Question 1

Why did Gregor Mendel choose the garden pea as his model organism for genetic experiments?

Accepted Answer

Peas were inexpensive, easy to grow, had a short generation time, produced many seeds, and allowed controlled matings.

Question 2

According to Mendel’s principle of segregation, what happens to alleles during gamete formation?

Accepted Answer

Two members of each gene pair segregate into different gametes during egg and sperm formation.

Question 3

A pea plant with genotype Rr is crossed with another Rr plant. What is the expected phenotypic ratio of the offspring if R is dominant for round seeds and r is recessive for wrinkled seeds?

Accepted Answer

$$3:1 ($$round:wrinkled)

Question 4

Which of the following best describes the principle of independent assortment?

Accepted Answer

Alleles of different genes assort independently of one another during meiosis if they are on different chromosomes.

Question 5

In a dihybrid cross between two heterozygotes for seed color (Yy) and seed shape (Rr), what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

$$9:3:3:1$$

Question 6

A testcross is performed between a plant with a dominant phenotype and an unknown genotype and a plant with a recessive phenotype. What result would indicate the unknown plant is heterozygous?

Accepted Answer

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

Question 7

How does crossing over during meiosis affect the inheritance of linked genes?

Accepted Answer

It can separate linked genes, especially if they are far apart, leading to recombinant offspring.

Question 8

Which of the following is an example of codominance?

Accepted Answer

A person with AB blood type expressing both A and B antigens equally.

Question 9

If a trait is determined by multiple genes and shows a continuous range of phenotypes, what is this trait called?

Accepted Answer

Quantitative trait

Question 10

A pedigree shows a trait that appears in every generation and affects both males and females equally. What is the most likely mode of inheritance?

Accepted Answer

Autosomal dominant

Question 11

Which scenario best illustrates incomplete dominance?

Accepted Answer

A cross between a red-flowered and a white-flowered plant produces pink-flowered offspring.

Question 12

Which of the following statements about the ABO blood group system is correct?

Accepted Answer

The IA and IB alleles are codominant, and both are dominant over the i allele.

Question 13

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

Accepted Answer

A or B

Question 14

Which of the following best explains why most phenotypes are influenced by both genes and the environment?

Accepted Answer

Environmental factors can influence the expression of genes, resulting in variation in phenotypes.

Question 15

A geneticist observes that two genes are inherited together more often than not. What is the most likely explanation?

Accepted Answer

The genes are linked and located close together on the same chromosome.

Question 16

If a male is affected by an X-linked recessive disorder, which of the following is true?

Accepted Answer

He inherited the allele from his mother, who is a carrier or affected.

Question 17

Which of the following is a correct statement about the use of testcrosses in genetics?

Accepted Answer

A testcross can determine whether an individual with a dominant phenotype is homozygous or heterozygous.

Question 18

A trait is observed to skip generations in a pedigree and appears more frequently in males. What is the most likely mode of inheritance?

Accepted Answer

X-linked recessive

Question 19

Which of the following equations correctly represents the probability of two independent events both occurring?

Accepted Answer

$$P(A \ 	ext{and} \ B) = P(A) 	imes P(B)$$

Mendel and the Gene: Principles of Inheritance and Extensions

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