9 Nutrition and gas exchange
in plants II
2nd Term WS 09
1 (a) As
light intensity increases from 0 to 500 arbitrary units, the rate of
photosynthesis of the plant increase 1
More carbon dioxide is taken in by the
plant for photosynthesis 1
while the amount of carbon dioxide
released in respiration remains unchanged. 1
(b) At light intensity of 400
arbitrary units, the rate of respiration of the plant is higher than the rate of photosynthesis. 1
More food is consumed in respiration than
is produced in photosynthesis. 1
2 (a) The
leaf is thin. 1
This reduces the diffusion distance of
the gas needed for photosynthesis (i.e. carbon dioxide) from the atmosphere to cell X. 1
There are many air spaces among spongy
mesophyll cells. 1
This allows carbon dioxide to diffuse
freely to cell X. 1
(or other reasonable answers)
the rate of respiration. 1
There
is a net release of oxygen from the leaf cells. 1
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