UPSC Prelims 2010 · General Studies

Question 123: Science and Technology

Which one of the following processes in the bodies of living organisms is a digestive process ?

aBreakdown of proteins into amino acids

bBreakdown of glucose into CO₂ and H₂O

cConversion of glucose into glycogen

dConversion of amino acids into proteins

AnswerThe answer is (a).

Digestion is the breakdown of large food molecules into small, absorbable ones by enzymes. The conversion of proteins into amino acids takes place in the stomach and small intestine (pepsin, trypsin and others), so that is digestion. Breakdown of glucose to carbon dioxide and water is cellular respiration, conversion of glucose to glycogen is storage, and conversion of amino acids into proteins is protein synthesis; these happen inside cells. Remember: digestion happens in the gut and splits big molecules into small ones.

Why each option is right or wrong

(a) Right: proteins are broken into amino acids by digestive enzymes.
(b) That is cellular respiration.
(c) That is storage of glucose as glycogen.
(d) That is protein synthesis inside cells.

Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2010, General Studies, Series A. The paper on upsc.gov.in.