Question

1. if a plant is releasing co2 and taking in oxygen during the day,does it mean that there is no photosynthesis occurring? justify your answer.

2.in each of the situations what will happen to the rate of photosynthesis:

a) cloudy days b)no rainfall in the area c)good manuring in the area d)stomata gets blocked due to dust

Answer 1

1.Answer—The photosynthesis and respiration takes place in day time. If a plant is releasing Co2 and taking O2 during day,that doesn't mean that photosynthesis is not occurring. Respiration releases Co2. Plants are living beings and metabolism constantly ‘burns’ food taking oxygen and releasing carbon dioxide. If plants give out carbon dioxide it is also possible that there is no breakdown of carbon and water.So ,it is not correct to say that if plant releases carbon dioxide and takes in oxygen during day time, no photosynthesis is taking place.

2.(a)cloudy days:- Due to clouds sunlight will not be able to reach the stomata for photosynthesis and sunlight has an essential role in photosynthesis. So the rate of photosynthesis will decrease.
(b)no rainfall in the area means that there is no water and according to the definition of photosynthesis it is the process by which green plants make their own food using water, sunlight and nutrients. So the rate of photosynthesis will decrease.
(c)Good manuring in the area will increase the rate of photosynthesis as there will be nutrients as well as water in the manure.
(d)Dust on stoma will decrease the rate of photosynthesis as the role of stoma is to trap the sunlight with the help of chlorophyll and if sunlight is not there , photosynthesis can't take place.