Question 1

Which of the following best explains why meiosis, but not mitosis, leads to genetic variation in offspring?

Accepted Answer

Meiosis includes crossing over and independent assortment, which shuffle genetic material.

Question 2

A diploid cell with $$2n = 4$$ undergoes meiosis. How many genetically unique gametes can be produced due to independent assortment alone?

Accepted Answer

$$2^2 = 4$

Question 3

In Mendel’s monohybrid cross between true-breeding round-seeded (RR) and wrinkled-seeded (rr) pea plants, what is the expected phenotypic ratio in the F2 generation?

Accepted Answer

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

Question 4

Which principle states that alleles of different genes are distributed independently of one another during gamete formation?

Accepted Answer

Principle of Independent Assortment

Question 5

A plant with genotype RrYy is testcrossed with a plant with genotype rryy. If the genes assort independently, what fraction of the offspring are expected to have round, yellow seeds?

Accepted Answer

$$1/4$$

Question 6

Which of the following scenarios would violate Mendel’s principle of independent assortment?

Accepted Answer

Genes located close together on the same chromosome (linked genes)

Question 7

In a dihybrid cross between two heterozygotes (RrYy x RrYy), what is the expected phenotypic ratio among the offspring if the genes assort independently?

Accepted Answer

$$9:3:3:1$$

Question 8

A fruit fly with genotype $$X^W X^w is $$crossed with a male $$X^w Y. $$What proportion of male offspring will have white eyes if the white-eye gene is X-linked and recessive?

Accepted Answer

$$1/2$$

Question 9

If two genes are 19.6 map units apart on a chromosome, what percentage of recombinant offspring would you expect?

Accepted Answer

$$19.6\%$$

Question 10

Which blood type results from the genotype $$I^A I^B in $$the ABO blood group system?

Accepted Answer

Type AB

Question 11

In four-o’clocks, red flowers crossed with white flowers produce all pink flowers in the F1 generation. What type of inheritance is this?

Accepted Answer

Incomplete dominance

Question 12

A testcross is performed between a plant of unknown genotype and a homozygous recessive plant. If the unknown plant is heterozygous for both genes, what phenotypic ratio is expected among the offspring (assuming independent assortment)?

Accepted Answer

$$1:1:1:1$$

Question 13

Which of the following best describes the effect of crossing over during meiosis?

Accepted Answer

It creates new combinations of alleles on chromosomes.

Question 14

A geneticist observes that two traits are inherited together more often than expected by chance. What is the most likely explanation?

Accepted Answer

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

Question 15

Which of the following is an example of a multigenic (polygenic) trait in humans?

Accepted Answer

Height

Question 16

If a plant with genotype Rr is self-fertilized, what is the probability that an offspring will be homozygous recessive?

Accepted Answer

$$1/4$$

Question 17

Which of the following statements about Mendel’s experiments is FALSE?

Accepted Answer

Mendel’s results supported the blending inheritance hypothesis.

Question 18

A cross between a rose-combed chicken and a pea-combed chicken produces all walnut-combed offspring. What does this suggest about the genetic control of comb shape?

Accepted Answer

Comb shape is determined by two genes with interaction (epistasis).

Question 19

Which of the following best explains why the actual frequencies of recombinant offspring are used to map genetic distance between genes?

Accepted Answer

The farther apart two genes are, the more likely crossing over will occur between them.

Question 20

Which of the following is a direct result of the principle of segregation?

Accepted Answer

Each gamete receives only one allele of each gene.

Mendelian Genetics and Chromosomal Basis of Inheritance: Study Notes

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