6. Plant nutrition

6.1 Photosynthesis

Core

• Define photosynthesis as the process by which plants manufacture carbohydrates from raw materials using energy from light

• State the word equation for photosynthesis: carbon dioxide + water → glucose + oxygen, in the presence of light and chlorophyll

• Investigate the necessity for chlorophyll, light and carbon dioxide for photosynthesis, using appropriate controls

• Investigate and describe the effects of varying light intensity, carbon dioxide concentration and temperature on the rate of photosynthesis, e.g. in submerged aquatic plants

Supplement

• State the balanced chemical equation for photosynthesis 6CO2 + 6H2O light chlorophyll C6H12O6 + 6O2

• Explain that chlorophyll transfers light energy into chemical energy in molecules, for the synthesis of carbohydrates

• Outline the subsequent use and storage of the carbohydrates made in photosynthesis

• Define the term limiting factor as something present in the environment in such short supply that it restricts life processes

• Identify and explain the limiting factors of photosynthesis in different environmental conditions

• Describe the use of carbon dioxide enrichment, optimum light and optimum temperatures in glasshouses in temperate and tropical countries

• Use hydrogencarbonate indicator solution to investigate the effect of gas exchange of an aquatic plant kept in the light and in the dark

6.2 Leaf structure

Core

• Identify chloroplasts, cuticle, guard cells and stomata, upper and lower epidermis, palisade mesophyll, spongy mesophyll, vascular bundles, xylem and phloem in leaves of a dicotyledonous plant

Supplement

• Explain how the internal structure of a leaf is adapted for photosynthesis

6.3 Mineral requirements

Core

• Describe the importance of:

– nitrate ions for making amino acids

– magnesium ions for making chlorophyll Supplement

• Explain the effects of nitrate ion and magnesium ion deficiency on plant growth