Exchange of materials: in plants Flashcards
1
Q
what chemicals are exchanged in plants?
A
- oxygen: waste product from photosynthesis/useful for respiration
- water: waste product of respiration/ used in photosynthesis/ maintains structure
- mineral ions: moved by active transport by root hair cells which increase surface area for absorption
- carbon dioxide: used in photosynthesis/ waste product of respiration
2
Q
what is transpiration?
A
- continuous movement of water through a plant from roots to leaves (as a result of water loss by evaporation at surface)
3
Q
how is water loss prevented?
A
- guard cells
- wilting
4
Q
how can a plant dehydrate?
A
if rate of evaporation is greater than water uptake
5
Q
How is the rate of transpiration increased?
A
- hot: more evaporation - helps process because water needs to be a gas before it can diffuse
- dry: less water in air and lots in leaf so diffsuion gradient
- windy: moves water away so diffusion gradient
6
Q
Where does water vapour escape?
A
through stomata
7
Q
What does phloem transport?
A
- transport food substances (dissolved sugars) in leaves to growing regions and storage organs
- made of columns of living cells with small holes to allow stuff to flow through
- transport in both directions
8
Q
What does xylem transport?
A
- dead cells joined end to end
- carry water and minerals rom roots to stem and leaves in a transpiration stream
9
Q
overview of exchange system in transpiration
A
- root hair -osmosis
- mineral ions - active transport
- gases - diffusion
10
Q
Why is the rate of transpiration higher on a bright day?
A
- faster rate of photosynthesis
- stomata open as wide as possible to allow more carbon dioxide in
11
Q
On humid days, the rate of transpiration is slow even when it is hot. Explain why
A
- air already contains water vapour
- wont be a steep concentration gradient
- diffusion of water vapour from the leaf is reduced
