NEET Biology: Factors affecting photosynthesis Practice Questions

Correct answer: A — Concentration of carbon dioxide

In a closed system where light and water are abundant, the concentration of carbon dioxide (CO₂) is often the limiting factor that determines the maximum rate of photosynthesis, as it is a reactant required for the Calvin cycle.

Correct answer: A — 10°C to 20°C

Photosynthesis generally occurs most efficiently at moderate temperatures, typically between 20°C to 30°C for most plants.

Correct answer: B — Visible light

Plants primarily utilize light in the visible spectrum (which includes red and blue wavelengths) for the process of photosynthesis.

Correct answer: B — Light energy

Light energy (from the sun) is the primary energy source required to initiate the process of photosynthesis.

Correct answer: C — Capturing light energy

Chlorophyll is the green pigment that absorbs the energy from sunlight, which is the initial energy source for the entire photosynthetic reaction.

Correct answer: B — Rate decreases

Carbon dioxide is a necessary raw material for photosynthesis; thus, a decrease in its concentration will lead to a decrease in the rate of photosynthesis.

Correct answer: B — It increases

Light intensity is a direct factor; increasing the intensity provides more energy, thus increasing the rate of photosynthesis up to a saturation point.

Correct answer: B — It decreases

Enzymes involved in the photosynthetic process are temperature-dependent. Below the optimum temperature, enzyme activity decreases, thereby lowering the rate of photosynthesis.

Correct answer: B — Carbon Dioxide

Carbon dioxide (CO₂) is the primary raw material used by plants in the Calvin cycle to synthesize glucose (food).

Correct answer: A — Chlorophyll

Chlorophyll is the primary pigment responsible for absorbing light energy, which is the initial step required for the entire process of photosynthesis.

Correct answer: D — Efficiency increases because red light is absorbed more efficiently

Chlorophyll strongly absorbs red and blue wavelengths. Shifting to red light increases the energy captured by chlorophyll, thus increasing the efficiency of the light-dependent reactions.

Correct answer: D — Water

Water is a crucial raw material required for the process of photosynthesis, as it is involved in the production of glucose and the overall chemical reactions.

Correct answer: D — All of the above

Photosynthesis rate is dependent on the availability of light energy, the presence of water, and the concentration of carbon dioxide, all of which interact to determine the overall rate.

Correct answer: A — It is a raw material

Water is absorbed by the roots and transported to the leaves, serving as a necessary reactant (raw material) for the synthesis of glucose during photosynthesis.