1998 General Studies, all questions
UPSC Prelims 1998 · General Studies
Question 121: Science and Technology
Which one of the following statements regarding starch and cellulose is NOT correct?
aBoth of them are of plant origin
bBoth of them are polymers
cBoth of them give colour with iodine
dBoth of them are made up of glucose molecules
AnswerThe answer is (c).
Starch and cellulose are both plant polysaccharides: long polymers built from glucose units. Starch is the plant's food store and cellulose forms the cell wall. Only starch gives a blue-black colour with iodine; cellulose gives no colour, so the statement that both give colour with iodine is the one that is not correct.
Why each option is right or wrong
- (a) Both are made by plants, so this statement is correct.
- (b) Both are polymers, so this statement is correct.
- (c) Right: only starch turns blue with iodine; cellulose does not.
- (d) Both are made of glucose units, so this statement is correct.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1998, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.