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Title: GCSE Biology Photosynthesis
Description: GCSE Biology photosynthesis notes and diagrams
Description: GCSE Biology photosynthesis notes and diagrams
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Photosynthesis
l
ight energy
Carbon dioxide + water > glucose + oxygen
6CO
+ 6H
O > C 12 6
H + 6O
O
2
2
6
2
Leaf adaptations for photosynthesis:
Most leaves are broad giving them a large surface area for the light to
fall on
They contain chlorophyll in the chloroplasts to absorb the light energy
Air spaces allow carbon dioxide to get to the cells and oxygen to leave
them by diffusion (also short distance for diffusion)
They have veins that carry water in the leaves
Stomata
opening is the leaves that allow gases to enter and leave
the plant that are opened and closed by guard cells
Xylem
transport tissue in plants transports water around the plant
Phloem
transport tissue that transports sugars around the plant
Translocation
the movement of sugars around the plant
Guard cells
the cells surrounding the stomata that control the
opening and closing of it
Paliside cells
contain chloroplasts which contain chlorophyll for
photoythesis
Diffusion
the spreading out of particles from low to high
concentration
Limiting factors
❖ Light
Light is the most limiting factor so if there is plenty of light there is a very
high rate of photosynthesis however if there is no light photosynthesis
will stop
...
Photosynthesis is controlled by
enzymes and enzymes are denatured if the temperature gets too high
oC
(4050
) therefore the rate of photosynthesis decreases
...
If there are high carbon
dioxide levels in the atmosphere the rate of photosynthesis increases
...
Plants don’t need carbon
dioxide all the time for instance when is it dark
...
Leaves have a flat
thin shape and internal air spaces to increase area for
diffusion
❏ Plants lose water vapour from the leaves mainly through the
stomata
❏ Most of the water and mineral ions are absorbed by the root
hair cells which increase surface area of the roots
Guard cells control the
opening and closing of the
stomata
Uptake of water and mineral ions
Plants take in water and mineral ions from the roots in the soil
...
Water moves into the root hair cells by osmosis across the partially
permeable membrane
...
Plant roots take in mineral ions using active transport
...
Evaporation and transpiration
The stomata open and close (controlled by the guard cells) to take
in carbon dioxide and
lose water vapour by diffusion
...
As water evaporates from the surface of the leaves, more water is
pulled up through the xylem to take its place
...
Environmental factors affecting transpiration
Light highe
the r the light intensity, the
higher the rate of transpiration
Temperature higher
the
the temperature, the
higher the rate of
transpiration
Wind more
the windy conditions, the
higher the rate of transpiration
Humidity more
the humid, the
slower the rate of transpiration
Title: GCSE Biology Photosynthesis
Description: GCSE Biology photosynthesis notes and diagrams
Description: GCSE Biology photosynthesis notes and diagrams