Traits and Probability

The Punnett square predicts the ratio of genotypes in the offspring, based on the genotypes of the parents. The Punnett square below examines the chance of offspring having freckles, which is a dominant trait.

Based on the Punnett square, what is the probability that the offspring will have freckles?

• 25%

• 50%

• 75%

• 100%

Which term describes an organism that has identical alleles for a trait?

• homozygous

• heterozygous

• dominant

• recessive

The offspring of a particular cross are 100 percent heterozygous for the trait of plant height. What were the most likely genotypes of the parents?

• Tt x tt

• Tt x Tt

• tt x tt

• TT x tt

Mendel crossed two plants that were heterozygous for the trait of flower color. Which genotypes could he have used to represent the cross?

• PP x PP

• Pp x Pp

• pp x pp

• Pp x PP

In pea plants, tallness (T) is dominant to shortness (t). What are the predicted percentages of the genotypes of the offspring if a homozygous short plant is crossed with a heterozygous tall plant?

• 25 percent Tt, 75 percent tt

• 25 percent tall, 75 percent short

• 50 percent Tt, 50 percent tt

• 50 percent tall, 50 percent short

Which describes the mating of organisms that have different homozygous alleles for a single trait?

• monohybrid cross

• dihybrid cross

• homozygous cross

• heterozygous cross

A dihybrid cross is created from plants that are heterozygous for both round seeds and yellow seed color. What is the ratio of offspring that have round seeds and yellow seed color?

• 1:16

• 3:16

• 9:16

• 16:16

The Punnett square predicts the ratio of genotypes in the offspring, based on the genotypes of the parents. In this cross, tallness (H) is dominant to shortness (h).

Based on the Punnett square, what is the phenotype of the offspring?

• Hh

• HH

• tall

• short

A plant can produce either purple flowers or white flowers. What is the probability of purple-flowered offspring if two plants that are heterozygous for purple flowers are crossed?

• 1:4

• 2:4

• 3:4

• 4:4

What can you surmise from the labeled image?

• The genotype is heterozygous.

• White petal color is a recessive trait.

• White petal color is a dominant trait.

• The phenotype is heterozygous.

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2