Flashcards · Biology · Plant Adaptations and Hormones
Plants in Extreme Environments
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What is an adaptation?
A feature that helps an organism to survive in its environment.
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How are cactus leaves adapted?
They are reduced to spines, so there is a very small surface area for water loss.
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Why does a cactus have a thick cuticle?
To reduce the loss of water through the surface.
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Why do some desert plants open their stomata only at night?
It is cooler, so less water is lost.
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Why are stomata sunk in pits?
The pit traps humid air, which slows the diffusion of water vapour out.
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Why does marram grass roll its leaves?
To trap humid air around the stomata and reduce water loss.
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Where are the stomata of a water lily?
On the upper surface of the leaf.
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Why does a water lily have a thin cuticle?
Water is always available, so it does not need to prevent water loss.
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What do air spaces do in a water lily?
They keep the plant afloat and carry oxygen.
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Why do cushion plants grow low to the ground?
It is warmer and less windy, and the shape has a small surface area.
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What is a xerophyte?
A plant that is adapted to a very dry habitat.
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What does a small surface area to volume ratio do?
Reduces the rate of loss of water.
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Why do many cacti store water in their stems?
To survive the long periods between rain.
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How does the cuticle affect gas exchange?
A thick cuticle reduces it, so it is only thick where water loss is the main problem.
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Why do hairs on leaves reduce water loss?
They trap a layer of humid, still air next to the leaf surface.
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Common mistake about desert plants?
Saying they have no stomata. They have stomata, but fewer, and often open at night.