Xerophytes Flashcards

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1
Q

describe adaptions insects have evolved to conserve water

A
  • small surface area to volume ratio to minimise the area over which water is lost
  • waterproof coverings over their body surfaces, insects have a rigid outer skeleton made from chitin that is covered with a waterproof cuticle
  • spiracles opening of tracheae at the body surface that can be closed to reduce water-loss. only occurs when insect is at rest to prevent lack of oxygen
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2
Q

describe the adaptions that plants have evolved to conserve water

A
  • a thick cuticle the thicker the cuticle the less water than can evaporate through
  • rolling up of leaves stomata are predominantly on the lower epidermis of leaves, the rolling of leaves traps a layer of air within, the air becomes saturated with water vapour meaning there is a very high water potential. this ensures no water potential gradient so no water loss from the leaves.
  • hairy leaves a thick layer of hair on the leaves traps moist air next to the leaf surface and reduces the water potential gradient
  • stomata in pits or grooves same as hairy leaves
  • reduced SA:V ratio leaves a reduced surface area means less water can be evaporated
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3
Q

what’s a complication with plants and water loss?

A

whilst plants can have waterproof coverings, they cannot have a small surface area to volume ratio.
- this is because they have to photosynthesise

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