Question

Respiration is a continuous process in green plants. Then why is it that they give out O2 and not CO2 during the day?

Answer 1

Explanation:

because they use CO2 for photosynthesise

Answer 2

Explanation:

Respiration is  a continuous process in green plants but they give out oxygen and not carbon dioxide during the day because carbon dioxide is the raw material for photosynthesis and hence it is used up. The rate of photosynthesis is greater than the rate of respiration during the day and Oxygen being the by-product of photosynthesis is produced  at a faster rate . Due to this, the amount of oxygen is greater than the amount used up by the plant and the surplus oxygen is given out through the stomata.