Biology AQA Photosynthesis

Key points of AQA Biology unit 2 topic 12.3

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  • Created by: lrmm
  • Created on: 01-05-10 12:29

Photosynthesis

1.) CARBON DIOXIDE + WATER (+LIGHT ENERGY) = GLUCOSE + OXYGEN

2.) During p/s, light energy is absorbed by the chlorophyll in the chloroplasts and is used to convert carbon dioxide and water into sugar(glucose). Oxygen is released as a by-product.

3.) Leaves are well adapted to allow the maximum photosynthesis to take place.

4. The glucose produced in p/s may be converted into insoluble starch for storage. Plant cells use some of the glucose produced during p/s for respiration.

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Limiting Factors

1.) There are three main factors that limit the rate of p/s: light

temperature

carbon dioxide

2.) We can artificially change the environment in which we grow plants. We can observe the effect of different factors on the rate of p/s and can control their rate of photosynthesis.

3.) Light, temperature and the availability of carbon dioxide interact and in practice any one of them may be the factor that limits photosynthesis.

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How plants use glucose

1.) Plant cells use some of the glucose they make during photosynthesis for respiration.

2.) Some of the soluble glucose produced during p/s is converted into insoluble starch for storage.

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Why do plants need minerals?

1.) Nitrates and magnesium are two important mineral ions needed for healthy plant growth.

2.) If mineral ions are deficient, a plant develops symptoms because it cannot grow properly.

3.) Plant roots absorb mineral salts including nitrate and magnesium.

4.) Nitrates are needed to make amino acids which are needed to make proteins. A shortage leads to stunted growth.

5.) Magnesium is needed for chlorophyll production and a shortage leads to pale, yellow leaves.

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