Please help me

Dear Student, 

(A) The presence of starch is regarded as evidence of photosynthesis .Hence before starting an experiment on photosynthesis ,it is necessary to place a plant in the dark for 24 to 48 hours to remove the starch from the leaves.In this period , all the starch from the leaves will be sent to the storage organ and hence the leaves will have now absence of starch . So, the various experiments can be carried out effectively.

(B) Because during day time plants perform photosynthesis. During this oxygen is evolved and carbon dioxide is used up by the plants. But during respiration oxygen is consumed by the plant so it is demonstrated. 


  • 0
What are you looking for?