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Year 11 - Science

Photosynthesis and limiting factors

Photosynthesis: factors affecting the rate

Unit Summary

This unit explores factors affecting photosynthesis rates and focuses on planning and conducting experiments. It includes selecting techniques, accurate measurements, data analysis, and evaluating methods to improve reliability and suggest further investigations.

Lesson Summary

You will learn to explain the effects of limiting factors on the rate of photosynthesis.

Key Notes

  • Rate of photosynthesis increases as CO₂ concentration, temperature and light intensity increase from low levels.
  • The rate of photosynthesis can be limited by one of these factors even if the others continue to increase.
  • The rate of photosynthesis increases until one of more factors becomes limiting, then does not increase further.
  • Interpretation and explanation of graphs depicting effect of interacting limiting factors on the rate of photosynthesis.

Vocabulary To Learn

  • photosynthesis: The process used by producers to make their own food via a series of chemical reactions.
  • rate: A measure of how much change occurs per unit of time.
  • limiting factor: A condition that, when in short supply, slows down or limits the rate of photosynthesis.
  • enzyme: A biological catalyst that speeds up a chemical reaction without itself being used up.
  • optimum: The conditions where maximum rate of reaction occurs.

Common Mistakes To Avoid

  • Failing to realise that the plateau on a rate graph can occur because another factor (not named on the axes) has become limiting.

3 Quick Questions (With Answers)

1. Explain the scientific idea in this lesson using two key points.

Rate of photosynthesis increases as CO₂ concentration, temperature and light intensity increase from low levels. The rate of photosynthesis can be limited by one of these factors even if the others continue to increase.

2. Define this scientific word and use it in context. 'photosynthesis'

The process used by producers to make their own food via a series of chemical reactions. Include the word in a full scientific explanation, not as a single label.

3. Correct this common scientific misunderstanding.

Mistake: Failing to realise that the plateau on a rate graph can occur because another factor (not named on the axes) has become limiting. Correction: The lesson explores rate graphs in which multiple limiting factors are affecting the rate of photosynthesis.

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