Photosynthesis B8

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What is photosynthesis?
An endothermic reaction in which plants synthesise glucose and energy is transferred from the environment to the chloroplasts by light.
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Photosynthesis word equation
carbon dioxide + water → glucose + oxygen

(light over the arrow)
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How can you show that a plant gives off oxygen during photosynthesis?
Use a water plant to collect gas bubbles produced during photosynthesis.
The gas will relight a glowing splint
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What are the four main factors that effect photosynthesis?
-CO₂ conc
-Light intensity
-Temperature
-Amount of chlorophyll
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Effect of temp on photosynthesis
Increasing temp increases rate of photosynthesis as enzymes have more KE
The rate decreases past the optimum temp as enzymes become denatured
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Effect of light on photosynthesis
Increasing light intensity increases rate of photosynthesis until another factor becomes limiting
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Effect of CO₂ conc on photosynthesis
Increasing CO₂ increases rate of photosynthesis until another factor becomes limiting

CO₂ is required to make glucose
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Effect of amount of chlorophyll on photosynthesis
Decreasing amount of chlorophyll decreases the rate of photosynthesis as chlorophyll is required absorb light energy
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What is a limiting factor?
An environmental factor which can restrict rate of photosynthesis

eg light intensity, temp, CO₂ conc
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How can farmers use their knowledge of limiting factors to increase their profits?
They can control temp, light intensity and carbon dioxide conc to achieve fastest possible rate of photosynthesis, leading to a greater yield
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State the law which describes the relationship between the distance of a light source from a plant and light intensity
Inverse square law

Light intensity is proportional to 1/distance²
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State 5 uses of the glucose produced during photosynthesis
• used for respiration
• converted into insoluble starch for storage
• used to produce fat or oil for storage
• used to produce cellulose, which strengthens the cell wall
• used to produce amino acids for protein synthesis.
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Why is it advantageous for plants to store carbohydrates as starch rather than as a sugar?

(same for glycogen in animals)
Starch is insoluble. This means that it will not decrease the water conc in the roots, so water will not move into cells via osmosis, and become too turgid. Starch will also remain in the cells in the roots (not move to other parts of plant)
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Other cards in this set

Card 2

Front

Photosynthesis word equation

Back

carbon dioxide + water → glucose + oxygen

(light over the arrow)

Card 3

Front

How can you show that a plant gives off oxygen during photosynthesis?

Back

Preview of the front of card 3

Card 4

Front

What are the four main factors that effect photosynthesis?

Back

Preview of the front of card 4

Card 5

Front

Effect of temp on photosynthesis

Back

Preview of the front of card 5
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