Topic 3: Transport in plants p2 Flashcards
Ways for xerophytes to conserve water
Ways for xerophytes to conserve water:
-A thick waxy cuticle
-Sunken stomata at pits
-Reduced number of stomata
-Reduced leaves
-Hairy leaves
-Curled leaves
-Succulents
-Leaf loss
-Root adaptation
-Avoiding the problems
Thick waxy cuticle as an adaptation for conserving water
Thick waxy cuticle - minimises water loss - common in evergreen plants to surviving hot dry summers and cold winters where water is hard to obtain
Sunken stomata as an adaptation to conserve water
Sunken stomata - stomata located in pits - reduced air movement - producing a microclimate of still humid moist air that reduces water vapour potential gradient - reduces transpiration
Reduced number of stomata as an adaptation to conserve water
Reduced numbers of stomata - reduces the water loss by transpiration but also reduces their gas exchange capabilities
Reduced leaves as a way of conserving water
Reduces leaves - reducing leaf area - reduces water loss - eg leaves of conifers reduced to thin needles - reduced sa:v ratio
Hairy leaves as a way to conserve water
Hairy leaves - creates a microclimate of still, humid air reducing the water vapour potential and minimising the loss of water by transpiration from the surface of the leaf
Curled leaves as a way to conserve water
Curled leaves - confines all the stomata within a microenvironment of still, humid air to reduce diffusion of water vapour from the stomata eg marram grass has this adaptation
Succulents as a way to conserve water
Succulent - succulent plants store water in a specialised parenchyma tissue in their stems and roots - water is stored when it is in plentiful supply nd then used in times of drought
Leaf loss as a way to conserve water
Leaf loss - some plants lose their lives when water is not available
Root adaptations a way to conserve water
-Long tap roots grow deep into the ground and penetrate deep into the ground to acess water far from the surface
-Mass of widespread, shallow roots with a large surface area able to absorb any available water before a rain shower evaporates
Avoiding water loss problems as xerophytes
Some xerophytes avoid water loss problems by losing their leaves and becoming dormant, or dying completely and leaving seeds behind to germinate and grow rapidly
-Others may survive as storage organs such as bulbs (onions, daffodils) etc
Hydrophytes
Hydrophytes = plants that live in water and has special adaptations to cope with growing in water or being in permanetly saturated soil eg water lillies, water cress etc
Why is it important for surface water plants that the leaves float?
It is important for surface water plants that the leaves float so they are near the surface of the water to get light needed for photosynthesis
Adaptations of hydrophytes
Adaptations of hydrophytes:
-Very thin or no waxy cuticle as there is always water availble
-Many always-open stomata on the upper surfaces
-Reduced structure to the plant
-Wide flat leaves
-Small roots
-Large surface area of stems and roots under water
-Air sacs
-Aerenchyma (specialised parenchyma packing tissue)
What is the turgor pressure in plant cells?
Turgor is pressure exerted by fluid in a cell that presses the cell membrane against the cell wall. Turgor is what makes living plant tissue rigid. Loss of turgor, resulting from the loss of water from plant cells, causes flowers and leaves to wilt.