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Osmosis- Transfer of water from one material to another. Usually from high concentration to low.
Leafs adaptations :
Flat and large to absorb the most sunlight
Network of veins to transport water and remove waste products
Thin structure to allow gasses shorter distance to the cells
It has stomata to allow carbon dioxide and oxygen to diffuse
Leaf is made up of 4 layers ( In Order ):
The features of the Leaf:
Waxy cuticle restricts water loss from the leaf
Upper epidermis is transparent to allow sunlight through
The spongy mesophyll contains lots of air spaces connected to the stomata to ensure
the optimum exchange of gasses
The lower epidermis contains most of the stomata
Stomata allows the diffusion of gasses in and out of the leaf.
Guard cells control the size of the stomata to restrict the loss of water
Veins contain xylem and phloem to transport water and sugars through the leaf
Water in plants:
Use it to keep the leaves cool
Enables them to photosynthesise to produce glucose
Keeps cells firm and therefore keeping the plant ridged
In the leaf, water moves out of the cell by osmosis and into the spaces in the spongy mesophyll layer
from where it will pass out of the leaf into the atmosphere.
When there is not enough water available in the soil, stomata close to try to prevent transpiration
and the diffusion of gasses, so photosynthesis has to stop. The plant cells are short of water so they
are not strong, which causes them to wilt.
Cells that lose a lot of water and contract like a deflating balloon.
The xylem and phloem form a continuous system of tubes and roots to the leaves.
Xylem vessels carry water up from the roots and phloem tubes carry food up and down the plant.
Water evaporates from the internal leaf cells through the stomata
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Water passes by osmosis from the xylem vessels to leaf cells, which pulls the entire thread
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Water enters the xylem from root tissue to replace water which has moved upwards.
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Xylem vessels are hollow tubes made from dead plant cells. The cellulose cell walls are thickened and
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Saprophytes are essential for decay.
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