Question 1

Which of the following statements best describes the central dogma of molecular biology?

Accepted Answer

DNA is transcribed into RNA, which is then translated into protein.

Question 2

A segment of DNA has the sequence 5'-ATTCGATC-3'. What is the sequence of the complementary DNA strand?

Accepted Answer

5'-GATCGAAT-3'

Question 3

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Question 4

What is the function of telomerase in eukaryotic cells?

Accepted Answer

It extends the 3' end of chromosomes by adding repetitive DNA sequences.

Question 5

Which of the following codons serves as the start codon for translation in most organisms?

Accepted Answer

$$\mathrm{AUG}$$

Question 6

During DNA replication, which direction does the new DNA strand grow?

Accepted Answer

5' to 3'

Question 7

Which of the following best explains why Okazaki fragments are formed during DNA replication?

Accepted Answer

The lagging strand is synthesized discontinuously because DNA polymerase can only add nucleotides to the 3' end.

Question 8

Which experimental result from the Meselson-Stahl experiment ruled out the conservative model of DNA replication?

Accepted Answer

After one round of replication, only a single band of intermediate density was observed.

Question 9

Which of the following is a property of the genetic material that allows for genetic variation?

Accepted Answer

Ability to mutate

Question 10

Which of the following statements about the structure of DNA is correct?

Accepted Answer

The two strands are antiparallel and held together by hydrogen bonds between complementary bases.

Question 11

Which enzyme removes RNA primers and replaces them with DNA during replication in E. coli?

Accepted Answer

DNA polymerase I

Question 12

A mutation in which enzyme would most likely result in increased supercoiling ahead of the replication fork?

Accepted Answer

Topoisomerase (DNA gyrase)

Question 13

Which of the following is NOT a difference between DNA and RNA?

Accepted Answer

DNA contains phosphodiester bonds, RNA does not.

Question 14

Which of the following best describes the role of tRNA during translation?

Accepted Answer

It brings amino acids to the ribosome and matches them to the mRNA codon.

Question 15

A DNA molecule is found to contain 17.5% cytosine. According to Chargaff’s rules, what percentage of adenine would you expect?

Accepted Answer

$$32.5\%$$

Question 16

Which of the following is a direct result of the antiparallel structure of DNA?

Accepted Answer

Okazaki fragments are formed on the lagging strand.

Question 17

Which of the following best describes the function of restriction enzymes in recombinant DNA technology?

Accepted Answer

They cut DNA at specific sequences.

Question 18

Which of the following is a real-world application of biotechnology discussed in the study materials?

Accepted Answer

Genetically modifying crops for insect resistance.

Question 19

Which of the following statements about the Meselson-Stahl experiment is correct?

Accepted Answer

It used isotopes of nitrogen to distinguish old and new DNA strands.

Question 20

Which of the following is a consequence of telomerase deficiency in somatic cells?

Accepted Answer

Chromosomes shorten with each cell division, leading to senescence.

DNA Structure, Replication, and Gene Expression: Foundational Concepts in Genetics

Study Guide - Practice Questions