Question:
If a plant is releasing carbon dioxide and taking in oxygen during the day, does it mean that there is no photosynthesis occurring ? Justify your answer.
Solution:
A plant releases carbon dioxide and takes in oxygen only when photosynthesis is either absent or too small as not to compensate for respiration.
(In photosynthesis, plants absorb CO2 and release O2. The normal rate of photosynthesis is many times the rate of respiration. As a result,
CO2 produced during respiration is consumed and a lot of more is absorbed from outside. Oxygen produced during photosynthesis is much more
than required for respiration. Therefore, oxygen passes out.)