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Year 11
AQA
Higher

The effect of light intensity on rate of photosynthesis in algae: plan

I can plan an investigation into the effect of light intensity on the rate of photosynthesis in algae.

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New
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Year 11
AQA
Higher

The effect of light intensity on rate of photosynthesis in algae: plan

I can plan an investigation into the effect of light intensity on the rate of photosynthesis in algae.

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Lesson details

Key learning points

  1. Algae are living organisms that photosynthesise in the light, carbon dioxide is a reactant.
  2. Planning an investigation into the effect of light intensity on the rate of photosynthesis in algae.
  3. Identifying the independent variable (light intensity) and planning how to vary it.
  4. Identifying factors that should be controlled and how they could be (e.g. temperature).
  5. Planning a method to measure the dependent variable (colour change of indicator).

Keywords

  • Rate - a measure of how much change occurs per unit of time

  • Light intensity - the amount of light reaching a given surface area in a period of time

  • Hypothesis - an idea, for example an idea about an outcome of an experiment, based on observations and understanding

  • Variable - a factor that can be changed during an experiment

  • Control variable - a factor that is kept the same during an experiment

Common misconception

Some pupils do not consider how to control variables carefully enough. This means results are likely to be less accurate and so do not provide conclusions that can be used to support a hypothesis.

Each type of variable is considered during the lesson and repeated to help pupils to understand the differences between each type of variable.


To help you plan your year 11 biology lesson on: The effect of light intensity on rate of photosynthesis in algae: plan, download all teaching resources for free and adapt to suit your pupils' needs...

Use real practical equipment to provide pupils the chance to think about the types of equipment that can be used, and to help pupils analyse risk effectively. Ask pupils to handle the equipment and consider how they might use it, so they can approach the tasks with workable ideas.
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Teacher tip
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Content guidance

  • Risk assessment required - equipment
supervision-level

Supervision

Adult supervision required

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Licence

This content is © Oak National Academy Limited (2025), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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Starter quiz

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6 Questions

Q1.
What is the basic purpose of photosynthesis in plants?
To absorb nutrients from the soil.
To produce carbon dioxide and water.
Correct answer: To produce glucose and oxygen.
To store sunlight.
Q2.
Where in the plant cell does photosynthesis occur?
Correct answer: In the chloroplasts.
In the mitochondria.
In the nucleus.
In the cytoplasm.
Q3.
What is an independent variable in an experiment?
A factor that cannot be measured.
Correct answer: A factor that is changed during an experiment.
A factor that is kept the same.
A factor that doesn’t affect the results of the experiment.
Q4.
Which type of variable is kept the same during an experiment?
independent
dependent
Correct answer: control
Q5.
What safety measures should be considered when handling experimental apparatus?
Ignore safety guidelines.
Use equipment without checking it first.
Correct answer: Wear safety goggles and handle equipment carefully.
Correct answer: Ensure all equipment is correctly set up before use.
Q6.
What is measured as the dependent variable in this photosynthesis experiment?
Amount of light absorbed by the plant.
Correct answer: pH change.
Temperature of the water.
The mass of the plant before and after the experiment.

Exit quiz

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6 Questions

Q1.
What is the main product of photosynthesis?
carbon dioxide
Correct answer: glucose
water
light
Q2.
Which part of the plant cell captures light for photosynthesis?
cell membrane
mitochondria
nucleus
Correct answer: chloroplasts
Q3.
What is the independent variable in an experiment investigating the effect of light intensity on the rate of photosynthesis?
carbon dioxide concentration
Correct answer: light intensity
temperature
type of plant
Q4.
Which of the following is an example of a control variable in a light intensity experiment?
Correct answer: distance of the plant from the lamp
type of plant
number of oxygen bubbles produced
change of colour of universal indicator
Q5.
How can the distance of the plant from the lamp be controlled in the experiment?
Correct answer: By using a ruler to measure the distance.
Correct answer: By marking a fixed position for the lamp.
Correct answer: By placing the plant on a stand at a set height.
By trying to keep the plant and lamp in the same position throughout.
Q6.
What would be plotted on the x-axis in a graph of light intensity and photosynthesis rate?
rate of photosynthesis
Correct answer: light intensity
temperature of the water
carbon dioxide concentration