Question 1

Which of the following statements correctly describes the synthesis of the leading and lagging strands at the DNA replication fork?

Accepted Answer

The leading strand is synthesized continuously toward the replication fork, while the lagging strand is synthesized discontinuously away from the fork in the form of Okazaki fragments.

Question 2

In a genetic cross involving two genes on the same chromosome, which condition is necessary for Mendel's law of independent assortment to apply?

Accepted Answer

The genes must be on separate chromosomes or far enough apart on the same chromosome that they assort independently.

Question 3

A linkage map is constructed using recombination frequencies. Which statement best describes what a linkage map shows?

Accepted Answer

It shows the genetic distance between genes based on recombination frequency, not physical distance.

Question 4

If the recombination frequency between genes A and B is 6.4%, between B and C is 13.2%, and between A and C is 18.5%, which of the following is true?

Accepted Answer

$$RF(B-C) + RF(A-B) \u003e RF(A-C)$$

Question 5

During meiosis, homologous chromosomes pair and undergo recombination. What is the primary outcome of this process?

Accepted Answer

It increases genetic diversity through allele shuffling.

Question 6

Which enzyme is responsible for actively producing double-strand breaks (DSBs) during meiotic recombination in eukaryotes?

Accepted Answer

Spo11

Question 7

In the Double-Strand Break Repair (DSBR) model, what is the role of the 3' overhang created by exonuclease activity?

Accepted Answer

It invades a homologous region in the donor duplex to initiate strand exchange.

Question 8

Which of the following best explains why crossover frequency increases as the distance between two genes on a chromosome increases?

Accepted Answer

Genes that are farther apart have a higher probability of a crossover event occurring between them.

Question 9

Which repair mechanism is most likely to result in gene conversion rather than crossover during double-strand break repair?

Accepted Answer

Synthesis-Dependent Strand Annealing (SDSA)

Question 10

A patient is found to have a genetic disease caused by the loss of DNA between direct repeats. Which repair mechanism is most likely responsible for this deletion?

Accepted Answer

Single-Strand Annealing (SSA)

Question 11

Which of the following is NOT a consequence of non-homologous repair of double-strand breaks?

Accepted Answer

Precise repair using a homologous chromosome as a template

Question 12

In the context of recombination, what is a heteroduplex DNA?

Accepted Answer

A region where two non-sister chromatids anneal and contain mismatched base pairs due to sequence differences.

Question 13

Which of the following best describes the outcome if both Holliday junctions in the DSBR model are resolved by cutting the same strands?

Accepted Answer

Non-crossover (patch) recombinant DNA is produced.

Question 14

A geneticist observes that two genes do not assort independently and the offspring ratios deviate from the expected 9:3:3:1. 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 scenarios is most likely to result in a crossover event during meiosis?

Accepted Answer

Homologous chromosomes are paired and aligned with each other.

Question 16

In a test cross involving a double heterozygote and a tester (homozygous recessive), which progeny types indicate recombination between the two genes?

Accepted Answer

Progeny with new combinations of alleles not found in the parents.

Question 17

Which of the following is a key difference between recombination during mitosis and meiosis?

Accepted Answer

Homologous chromosomes pair and recombine during meiosis, but not during mitosis.

Question 18

Which of the following best describes gene conversion?

Accepted Answer

A process where the DNA sequence is changed, resulting in one allele being converted to another without crossover.

Question 19

Which repair pathway is most likely to result in the loss of genetic information between direct repeats, potentially causing diseases such as Fabry disease or diabetes?

Accepted Answer

Single-Strand Annealing (SSA)

DNA Recombination and Genetic Linkage: Mechanisms and Applications

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