Question 1:

The structure of DNA is a double helix, which consists of:

Explanation: The structure of DNA is a double helix, which consists of two anti-parallel strands of nucleotides. The strands are held together by hydrogen bonds between complementary base pairs. Therefore, option B is correct.

Question 2:

During DNA replication, the enzyme responsible for synthesizing new DNA strands is called:

Explanation: During DNA replication, the enzyme responsible for synthesizing new DNA strands is called DNA polymerase. DNA polymerase adds complementary nucleotides to the existing strands, following the base pairing rules. Therefore, option C is correct.

Question 3:

The process of DNA replication is considered semi-conservative because:

Explanation: The process of DNA replication is considered semi-conservative because each newly synthesized DNA molecule consists of one old strand (conserved) and one new strand (synthesized). The original DNA molecule serves as a template for the synthesis of the new complementary strand. Therefore, option C is correct.

Question 4:

The base pairing rule in DNA states that:

Explanation: The base pairing rule in DNA states that adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). This complementary base pairing allows the DNA strands to be copied accurately during replication. Therefore, option A is correct.

Question 5:

Which of the following is NOT a component of a nucleotide in DNA?

Explanation: The components of a nucleotide in DNA include a phosphate group, a deoxyribose sugar, and a nitrogenous base. The sugar in DNA is deoxyribose, not ribose. Therefore, option B is correct.