(i) What is compensation point? (ii) "All plants give out oxygen during day and carbon dioxide during night. Do you agree with this statement? Give reason.
Answer - (i) When the rate of photosynthesis is equal to rate of respiration, it is called as compensation point. The rate of liberation of O during photosynthesis is equal to the rate of liberation of CO, during respiration. Thus, there is no net uptake of gases from the environment. Compensation point is usually reached at dusk and dawn and on a cloudy day.
(ii) During day time, as the rate of photosynthesis is more than the rate of respiration, the net result is evolution of oxygen. At night there is no photosynthesis, so they give out carbon dioxide due to respiration.