Question

Given alongside is an experimental set up to demonstrate a phenomenon in a plant:

(a) What is the aim of this experiment?

(b) Why was the bell jar covered with a black cloth?

(c) What is the function of caustic soda in this experiment?

(d) Give an overall chemical equation of the process mentioned in (a) above.

(e) Mention one precaution that should be taken to ensure more accurate results. What change, if any, would you observe in the lime water in Flask A and B? In each case give a reason for your answer.

Answer 1

(a) Aim - To show that carbon dioxide is released during respiration.

(b) To prevent photosynthesis

(c) To absorb carbon dioxide from incoming air.

(d) C₆H₁₂O₆ + 6O₂ → 6CO₂ + H₂O + 673 kcal energy {38 ATP}

(e) The respiratory chamber should be covered with black cloth to prevent photosynthesis.

The lime water in Flask A turns milky as the plant respires and gives out carbon dioxide which turns the lime water milky. The lime water in Flask B remains clear as the incoming air is free from carbon dioxide.