Question 1

Which of the following best describes bacterial conjugation involving an Hfr strain and an F- cell?

Accepted Answer

A segment of the bacterial chromosome is transferred, and the recipient cell remains F- after recombination.

Question 2

During bacterial transformation, which of the following is most likely to occur?

Accepted Answer

A bacterium takes up a small DNA fragment from the environment and incorporates it into its chromosome.

Question 3

Which experimental evidence most directly demonstrated that DNA is the genetic material in phages?

Accepted Answer

The use of radioactive $$^{32}P to $$label DNA and $$^{35}S to $$label protein in Hershey-Chase experiments.

Question 4

What is the main function of the F plasmid in bacterial conjugation?

Accepted Answer

It provides the genetic information necessary for the formation of the sex pilus and transfer of DNA.

Question 5

A bacterium is described as 'competent.' What does this mean in the context of transformation?

Accepted Answer

It is able to take up extracellular DNA from its environment.

Question 6

Which of the following statements about R plasmids is correct?

Accepted Answer

R plasmids confer resistance to antibiotics and can be transferred between bacteria.

Question 7

In the interrupted mating technique for time mapping, what does the order of gene transfer indicate?

Accepted Answer

The sequence of genes on the bacterial chromosome.

Question 8

Which of the following best explains why DNA, and not protein, is considered the genetic material based on UV mutagenesis experiments?

Accepted Answer

DNA absorbs UV light at 260 nm, which correlates with the wavelength most effective for inducing mutations.

Question 9

Which of the following is a real-world application of recombinant DNA technology mentioned in the study materials?

Accepted Answer

Production of human insulin using bacterial cells.

Question 10

A bacterium carrying a Col plasmid is described as colicinogenic. What is the significance of this?

Accepted Answer

It produces proteins that can kill other bacteria lacking the same plasmid.

Question 11

Which of the following best describes generalized transduction?

Accepted Answer

A phage transfers random segments of bacterial DNA to another bacterium during infection.

Question 12

What is the main difference between virulent and temperate bacteriophages?

Accepted Answer

Virulent phages immediately replicate and lyse the host cell, while temperate phages can either lyse the cell or integrate into the host genome as a lysogen.

Question 13

If a previously integrated F factor excises from the chromosome and carries adjacent bacterial genes with it, what is the resulting plasmid called?

Accepted Answer

F' (F prime) plasmid

Question 14

Which of the following is NOT a direct piece of evidence that DNA is the genetic material?

Accepted Answer

Protein is abundant in the cytoplasm.

Question 15

A merozygote is formed when:

Accepted Answer

An F' plasmid is transferred to an F- cell, resulting in a cell partially diploid for certain genes.

Question 16

Which of the following best explains the advantage of plasmids to bacteria under stressful conditions?

Accepted Answer

Plasmids can carry genes that confer resistance to antibiotics, increasing the likelihood of survival.

Question 17

Which formula correctly represents Chargaff's rule for base pairing in DNA?

Accepted Answer

$$\mathrm{A} = \mathrm{T}$$ \, 	ext{and} \, \mathrm{G} = \mathrm{C}$

Question 18

In a time mapping experiment, the transfer of the gal gene occurs at 25 minutes and the lac gene at 15 minutes. What does this suggest about their relative positions on the chromosome?

Accepted Answer

The lac gene is transferred before the gal gene, indicating it is closer to the origin of transfer.

Question 19

Which of the following is a limitation of bacteriophage therapy for treating bacterial infections?

Accepted Answer

Phages require identification of the specific bacterial strain before use.

Genetics: Bacterial Reproduction, Genetic Exchange, and Phages

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