Allele Combinations

The ability to roll the tongue is thought to be controlled by a dominant allele (R). What percent of offspring from two heterozygous (Rr) parents are most likely to have the tongue-rolling trait?

• 25%

• 50%

• 75%

• 100%

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

NGSS.HS-LS3-3

If a plant that is homozygous tall and wrinkled is crossed with a short, wrinkled plant, which percentage of genotypes would most likely be found in the first-generation offspring?

• 50% TTss, 50% ttSS

• 100% TtSs

• 100% Ttss

• 50% TtSS, 50% ttSS

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

This Punnett square shows the results of a cross between a tall (Tt) corn plant and a short (tt) corn plant. According to this information, what percent of the offspring were tall?

• 0%

• 25%

• 50%

• 75%

Tags

NGSS.HS-LS3-1

The birds shown above are sisters from the same set of parents. In this species of bird, long beak (L) is dominant over short beak (l). They are the only surviving offspring of their parents, and they do not necessarily represent the expected ratio of phenotypes. Which cross shown below could not represent the mating of thier parents?

• 
• 
• 
• 

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

When a black mouse that is homozygous for coat color (BB) is crossed with a white mouse that is homozygous for coat color (bb), all of the F₁ generation offspring have black coats.

What are the expected genotypes and phenotypes of coat color in the F₂ generation?

• All F₂ mice have BB genotypes and black phenotypes.

• All F₂ mice have bb genotypes and white phenotypes.

• The genotypes of the F₂ mice are 25% BB, 50% Bb, and 25% bb. The phenotypes are 75% black and 25% white.

• The genotypes of the F₂ mice are 50% BB and 50% bb. The phenotypes are 50% black and 50% white.

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

In cattle the allele for cloven hooves (H) is dominant over the allele for mute-foot hooves (h). The phenotype for each trait is shown in this picture.

What is the probability of cloven hooves in the offspring of parents that are heterozygous for the trait?

• 25%

• 50%

• 75%

• 100%

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

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

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

Which statement is best suppoted by the phenotypes of these offspring?

• The F₁ generation is composed only of males.

• Two of the offspring in the F₁ generation will not be able to reproduce

• The F₁ generation is the result of a dihybrid cross

• Two of the offspring in the F₁ generation will experience a spontaneous mutaion.

Tags

NGSS.HS-LS3-1

The inheritance pattern for an autosomal dominant trait is shown in the pedigree. Shaded symbols represent individuals that express the dominant trait.

Based on this pedigree, what are the most likely genotypes of individuals in I-1 and I-2?

• I-1: aa

  I-2: Aa

• I-1: AA

  I-2: Aa

• I-1: Aa

  I-2: aa

• I-1: aa

  I-2: AA

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

In humans blood type is determined by the A, B, and O alleles. The A and B alleles are codominant to each other and dominant over the O allele. An individual with the AO genotype and an individual with the BO genotype can produce offspring with which of the following phenotypes?

• O only

• A or B Only

• A, B, or O only

• A, B, AB, or O

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2