Ananya took four test tubes and filled three- fourth of each test tube with water. She labelled them A, B, C, and D Class 7

Ananya took four test tubes and filled three- fourth of each test tube with water. She labelled them A, B, C, and D Class 7

Ananya took four test tubes and filled three- fourth of each test tube with water. She labelled them A, B, C, and D (Fig. 10.12). In test tube A, she kept a snail; in test tube B, she kept a water plant; in test tube C, she kept both a snail and a plant. In test tube D, she kept only water. Ananya added a carbon dioxide indicator to all the test tubes. She recorded the initial colour of water and observed if there are any colour changes in the test tubes after 2-3 hours. What do you think she wants to find out? Class 7

Answer:

Ananya wants to find out who released carbon dioxide and oxygen during photosynthesis and respiration.

How will she know if she is correct?

Answer:

If she know the carbon indicator shows increase, decrease and no change in the level of carbon dioxide. She is correct because she gets the following information:

A. Test Tube A (Water and snail): Due to snail's respiration, carbon dioxide is released. The indicator will turn yellow/orange, showing increased carbon dioxide in water.

B. Test Tube B (Water and plant): The indicator will turn blue/purple, showing decreased carbon dioxide because the plant uses this carbon dioxide during photosynthesis.

C. Test Tube C (Snail, plant and water): The colour may stay neutral or slightly blue, showing a balance as the snail gives out carbon dioxide and the plant uses it in the process of photosynthesis.

D. Test Tube D (Only water): No colour change, as there is no living organism to add or remove carbon dioxide.