Grade 9 · Science · Unit 3 of 11
Photosynthesis & Respiration
How cells make and use energy
What your child practises
The reactants, products and location of photosynthesis and cellular respiration, why they are complementary, and how they link plants, animals and the carbon cycle.
Ontario Curriculum expectation: B2.3, B2.2 · comparing photosynthesis and cellular respiration and how they balance each other in ecosystems
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
Where in a cell is most of the energy released by cellular respiration?
- mitochondria
- the cell membrane
- the nucleus
- chloroplasts
Show answer
mitochondria
Hint: Mitochondria are the cell's energy converters.
Question 2
A sealed jar holds a healthy plant and a small snail in the light. Why can both survive for a while?
- The plant makes no oxygen
- The plant's oxygen supports the snail's respiration, and the snail's carbon dioxide supports the plant
- Neither one uses energy
- The snail makes oxygen
Show answer
The plant's oxygen supports the snail's respiration, and the snail's carbon dioxide supports the plant
Hint: Each organism provides what the other needs.
Question 3
Why are photosynthesis and cellular respiration called complementary?
- They both make oxygen
- The products of each are the reactants of the other
- They both happen only in animals
- They both need light
Show answer
The products of each are the reactants of the other
Hint: Together they cycle carbon and oxygen through ecosystems.
Question 4
What happens to the dynamic equilibrium of the atmosphere if photosynthesis falls and respiration and burning continue?
- Oxygen levels rise sharply
- Nitrogen levels rise
- Nothing changes
- Carbon dioxide levels rise
Show answer
Carbon dioxide levels rise
Hint: Less carbon dioxide is removed, while it is still being added.
Question 5
Which gas released by photosynthesis do animals use in cellular respiration?
- hydrogen
- oxygen
- nitrogen
- carbon dioxide
Show answer
oxygen
Hint: The products of one process are the reactants of the other.
Question 6
Photosynthesis or cellular respiration? Sort each statement.
Sort into: ☀️ Photosynthesis · ⚡ Cellular respiration
- 🌿Happens in chloroplasts
- 🌫️Takes in carbon dioxide
- 🔥Breaks down glucose
- 💭Releases carbon dioxide
- 🌬️Uses oxygen
- 💨Releases oxygen
Show answer
☀️ Photosynthesis: Happens in chloroplasts, Takes in carbon dioxide, Releases oxygen · ⚡ Cellular respiration: Breaks down glucose, Releases carbon dioxide, Uses oxygen
Hint: Photosynthesis builds glucose using light. Cellular respiration breaks glucose down to release energy.