Practice question · Put in order
A CAM desert plant is running its daily cycle. Arrange these events in the order they occur, starting at dusk.
- Stomata close at dawn, sealing the leaf against water loss
- Carbon dioxide is taken up and stored as an organic acid
- Stomata open at night, when the air is cool and humid
- The stored acid releases carbon dioxide for photosynthesis in daylight
Hints
- The CAM strategy separates gas uptake from photosynthesis in TIME rather than space.
- Uptake happens at night; the carbon is used the following day.
Show the answer
- Stomata open at night, when the air is cool and humid
- Carbon dioxide is taken up and stored as an organic acid
- Stomata close at dawn, sealing the leaf against water loss
- The stored acid releases carbon dioxide for photosynthesis in daylight
Why
CAM plants uncouple carbon uptake from photosynthesis: they gather CO₂ at night when evaporation is lowest, store it chemically, and use it by day with the stomata shut. It costs energy and buys an enormous saving in water.
Practise Plant Meristems and Covering Tissues
The app has 4 more questions on this lesson, and keeps your place in the course. Biology I is free to start.
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