Question 1

Which of the following best describes a centimorgan (cM) in genetic mapping?

Accepted Answer

A unit representing a 1% chance of recombination occurring between two loci during meiosis.

Question 2

A geneticist observes that two genes in Drosophila are inherited together more often than predicted by Mendel’s law of independent assortment. What is the most likely explanation?

Accepted Answer

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

Question 3

If the recombination frequency between gene A and gene B is 12%, what is the genetic distance between them?

Accepted Answer

$$12$$ centimorgans

Question 4

Which of the following best describes a double crossover event during meiosis?

Accepted Answer

Two exchanges of genetic material between homologous chromosomes, resulting in segments being swapped twice.

Question 5

Which of the following is NOT a mechanism of horizontal gene transfer in bacteria?

Accepted Answer

Binary fission

Question 6

A bacterium that can grow on minimal medium but loses this ability after a mutation is called:

Accepted Answer

An auxotroph

Question 7

Which experiment provided the first strong evidence that DNA is the genetic material by using radioactive labeling of phage proteins and DNA?

Accepted Answer

Hershey and Chase’s blender experiment

Question 8

Which of the following base pairing rules is correct for DNA?

Accepted Answer

$$A$$ pairs with $$T$$ and $$G$$ pairs with $$C$$

Question 9

Which of the following best describes a phosphodiester bond in nucleic acids?

Accepted Answer

A bond between the 3’ hydroxyl group of one nucleotide and the 5’ phosphate group of the next

Question 10

Which form of DNA is most commonly found under physiological conditions in cells?

Accepted Answer

B-DNA

Question 11

In the Meselsohn and Stahl experiment, what was the key evidence supporting the semiconservative model of DNA replication?

Accepted Answer

The appearance of hybrid DNA after one generation and both hybrid and light DNA after two generations

Question 12

Which enzyme is responsible for synthesizing the majority of DNA during prokaryotic DNA replication?

Accepted Answer

DNA polymerase III

Question 13

Why can DNA polymerase III not replace the function of telomerase in eukaryotic cells?

Accepted Answer

DNA polymerase III cannot initiate DNA synthesis without a primer and cannot extend the ends of linear chromosomes.

Question 14

Which of the following best describes the role of Okazaki fragments in DNA replication?

Accepted Answer

They are short DNA fragments synthesized on the lagging strand.

Question 15

After DNA replication in eukaryotes, what is the composition of histones associated with the new DNA?

Accepted Answer

A mixture of old and new histones is present.

Question 16

Which protein recognizes and binds to the origin of replication (oriC) in prokaryotes to initiate DNA replication?

Accepted Answer

DnaA

Question 17

A scientist is mapping three genes (p, j, r) and observes the following offspring classes: parental, single crossover, and double crossover. Which class will be the least frequent?

Accepted Answer

Double crossover class

Question 18

Which of the following statements about bacterial conjugation is correct?

Accepted Answer

It requires direct cell-to-cell contact and involves transfer of plasmid DNA.

Question 19

Which scientist(s) used X-ray diffraction to reveal the helical structure of DNA?

Accepted Answer

Rosalind Franklin and Maurice Wilkins

Question 20

Which of the following is a key difference between DNA and RNA molecules?

Accepted Answer

DNA contains deoxyribose sugar, while RNA contains ribose sugar.

Genetics Study Guide: Linkage, Bacterial Genetics, DNA Structure, and Replication

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