Mass Transport In Plants Flashcards
Why do plants need a specialised exchange system
They have a low surface area to volume ratio
Can’t rely on diffusion alone
What is transpiration
The loss of water vapour from the stomata by evaporation
What four things effect the rate of transpiration
Light
Temperature
Humidity
Wind
Relationship between light and transpiration + why
More light more stomata open = larger surface area for evaporation
Relationship between temperature and transpiration
More heat means more kinetic energy so more evaporation
Relationship humidity and transpiration
More water vapour in the air will make the water potential more positive outside the leaf so reduces the water potential gradient less transpiration
Relationship between wind and transpiration
More wind will blow away humid air that has water vapour and therefore maintains the water potential gradient
What is cohesion
When water molecules stick together
What is adhesion
When water stick to other molecules
What 3 tings make it possible for the xylem to transport water all the way from the roots
Cohesion
Adhesion in capillary
Root pressure
Why does cohesion help is xylem
Water sticks as a column so is easier to be transported
The narrower/wider the xylem the impact of capillarity (adhesion)
Narrower
Explain root pressure + why helps water transportation
As water move in root increase volume of liquid in root so increases pressure
Increase pressure forces water upwards
What does the phloem transport
Organic substances
What two cells does the phloem contain
Sieve tube
Companion cells
Features of side tube elements in phloem
Living cells
No nucleus
Few organelle
What is the role of the companion cell
Provides ATP for active transport
What is translocation
The movement of sugars from the source(s) to the sink(s)
What is the growth tissue in plants called
Meristem
Explain why water moves up the stalk of plants
Water evaporates from leaves through stomata
Water potential gradient pulls up the water and osmosis creates tension
Cohesion maintains the column of water
When anomalies are present which average should you use
Mean
Mode or median
Median
How to use a scalpel correctly
Cut away from yourself
On a non-slip surface
Why can an organism exchange directly with its environment
SHORT DIFFUSION PATHWAY
The rate of water movement through the shoot in a photometer may not be the same as the rate of water movements through the shoots of a whole plant why
Plant had roots
