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Question
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? How will she know if she is correct?
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Answer
She wants to find out how plants and animals exchange gases like carbon dioxide.
Explanation
- The snail (A) respires and adds carbon dioxide to the water.
- The plant (B) uses up carbon dioxide in light for photosynthesis.
- In tube C, the plant and snail balance each other's gases.
- Tube D with only water is the control to compare with.
The indicator's colour change shows how carbon dioxide rises or falls.
← Back to concept: 10.4 Do Plants Respire?
