Leaf and Snail Swap Gases

In the picture

1. 1The large sunlit leaf, where light energy turns water and carbon dioxide into sugar.
2. 2The pale blue spheres rising from the leaf, the oxygen released by photosynthesis.
3. 3The snail’s shell, marking the animal that breaks down sugar using oxygen.
4. 4The dark grey spheres returning to the leaf, the carbon dioxide given off by respiration.
5. 5The amber sugar cubes at the stem base, the stored chemical energy both processes share.

Examples

• A planted aquarium, where the water plants release oxygen in daylight while the fish release carbon dioxide.
• Running for a bus: your muscles break down sugar using oxygen, so you breathe out more carbon dioxide.

Quiz: Leaf and Snail Swap Gases (Age 16)

1. 1

   Inside the sealed jar, which gas passes from the plant to the animal?

   • Oxygen
   • Carbon dioxide
   • Water vapour
2. 2

   The sealed jar is kept in total darkness for several days. What is the most likely result?

   • The plant stops releasing oxygen, so the oxygen in the jar runs low
   • The plant releases more oxygen because it no longer uses light
   • The oxygen level stays the same because the animal makes oxygen
3. 3

   Why are photosynthesis and respiration described as opposite exchanges?

   • What one process uses up, the other produces
   • Both use up oxygen but release different gases
   • One happens only in plants and the other only in animals

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.