In pea plants, the allele for tall stems (T) is dominant to the allele for short stems (t). A plant has the genotype Tt. How tall does this plant grow?

In guinea pigs, black coat (B) is dominant to white coat (b). What color is the coat of a guinea pig whose genotype is bb?

In fruit flies, red eyes (E) are dominant to white eyes (e). A fly has the genotype EE. What color are its eyes?

In cattle, the polled (hornless) allele (P) is dominant to the horned allele (p). A calf has the genotype Pp. What will the calf look like?

In rabbits, short fur (S) is dominant to long fur (s). Describe the fur of a rabbit whose genotype is ss.

In tomato plants, purple stems (A) are dominant to green stems (a). What color is the stem of a plant with the genotype Aa?

A mouse breeder records a mouse's genotype as BB, where black coat (B) is dominant to brown coat (b). What should the breeder write in the coat color column?

In corn, colored kernels (C) are dominant to colorless kernels (c). An ear grows on a plant with the genotype Cc. What do its kernels look like?

Mendel found that round seeds (R) are dominant to wrinkled seeds (r) in pea plants. A pea seed has the genotype rr. What is its shape?

In sunflowers, a tall stem (H) is dominant to a dwarf stem (h). A seed catalog lists a variety whose genotype is hh. What do these plants look like?

A pea plant has the genotype TT for stem height, where the recessive allele is written t. Which term describes this allele pair?

A guinea pig carries the alleles G and g for coat texture. Which term describes an organism with two different alleles for the same trait?

A fruit fly's genotype for wing shape is written ff. Which term names this allele pair?

Which term describes an organism whose two alleles for a trait are identical?

A seed company sells a true-breeding tall pea variety, so when these plants self-pollinate, every offspring is tall too. How should the allele pair of these plants be described?

Which term names the pair of alleles an organism carries for a trait, rather than the appearance those alleles produce?

An organism's genotype for a trait is Rr. Which statement about the alleles it carries is correct?

An organism whose genotype is bb is homozygous for that trait.

In pea plants, purple flowers (P) are dominant to white flowers (p). Which genotype must a white-flowered pea plant have?

In mice, black fur (B) is dominant to brown fur (b). Which genotypes are possible for a black mouse?

In tomatoes, red fruit (R) is dominant to yellow fruit (r). Which alleles can a yellow-fruited tomato plant pass on to its offspring?

A biologist catches a fruit fly with normal wings, where normal wings (N) are dominant to vestigial wings (n). She cannot tell its genotype by looking at it. Why not?

In cattle, the polled (hornless) allele (P) is dominant to the horned allele (p). A rancher has a horned bull. Which genotype must the bull carry, and why?

In dogs, a black coat (B) is dominant to a chocolate coat (b). Which coat color lets you know a dog's genotype for certain just by looking at it?

A student writes that every round pea seed has the genotype RR, where round (R) is dominant to wrinkled (r). Why is that incorrect?

Two pea plants both have purple flowers, where purple (P) is dominant to white (p). What can be said for certain about their genotypes?

In cats, short hair (S) is dominant to long hair (s). One cat has the genotype SS and another has the genotype Ss. How do the two cats compare?

Two pea plants both have white flowers, where purple (P) is dominant to white (p). What is true of these two plants?

In pea plants, tall stems (T) are dominant to short stems (t). One plant has the genotype TT and another has the genotype tt. Which comparison is correct?

In rabbits, brown fur (B) is dominant to white fur (b). A rabbit with the genotype BB and a rabbit with the genotype Bb look different from each other.

Two organisms can look exactly alike for a trait and still carry different pairs of alleles for it.

Two black mice look identical, but one is BB and the other is Bb, where black (B) is dominant to brown (b). How can the difference between them show up later?

A student claims that two organisms with the same phenotype must have the same genotype. In guinea pigs, black coat (B) is dominant to white coat (b). Which example shows the claim is wrong?

A trait is controlled by a dominant allele written G and a recessive allele written g. Which genotype produces the recessive appearance?

For a trait whose alleles are written H and h, which genotype is written correctly for a heterozygous organism?

When a trait's alleles are written with letters, what does the capital letter stand for?

A plant's genotype for a trait is written Ss. How many alleles for this trait does the plant carry, and where do they come from?

A student records a pea plant's genotype as "purple," where purple (P) is dominant to white (p). What is wrong with this?

A trait is controlled by the alleles R and r. An organism with the genotype Rr shows the recessive appearance.

In writing genotypes, why is the same letter used for both alleles of a trait, as in T and t, rather than two unrelated letters?