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PLANT NUTRITION (Leaf Structure (Leaf Structure, Cuticle: waxy later that…
PLANT NUTRITION
Leaf Structure
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Spongy Mesophyll Layer: irregularly shaped cells which create air spaces to allow gaseous exchange to take place; do not contain many chloropasts
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Xylem: vessel which transports water and dissolved minerals. Has lignified walls made out of cellulose
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Stomata: little holes that opens and closes to allow gaseous exchange to take place. The stomata closes to prevent water loss and opens to let gases come in and out.
When the guard cells lose water, the stoma close, while the stoma open when guard cells gain water and swell
Photosynthesis
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Chlorophyll is a dye, which traps light energy and converts it into to chemical energy for forming carbohydrates and storing it
Limiting Factors
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Light Intensity
It can become a limiting factor, but gradually, increasing the amount of light after a certain point has no effect on the rate.
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Temperature
As temperature increases, that rate of photosynthesis increases until it reaches optimum temperature of forty degrees Celsius,
Increasing it above forty degrees will cause the enzymes to denature, decreasing rate of photosynthesis
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Glasshouse Systems
To increase the crop yield, farmers control the limiting factors
CO2 enrichment: paraffin is burnt to increase CO2 concentration by three times the original amount and doubling the yield
Optimum temperature: thermostatically controlled heaters make the temperature right right for enzymes to work
Optimum light: light has a high intensity for more photosynthesis, the correct wavelength (red and blue, not green) and duration controls production of fruit
Phloem
bidirectional vessel that contains sieve elements which allow sugar to pass from one cell to the next onwards
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Still contains a small amount of cytoplasm along the walls but the organelle content is greatly reduced
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Mineral Requirements
Nitrogen
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Deficiency: small plant, slow growth, top leaves pale, bottom leaves dead, root and slightly affected
Magnesium
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Deficiency: plant lack chlorophyll, leaves yellow but normal roots
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