Question

UPSC Prelims 2014 Question:

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

1. Potential energy is released to form free energy.
2. Free energy is converted into potential energy and stored.
3. Food is oxidized to release carbon dioxide and water.
4. Oxygen is taken, and carbon dioxide and water vapour are given out.

Answer (Detailed Solution Below)

Option 2: Free energy is converted into potential energy and stored.

Detailed Solution

Explanation:

During photosynthesis, plants take in carbon dioxide (CO2) and water (H2O) from the air and soil. Within the plant cell, the water is oxidized, meaning it loses electrons, while the carbon dioxide is reduced, meaning it gains electrons. This transforms the water into oxygen and the carbon dioxide into glucose. The plant then releases the oxygen back into the air, and stores energy within the glucose molecules.
Chloroplasts are the plant cell inside the small organelles. They store the energy of sunlight. Within the thylakoid membranes of the chloroplast is a light-absorbing pigment called chlorophyll, which is responsible for giving the plant its green color. During photosynthesis, chlorophyll absorbs energy from blue- and red-light waves and reflects green-light waves, making the plant appear green.

Therefore, option (2) is the correct answer.

Subject: Environment | Plant and Animal Anatomy

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