Plant adaptations Flashcards
What are the 2 types of plant?
Xerophyte and hydrophyte
What is a xerophyte?
A plant that is adapted to reduce water loss so it can survive in very dry conditions
What are examples of xerophytes?
Conifers, marram grass and cacti
What are adaptations of xerophytes?
Stomata in sunken pits, hairs, thick waxy cuticle, rolled leaves, fewer stomata, water storage, less leaves, root adaptations and avoidance
What is the function of stomata in sunken pits?
Air is not moved away by air currents but becomes trapped around the stomata and water molecules saturated the air to create local humidity?
What is the effect of stomata sunken in pits?
It reduces the water vapour diffusion gradient
What is the effect of hairs?
They create local humidity next to leaf and decrease exposure to air currents by reducing air flow around stomata
What is the function of the thick waxy cuticle?
Leaf is more impermeable to water and less water is lost from leaf surface
What is the function of rolled leaves?
Stomata on inside of a rolled leaf to decrease exposure to air currents and air becomes trapped around stomata as water vapour molecules evaporate into a humid space
What is the effect of rolled leaves?
It reduces the water diffusion gradient
What is the function of fewer stomata?
It decreases transpiration as this is were water is lost
What is the function of water storage?
To store water for times of drought in specialised parenchyma tissue in roots and stems in succulents
What is the function of leaf loss?
Prevent water loss by losing their leaves in times of drought such as desert tree which trunk and leaves turn green to photosynthesis with minimum water loss
What is the function of root adaptations?
Long tap roots can penetrate several metres as widespread shallow roots provide large SA for absorbing as much water as possible
What is the function of avoidance?
Plants can lose their leaves, become dormant, die leaving their seeds behind or survive on storage organs so some can withstand complete dehydration and recover when rain arrives
What is trehalose?
To protect the cell and allows completely dehydrated to recover when rain arrives
What are the conditions marram grass is adapted to survive to?
Wind and sandy soil
Why is marram grass adapted to survive wind?
On the coast, there are windy conditions so the plant is vulnerable to excessive water loss
When is plant vulnerable to excess water loss?
When it is photosynthesis and stomata is open
Why is marram grass adapted to survive sandy soil?
Sand is free draining so any rainfall drains away quickly and water availability is reduced
What are adaptations of marram grass?
Rolled leaves, sunken stomata and leaf hairs
What are hydrophytes?
Aquatic plants that live in the water/edge of water
What are examples of hydrophytes?
Water lilies on surface of water, duckweed submerged or on surface no bulrush on edge of water
Where do hydrophytes live?
Where water availability is high
What must hydrophytes do?
Produce a transpiration stream to keep water and minerals circulating around the plant, even though air in the environment with water vapour molecules
What are adaptations of hydrophytes?
Very thin or no waxy cuticle, many open stomata on upper surface of leaf, reduced structure, wide flat leaves, small roots, large SA of stems and roots, air sacs and pneumatophores
What is the function of the very thin or no waxy cuticle?
Plants don’t need to conserve water as there is always plenty available
What is the function of many open stomata on upper surface of
Especially floating species to maximise gas exchange so are always open due to water abundance
What is the function of reduced structure?
Water supports leaves and flowers
What is the function of wide flat leaves?
They capture lots of light
What is the function of small roots?
Water can diffuse directly into stem and leaf tissue
What is the function of large SA of stem and roots?
Maintain diffusion gradient of oxygen to diffuse into plants
What is the function of air sacs?
They have aerenchyma
What are aerenchyma?
Parenchyma with many air spaces for buoyancy
What are pneumatophores?
Aerial roots grow upwards into the air where roots can become waterlogged and allow air in
