Monohybrid Practice

Chickens can have different types of feathers. Frizzled feathers curl toward a chicken’s head. Assume that feather type is determined by a single gene and that the allele for frizzled feathers is dominant over the allele for straight feathers. In a cross between two chickens with straight feathers, what percentage can be expected to have frizzled feathers?

• 0%

• 25%

• 50%

• 100%

Tags

NGSS.HS-LS3-3

In cocker spaniels the allele for a black coat color (B) is dominant over the allele for a brown coat color (b). If a brown cocker spaniel is crossed with a heterozygous black cocker spaniel, which of the following genotypic ratios can be expected?

• 0 BB: 2 Bb: 2 bb

• 1 BB: 2 Bb: 1 bb

• 2 BB: 2 Bb: 1 bb

• 2 BB: 1 Bb: 0 bb

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

NGSS.HS-LS3-3

Normal fruit flies have brownish-yellow bodies, and this body color is dominant. A mutation in the gene for body color can produce flies with an ebony body color. A homozygous normal fruit fly is crossed with a homozygous ebony fruit fly. What is the predicted outcome of this genetic cross?

• All of the offspring will have ebony bodies.

• Of the offspring, 75% will have brownish-yellow bodies, and 25% will have ebony bodies.

• All of the offspring will have brownish-yellow bodies.

• Of the offspring, 75% will have ebony bodies, and 25% will have brownish-yellow bodies.

In pea plants, purple flower color is caused by a dominant gene, and white flower color is caused by a recessive gene. The genotype for purple flower color is PP or Pp, and the genotype for white flower color is pp. A plant with purple flowers and the genotype is Pp is crossed with a plant with white flowers and the genotype pp. What is the probability that the offspring of these plants will have white flowers?

• 25%

• 50%

• 75%

• 100%

Tomato plants usually have hairy stems. Hairless stems are present in tomato plants that are homozygous recessive for this trait. If the stem characteristics are determined by a single gene, what is the expected outcome of crossing two tomato plants that are heterozygous for hairy stems?

• 75% hairy stems: 25% hairless stems

• 100% hairy stems

• 100% hairless stems

• 50% hairy stems: 50% hairless stems