UPSC Prelims 2004 · General Studies

Question 13: Science and Technology

In which organ of the human body are the lymphocyte cells formed?

aLiver

bLong bone

cPancreas

dSpleen

AnswerThe answer is (b).

All blood cells, lymphocytes included, originate from stem cells in the bone marrow, which lies in the long bones. Lymphocytes then mature (B cells in the marrow, T cells in the thymus) and settle in lymph nodes and the spleen. The spleen stores and activates them rather than forming them from stem cells; the liver and pancreas do not form lymphocytes.

Why each option is right or wrong

(a) The liver filters blood and makes plasma proteins; it is not where lymphocytes form.
(b) Correct: lymphocytes arise from stem cells in the bone marrow of long bones.
(c) The pancreas is a digestive and hormonal gland.
(d) The spleen stores and activates lymphocytes but the cells originate in the marrow.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2004, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.