Question

In the experimental set up to show that “CO₂ is given out during respiration.”

(1) Name the substance taken in the small test tube kept in the conical flask.

(2) State its function and the consequence of its use.

Answer 1

1) Name of substance:

1. For the experiment where CO₂ is given out during respiration, KOH solution or pellets are taken in a test tube and placed in the conical flask.
2. In this experiment,a few crystals of KOH are taken in a small test tube and dissolved in water, and this solution is hanged with the thread inside the conical flask.

2) Function of KOH:

1. In the experiment, CO₂ generated by the plant during respiration is absorbed using potassium hydroxide.
2. KOH absorbs CO₂, which causes the flask to become vacuum-sealed.
3. The conical flask receives the air that is in the bent glass tube.
4. This raises the water level in the curved tube.
5. The water level in the tube rises up to some extent.

Consequences:

1. The whole amount of CO₂ liberated gets absorbed by KOH to prevent it from being utilized by the plant for the process of photosynthesis.
2. This CO₂ absorption leads to creating a vacuum in a flask that causes an observable rise in the water level of the connected U tube.
3. Any gas produced can neither escape nor can get outside air in.
4. Germinating seed produces CO₂ via the following reactions:-
5. Aerobic respiration: :${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6+6{\mathrm{O}}_2\to 6{\mathrm{CO}}_2+6{\mathrm{H}}_2\mathrm{O}+38\mathrm{ATP}$