Q: In the sweet pea, flower color is determined by two genes, C and P. Both must have at least one dominant allele for purple flowers. What is the expected phenotypic ratio in the F2 generation from a dihybrid cross?

$$9:7$$ \text{ (purple:white)}$

Question 1

Which of the following best describes incomplete dominance?

Accepted Answer

The heterozygote expresses a phenotype that is intermediate between the two homozygotes.

Question 2

A woman with blood type AB and a man with blood type O have a child. What are the possible blood types of their child?

Accepted Answer

Type A or Type B

Question 3

Which of the following is an example of pleiotropy?

Accepted Answer

A single gene mutation causing multiple symptoms in cystic fibrosis, such as thick mucus, salty sweat, and poor weight gain.

Question 4

In a cross between two Manx cats (Mm x Mm), what is the expected phenotypic ratio among the surviving offspring?

Accepted Answer

$$2:1$$ 	ext{ (Manx:normal)}$

Question 5

Which of the following best explains the phenomenon of heterozygote advantage in sickle cell anemia?

Accepted Answer

Heterozygotes are resistant to malaria and do not suffer from sickle cell disease.

Question 6

A man with hemophilia (an X-linked recessive disorder) and a woman who is a carrier have a child. What is the probability that their son will have hemophilia?

Accepted Answer

$$0.5$$

Question 7

Which of the following is a possible molecular explanation for incomplete penetrance?

Accepted Answer

Environmental factors or modifier genes influence whether the phenotype is expressed.

Question 8

In the sweet pea, flower color is determined by two genes, C and P. Both must have at least one dominant allele for purple flowers. What is the expected phenotypic ratio in the F2 generation from a dihybrid cross?

Accepted Answer

$$9:7$$ 	ext{ (purple:white)}$

Question 9

Which of the following best describes codominance?

Accepted Answer

Both alleles are fully expressed in the heterozygote, as seen in AB blood type.

Question 10

A temperature-sensitive allele in Drosophila causes lethality at $$30^\circC $$but not at $$22^\circC. $$What is this an example of?

Accepted Answer

Conditional lethal allele

Question 11

Which of the following is true about gene redundancy?

Accepted Answer

Loss of function in one gene may have no effect due to compensation by a paralog.

Question 12

A cross between two true-breeding white-flowered sweet peas produces all purple-flowered offspring. What genetic phenomenon does this illustrate?

Accepted Answer

Complementation

Question 13

Which of the following is an example of a sex-influenced trait?

Accepted Answer

Scurs in cattle, where the allele is dominant in males but recessive in females.

Question 14

Which of the following best describes a dominant-negative mutation?

Accepted Answer

A mutant protein antagonizes the function of the normal protein.

Question 15

In the ABO blood group system, which genotype would result in blood type O?

Accepted Answer

$$ii$$

Question 16

A parakeet with genotype $$Yyaa$$ will have which feather color?

Accepted Answer

Yellow

Question 17

Which of the following is NOT a possible explanation for pleiotropy?

Accepted Answer

A gene is only expressed in one cell type at one stage of development.

Question 18

Which of the following best describes epistasis?

Accepted Answer

An allele of one gene masks the phenotypic effects of another gene.

Question 19

A woman with genotype $$I^A i$$ and a man with genotype $$I^B i$$ have a child. What is the probability that their child will have blood type AB?

Accepted Answer

$$0.25$$

Question 20

Which of the following is a real-world example of environmental influence on phenotype?

Accepted Answer

Arctic foxes changing coat color with the seasons due to temperature-sensitive alleles.

Extensions of Mendelian Inheritance: Patterns, Mechanisms, and Exceptions

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