The most likely explanation of the fact that the graph levels off at 180 Jm^-2 s^-1 is that the system is

Question

The graph shows the relationship between oxygen production in photosynthesis and light intensity for a unicellular green organism in 0.02% sodium hydrogencarbonate solution

The most likely explanation of the fact that the graph levels off at 180 Jm^-2 s^-1  is that the system is 

(a) light limited and carbon dioxide saturated 

(b) light limited and the temperature is below optimum 

(c) light saturated and carbon dioxide is unlimited 

(d) light saturated and the temperature is above optimum

Answer 1

Correct option is (d) light saturated and the temperature is above optimum

The amount of light given is saturated, not limited. Therefore the answer is (d). The concentration of carbon dioxide is in short supply, hence limiting the rate of photosynthesis.