Starter quiz
- What is the basic purpose of photosynthesis in plants?
- to absorb nutrients from the soil
- to produce carbon dioxide and water
- to produce glucose and oxygen ✓
- to store sunlight
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- Where in the plant cell does photosynthesis occur?
- in the chloroplasts ✓
- in the mitochondria
- in the nucleus
- in the cytoplasm
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- What is an independent variable in an experiment?
- a factor that cannot be measured
- 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
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- Which type of variable is kept the same during an experiment?
- independent
- dependent
- control ✓
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What is measured as the dependent variable in this photosynthesis experiment?- amount of light absorbed by the plant
- number of bubbles and volume of gas given off ✓
- temperature of the water
- the mass of the plant before and after the experiment
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- What safety measures should be considered when handling experimental apparatus?
- Ignore safety guidelines.
- Use equipment without checking it first.
- Wear safety goggles and handle equipment carefully. ✓
- Ensure all equipment is correctly set up before use. ✓
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Exit quiz
- What is the main product of photosynthesis?
- carbon dioxide
- glucose ✓
- water
- light
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- Which part of the plant cell captures light for photosynthesis?
- cell membrane
- mitochondria
- nucleus
- chloroplasts ✓
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- What is the independent variable in an experiment investigating the effect of light intensity on the rate of photosynthesis?
- carbon dioxide concentration
- light intensity ✓
- temperature
- type of plant
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- Which of the following is an example of a control variable in a light intensity experiment?
- distance of the plant from the lamp ✓
- type of plant
- number of oxygen bubbles produced
- change of colour of universal indicator
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- How can the distance of the plant from the lamp be controlled in the experiment?
- by using a ruler to measure the distance ✓
- by marking a fixed position for the lamp ✓
- by placing the plant on a stand at a set height ✓
- by trying to keep the plant and lamp in the same position throughout
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- What would be plotted on the x-axis in a graph of light intensity and photosynthesis rate?
- rate of photosynthesis
- light intensity ✓
- temperature of the water
- carbon dioxide concentration
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Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- Pondweed is a plant that photosynthesises in the light, releasing oxygen gas as a waste product.
- Planning an investigation into the effect of light intensity on the rate of photosynthesis in pondweed.
- Identifying the independent variable (light intensity) and planning how to vary it.
- Identifying factors that should be controlled and how they could be controlled (e.g. temperature).
- Planning methods to measure the dependent variable (number of bubbles and volume of gas given off).
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.
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
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