Question

The diagram below shows two test tubes A and B. Test tube A contains a green water plant. Test tube B contains both a green water plant and a snail. Both test tubes are kept in sunlight. Answer the questions that follow:

(i) Name the physiological process that releases the bubbles of oxygen.

(ii) Explain the physiological process as mentioned above.

(iii) What is the purpose of keeping a snail in test tube 'B'?

(iv) Why does test-tube 'B' have more bubbles of oxygen?

(v) Give an example of a water plant that can be used in the above experiment.

(vi) Write the overall chemical equation for the above process.

Answer 1

(i)

Photosynthesis:

1. Photosynthesis is a biochemical process by which phototrophs convert light energy into chemical energy to produce their own food.
2. In this process, 6 molecules of CO₂ and 12 molecules of H₂O react in presence of sunlight and chlorophyll to produce one molecule of carbohydrate and 6 molecules of O_2, and 6 molecules of H₂O.
3. Oxygen is the by-product of this process.

Chemical equation: -

Hence, The physiological process that releases oxygen is photosynthesis.

(ii) Process of Photosynthesis:

1. Photosynthesis is a physiological process in phototrophs by which green plant make their own food by converting light energy into chemical energy.
2. In this process, 6 molecules of CO₂ and 12 molecules of H₂O react in presence of sunlight and chlorophyll to produce one molecule of carbohydrate and 6 molecules of O_2, and 6 molecules of H₂O.
3. Oxygen is the by-product of this process.

Chemical equation:

Factors of photosynthesis:

1. There are 5 - different factors that affect photosynthesis. They are-(1) Sunlight (2) Carbon dioxide (3) Water (4) Chlorophyll (5) Temperature.
2. Increasing the concentration of CO₂ increases the rate of photosynthesis up to a certain level.

(iii)

Aquatic animals provide CO₂ to aquatic plants for photosynthesis:

1. The snail is an aquatic animal,
2. During respiration, the snail takes O₂ and releases CO₂.
3. It increases the concentration of CO₂ in this experimental condition.
4. An increased level of CO₂ helps to increase the rate of photosynthesis.
5. The rate of oxygen bubble production will be increased.

In test-tube B Snail provides CO₂ for photosynthesis to the aquatic plant.

(iv)

The concentration of CO₂ is increased due to the respiration of the snail in test tube B.

1. An increase in the level of CO₂ in test tube B help in increasing the rate of photosynthesis.
2. An increased rate of photosynthesis will produce more oxygen bubbles in test tube B.

Hence, Test tube B has more bubbles of oxygen because of concentration of CO₂ is increased due to the respiration of the snail in test tube B.

(v) Hydrilla is a water plant that can be used for this given experiment.

(vi) Chemical equation: