Year 11 / Cellular energy, gas exchange and plant physiology
Capture light. Release energy.
Photosynthesis converts light energy into chemical energy stored in organic molecules. Chloroplasts use carbon dioxide and water and release oxygen. Respiration transfers energy from organic molecules into ATP for cellular work.
Light intensity, carbon dioxide supply and temperature can each limit photosynthetic rate. Increasing one factor has little effect once another factor becomes limiting. Gas exchange supplies carbon dioxide and removes oxygen through stomata, with a water-loss trade-off.
Limiting factors
Explore: Move light and carbon dioxide controls to find which factor currently limits the rate.
A plant receives more light, yet photosynthesis no longer increases.
- Light is no longer the limiting factor.
- Carbon dioxide supply or enzyme-controlled reactions may now limit the rate.
Assumed knowledge
Energy transfer and simple graphs.
Learning checkpoints & source
YOUR LEARNING CHECKPOINT- Connect photosynthesis and respiration.
- Recognise limiting factors in photosynthesis.
READY TO TRY IT?