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Lower Epidermis
The outermost tissue on the lower side of the leaf. It protects the leaf.
Upper Epidermis
The outermost tissue on the upper side of the leaf. It protects the leaf
Palisade mesophyll layer
Rows of elongated cells in the upper half of the leaf where photosynthesis (mainly) occurs
Stomata
Pores in the leaf between the guard cells which allow gas exchange and movement of water vapour to happen
Guard cell
Surrounds the stomata controlling the opening and closing of the stomata
Spongy mesophyll layer
Irregular shaped cells in the lower half of the leaf. They allow gases to pass through the leaf
Xylem
Found in the veins of a leaf and transport water (and minerals) up from roots to shoots
Phloem
Found in the veins of the leaf and transport sugar made by photosynthesis down from the leaves to the other parts of the plant
Roots function
Water (containing salts and minerals that plants need for healthy growth ) is absorbed through the roots and travels up the plant to the leaves. Roots are adapted for this by having root hair cells which increase surface area. They also branch out allowing them to absorb water from a large volume of soil
Stems function
Provides mechanical support for the plant
Transports water from roots to shoots through the xylem
Transports sugar from the leaves to the rest of the plant through the phloem
Leaves function
Turn light into sugar by photosynthesis and transport it to the rest of the plant
Gas exchange - absorb CO2 and release O2
Transpiration
The loss of water by evaporation through the stomata
Transpiration stream definition
The movement of water in a plant
Describe the transpiration stream in a plant
Water is absorbed by osmosis into the root hair cells. It enter the xylem and travels up the stem. It then diffuses out of the top of the leaf through the stomata
Translocation
The movement of sugar solution in a plant
How are Phloem adapted for translocation?
Long thin cells - Fewer cells to travel through
Cells are end to end - cell sap can move easily from cell to cell
Cells have pores in end walls - cell sap can move from cell to cell easily
No nucleus - more space for movement of cell sap
How is the Xylem adapted for transpiration?
Hollow tubes (dead cells) - water can move easily
Tubes are strengthened by lignin - holds the tubes open to let water flow
easily
Differences between xylem and phloem
Xylem cells are dead, Phloem cells are alive
Xylem goes up, Phloem goes both ways
Xylem has lignin, Phloem does not
Xylem carries water, Phloem carries sugar solution
Note 
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