New
New
Year 11
OCR
Foundation

Factors affecting the rate of photosynthesis

I can describe and explain the effects of various factors on the rate of photosynthesis.

New
New
Year 11
OCR
Foundation

Factors affecting the rate of photosynthesis

I can describe and explain the effects of various factors on the rate of photosynthesis.

Lesson details

Key learning points

  1. The rate of photosynthesis depends on factors including light, chlorophyll, water, temperature and carbon dioxide.
  2. A factor that when in short supply slows down or limits the rate of photosynthesis is called a limiting factor.
  3. Increased temperature increases photosynthesis rate up to the optimum (due to increased enzyme-substrate collisions).
  4. Above the optimum temperature, enzymes are denatured and rate of photosynthesis decreases.
  5. Increased CO2 concentration increases rate of photosynthesis up to the optimum, when all enzyme active sites are full.

Common misconception

Students may mistakenly believe that only one factor can limit the rate of photosynthesis at any given time.

The lesson teaches that multiple factors, such as light intensity, carbon dioxide concentration, and temperature, can simultaneously influence 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.

Pupils could develop their ideas about how they might design a greenhouse in a cold country to grow a tropical fruit or vegetable. Pupils would need to think about how to overcome limiting factors in their designs.
Teacher tip

Equipment

None required.

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.
Which of the following are reactants for photosynthesis?
Carbon dioxide, water, and energy
Oxygen, glucose, and energy
Correct answer: Carbon dioxide and water
Carbon dioxide and oxygen
Q2.
What is the correct summary word equation for photosynthesis?
carbon dioxide + oxygen → glucose + water
Correct answer: carbon dioxide + water → glucose + oxygen
glucose + oxygen → carbon dioxide + water
water + glucose → carbon dioxide + oxygen
Q3.
Where in the plant cell does photosynthesis occur?
Correct answer: Chloroplasts
Mitochondria
Nucleus
Ribosomes
Q4.
What is the correct summary symbol equation for photosynthesis?
6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O
Correct answer: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
CO₂ + H₂O → O₂ + C₆H₁₂O₆
Q5.
How is light energy absorbed by plants?
Correct answer: By chlorophyll in the chloroplasts.
By the cell wall.
By the mitochondria.
By the nucleus.
Q6.
What effect does temperature have on enzyme activity?
It always increases activity.
It decreases activity.
It has no effect.
Correct answer: It increases activity up to an optimum point.

6 Questions

Q1.
What are the products of photosynthesis?
carbon dioxide and water
glucose and carbon dioxide
Correct answer: glucose and oxygen
oxygen and water
Q2.
What is a limiting factor in photosynthesis?
a condition that has no effect on the rate of photosynthesis
Correct answer: a condition that slows down the rate of photosynthesis when in short supply
a condition that speeds up photosynthesis
a factor that always increases the rate of photosynthesis
Q3.
What happens to the rate of photosynthesis at very high temperatures?
Correct answer: it decreases
it increases continuously
it increases slightly
it remains constant
Q4.
Why does the rate of photosynthesis decrease at high temperatures?
An image in a quiz
Enzymes involved in photosynthesis become more effective at high temperatures.
High temperatures increase the availability of water to the plant.
Correct answer: Enzymes involved in photosynthesis can denature, reducing their effectiveness.
High temperatures increase the rate of photosynthesis.
Q5.
How does carbon dioxide concentration affect the rate of photosynthesis?
it decreases the rate
it decreases the rate after a certain point
it has no effect
Correct answer: it increases the rate until an optimum level is reached
Q6.
At carbon dioxide concentrations above the optimum, what limits the rate of photosynthesis?
An image in a quiz
Correct answer: light intensity
Correct answer: water availability
Correct answer: temperature
nutrient supply
oxygen concentration