Transport in Plants - Xerophytes and Hydrophytes Flashcards
define xerophytes
plants adapted to survive in dry conditions
how does leaves reduced to spines reduce water loss
greatly reduced surface area, minimising water lost by transpiration
how do succulents reduce water loss
- store water in a specialised parenchyma tissue in their stem and roots
- water is stored when it is in plentiful supply and then used in times of drought
how do hairs reduce water loss
create a microclimate of still, humid air reducing the water vapour potential gradient and minimising loss of water by transpiration from surface of leaf
how does dense spongy mesophyll reduce water loss
reduces cell surface area that is exposed to the air inside leaves, so less water will evaporate into the leaf air spaces, reducing water loss
how do rolled leaves reduce water loss
confines all the stomata within a microenvironment of still, humid air to reduce diffusion of water vapour from the stomata
how do sunken stomata reduce water loss
reduce air movement, producing a microclimate of still, humid air that reduces the water vapour potential gradient and so reduces transpiration
how does a thick waxy cuticle minimise water loss
some plants have a particularly thick waxy cuticle to help minimise water loss
how does reduced number of stomata reduce water loss
reduced water loss by transpiration
how does leaf loss reduce water loss
some plants prevent water loss through their leaves by simply losing their leaves when water is not available
what are hydrophytes and what challenges do they face
plants that live in water.
- Need to ensure they get enough oxygen for respiration and that they receive enough light for photosynthesis.
- Also need to ensure they maintain the transpiration stream so that dissolved mineral ions are transported to leaves
how do wide flat leaves help plants that live in water
spread across the surface of the water to capture as much light as possible
how do aerenchyma help the plant to live in water
specialised parenchyma tissue forms in the leaves, stem and roots of hydrophytes, It has many large air spaces.
- makes leaves and stems more buoyant
- forms a low-resistance internal pathway for the movement of substances to tissues below the water
how do stomata on the upper surface help the plant to live in water
maximising the number of stomata maximises gaseous exchange
in some plants with floating leaves the stomata need to be on the upper surface so they are in contact with the air
how does a very thin or no waxy cuticle help the plant to live in water
do not need to conserve water as it is always in plentiful supply so water loss by transpiration is not an issue
how does reduced structure to the plant help the plant to live in water
the water supports the leaves and flowers so there is no need to strong supporting structures
how do small roots help the plant to live in water
water can diffuse directly into the stem and leaf tissue so there is less need for uptake by roots
how does large surface area of stems and roots underwater help the plant to live in water
maximises the area for photosynthesis and for oxygen to diffuse into submerged plants
how do air sacs help the plant to live underwater
some hydrophytes have air sacs to enable the leaves and/or flowers to float to the surface of the water
