BioInteractive Regulation and Efficiency of Photosynthesis

Question 1

What is the light compensation point in photosynthesis?

Accepted Answer

The light intensity at which photosynthesis exactly equals cellular respiration

Answer

At the light compensation point, the rate of CO2 fixed by photosynthesis equals the rate of CO2 released by cellular respiration, resulting in no net gas exchange.

Question 2

How does temperature affect the rate of photosynthesis?

Accepted Answer

It affects enzyme activity; rates increase with temperature up to an optimum, then fall sharply

Answer

Photosynthesis increases with temperature up to the enzyme's optimal temperature, above which enzymes denature and the rate falls rapidly.

Question 3

Which environmental factor is a limiting factor for photosynthesis at low concentrations despite abundant light?

Accepted Answer

Carbon dioxide

Answer

When CO2 levels are low, they limit the rate of the Calvin cycle even if light and water are abundant, because RuBisCO cannot fix carbon faster than CO2 diffuses in.

Question 4

What is the concept of limiting factors in photosynthesis?

Accepted Answer

The factor in shortest supply relative to the plant's needs that controls the overall rate of photosynthesis

Answer

Blackman's law of limiting factors states that the rate of photosynthesis is controlled by whichever factor — light, CO2, or temperature — is present at the least favorable level.

Question 5

How do stomata regulate photosynthesis?

Accepted Answer

By controlling CO2 entry and water vapor exit, balancing gas exchange with water conservation

Answer

Stomata open to allow CO2 in for photosynthesis but simultaneously allow water to escape; plants regulate stomatal aperture to balance carbon gain against water loss.

BioInteractive - Photosynthesis BioInteractive Test Practice Test

BioInteractive - Photosynthesis BioInteractive Test Practice Test

BioInteractive Regulation and Efficiency of Photosynthesis