Question 1

Which of the following best describes Mendel's Law of Segregation?

Accepted Answer

Two alleles for a gene separate during gamete formation, so each gamete receives only one allele.

Question 2

A true-breeding pea plant with purple flowers (PP) is crossed with a true-breeding plant with white flowers (pp). What is the expected genotype and phenotype ratio in the F1 generation?

Accepted Answer

Genotype: 1 Pp; Phenotype: 100% purple

Question 3

In a dihybrid cross between two heterozygous pea plants (YyRr × YyRr), what is the expected phenotypic ratio among the offspring?

Accepted Answer

$$9:3:3:1$$

Question 4

Which of the following is an example of pleiotropy?

Accepted Answer

A gene that affects both red blood cell shape and malaria resistance in humans.

Question 5

A man and a woman are both carriers for cystic fibrosis (heterozygous). What is the probability that their child will have cystic fibrosis?

Accepted Answer

$$\frac{1}{4}$$

Question 6

Which inheritance pattern is illustrated by the ABO blood group system in humans?

Accepted Answer

Codominance and multiple alleles

Question 7

A testcross is performed between a pea plant with a dominant phenotype and a homozygous recessive plant. If the dominant plant is heterozygous, what is the expected outcome?

Accepted Answer

Half the offspring will show the dominant phenotype, and half will show the recessive phenotype.

Question 8

Which of the following best explains why traits controlled by polygenic inheritance, such as human skin color, show a wide range of phenotypes?

Accepted Answer

Multiple genes contribute additively to the phenotype.

Question 9

In Labrador retrievers, coat color is determined by two genes: one for pigment color (B = black, b = brown) and one for pigment deposition (E = pigment, e = no pigment). What color will a dog with genotype bbEe be?

Accepted Answer

Brown

Question 10

Which of the following scenarios demonstrates the concept of epistasis?

Accepted Answer

A gene that prevents pigment expression, masking the effect of another gene for pigment color.

Question 11

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

Accepted Answer

A or B

Question 12

Which of the following best describes incomplete dominance?

Accepted Answer

The heterozygote has a phenotype intermediate between the two homozygotes.

Question 13

A couple has a child with albinism, a recessive disorder. Both parents have normal pigmentation. What are the genotypes of the parents?

Accepted Answer

Both are heterozygous carriers.

Question 14

Which of the following is a real-world example of heterozygote advantage?

Accepted Answer

Carriers of the sickle-cell allele are more resistant to malaria.

Question 15

If a genetic counselor is using a pedigree to determine the inheritance pattern of a trait, which of the following would suggest a dominant inheritance?

Accepted Answer

The trait appears in every generation.

Question 16

Which of the following best explains why cystic fibrosis is considered pleiotropic?

Accepted Answer

The gene affects multiple organ systems, including lungs, pancreas, and digestive tract.

Question 17

A plant with genotype AaBb is self-crossed. Assuming independent assortment, what fraction of the offspring will have the genotype aabb?

Accepted Answer

$$\frac{1}{16}$$

Question 18

Which of the following is NOT a reason Mendel chose pea plants for his experiments?

Accepted Answer

They have a long generation time.

Question 19

Which of the following best describes the effect of environment on phenotype?

Accepted Answer

Environmental factors such as temperature and nutrition can influence the expression of genetic traits.

Question 20

A woman with Huntington's disease (autosomal dominant) and a man without the disease have a child. What is the probability that the child will inherit the disease if the woman is heterozygous?

Accepted Answer

$$\frac{1}{2}$$

Mendel and the Gene Idea: Patterns and Mechanisms of Genetic Inheritance

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