Plant Flashcards
Stomata
Stomata are gaps in the lower epidermis of leaves that facilitate (make easier) the diffusion of gases, including evaporated water, in and out of the leaf.
Guard cell
Guard cells can open and close the stomata.
The guard cells can open the stomata by taking up lots of water, causing them to swell.
To close the stomata the guard cells lose water and return to a limp state
Why do stomata close at night?
Time of day affects the state of stomata.
At night, they close because, in the absence of sunlight, carbon dioxide is not required for photosynthesis.
At this time, their only objective is to prevent water loss.
What is transpiration ?
Transpiration transports water and the minerals dissolved in it through the plant.
Water moves in one direction only: from the roots to the leaves.
Method of transport : in xylem
Xylem are dead hollow tube
Air flow
Increased air flow carries water away from the plant’s leaves, encouraging more water to evaporate.
Increased air flow increases the rate of transpiration.
Light intensity
Increased light intensity makes water evaporate faster, which increases the rate of transpiration.
Humidity
The concentration of water vapour in the air
Increased humidity increases the amount of water in the air. This makes it more difficult for more water to evaporate.
Increasing humidity decreases the rate of transpiration.
Temperature
Increased temperature makes water evaporate faster, which increases the rate of transpiration.
When measuring the rate of transpiration with a potometer, why is the calculation only an estimate?
A small amount of the water taken up by the shoot is used in the leaves and is not transpired.
Phloem
The phloem is specialised to transport food products to parts of the plant where they are needed. Phloem vessels are made up of columns of living cells.
The end walls of phloem cells contain small holes to allow food products to move up and down the phloem vessels throughout the plant.
Translocation
Translocation is the process by which food produced in photosynthesis is transported from the leaves to the growing regions of plants and storage organs.
It’s bidirectional (goes up and down)
Transport cells are living
Transport : in phloem
Translocation is the movement of sucrose
Phloem tubes
Translocation happens through phloem tubes.
They carry sucrose
Phloem tubes are made up of columns of elongated cells that have holes in the end walls.
These holes allow cell sap (a liquid in plants that stores sugars, salts and amino acids) to pass between the cells.
Biomass
materials in a organism
What is photosynthesis ?
Photosynthesis is process where plants and algae can trap energy from the sunlight and you it to transferred to molecule of sugar called glucose
Is photosynthesis endothermic or exothermic ?
endothermic so it takes in energy
