SSC CGL 2025 Tier-I · 18 September 2025, Shift 2 · General Awareness · Question 14 of 100

We transcribed this text from the pictures on a candidate's response sheet for this shift; the answer is the key SSC colour-marked on that sheet. Solution last reviewed 11 September 2026.

Where this paper and its answers come from

SSC does not publish CGL question papers or a public answer key. From 2025 the candidate response sheet prints every question and option as a picture, so the text here is transcribed from those pictures for this shift and checked against them independently; where the layout carries meaning, the picture is shown as well. Each answer is the key SSC colour-marked on that sheet. SSC released a tentative key for challenge and later its final one, both only to candidates behind a login, and the sheet does not say which of the two it carries. The solutions are written by UnlockIAS.

Which of the following statements regarding human antibodies is/are accurate? 1. IgG constitutes the largest proportion of antibodies in human blood. 2. IgE plays a key role in allergic responses. 3. IgA is primarily located in bodily secretions such as saliva and breast milk.

(a)Only 1 and 2 are correct
(b)Only 2 and 3 are correct
(c)Only 1 and 3 are correct
(d)1, 2 and 3 all are correct

Answer

Why

Correct — D. All three statements are true.

Statement 1: IgG is the most abundant antibody class in human blood serum.

Statement 2: IgE is the allergy antibody. It sits on mast cells, which release histamine when the allergen returns.

Statement 3: IgA guards the body's secretions: saliva, tears, mucus and breast milk, including colostrum.

Nothing fails, so the answer is 1, 2 and 3 → option (d).

Why the others are wrong

(a)
Only 1 and 2 are correct — Statement 3 is also true. IgA is the antibody of secretions such as saliva, tears and breast milk, so leaving it out drops a correct statement.
(b)
Only 2 and 3 are correct — Statement 1 is true. IgG is the most abundant antibody class in blood serum, so an answer without statement 1 is incomplete.
(c)
Only 1 and 3 are correct — Statement 2 is true. IgE drives allergic reactions by triggering histamine release from mast cells, so statement 2 belongs in the answer.

Concept

Antibodies, or immunoglobulins, are Y-shaped proteins made by plasma cells, which develop from B lymphocytes. Each has two heavy and two light chains, written H2L2.

Five classes are recognised: IgG, IgA, IgM, IgD and IgE. They differ in where they work.

IgG circulates in blood and is the class that crosses the placenta. IgM is the first made in a new infection. IgA sits in secretions. IgE drives allergy.

Statements 1 and 3 do not clash. Statement 1 is about blood, where IgG leads. Statement 3 is about secretions, where IgA is the main antibody.

Key facts

IgG is the most abundant antibody class in human blood serum.
IgG is the antibody class that crosses the placenta to the foetus.
IgE triggers allergic reactions by making mast cells release histamine.
IgA is the main antibody in saliva, tears and breast milk, including colostrum.

Study next

Active and passive immunity, including antibodies passed on through colostrumPrimary and secondary immune responses and the role of IgMAllergy, histamine and how antihistamines work

Common traps

Dropping statement 1 because IgA is taken to be the commonest antibody: IgA leads in secretions, IgG leads in blood.
Reading 'is/are' in the stem as a hint that one statement must be false: all three can be true, as here.

The three statements are independent facts about three antibody classes. Judge each one on its own, then match the set to the options.

Related PYQs

No directly related past PYQ was found.

Topic: Scientific Research — all 178 SSC CGL questions on it, every solved shift.