is dominant), and tall versus dwarf stems (tall is dominant).Of the 64 offspring, how many had wrinkled seeds, purple flowers, and dwarf stems?

In Drosophila, the recessive allele p, when homozygous, determines pink eyes.Pp or PP results in wild-type eye color.On the same chromosome of Drosophila that carries the p (pink eyes) locus there is another locus that affects the wings.Homozygous recessives, byby, have blistery wings, whereas the dominant allele By produces wild-type wings.The P and By loci are very close together on the chromosome; that is, the two loci are tightly linked.For the cross PPbyby  ppByBy, what phenotype(s) would appear in the F₂ generation if crossing over occurred?

In humans, spotted teeth are caused by a dominant sex-linked gene.A man with spotted teeth whose father had normal teeth marries a woman with normal teeth.Therefore