Topic 2 E Flashcards
(25 cards)
Layers of leaf
Epidermal
Palisade mesophyll tissue
Spongy mesophyll tissue
Xylem and phloem
Stomata
Guard cell
What does epidermal do
Transparent so light can pass through
What does the palisade do
Lots of chloroplast for photosynthesis
What does spongy do
Air spaces for gas to diffuse
Xylem and phloem
Transport water , minerals and food
Stomata
Gass exchange
Guard cell
Controll how much gass gets in and out
Phloem
Food
Both directions ( translocation)
Xylem
Water
From roots to leaves ( transpiration)
What is transpiration
Loss of water from plant
What is transpiration caused by
Evaporation
Diffusion
What effects rate of transpiration
Light intensity ( more = increase as water evaporates faster)
Temperature (higher = increase as water evaporates faster)
Air flow (more = increase as the wind carrys water away from the plant
)
Humidity ( more = decrease as there is more water in the air)
How can you estimate the rate of transpiration
Measure the uptake of water
When do stomata open and close
Open when lots of water in leaf
Closes when less water in leaf to stop water vapour escaping
How are phloem adapted for translocation
Columns of elongated cells with holes at the end to create tubes for the cell sap to pass through
How are Xylem adapted for transpiration
No end of the cells creating a tube for the minerals and water
Lignin strengthens and waterproofs walls
Dead so little resistance to water flow
How is root hair cell adapted for transpiration
Lots of mitochondria so cells have enough energy for active transport of minerals
Long projections stick out to increase surface area
Absorb water via osmosis
Absorb minerals via active transport
How do guard cells open and close Stomata
To open the guard cells take up lots of water causing them to swell
To close the guard cells loose water and return to limp state
What happens to Stomata when water is scarce
They close to prevent water loss
What happens to Stomata when there is an abundance of water
Can afford to loose water so open the Stomata to allow gasses for photosynthesis to move freely
Aim of Stomata
Achieve a balance between allowing in gasses for photosynthesis and conserving water
What happens to Stomata at night
Close as no sunlight means that there isn’t co2 for photosynthesis so instead the Stomata focus on conserving water
Process of transpiration
Root hair absorbs water by osmosis and minerals by active transport
They are carried by Xylem cells to leaves
Once water reaches the leaves it evaporates
