Limiting Water Loss Flashcards
How do insects reduce water loss
Small SA to volume ratio - to minimise the area over which water is lost
Waterproof coverings over their body surfaces - a rigid outer skeleton of chitin that is covered with a waterproof cuticles
Spiracles - they are the openings of the trachea at the body surface. They can be closed to reduce water loss
What’s a xerophyte
Plants that are adapted to living in areas where water is short in supply
How do plants limit water loss
Waterproof covering over parts of the leaves
Ability to close stomata when necessary
What modifications do xerophytes have to reduce water loss
Thick cuticle - thicker the cuticle the less water can escape
Rolling up leaves - process lower epidermis from the outside helps trap a region of still air within the rolled leaf - becomes saturated with water vapour so has a high water potential( no water potential gradient between inside and outside of leaf therefore no water loss)
Hairy leaves - traps moist air, water potential gradient between inside and outside of the leaves is reduced and therefore less water is lost by evaporation
Stomata in pits or grooves - trap moist air next to the leaf and reduce the water potential gradient
A reduced surface area to volume ratio of the leaves- smaller the SA to volume ratio, the slower the rate of diffusion, by having small and roughly circular in cross section, the rate of water loss can be considerably reduced
Insects and plants face the same problems when it comes to living on land. What is the main problem they share
Efficient gas exchange requires a thin, permeable surface with a large area. On land these features can lead to a considerable loss of water by evaporation
State one modification to reduce water loss that is shared by plants and insects
Waterproofing covering to the body
Ability to close the openings of the gas exchange ( stomata/spiracles )
Insects limit water loss by having having a small surface area to volume ratio. Why is this not feasible way of limiting water loss in plants
Plants photosynthesise and therefore need a large surface area to capture light
