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Doc Brown's Biology AQA GCSE Additional Science-BIOLOGY 2 Revision Notes

Biology Unit B2.3 Photosynthesis Study Notes

BIOLOGY UNIT 2 Biology 2 for GCSE Additional Science or GCSE Biology

REVISION NOTES GUIDE SUMMARY: What do you need to know for the examinations? What do you need to able to do in the exams? In AQA GCSE Science A examinations HT means for higher tier students only. Sorry, but I don't have much time to answer questions, but if you see any apparent errors or wish to comment, please email me. All my notes, learning objectives, comments for exam revision are based on the official AQA GCSE Science A Key Stage 4 syllabus specification.

AQA GCSE Science BIOLOGY 2 Unit B2.3 Photosynthesis

  • Know that all green plants and algae use light energy to make their own food.

  • Know that all green plants and algae obtain the raw materials they need to make this food from the air and the soil.

  • Know that the conditions in which plants are grown can be changed to promote growth.

  • You should be able to use your skills, knowledge and understanding to be able to:

    • interpret data showing how factors affect the rate of photosynthesis

    • evaluate the benefits of artificially manipulating the environment in which plants are grown.


Photosynthesis - factors affecting the rate - light temperature & carbon dioxide concentration


AQA GCSE Science BIOLOGY Unit B2.3.1 Photosynthesis

  • a) Know that photosynthesis is summarised by the equation:

    • carbon dioxide + water == light energy/chlorophyll  ==> glucose + oxygen

  • b) Know that during photosynthesis:

    • Light energy is absorbed by a green substance called chlorophyll, which is found in chloroplasts in some plant cells and algae,

    • This energy is used by converting carbon dioxide (from the air) and water (from the soil) into sugars (e.g. glucose),

    • Oxygen is released as a by-product.

    • Photosynthesis takes place in the leaves of all green plants and is the main function of leaves.

  • c) Know that the rate of photosynthesis may be limited by:

    • (i) shortage of light (usually sunlight) slows photosynthesis

    • (ii) low temperature, slows down the rate of photosynthesis

    • (iii) shortage of carbon dioxide will also slow down the rate of photosynthesis,

  • d) Know that light, temperature and the availability of carbon dioxide interact and in practice any one of them may be the factor that limits photosynthesis.

  • e) Know that the glucose produced in photosynthesis may be converted into insoluble starch for storage in leaves, roots and stems.

  • f) Know that some glucose in plants and algae is used:

  • g) Know that to produce proteins, plants also use nitrate ions that are absorbed from the soil.


Photosynthesis - factors affecting the rate - light temperature & carbon dioxide concentration


  • Your practical work to develop your skills and understanding may have included the following:

    • investigating the need for chlorophyll for photosynthesis with variegated leaves

    • taking thin slices of potato and apple and adding iodine to observe under the microscope

    • investigating the effects of light, temperature and carbon dioxide levels (using Cabomba, algal balls or leaf discs from brassicas) on the rate of photosynthesis

    • computer simulations to model the rate of photosynthesis in different conditions

    • the use of sensors to investigate the effect of carbon dioxide and light levels on the rate of photosynthesis and the release of oxygen.


GCSE Science-Biology courses AQA GCSE Science A BIOLOGY  *  EDEXCEL GCSE Science BIOLOGY

OCR GCSE 21st Century Science A - BIOLOGY  *  OCR GCSE Gateway Science A BIOLOGY


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