Adaptations Of Xerophytes And Hydrophytes Flashcards
what are xerophytes
Plant that have evolved to live in conditions where water is very scarce
Where are cacti found
In the desert
What are the adaptations of cacti (1) (leaves)
The cacti leaves have been replaced with fibrous spines, with photosynthesis taking place in the stem of the cacti. It also reduces the SA:VOL ratio
They also trap moist air near the cactus, reducing the rate of transpiration
They also provide some shade for the stem from the heat
What are the adaptations of cacti (2) stem
The stomata are found on the surface of the stem
What are the adaptations of cacti (3) (waxy cuticle)
They have a thick waxy cuticle to reduce the evaporation of water
What are the adaptions of cacti (stomata)
The stomata are found on the surface of the stem
The stomata are sunken into pits trapping a layer of moist air around the stomata, reducing water loss through the stomata.
What is an adaption of cacti (when stomata open)
The stomata only open at night to absorb carbon dioxide when conditions are relatively cooler. Reducing the water loss during the heat of daytime.
The CO2 is then used during the day for photosynthesis.
What are the adaptions of cacti (roots)
They often have extensive shallow roots allowing the cacti to absorb water after precipitation before it evaporates.
They also have very deep roots to access water from lower levels of the soil.
What are succulents and why are cacti examples
Plants that can store water in their stems, which cacti can do making them succulents.
Where is marram grass found and what are the conditions there
Marram grass is found in sand dunes and in sand dunes water is scarce. Windy conditions also increase evaporation of water from plants.
What are the adaptations of marram grass (leaves)
The leaves of marram grass roll into a tube with the stomata on the inside, and moist air is trapped in the tube rather than being blown away by the wind.
What are the adaptions of marram grass (stomata)
The stomata in marram grass are found in sunken pits with fine hairs projecting inwards towards the centre.
What are the adaptions of stomata (moist air)
These adaptions ensure moist air is trapped around the stomata
Reducing the concentration gradient for water vapour between the air and the internal spaces between the leaf cells.
Reducing the rate of diffusion of water vapour out of the stomata.
What is an adaptation of marram grass (cuticle)
they have a very thick waxy cuticle, to reduce evaporation from the surface.
What is an adaptation of marram grass (roots)
The roots of marram grass can be very long, extending deep into sand to find water.
What are hydrophytes and examples
They are plants that live in water and examples include water lillies, duckweeds etc.
What are the adaptions of hydrophytes (waxy cuticle)
They have a very thin or no waxy cuticle as they don’t need to conserve water as plenty is available.
What are the adaptions of hydrophytes (stomata)
They have many open stomata on their upper surfaces - maximising gaseous exchange as there is no risk of loss of turgor because there is lots of water available. They need to be on the upper surface so that they are in contact with the air.
What is an adaptation of hydrophytes (structure)
Reduced structure to the plant as the water supports the leaves and flowers, so doesn’t need supporting structures.
What is an adaptation of Hydrophytes (leaves)
wide flat leaves to capture as much light as possible
What is an adaptation of Hydrophytes (small roots)
Water can diffuse directly into stem and leaves so less uptake by roots.
What is an adaptation of Hydrophytes (air sacs)
To enable the leaves or flowers to float on top of the water
What is an adaptation of Hydrophytes (parenchyma)
Specialised parenchyma forms in the hydrophytes, which has many large air spaces
Making leaves and stems more buoyant
Forms low resistance internal pathways for the
Movement of substances such as oxygen to tissues below the water.
