Patterns of Inheritance

All of the offspring produced in a test cross involving a brown rabbit and a white rabbit are brown. The result of this cross is best explained by

• incomplete dominance.

• codominance.

• crossing over.

• dominance.

In certain rats, black fur (B) is dominant over white fur (b). If two rats, both heterozygous (Bb) for fur color, are mated, their offspring would be expected to have

• three different genotypes and three different colors.

• three different genotypes and two different colors.

• two different genotypes and three different colors.

• four different genotypes and two different colors.

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NGSS.HS-LS3-1

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Sickle cell anemia results from a gene mutation that causes abnormalities in red blood cells. The sickle-cell gene is more common in tropical areas, and the individual who is heterozygous for the gene (Ss) has increased resistance to malaria. If two individuals heterozygous (Ss) for the sickle-cell gene have offspring, what percent of their offspring are expected to be heterozygous?

• 100%

• 75%

• 50%

• 25%

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In a certain variety of chicken, the genes for black feather color and the genes for white feather color are codominant. This condition produces

• three possible phenotypes for feather color.

• only two genotypes for feather color.

• white feather color, only.

• black feather color, only.

Color-blindness, resulting from a sex-linked trait, is more common in males than in females because

• the allele for the trait is located on the X chromosome.

• the allele for the trait is located on the Y chromosome.

• males have two copies of an allele for the trait.

• fathers pass the allele to their sons.

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NGSS.HS-LS3-1

Hemophilia is a sex‐linked, recessive trait. Which of the following describes the probability of hemophilia in the offspring of a man who does not have hemophilia and a woman who is a heterozygous carrier?

• There is a 100% chance that their sons will have hemophilia.

• There is a 0% chance that their daughters will have hemophilia.

• There is a 25% chance that their sons will have hemophilia.

• There is a 50% chance that their sons will have hemophilia.

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NGSS.HS-LS3-2

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When an organism has more than 10 fingers or toes, the condition is known as polydactylism. Although polydactylism is rare, it is a dominant trait. If two cats that are heterozygous for polydactylism mate and have a litter with a total of 12 kittens, how many of them would you expect to have more than 10 fingers or toes?

• 0

• 6

• 9

• 12

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NGSS.HS-LS3-1

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In humans, having freckles (F) is dominant to not having freckles (f). Having a cleft chin (C) is also dominant to not having a cleft chin (c). Which statement is true of the offspring of a cross between parents that are both heterozygous for both traits (FfCc)?

• Any offspring with freckles must also have a cleft chin.

• All of the offspring will be heterozygous for both traits.

• Any offspring who does not have freckles must have a cleft chin.

• The offspring could exhibit both traits, neither trait, nor only one of the traits.

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

A population of crabs living on a sandy beach exhibits three colors: dark brown, light brown, and speckled. The genotypes for these colors are BB for dark brown, bb for light brown, and Bb for speckled. If a dark brown crab were crossed with a light brown crab, what would be the probable phenotypic ratio of their offspring?

• all speckled

• all dark brown

• 3 dark brown : 1 light brown

• 1 dark brown : 2 speckled : 1 light brown

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

A gardener crossed a plant with red flowers with a plant that had white flowers. The offspring plants had pink flowers. What is the most likely genetic reason for these differences in color?

• codominance

• recessive pink genes

• polygenic inheritance

• incomplete dominance