Q: Which of the following equations correctly calculates the density of bacteriophage in a sample, given the number of plaques, dilution factor, and volume plated?

$$density = \frac{\text{number of plaques} \times \text{dilution factor}}{\text{volume plated (in mL)}}$$

Question 1

Which of the following statements best explains why bacteria are ideal organisms for genetic studies?

Accepted Answer

Bacteria have haploid genomes, reproduce rapidly, and produce many progeny, making mutations easy to observe.

Question 2

Which process involves the direct transfer of DNA from a donor to a recipient bacterium via a physical connection?

Accepted Answer

Conjugation

Question 3

A bacterial cell that contains an F plasmid integrated into its chromosome is called:

Accepted Answer

Hfr cell

Question 4

Which of the following best describes generalized transduction?

Accepted Answer

Random incorporation of bacterial DNA fragments into a phage during the lytic cycle

Question 5

In an interrupted conjugation experiment, gene A enters the recipient cell at 10 minutes, gene B at 15 minutes, and gene C at 20 minutes. Which gene is closest to the origin of transfer?

Accepted Answer

Gene A

Question 6

Which of the following is a key feature of plasmids that makes them useful in genetic engineering?

Accepted Answer

They can replicate independently of the bacterial chromosome.

Question 7

A bacterium that cannot synthesize a particular nutrient and requires it to be supplied in the growth medium is called:

Accepted Answer

Auxotroph

Question 8

Which of the following statements about the F factor is TRUE?

Accepted Answer

The F factor contains genes required for conjugation, including those encoding sex pili.

Question 9

During transformation, which of the following steps occurs first?

Accepted Answer

Uptake of extracellular DNA by a competent cell

Question 10

Which of the following best explains why gene co-transformation frequency is inversely proportional to the distance between genes?

Accepted Answer

Genes that are closer together are more likely to be incorporated into the same DNA fragment during transformation.

Question 11

A bacterium is infected by a bacteriophage that accidentally packages a fragment of the host DNA. This DNA is then injected into another bacterium, where it recombines with the host genome. This process is called:

Accepted Answer

Generalized transduction

Question 12

Which of the following is NOT a characteristic of bacterial genomes?

Accepted Answer

They are always diploid.

Question 13

Which of the following is a function of transposons in bacterial genomes?

Accepted Answer

They can disrupt gene function and cause genome rearrangements.

Question 14

In a gene mapping experiment using generalized transduction, the cotransduction frequency between two genes is found to be 0.8. What does this suggest about the physical distance between these genes?

Accepted Answer

They are close together on the chromosome.

Question 15

Which of the following equations correctly calculates the density of bacteriophage in a sample, given the number of plaques, dilution factor, and volume plated?

Accepted Answer

$$density = \frac{	ext{number of plaques} 	imes 	ext{dilution factor}}{	ext{volume plated (in mL)}}$$

Question 16

A laboratory strain of E. coli is described as prototrophic. What does this mean?

Accepted Answer

It can grow on minimal medium because it synthesizes all essential compounds.

Question 17

Which of the following best describes the outcome of conjugation between an Hfr cell and an F- cell?

Accepted Answer

The F- cell may receive chromosomal genes but rarely becomes F+ because the entire F factor is seldom transferred.

Question 18

Which of the following is a practical application of metagenomics?

Accepted Answer

Analyzing the collective genomes of microbial communities to correlate with human health and disease.

Question 19

Which of the following is TRUE regarding the medical importance of bacteria and their genetic analysis?

Accepted Answer

Bacterial genetic analysis has led to the identification of genes associated with diseases such as obesity.

Question 20

A partially diploid (merodiploid) bacterial cell is formed when:

Accepted Answer

An F' plasmid carrying bacterial genes enters an F- cell.

Genetics Lecture 5: Chromosome Mapping in Prokaryotes and Eukaryotes

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