Knowledge Check: Punnett Squares

Match the following vocabulary terms:

• heterozygous

• an individual containing two copies of the same allele for a particular trait

• genotype

• the observable characteristics of an organism

• homozygous

• an individual containing two different alleles for a particular trait

• phenotype

• the genetic makeup of an individual cell or organism that determines or contributes to its phenotype

The gene for curled ears (C) is dominant over the gene for straight ears (c). The picture shows a cat with curled ears (Cc) and a cat with straight ears (cc). What percent of the offspring are expected to have curled ears as a result of a cross between the cats shown?

• 100

• 75

• 50

• 25

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

NGSS.HS-LS3-3

The diagram shows the location of genes for three specific traits of a fly. A fly inherits the genotypes Aa, BB, and cc. Which of the following traits will this organism express?

• short appendages on its head, normal wings, and brown eyes

• long appendages on its head, normal wings, and brown eyes

• long appendages on its head, vestigial wings, and red eyes

• short appendages on its head, normal wings, and red eyes

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

The Punnett square shows a cross between two pea plants. The gene for green pods (G) is dominant over the gene for yellow pods (g). What percentage of plants produced by the cross shown are expected to have yellow pods?

• 100%

• 75%

• 50%

• 25%

Tags

NGSS.HS-LS3-3

For a particular trait, the allele F is dominant over the allele f. The Punnett square below shows the genetic cross of two parents, each with the genotype Ff. Which box in this Punnett square would contain two dominant alleles?

• 1

• 2

• 3

• 4

Tags

NGSS.HS-LS3-1

The Punnett squares show two different crosses, A and B. Which statement is true about both of these Punnett squares?

• The phenotype that results from the dominant allele cannot appear in either cross.

• The phenotype resulting from the dominant allele can appear in Cross B, but not Cross A.

• The phenotype that results from two recessive alleles can appear in Cross A, but not in Cross B.

• The phenotype that results from two recessive alleles can appear in Cross B, but not in Cross A.

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

For a particular trait, R is dominant to r. Look closely at the Punnett square. What is the probability of an offspring having the genotype that results in the appearance of the recessive trait?

• 50 %

• 25%

• 75%

• 100%

Tags

NGSS.HS-LS3-3