High concentrations of gas retards that the rate of photosynthesis

Rate of photosynthesis is

Rate of photosynthesis is

Rate of photosynthesis is

Which gas retard the rate of photosynthesis?

If we keep on increasing CO_2 concentration in air what will be the rate of photosynthesis?

If CO_(2) concentration increases upto 0.05% the rate of photosynthesis -

Give the value of CO_2 concentration at which saturation of the rate of photosynthesis occurs in : C_3 plants

Give the value of CO_2 concentration at which saturation of the rate of photosynthesis occurs in : C_4 plants respectively.