Plants Flashcards
Name the gas exchange surface in plants
Mesophyll cells
How is a large surface area achieved in plants?
Wide and flat leaves
How is water loss reduced from the gas exchange surface?
Guard cells close stomata
What’s the equation for photosynthesis?
Carbon dioxide water → glucose + oxygen
(Light energy)
What is the respiration equation?
Glucose + oxygen → carbon dioxide x water
Name the 6 ways leaves adapted for photosynthesis ?
Thin, lots of chloroplasts, wide and flat, veins, airspaces, stomata
Why is being thin an adaption for photosynthesis?
It creates a short diffusion pathway and allows gases to reach cells easily
Why is lots of chloroplasts an adaption for photosynthesis?
Located in the palisade layer of cels near the top of the leaf for light and air space for the gases
Why is a leaf being wide and flat an adaption for photosynthesis?
Creates a large surface area to volume ratio to absorb as much light as possible
How do veins allow for effective photosynthesis?
They carry water to the cells and carry glucose away and also support leaves
How do air spaces allow for efficient photosynthesis?
They allow easy movement and exchange of gases
How do stomata allow for efficient photosynthesis?
Allow gases in and out of the leaf
Where are the stomata found?
On the underside of leaves
What is each stoma surrounded by?
2 guard cells
Explain what happens when the stoma is turgid
The guard cells curve outwards as they gain water, his opens the stoma, allowing gases in and out
explain what happens when the stoma is flaccid
The guard cells move closer together as they lose water, which closes the stoma. This stops the movement of gases, but also prevents water loss by evaporation
What are xerophytes?
Plants that are adapted to reduce water loss.
In what 5 ways are plants adapted to reduce water loss?
Thick waxy cuticle, hairs on leaves, curled leaves, sunken / fewer stomata, reduced sa:v
Why does a thick waxy cuticle reduce water loss?
It increases diffusion pathway so less chance of gas diffusing out. Helps to reduce water loss via evaporation as there’s increased thickness
How do hairs on leaves help to reduce water loss?
They trap water vapour / moist air next to the leaf surface. Water potential gradient between inside and outside of leaf is reduced. Less water lost by transpiration
How do curled leaves reduce water loss?
Stomata on lower epidermis are trapped with still air. No water potential gradient between inside and outside of leaf so transpiration is reduced
How do sunken stomata or fewer stomata reduce water loss?
Traps water vapour next to the leaf and reduces the water potential gradient. Reduces air movement
How does a reduced SA:V ratio help to reduce water loss?
No leaves means less SA and stomata. Slower rate of diffusion of gases
