السؤال 32

Above its optimum temperature the rate of photosynthesis in a plant falls sharply. What causes that fall?

The chlorophyll melts and can no longer absorb light
The plant runs out of carbon dioxide at high temperatures
The enzymes that control the reaction are denaturedالإجابة الصحيحة
The water in the leaf boils away and stops the reaction

الشرح

The reaction is controlled by enzymes, and heating them beyond a certain point changes the shape of their active sites so that they can no longer do their work, which is why the rate collapses instead of simply levelling off. The green pigment does not melt at temperatures a plant meets, and nothing about warming the air removes the gas supply.

الشرح

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