Question 1

Which of the following best describes Mendel's principle of segregation?

Accepted Answer

The two members of each gene pair must segregate into different gamete cells during the formation of eggs and sperm.

Question 2

In a cross between two heterozygous pea plants for seed shape ($$Rr 	imes Rr$$), what is the expected phenotypic ratio in the offspring?

Accepted Answer

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

Question 3

Which statement about the chromosomal theory of inheritance is correct?

Accepted Answer

Genes are located on chromosomes, and their physical separation during meiosis explains Mendel's principles.

Question 4

A dihybrid cross ($$YyRr 	imes YyRr) $$produces offspring with four phenotypes in a $$9:3:3:1$$ ratio. What principle does this result support?

Accepted Answer

Principle of independent assortment

Question 5

Which of the following is an example of codominance?

Accepted Answer

A heterozygote expressing both alleles equally, such as AB blood type

Question 6

If a gene is located on the X chromosome and shows recessive inheritance, which of the following is most likely true?

Accepted Answer

Males are more frequently affected than females.

Question 7

Which scenario best illustrates pleiotropy?

Accepted Answer

A single gene mutation causing multiple, seemingly unrelated phenotypes.

Question 8

What is the expected genotypic ratio from a cross between two heterozygous individuals ($$Rr 	imes Rr$$)?

Accepted Answer

$$1:2:1 (RR$$:Rr:rr)

Question 9

Which of the following best explains why linked genes do not always assort together?

Accepted Answer

Crossing over during meiosis can separate linked genes, resulting in recombinants.

Question 10

A testcross is performed between a pea plant with an unknown genotype for seed shape and a homozygous recessive plant. If all offspring have round seeds, what is the genotype of the unknown parent?

Accepted Answer

Homozygous dominant ($$RR)$$

Question 11

Which of the following is NOT a feature of Mendel's model organism, the garden pea?

Accepted Answer

It has only one observable trait.

Question 12

Which of the following is a quantitative trait?

Accepted Answer

Height in humans, which shows continuous variation.

Question 13

If two genes are located far apart on the same chromosome, what is most likely to occur during meiosis?

Accepted Answer

They are more likely to cross over and assort independently.

Question 14

Which of the following best describes incomplete dominance?

Accepted Answer

Heterozygotes have an intermediate phenotype between the two homozygotes.

Question 15

A pedigree shows a trait that skips generations and affects males more frequently than females. What is the most likely mode of inheritance?

Accepted Answer

X-linked recessive

Question 16

Which equation represents the probability of obtaining a specific genotype from a dihybrid cross ($$AaBb 	imes AaBb) $$using the product rule?

Accepted Answer

$$P(AaBb) = P(Aa) 	imes P(Bb)$$

Question 17

Which of the following is true about the inheritance of acquired characteristics?

Accepted Answer

Traits are inherited as discrete units called genes.

Question 18

Which of the following is a real-world example of gene-environment interaction?

Accepted Answer

Phenylketonuria (PKU) can be managed with a low-phenylalanine diet, preventing mental handicap.

Question 19

Which of the following statements about testcrosses is correct?

Accepted Answer

A testcross involves crossing an individual with a dominant phenotype to a homozygous recessive individual to determine the unknown genotype.

Mendel and the Gene: Patterns of Inheritance

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