Multiple choice

An antibody is a

  1. component of blood

  2. WBC which invades bacteria

  3. secretion of mammalian RBC

  4. molecule that superficially inactivates the antigen
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Antibodies are Y-shaped proteins produced by white blood cells (specifically B cells) in response to antigens. They bind specifically to antigens and neutralize them or mark them for destruction by other immune cells. Option A is too general (blood has many components), Option B is incorrect because antibodies don't invade bacteria themselves, and Option C is wrong because RBCs don't secrete antibodies - plasma cells do.

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