Question 1

Which of the following best describes the semiconservative model of DNA replication?

Accepted Answer

Each new DNA molecule consists of one parental strand and one newly synthesized strand.

Question 2

A mutation changes a DNA codon from AAA to AAG, but both codons code for lysine. What type of mutation is this?

Accepted Answer

Silent mutation

Question 3

Which enzyme is responsible for joining Okazaki fragments during DNA replication?

Accepted Answer

DNA ligase

Question 4

During transcription, which of the following sequences would be transcribed from a DNA template strand with the sequence 5'-ATGCGT-3'?

Accepted Answer

5'-AUGCGU-3'

Question 5

Which of the following best explains why a frameshift mutation is often more damaging than a point mutation?

Accepted Answer

It alters the reading frame, potentially changing every amino acid downstream of the mutation.

Question 6

A scientist introduces a mutagen into a bacterial culture. Which of the following best describes a mutagen?

Accepted Answer

A substance that increases the rate of mutation

Question 7

Which of the following is the correct sequence of events during gene expression in a eukaryotic cell?

Accepted Answer

Transcription → RNA splicing → Translation

Question 8

Which of the following statements about the sugar-phosphate backbone of DNA is correct?

Accepted Answer

It contains alternating deoxyribose sugars and phosphate groups.

Question 9

A patient is diagnosed with a genetic disorder caused by a nonsense mutation. What is the most likely effect of this mutation on the protein product?

Accepted Answer

The protein will be prematurely truncated.

Question 10

Which of the following best describes the function of transfer RNA (tRNA) during translation?

Accepted Answer

It carries amino acids to the ribosome and matches them to the coded mRNA message.

Question 11

A DNA molecule contains 30% adenine (A). According to Chargaff's rules, what percentage of thymine (T) would you expect?

Accepted Answer

$$30\%$$

Question 12

Which of the following is a correct description of a codon?

Accepted Answer

A sequence of three nucleotides on mRNA that codes for a specific amino acid

Question 13

Which of the following is true about the difference between DNA and RNA?

Accepted Answer

DNA contains deoxyribose sugar, while RNA contains ribose sugar.

Question 14

A mutation in the promoter region of a gene would most likely affect which process?

Accepted Answer

Transcription initiation

Question 15

Which of the following best describes the role of ribosomal RNA (rRNA) in the cell?

Accepted Answer

It forms the structural and catalytic core of the ribosome.

Question 16

A scientist observes that after transformation, a non-pathogenic bacterial strain becomes pathogenic. What is the most likely explanation?

Accepted Answer

The bacteria acquired new genetic material from the environment.

Question 17

Which of the following is the correct function of RNA polymerase?

Accepted Answer

Synthesizes RNA from a DNA template

Question 18

Which of the following best describes the triplet code?

Accepted Answer

Three nucleotides code for one amino acid

Question 19

A mutation changes a codon from UAU (tyrosine) to UGU (cysteine). What type of mutation is this?

Accepted Answer

Missense mutation

Question 20

Which of the following is a function of the A site of the ribosome during translation?

Accepted Answer

It is the site where the next aminoacyl-tRNA enters and base-pairs with the mRNA codon.

Molecular Biology of the Gene: Key Terms and Concepts

Study Guide - Practice Questions