New
New
Year 11
OCR
Higher

Photosynthesis and limiting factors

I can explain the effects of limiting factors on the rate of photosynthesis.

New
New
Year 11
OCR
Higher

Photosynthesis and limiting factors

I can explain the effects of limiting factors on the rate of photosynthesis.

Lesson details

Key learning points

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

Common misconception

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

The lesson explores rate graphs in which multiple limiting factors are affecting the rate of photosynthesis.

Keywords

  • 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.

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
What is the main function of chloroplasts in plant cells?
Correct answer: to carry out photosynthesis
to provide structural support
to store genetic information
to transport water
Q2.
Which gas is essential for photosynthesis?
Correct answer: carbon dioxide (CO₂)
hydrogen (H₂)
nitrogen (N₂)
oxygen (O₂)
Q3.
What is the chemical formula for glucose?
C₁₂H₂₂O₁₁
Correct answer: C₆H₁₂O₆
CO₂
H₂O
Q4.
Which part of the plant leaf contains the most chloroplasts?
the cuticle
Correct answer: the palisade mesophyll
the spongy mesophyll
the stomata
Q5.
How does carbon dioxide enter the plant leaves?
through the cuticle
through the roots
Correct answer: through the stomata
through the veins
Q6.
What is the main product of photosynthesis?
carbon dioxide
Correct answer: glucose
oxygen
water

6 Questions

Q1.
What does it mean when a factor is described as a limiting factor?
it enhances the rate of photosynthesis when in short supply
it has no effect on photosynthesis
Correct answer: it slows down or limits the rate of photosynthesis when in short supply
it stops the process of photosynthesis
Q2.
Which of the following are not limiting factors of photosynthesis?
Correct answer: oxygen concentration
carbon dioxide concentration
light intensity
chlorophyll availability
Q3.
What occurs when light intensity reaches optimum levels in photosynthesis?
An image in a quiz
the rate of photosynthesis decreases
photosynthesis stops completely
Correct answer: the rate of photosynthesis no longer increases
the rate of photosynthesis increases indefinitely
Q4.
What is the relationship between temperature and the rate of photosynthesis?
An image in a quiz
temperature has no effect on the rate of photosynthesis
the rate decreases with temperature
Correct answer: the rate increases with temperature until enzymes denature
the rate remains constant with temperature changes
Q5.
Which of the following is most likely to be limiting the rate of photosynthesis at point A of the graph?
An image in a quiz
light intensity
Correct answer: carbon dioxide concentration
oxygen concentration
temperature
Q6.
Which of the following can be concluded from this graph?
An image in a quiz
Correct answer: the rate is limited by CO₂ concentration
the rate is limited by light intensity
Correct answer: the rate is limited by temperature
Correct answer: CO₂ concentration has a greater effect on the rate than temperature
the rate is unaffected by CO₂ concentration