Problem #1: Basic Monohybrid Cross

The ability to roll the tongue is dominant over the inability to do so in humans.

(A) If two heterozygous tongue-rollers have children, what genotypes could their children have?

(B) If a non-tongue-roller has children with a homozygous tongue-roller, what will their children's genotypes be?

Problem #2

In an alien species, eye colors can be black, white, or gray. A white-eyed mother and a black-eyed father have all gray-eyed children.

(A) What genetic pattern is most likely demonstrated here?

(B) A gray-eyed couple has two babies: one white-eyed and one black-eyed. Does this confirm or deny your answer to part A? If necessary, revise your hypothesis.

(C) A gray-eyed alien and her black-eyed husband want a white-eyed baby. Is this possible?

Problem #3

A mother has blood type A and genotype AA. A father has blood type B and genotype BO. What blood types are possible for the offspring?

Problem #4

Pattern baldness is sex-linked dominant, but cannot be expressed normally in females because it is suppressed by female hormones.

(A) If a carrier female marries a pattern-bald man, what are the possible genotypes and phenotypes of their children?

(B) If female is homozygous for pattern baldness (but does not express the trait due to hormones), and she marries a normal man, what percentage of her sons will be pattern-bald?

Problem #5

In pea plants, tallness is dominant over shortness and smooth seeds are dominant over wrinkled seeds. If two heterozygous tall plants which are heterozygous for smooth seeds are crossed, what are the genotype and phenotype ratios of the offspring?