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Feeding in plants
Photosynthesis:
Carbon dioxide + water glucose + oxygen
6CO2 6H20 C6H1206 602
Chlorophyll absorbs light
Light energy converts carbon dioxide and water into glucose
Before testing for photosynthesis, you must de-starch the plant by
leaving it in the dark for 24 hours.…read more

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Rate of photosynthesis
Scientists try to increase the rate of photosynthesis to increase the yield of a
crop.…read more

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Structure of a leaf
WAXY CUTICLE: waterproof layer. Cuts down water lost by evaporation
UPPER EPIDERMIS: single layer of cells with no chloroplasts. Light goes
straight through.
PALISADE LAYER: Contains lots of chloroplasts. Most photosynthesis
occurs here.
SPONGY LAYER: rounded cells with space between for gas exchange
VEIN: contain xylem and phloem
LOWER EPIDERMIS: no thick cuticle.…read more

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Stomata
Small holes on the underside layer of the leaf that allows gases to diffuse in
and out.
Stomata can be opened and closed by guard cells
Open during the day, closed during the night
Water passes into the guard cells by osmosis
Close in hot weather to prevent water loss
Gas Exchange
All living things respire:
Glucose + oxygen carbon dioxide + water
Takes place ALL the time.
The gases pass in and out of the leaf through the stomata.…read more

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Plant Nutrients
Plants need mineral salts and nutrients for growth found in the soil and
taken up by roots by active transport
The 3 main minerals need are:
When soil does not contain enough nutrients, fertilisers are added to replace
the missing ones.…read more

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Phosphate Phosphate is needed for Poor root growth and
healthy roots purple leaves
Potassium Needed for healthy Yellow leaves with dead
leaves and flowers spots
Magnesium Magnesium is needed Yellow leaves
for chlorophyll
Natural and Chemical Fertilisers
Easy to store and add to the land (+)
Rain can wash fertilisers into rivers and streams causing water pollution (-)
Natural fertilisers include manure and compost
Some farmers prefer natural fertilisers because they add humus to the soil
Humus improves structure of the soil (+)
Natural fertilisers…read more

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Carbon Dioxide
o Growers can pump carbon dioxide into the glass houses to increase
photosynthesis
o Paraffin heaters release CO2
Water
o Automatic watering systems are used
o Sprinklers and humidifiers turn on when needed
(All these factors are controlled by computer. Sensors are used to detect each
factor.)
Growth in plants
Cell division and growth takes place mainly in root tips and shoots.…read more

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The Roots
Into the roots
Root hairs = long, thin, large surface area
Anchor the plants into the soil
Water passes into root hairs by osmosis ­ water in soil has high water
concentration and cell sap in root hairs has lower water concentration
The Stem…read more

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Cambi
um
Cel
ls Make new xylem and
phloem as the cell
grows
Epi
der
mis Single layer of cells
on the outside of the
stem which protects
the stem and cuts
down water loss
Vasc
u l
ar Contain phloem,
bundl
es cambium and xylem
Transpiration
When water evaporates from leaves to air
Continuous flow of water from roots to leaves
The movement of water up the xylem is called the transpiration stream
Factors affecting transpiration:
o Wind increase transpiration…read more

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