Genetics Test Review

Gregor Mendel crossed true-breeding plants with green pea pods with true-breeding plants with yellow pea pods. The resulting F₁ generation all had green pea pods. What did he observe in the F₂ generation?

• Mendel observed green and yellow pea pods in a 3:1 ratio because the F₁ generation was heterozygous.

• Mendel observed green and yellow pea pods in a 4:1 ratio because the allele for green pea pods is dominant.

• Mendel observed green and yellow pea pods in a 1:1 ratio because the F₂ generation had the same characteristics as the parent generation.

• Mendel observed only green pea pods because both parents had green pea pods.

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NGSS.HS-LS3-2

Which pair of traits is most likely to be inherited together?

• purple eye and brown eye because they are both eye traits

• aristaless and speck body because they have the greatest chance of crossing over

• curved wing and arc (bent wings) because they have the least chance of crossing-over

• black body and light eye because they are closest together on chromosome 2

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NGSS.HS-LS3-1

NGSS.HS-LS3-2

In pea plants, green peas (G) are dominant over yellow peas (g), and tall height (T) is dominant over short height (t). In a dihybrid cross of the two traits, what is the expected fraction of the offspring that show the recessive form of both traits, meaning they are short and have yellow peas? Assume the traits sort independently of each other.

• 1/100

• 1/16

• 1/8

• 1/4

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NGSS.HS-LS3-3

When Mendel crossed true-breeding tall pea plants with true-breeding short pea plants, all the offspring were tall. Then he allowed the first generation tall plants to self-pollinate. What were the expected ratios of phenotypes in the F₂ generation?

• Because this is a monohybrid cross of pea plants that carry two alleles for plant height, the expected ratio is 3 tall : 1 short.

• Because this is a dihybrid cross of pea plants that carry three alleles for plant height, the expected ratio is 9 tall : 3 intermediate: 1 short.

• Because this is a dihybrid cross of pea plants that carry four alleles for plant height, the expected ratio is 4 tall : 1 short.

• Because this is a monohybrid cross of pea plants that carry two alleles for plant height, the expected ratio is 1 tall : 1 short.

Mendel studied 7 traits in pea plants. He concluded that the factors, or genes, for the 7 traits sorted independently of one another. Today, how do scientists explain Mendel's results?

• The genes for the 7 traits are located on the same chromosome.

• Crossing over events did not occur during Mendel's experiments.

• Crossing over events occurred very frequently during Mendel's experiments.

• The genes for the 7 traits are located on 7 chromosomes.

In guinea pigs, the allele for black fur (B) is dominant over the allele for white fur (b). A cross of two black guinea pigs produces three offspring, all of which have black fur. What conclusion is supported about the genotypes of the two parent guinea pigs of the cross?

• Both parents were homozygous dominant (BB).

• At least one parent was homozygous dominant (BB), but the other parent could be heterozygous (Bb).

• Either parent could be homozygous dominant (BB) or heterozygous (Bb).

• Both parents were heterozygous (Bb).

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NGSS.HS-LS3-1

NGSS.HS-LS3-2

If two people with L^ML^N genotypes have children, what is the expected ratio of genotypes among the children?

• 1 L^ML^M: 2 L^ML^N: 1 L^NL^N

• 9 L^ML^M: 3 L^ML^N: 1 L^NL^N

• 4 L^ML^M: 1 L^NL^N

• 1 L^NL^N : 1 L^ML^M

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NGSS.HS-LS3-1

NGSS.HS-LS3-2

Marissa and Gene have phenotypes at the opposite extremes of a polygenic trait. What phenotype will their children most likely have?

• They will have the intermediate phenotype for the trait at the middle of the bell curve.

• They will have either of the two extreme phenotypes of the trait inherited from their mother or father.

• They will have a phenotype that is determined by the typical distribution of phenotypes in the 9:3:3:1 ratio.

• They will resemble other family members but not their parents, because the alleles’ expression is hidden in the F₁ generation.

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NGSS.HS-LS3-2

Which pattern of inheritance is consistent with the pedigree?

• sex-linked

• multiple allele

• co-dominant

• dominant allele

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NGSS.HS-LS3-1

NGSS.HS-LS3-2

Huntingons diseases is caused by a dominant allele. How could a doctor determine the chances that a patient would have Huntingtons disease?

• By identifying if the patient’s parents carry the dominant allele for Huntington’s disease

• By identifying if the patient is married to a person that exhibits symptoms of Huntington’s disease.

• By identifying if the patient had been in close contact with someone that exhibits symptoms of Huntington’s disease

• By identifying if the patient had been in close contact with someone that carries the dominant allele for Huntington’s disease

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NGSS.HS-LS3-1

NGSS.HS-LS3-2