UPSC Prelims 2005 · General Studies

Question 89: Science and Technology

Assertion (A): The person with diabetes insipidus feels thirsty. Reason (R): A person with diabetes insipidus suffers from excess secretion of vasopressin.

aBoth A and R are individually true and R is the correct explanation of A

bBoth A and R are individually true but R is not the correct explanation of A

cA is true but R is false

dA is false but R is true

AnswerThe answer is (c).

Diabetes insipidus makes the kidneys pass large amounts of dilute urine, so the person loses water and feels very thirsty; A is true. R is false: the disease comes from too little vasopressin (ADH), or from kidneys not responding to it, not from excess secretion. So A is true and R is false.

A. Water loss in the urine causes intense thirst.
R. The cause is a deficiency of vasopressin, not an excess.

How you could have got this

If you were sure statement 1 is correct, (d) goes. Then judge the second statement; if it is correct too, decide whether it explains the first.

This follows an unofficial answer: UPSC has not published its key for this year, and if that answer is wrong, so is this path.

Which options go is worked out from UPSC’s key and the options, not by a model.

Why each option is right or wrong

(a) R is false, so it cannot explain A.
(b) R is false.
(c) Correct: A is true, R is false.
(d) A is true, so this is wrong.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2005, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.