UPSC Prelims 2005 · General Studies

Question 86: Science and Technology

Assertion (A): Amoeba reproduces by fission. Reason (R): All unicellular organisms reproduce by asexual methods.

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).

Amoeba reproduces by binary fission, a form of asexual reproduction, so A is true. R is false: many unicellular organisms also reproduce sexually, for example Chlamydomonas and Plasmodium (which has a sexual stage in the mosquito), and Paramecium exchanges genes by conjugation. So A is true and R is false.

A. Amoeba divides by binary fission.
R. Many unicellular organisms also reproduce sexually.

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.