NEET 2025 MCQ with Answer Explanation : “Molecular Basis of Inheritance”.

Here below some basic MCQ with Answer molecular basis of inheritance. Which is explained in details. Let’s check one by one.

1. DNA is a polymer of nucleotides, which are made of three components. Which of the following is NOT a component of a nucleotide?
   a) Phosphate group
   b) Ribose sugar
   c) Deoxyribose sugar
   d) Nitrogenous base

Answer: b) Ribose sugar

Explanation: Nucleotides in DNA consist of a phosphate group, a deoxyribose sugar (not ribose, which is found in RNA), and a nitrogenous base (adenine, thymine, cytosine, or guanine). Ribose is present in RNA, not DNA.

2. Which of the following is responsible for the semiconservative nature of DNA replication?
   a) DNA polymerase I
   b) DNA helicase
   c) Meselson and Stahl experiment
   d) Okazaki fragments

Answer: c) Meselson and Stahl experiment

Explanation: The Meselson and Stahl experiment demonstrated the semiconservative nature of DNA replication, where each daughter DNA molecule consists of one parental and one newly synthesized strand.

3. The enzyme that facilitates the unwinding of the DNA double helix during replication is:
   a) Ligase
   b) DNA polymerase
   c) Primase
   d) Helicase

Answer: d) Helicase

Explanation: Helicase unwinds the DNA double helix by breaking the hydrogen bonds between the two strands, allowing replication to proceed.

4. Which type of RNA is involved in carrying amino acids to the ribosome during protein synthesis?
   a) mRNA
   b) tRNA
   c) rRNA
   d) snRNA

Answer: b) tRNA

Explanation: Transfer RNA (tRNA) is responsible for transporting specific amino acids to the ribosome, where they are added to the growing polypeptide chain during translation.

5. In eukaryotic cells, which of the following processes occurs in the nucleus?
   a) Transcription
   b) Translation
   c) Glycolysis
   d) Electron transport chain

Answer: a) Transcription

Explanation: Transcription (the process of copying DNA into mRNA) occurs in the nucleus of eukaryotic cells. Translation occurs in the cytoplasm, while glycolysis happens in the cytosol and the electron transport chain takes place in the mitochondria.

6. In a DNA molecule, the amount of adenine is always equal to the amount of thymine because of:
   a) Meselson-Stahl rule
   b) Chargaff’s rule
   c) Watson-Crick rule
   d) Central dogma

Answer: b) Chargaff’s rule

Explanation: Chargaff’s rule states that in a DNA molecule, the amount of adenine (A) equals the amount of thymine (T), and the amount of guanine (G) equals the amount of cytosine (C), due to the base pairing between them.

7. Which enzyme is responsible for adding new nucleotides to a growing DNA strand during replication?
   a) DNA ligase
   b) DNA helicase
   c) DNA polymerase
   d) RNA polymerase

Answer: c) DNA polymerase

Explanation: DNA polymerase catalyzes the addition of new nucleotides to the growing DNA strand during replication, ensuring accurate DNA synthesis.

8. The discontinuous segments of newly synthesized DNA on the lagging strand are called:
   a) Okazaki fragments
   b) Leading strands
   c) Replication bubbles
   d) Primers

Answer: a) Okazaki fragments

Explanation: The lagging strand is synthesized in short segments called Okazaki fragments, which are later joined by DNA ligase to form a continuous strand.

9. Which of the following sequences represents the flow of genetic information according to the central dogma of molecular biology?
   a) DNA → Protein → RNA
   b) RNA → DNA → Protein
   c) DNA → RNA → Protein
   d) Protein → RNA → DNA

Answer: c) DNA → RNA → Protein

Explanation: The central dogma of molecular biology describes the flow of genetic information from DNA to RNA (transcription) and from RNA to protein (translation).

10. Which of the following scientists is credited with the discovery of the structure of DNA?
    a) Rosalind Franklin
    b) Erwin Chargaff
    c) James Watson and Francis Crick
    d) Frederick Griffith

Answer: c) James Watson and Francis Crick

Explanation: James Watson and Francis Crick are credited with discovering the double helix structure of DNA in 1953, though they used critical data from Rosalind Franklin’s X-ray diffraction work.