Transport in Plants Flashcards
What is a xerophyte?
A plant that reproduces and lives in an area where water availability is very low. (e.g: cactus)
How does a thick waxy cuticle help conserve water for xerophytes?
Helps minimise water loss by stopping the water vapour escaping from the epidermis.
How does a sunken stomata help conserve the water for xerophytes?
Sunken stomate reduce air movement and produces a microclimate of humid air that reduces the water vapour potential gradient and so reduces transpiration.
How does the reduced number of stomata help conserve water for xerophytes?
Reduces water loss by transpiration and also reduces their gas exchange capabilities.
How does the reduced number of leaves conserve the water for xerophytes?
Less amount of stomata, and so less loss of water vapour.
How do hairy leaves help conserve water for xerophytes?
They create a microclimate of still and humid air, reducing the water vapour potential gradient and minimising loss of water by transpiration from the surface of the leaf.
How do curled leaves help conserve water for xerophytes?
Limits all of the stomata within a microenvironment of still, humid air to reduce diffusion of water vapour from the stomata.
What is an example of a plant that has curled leaves as a feature to conserve water?
Marram Grass
How do succulents help conserve water for xerophytes?
Succulent plants store water in parenchyma tissue in their stems and roots. Water is stored when it is in supply and then used in times of drought.
What feature of a xerophyte’s roots help conserve water?
They have long roots that grow deep into the ground and can penetrate several metres. They also have shallow roots with a large surface area that is available to absorb rain shower.
What is a hydrophyte?
A plant that lives in water.
Why don’t hydrophytes have a waxy cuticle?
They don’t need to conserve water and so water loss is not an issue, meaning they don’t need a cuticle.
How does the adaptation of always-open stomata on the upper surfaces help a hydrophyte survive?
Maximising the number of stomata increases gas-exchange.
How do wide, flat leaves help a hydrophyte survive?
This lets them capture as much light as possible to photosynthesise.
Why do hydrophytes only need small roots?
Because water can defuse directly into stem and leaf tissue so there is less need for the uptake of water in the roots.
How do air sacs help a hydrophyte survive?
This enables the leaves and flowers of the hydrophytes to float to the surface of the water so they can access air.
What is aerenchyma?
Specialised parenchyma (packing) tissue that forms in the leaves, stems and roots of hydrophytes.
What are the functions of aerenchyma?
Makes the leaves and stems flotable.
It forms a low-resistance internal pathway for the movement such as oxygen to tissues below the water.
What does anoxic mean?
Extreme low oxygen conditions.
How does aerenchyma help hydrophytes cope with anoxic conditions?
They transport oxygen into the plants tissues.
How is water taken up from the soil?
Through root hair cells.
How is the process of osmosis able to uptake water from the soil into the plant?
Cells in the root contain mineral ions and solutes and so have lower water potential than the soil solution that surrounds them. So, water moves down a water potential gradient and into the root hair cell.
Once the water has been absorbed, where does the water move through?
The cortex.
What are the two pathways that water can run through once in the cortex?
The symplastic and apoplastic pathways.
