Edexcel IGCSE Biology · Spec 2.40B-2.44B
Gas Exchange in Plants
Net gas exchange in plants in the light and in the dark, and the compensation point where the two rates are equal.
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Gas Exchange in Plants
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Spec 2.40B-2.44B
What you need to know
- Explain that plants both respire and photosynthesise
- Describe the net gas exchange in light and in the dark
- Explain what is meant by the compensation point
Active recall
Quick check
Answer each question before opening the answer.
What is the net gas exchange in a leaf during the day and at night?
Day: net carbon dioxide in, oxygen out (photosynthesis faster than respiration). Night: oxygen in, carbon dioxide out (only respiration).
Where does gas exchange occur in a leaf?
At the stomata (opened and closed by guard cells), with gases diffusing through air spaces in the leaf.
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