SAT - Biology Subject DNA Structure and Replication Questions and Answers

Question 1

In a DNA double helix, the two polynucleotide chains are held together by which type of bond between the complementary nitrogenous bases?

Accepted Answer

Hydrogen bonds

Answer

Covalent bonds

Answer

Ionic bonds

Answer

Peptide bonds

Question 2

A scientist analyzes a sample of DNA and finds that it contains 28% adenine. Based on the rules of base pairing, what percentage of guanine should be present in this sample?

Accepted Answer

22%

Answer

28%

Answer

72%

Answer

44%

Question 3

Which of the following enzymes is responsible for unzipping the DNA double helix by breaking the bonds between complementary bases to initiate replication?

Accepted Answer

DNA helicase

Answer

DNA polymerase III

Answer

DNA ligase

Answer

Primase

Question 4

A researcher uses a chemical that specifically inhibits the function of DNA ligase. Which of the following would be an expected result of this inhibition during DNA replication?

Accepted Answer

The newly synthesized lagging strand would consist of unjoined Okazaki fragments.

Answer

The parental DNA strands would fail to separate.

Answer

Synthesis of the leading strand would be unable to start.

Answer

RNA primers would not be replaced with DNA nucleotides.

Question 5

The semiconservative model of DNA replication was confirmed by the Meselson-Stahl experiment. This model proposes that after one round of replication, each new DNA molecule consists of:

Accepted Answer

One parental strand and one newly synthesized strand.

Answer

Two newly synthesized strands.

Answer

Two parental strands.

Answer

A mix of parental and new DNA segments on each strand.

Question 6

Which of the following statements correctly describes a key difference between the leading and lagging strands during DNA synthesis?

Accepted Answer

The lagging strand is synthesized as a series of Okazaki fragments, while the leading strand is synthesized continuously.

Answer

The leading strand is synthesized in the 3' to 5' direction, while the lagging strand is synthesized in the 5' to 3' direction.

Answer

The leading strand requires multiple RNA primers, while the lagging strand requires only one.

Answer

The lagging strand serves as the template, while the leading strand is the newly synthesized DNA.