Ananya wants to find out how plants and animals affect the amount of carbon dioxide in water. She is testing the role of respiration and photosynthesis. The carbon dioxide indicator changes colour depending on how much carbon dioxide is present in the water. Ananya will know she is correct by observing the colour changes in the carbon dioxide indicator in each test tube: Test Tube A (Snail only): The indicator will turn yellow/orange, showing increased carbon dioxide due to the snail’s respiration. Test Tube B (Plant only): The indicator will turn blue/purple, showing decreased carbon dioxide because the plant uses it during photosynthesis. Test Tube C (Snail + Plant): The colour may stay neutral or slightly blue, showing a balance as the snail gives out carbon dioxide and the plant uses it. Test Tube D (Only water): No colour change, as there is no living organism to add or remove carbon dioxide.