Question 1

Which experiment provided the first direct evidence that DNA, and not protein, is the hereditary material in cells?

Accepted Answer

Hershey-Chase blender experiment

Question 2

In the Avery-MacLeod-McCarty experiment, which enzyme treatment abolished the transformation of R-strain bacteria into S-strain?

Accepted Answer

DNase

Question 3

Which of the following best explains why DNA is described as 'antiparallel'?

Accepted Answer

The two strands run in opposite 5’ to 3’ directions

Question 4

Which feature of DNA is responsible for Chargaff’s rules ($$A = T$$ and $$C = G$$)?

Accepted Answer

Complementary base pairing

Question 5

During DNA denaturation, which bonds are broken?

Accepted Answer

Hydrogen bonds between complementary bases

Question 6

Which enzyme is responsible for introducing negative supercoiling in bacterial DNA?

Accepted Answer

DNA gyrase (topoisomerase II)

Question 7

A bacterial cell is exposed to a drug that inhibits DNA gyrase. What is the most likely immediate effect during DNA replication?

Accepted Answer

Supercoiling ahead of the fork would prevent further unwinding

Question 8

Which of the following statements about plasmids is FALSE?

Accepted Answer

They are always required for cell survival

Question 9

Why are Okazaki fragments formed during DNA replication?

Accepted Answer

Because DNA polymerase can only synthesize DNA in the 5’ to 3’ direction

Question 10

Which enzyme removes RNA primers during DNA replication in E. coli?

Accepted Answer

DNA polymerase I

Question 11

Which of the following is a key difference between prokaryotic and eukaryotic DNA replication?

Accepted Answer

Eukaryotes have telomeres and use telomerase

Question 12

Which of the following best describes the 'one gene-one enzyme' hypothesis demonstrated by Beadle and Tatum?

Accepted Answer

Each gene encodes a single enzyme that catalyzes a specific step in a metabolic pathway

Question 13

Which of the following is NOT a function of nucleoid-associated proteins (NAPs) in prokaryotes?

Accepted Answer

Introducing negative supercoiling

Question 14

Which of the following statements about transposons is TRUE?

Accepted Answer

They can move within or between DNA molecules

Question 15

Which of the following best describes semiconservative DNA replication?

Accepted Answer

Each new DNA molecule consists of one parental and one new strand

Question 16

Which activity of DNA polymerase III is responsible for its proofreading function?

Accepted Answer

3’ → 5’ exonuclease

Question 17

A mutation in the gene encoding primase would most directly affect which step of DNA replication?

Accepted Answer

Synthesis of RNA primers

Question 18

Which of the following is a property of prokaryotic chromosomes?

Accepted Answer

They are circular and haploid

Question 19

Which of the following best explains why the melting temperature ($$T_m) of $$DNA increases with higher GC content?

Accepted Answer

GC pairs form three hydrogen bonds, requiring more energy to break

Question 20

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

Accepted Answer

RNA contains ribose instead of deoxyribose

Prokaryotic Genome Structure, DNA Organization, and Replication: Microbiology Study Notes

Study Guide - Practice Questions