Question

In the bell jar experiment, which has a green plant to study the photosynthesis why is potassium hydroxide (KOH) kept?

• A. To help in photosynthesis
• B. To check photosynthesis
• C. To produce CO₂
• D. To absorb CO₂ present in air inside the bell jar.

Answer 1

The correct option is D

To absorb CO₂ present in air inside the bell jar.

The correct option is (D)

Explanation for the correct option

1. Photosynthesis is the process of the formation of glucose by using water and carbon dioxide as raw materials in the presence of sunlight.
2. To check the necessity of carbon dioxide (CO₂) for photosynthesis, two plants were placed in two separate glass chambers.
3. In one chamber plant was kept with potassium hydroxide (KOH), and in another chamber, no KOH was present.
4. Plant with KOH died after some time, and another one survived.
5. It is because KOH absorbs all the carbon dioxide, which is essential for photosynthesis.

Explanation for incorrect options

Option (A)

1. Water, carbon dioxide, sunlight and chlorophyll are the main and only essentials that help in photosynthesis.
2. Chlorophyll absorbs sunlight which is used in the splitting of water molecules.
3. Carbon dioxide is used to form glucose.

Option (B)

1. To check the photosynthesis starch test can be used.
2. Scratch test involves the use of iodine solution and not KOH.

Option (C)

1. Plants consume carbon dioxide (CO₂) and release oxygen.
2. CO₂ is released by animals while breathing.

KOH helps in the absorption of carbon dioxide present in the bell jar and thus facilitates the studies.