Question 63 from UPSC CSE 2014 - Science and Technology

Question

Which one of the following is the process involved in photosynthesis?

Accepted Answer

Correct Option: B. Free energy is converted into potential energy and stored.

Strategy: Focus on the type of energy transformation. Photosynthesis stores energy, contrasting with energy-releasing processes like respiration. The correct option describes light energy being converted into chemical potential energy in glucose.

Key Info: **Photosynthesis Overview**

Photosynthesis is the biochemical process where green plants, algae, and some bacteria convert light energy into chemical energy.

**Key Process**

- Chlorophyll in chloroplasts captures sunlight.
- Carbon dioxide (CO2) and water (H2O) are converted into glucose (C6H12O6) and oxygen (O2).
- The general equation is: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2.

**Energy Transformation**

The free energy from sunlight is trapped and stored as potential energy in the chemical bonds of glucose. This makes photosynthesis a building-up (anabolic) process, unlike respiration which releases energy. The oxygen released is a byproduct.

**Ecological Importance**

This process sustains the global food chain and maintains atmospheric oxygen balance.

Answer

Option A: Potential energy is released to form free energy.

Answer

Option C: Food is oxidized to release carbon dioxide and water.

Answer

Option D: Oxygen is taken, and carbon dioxide and water vapour are given out.