Question

Which among the following factors are necessary for photosynthesis to occur?

• A. Sunlight
• B. Chlorophyll
• C. Protoplasm
• D. All of the above

Answer 1

The correct option is D All of the above

The factors necessary for photosynthesis can be divided into two main headings:
1. External factors
2. Internal factors

1. External factors:

(i) Sunlight. Sunlight serves as a source of energy during the process. In absence of sunlight, photosynthesis will not occur.
(ii) Carbon dioxide. It is used as a raw material for the manufacture of carbohydrates. It is obtained from the atmosphere, which contains about 0.03%. In the absence of $C{O}_2$ photosynthesis stops.
(iii) Water. It also serves as raw food for photosynthesis. Hydrogen received from water reduces $C{O}_2$. It is also necessary for all vital activities of the plant.
(iv) Temperature. Photosynthesis occurs between a temperature range of $10-{35}^{0}C$. Below ${10}^{0}C$ it is reduced and completely stops at $5^{0}C$. Similarly, the rate becomes low above ${40}^{0}C$ and completely stops at ${70}^{0}C$.
(v) Open condition of stomata. $C{O}_2$ enters the plant through stomata. If the stomata are closed, no photosynthesis will occur.

2. Internal factors:

(i) Chlorophyll. Chlorophyll is necessary for the process of photosynthesis. Both stroma and grana part of the chlorophyll take part in the process.
(ii) Protoplasm. Active stage of the protoplasm is necessary for different biochemical reactions necessary for photosynthesis.