Question 1

Which of the following features makes bacteria especially useful for genetic analysis?

Accepted Answer

They have short generation times and produce large numbers of progeny.

Question 2

A bacterial strain that can grow on minimal medium but not on medium lacking threonine is best described as:

Accepted Answer

An auxotroph for threonine.

Question 3

Which process involves the uptake of free DNA from the environment by a bacterial cell?

Accepted Answer

Transformation

Question 4

In Lederberg and Tatum’s experiment, why did prototrophic colonies appear only when two auxotrophic strains were mixed?

Accepted Answer

Physical contact between cells allowed genetic recombination.

Question 5

Which of the following best describes the function of the F (fertility) plasmid in E. coli?

Accepted Answer

It promotes its own transfer from donor to recipient cells during conjugation.

Question 6

During Hfr × F⁻ conjugation, which of the following outcomes is most likely?

Accepted Answer

The recipient cell remains F⁻ but may acquire donor alleles via homologous recombination.

Question 7

In an interrupted mating experiment, the time at which a gene first appears in exconjugants is most closely related to:

Accepted Answer

The distance of the gene from the origin of transfer (oriT).

Question 8

Which of the following statements about cotransduction is correct?

Accepted Answer

Cotransduction frequency is higher for genes that are close together on the chromosome.

Question 9

Which experiment provided definitive proof that DNA is the hereditary material?

Accepted Answer

Hershey and Chase’s bacteriophage labeling experiment.

Question 10

Which of the following best describes the structure of B-form DNA?

Accepted Answer

A right-handed helix with 10.5 base pairs per turn and a diameter of 20 Å.

Question 11

Which enzyme is responsible for relieving supercoiling during DNA replication?

Accepted Answer

DNA topoisomerase

Question 12

In eukaryotic cells, which of the following modifications occurs to pre-mRNA before it becomes mature mRNA?

Accepted Answer

Addition of a 5' cap, polyadenylation at the 3' end, and removal of introns by splicing.

Question 13

Which of the following best explains the function of the sliding clamp during DNA replication?

Accepted Answer

It anchors DNA polymerase to the template, increasing processivity.

Question 14

A mutation that changes a codon from UAU (tyrosine) to UAA (stop) is best described as:

Accepted Answer

A nonsense mutation.

Question 15

Which of the following statements about the genetic code is correct?

Accepted Answer

The code is universal, with only a few exceptions in mitochondria and some protozoa.

Question 16

Which of the following is a real-world application of the polymerase chain reaction (PCR)?

Accepted Answer

Amplifying a specific DNA segment for forensic analysis.

Question 17

Which of the following best describes the role of telomerase in eukaryotic cells?

Accepted Answer

It synthesizes repetitive DNA sequences at chromosome ends to prevent loss of genetic material.

Question 18

Which of the following is a consequence of nondisjunction during meiosis I in humans?

Accepted Answer

All resulting gametes are aneuploid, with either n+1 or n-1 chromosomes.

Question 19

Which of the following chromatin features is associated with actively transcribed genes?

Accepted Answer

Euchromatin, which is less condensed and accessible.

Question 20

Which of the following best describes the function of enhancer sequences in eukaryotic gene regulation?

Accepted Answer

They increase the level of transcription by binding activator proteins and facilitating interaction with the promoter.

Genetic Analysis and Mapping in Bacteria and Bacteriophages: Mini-Textbook Study Notes

Study Guide - Practice Questions