# KS4 Photosynthesis

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# KS4 Photosynthesis Learning Objectives

4.1.1 Photosynthetic reaction

Students should:

• Know the word equation for photosynthesis:

carbon dioxide + water → (light)   glucose + oxygen

• Know the chemical equation for photosynthesis: (HT only)

6CO2 + 6H2 → (light)   C6 H12O6 + 6O2

• Be able to describe photosynthesis as an endothermic reaction in which energy is transferred from the environment to the chloroplast by light.

4.1.2 Rate of photosynthesis

Students should:

• Be able to explain the effects of temperature, light intensity and carbon dioxide concentration on the rate of photosynthesis and to interpret graphs of photosynthesis rate involving one limiting factor.
• Know that these factors interact and any one of them may be the factor that limits photosynthesis. (HT only)
• Be able to explain graphs of photosynthesis rate involving two or three factors and decide which is the limiting factor. (HT only)
• Understand and use inverse proportion – the inverse square law and light intensity in the context of photosynthesis. (HT only)
• Know that limiting factors are important in the economics of enhancing the conditions in greenhouses to gain the maximum rate of photosynthesis while still maintaining profit. (HT only)
• Be able to use data to relate limiting factors to the cost effectiveness of adding heat, light or carbon dioxide to greenhouses.
• Be able to:

- measure and calculate rates of photosynthesis

- extract and interpret graphs of photosynthesis rate involving one limiting factor

- plot and draw appropriate graphs selecting appropriate scale for axes

- translate information between graphical and numeric form.

4.1.3 Conversion of photosynthetic energy

Students should:

• Know that the glucose produced in photosynthesis may be:
- 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.
• Know that to produce proteins, plants also use nitrate ions that are absorbed from the soil.
• Know the tests to identify starch, glucose and proteins using simple qualitative reagents.

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