P2B6 - Plants Flashcards
How are root hair cells specialised?
No chloroplasts - Allows more water absorption
Long projections - Increase the surface area the plant can use to absorb water and minerals.
What does the xylem do?
Transport water up the stem of a plant and into the leaves.
How is the xylem specialised?
They’re made up of connected dead xylem cells.
The end walls of the dead cells are broken to allow water to move through.
Has lignin.
What is lignin?
A substance that strengthens the cell walls of xylem cells.
Why are xylem cells’ end walls broken?
To allow water and dissolved minerals to move through.
What is a stomata?
Gaps in the lower epidermis of leaves
What does the stomata do?
Facilitate (make easier) the diffusion of gases, including evaporated water, in and out of the leaf.
How do guard cells open the stomata?
By taking up lots of water, causing swelling.
How do guard cells close the stomata?
By losing water, returning to a limp state.
What is the state of stomata?
(open or closed) achieves a balance between allowing gases for photosynthesis into the leaves and conserving water in the plant.
State of stomata when water is abundant?
Open
State of stomata when water is scarce?
Closed
State of stomata at night?
Closed - The absence of sunlight, carbon dioxide is not required for photosynthesis.
What is transpiration (Water transport)?
Transpiration transports water and the minerals dissolved through the roots to the leaves.
How do root hair cells absorb water?
Osmosis
How are minerals transported through plant?
Active transport
Whats the process of transpiration?
- Root hair cells absorb water and minerals from soil
- Then transported in xylem vessels up stem and into leaves
- Once in leaves, the majority of water evaporates and the water vapour diffuses out through stomata.
This loss of water helps to pull water up from the roots.
What factors affect transpiration?
- Humidity
- Light intensity
- Temperature
- Air flow
How does a potometre measure the rate of transpiration?
As water is lost through the plant’s leaves, the air bubble moves.
The speed of the bubble’s movement shows the rate of water uptake.
Why is using a potometre to measure rate of transpiration only an estimate?
As a small amount of the water taken up by the shoot is used in the leaves.
What does the phloem do?
Transport food products to parts of the plant where they are needed
What are phloem vessels made up of?
Phloem vessels are made up of columns of living cells.
How is the phloem specialised?
The end walls of phloem cells contain small holes to allow food products to move up and down the phloem vessels throughout the plant.
What is translocation?
Process of food produced in photosynthesis transported from the leaves to the growing regions of plants and storage organs.
