2014 GS Paper I, all questions
UPSC Prelims 2014 · GS Paper I
Question 65: Science and Technology
Which one of the following is the process involved in photosynthesis?
aPotential energy is released to form free energy
bFree energy is converted into potential energy and stored
cFood is oxidized to release carbon dioxide and water
dOxygen is taken, and carbon dioxide and water vapour are given out
AnswerUPSC’s answer is (b).
In photosynthesis, green plants capture light energy and use it to build glucose from carbon dioxide and water, releasing oxygen. Free energy (light) is converted into stored chemical potential energy in the sugar bonds. The reverse happens in respiration, where food is oxidised to release energy, carbon dioxide and water. Photosynthesis takes in carbon dioxide and gives out oxygen, the opposite of option (d).
Why each option is right or wrong
- (a) Wrong. This reverses the process: photosynthesis stores energy, it does not release it.
- (b) Right. Light (free) energy is converted into chemical potential energy and stored.
- (c) Wrong. This describes respiration, not photosynthesis.
- (d) Wrong. Photosynthesis takes in carbon dioxide and gives out oxygen.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2014, General Studies Paper I, Series A. The paper on upsc.gov.in.