SL Content Statements

• C1.3.1

  Transformation of light energy to chemical energy when carbon compounds are produced in photosynthesis

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  This energy transformation supplies most of the chemical energy needed for life processes in ecosystems.

• C1.3.2

  Conversion of carbon dioxide to glucose in photosynthesis using hydrogen obtained by splitting water

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  Students should be able to write a simple word equation for photosynthesis, with glucose as the product.

• C1.3.3

  Oxygen as a by-product of photosynthesis in plants, algae and cyanobacteria

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  Students should know the simple word equation for photosynthesis. They should know that the oxygen produced by photosynthesis comes from the splitting of water.

• C1.3.4

  Separation and identification of photosynthetic pigments by chromatography

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  AOS: Students should be able to calculate Rf values from the results of chromatographic separation of photosynthetic pigments and identify them by colour and by values. Thin-layer chromatography or paper chromatography can be used.
  

• C1.3.5

  Absorption of specific wavelengths of light by photosynthetic pigments

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  Include excitation of electrons within a pigment molecule, transformation of light energy to chemical energy and the reason that only some wavelengths are absorbed. Students should be familiar with absorption spectra. Include both wavelengths and colours of light in the horizontal axis of absorption spectra.

• C1.3.6

  Similarities and differences of absorption and action spectra

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  AOS: Students should be able to determine rates of photosynthesis from data for oxygen production and carbon dioxide consumption for varying wavelengths. They should also be able to plot this data to make an action spectrum.

• C1.3.7

  Techniques for varying concentrations of carbon dioxide, light intensity or temperature experimentally to investigate the effects of limiting factors on the rate of photosynthesis

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  AOS: Students should be able to suggest hypotheses for the effects of these limiting factors and to test these through experimentation.
  NOS: Hypotheses are provisional explanations that require repeated testing. During scientific research, hypotheses can either be based on theories and then tested in an experiment or be based on evidence from an experiment already carried out. Students can decide in this case whether to suggest hypotheses for the effects of limiting factors on photosynthesis before or after performing their experiments. Students should be able to identify the dependent and independent variable in an experiment.
  

• C1.3.8

  Carbon dioxide enrichment experiments as a means of predicting future rates of photosynthesis and plant growth

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  Include enclosed greenhouse experiments and free-air carbon dioxide enrichment experiments (FACE).
  NOS: Finding methods for careful control of variables is part of experimental design. This may be easier in the laboratory but some experiments can only be done in the field. Field experiments include those performed in natural ecosystems. Students should be able to identify a controlled variable in an experiment.