This page contains the detailed and easy notes for GCSE EDUQAS Biology Photosynthesis for revision and understanding Photosynthesis  .

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 GCSE EDUQAS Biology Photosynthesis Complete Revision Summary

 Photosynthesis

Photosynthesis

• Photosynthesis
• Factors affecting photosynthesis
• How plants use glucose
• Greenhouses

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PHOTOSYNTHESIS

It is the process by which green plants prepare their own food by using water, carbon dioxide in presence of sunlight to form glucose and oxygen.

• Only leaves can photosynthesize as they have chloroplast which contains chlorophyll.
• Chlorophyll is the green pigment that traps light for the leaves and helps them to photosynthesis.
• Photosynthesis is ENDOTHERMIC
• Endothermic as it takes in heat from the sunlight.
• The energy released in making glucose and oxygen is less than the energy required to break the bonds of carbon dioxide and water.

LEAF ADAPTATIONS FOR PHOTOSYNTHESIS

Mesophyll – Photosynthetic cells lies parallel to the surface to absorb maximum light and are closed to the stomata for quick diffusion of gases.

Chloroplast – They have chloroplast which contains chlorophyll and traps light for photosynthesis

Guard cell – They have stomata which are the pores for gas exchange

FACTORS AFFECTING PHOTOSYNTHESIS

• As the light intensity increases the rate of photosynthesis increases and then it levels off.
• Initially the rate increases an€ then it has no effect as at that point other factors become limiting.

• As the light intensity increases the rate of photosynthesis increases and then it levels off.
• Initially the rate increases and then it has no effect as at that point other factors become limiting

• As the temperature increases the rate increases as the particles gain kinetic energy and moves faster causing greater collision and increase reaction rate.
• Beyond optimum the rate decreases as at the higher temperature the enzymes get denatured. The enzyme changes shape and is not functions if the shape changes

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_Photosynthesis

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LAW OF LIMITING FACTORS

• The factor that limits the rate OF photosynthesis
• Limiting factor is that factor that is present in a least amount than required and affect the rate of photosynthesis.

As the pH increases the rate increases upto optimum. Beyond optimum the rate decreases as enzymes get denatured.

Measuring Photosynthesis

FATE OF GLUCOSE

• Glucose is soluble in water and if present longer will disturb osmotic balance of the cell Starch is complex molecule which is insoluble and can store large amount of glucose.
• Also starch being insoluble does not disturb the osmotic balance of the cell.

GLUCOSE

• Principle source of energy.
• It broken down during respiration and produces energy for the plant to grow and reproduce.

STARCH

• Excess glucose is stored in the plant as starch and is used by the plant when needed.

CELLULOSE

• Excess glucose can be converted into structural carbohydrate called Cellulose
• Cellulose is the component of the cell wall which provide shape and support to the plant.

PROTEINS

• Glucose is combined with nitrates and other mineral ions from the soil to form protein.
• Proteins are responsible for growth and also to make enzymes for metabolic reactions.

LIPIDS

• Glucose can be converted to fats and oil to serve as energy source.
• Fats and oil can form the component of the cell membrane
• They are also stored in seeds as an energy store for germination.

 
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TEST FOR STARCH

• Add Iodine Solution
• If the solution turns blue black it indicates the presence of starch.

GREENHOUSE

• It controls all the limiting factors to provide maximum yield of photosynthesize
• Temperature, light, carbon dioxide and other factors affecting photosynthesis are controlled and monitored.
• It works on the principle of greenhouse effect in which light is allowed to enter but is not allowed to escape thereby increasing light and temperature inside the greenhouse.

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Key Terms

Photosynthesis – It is the process by which green plants prepare their own food carbon dioxide and water are combined to form glucose and oxygen in presence of sunlight

Respiration – breakdown of food to release energy

Limiting Factors — Factor that limits the rate of photosynthesis

Endothermic Reaction— Reaction that takes in heat

Exothermic Reaction — Reaction that releases heat

Glucose — product of photosynthesis and fuel for respiration

Starch — Storage carbohydrate in plants

Glycogen — Storage carbohydrate in animals

Aerobic Respiration – Breaking down of food in presence of oxygen

Anaerboic Respiration – breaking down of food in absence of oxygen

Fermentation – Anaerobic respiration in plants that produces ethanol and carbon dioxide

Greenhouse – A glass or a plastic house to control the limiting factors and increase the rate of photosynthesis.

Metabolism – Sum Of all the catabolic and anabolic reactions of the body.

Liver – An organ involved in metabolism.

Lactic Acid — The product of anaerobic respiration in animals

Oxygen Debt —The extra oxygen needed exercise to break down lactic acid and recover to pre exercise state.

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Disclaimer:

I have tried my level best to cover the maximum of your specification. But this is not the alternative to the textbook. You should cover the specification or the textbook thoroughly. This is the quick revision to help you cover the gist of everything. In case you spot any errors then do let us know and we will rectify it.

References:

BBC Bitesize

Wikipedia

Wikimedia Commons

Image Source:

Wikipedia

Wikimedia

Commons

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• Photosynthesis 1 MS
• Photosynthesis 1 QP
• Photosynthesis 2 MS
• Photosynthesis 2 QP
• Photosynthesis 3 MS
• Photosynthesis 3 QP