Identify the statement that is NOT correct.

Q: What is NEET?

NEET is a competitive examination conducted in India. This question is from the 2025 NEET Biology paper.

Q: How can I prepare for NEET Biology?

To prepare for NEET Biology, practice previous year questions (PYQs), understand concepts thoroughly, and solve mock tests regularly. This 2025 question covers Human Health and Disease topic.

Q: What is the difficulty level of this question?

This NEET 2025 Biology question has a easy difficulty level and is marked as an important question.

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You can find more NEET previous year questions on AspirantMitraa. Browse by subject, topic, year, and difficulty level to practice effectively.

Question

Identify the statement that is NOT correct.

Accepted Answer

Correct Answer: D — Antigen binding site is located at C-terminal region of antibody molecules.Step-by-step Solution:Antibodies (immunoglobulins) are Y-shaped glycoproteins produced by plasma cells (activated B lymphocytes). Verifying each statement:Option A (Correct statement): The constant (C) regions of both heavy and light chains are located at the C-terminus (carboxyl terminal end). These constant regions determine the class/subclass of the antibody and mediate effector functions.Option B (Correct statement): A typical antibody monomer consists of four polypeptide chains — two identical heavy chains (H chains, ~50–70 kDa each) and two identical light chains (L chains, ~25 kDa each), giving a total of 4 chains.Option C (Correct statement): The four chains are held together by inter-chain disulfide bonds (between H-H chains in the hinge region, and between each H-L chain pair) and non-covalent interactions.Option D (INCORRECT statement): The antigen-binding site (paratope) is located at the N-terminus (amino terminal end) of both the heavy and light chains, in the variable (V) region — NOT the C-terminal region. The variable regions of one heavy chain and one light chain together form one antigen-binding site. A typical IgG has two such sites (bivalent).Extended Explanation:Each heavy chain has one variable domain (VH) and 3–4 constant domains (CH1, CH2, CH3, ±CH4). Each light chain has one variable domain (VL) and one constant domain (CL). The antigen-binding site is formed by the Complementarity Determining Regions (CDRs) or hypervariable regions within the VH and VL domains — these are the most variable parts of the antibody and directly contact the antigen. The five classes of immunoglobulins are IgG, IgA, IgM, IgD, and IgE, differing in their heavy chain constant regions (γ, α, μ, δ, ε respectively). IgG is the most abundant in serum and crosses the placenta to provide passive immunity to the fetus.Key Concepts: Antibody structure, heavy and light chains, variable and constant regions, antigen-binding site (N-terminus), disulfide bonds, immunoglobulin classes.

Identify the statement that is NOT correct.

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Identify the statement that is NOT correct.

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More Questions from Human Health and Disease

Frequently Asked Questions