New
New
Year 11
OCR
Higher

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

I can evaluate and explain data from an investigation into the effect of light intensity on the rate of photosynthesis in algae.

New
New
Year 11
OCR
Higher

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

I can evaluate and explain data from an investigation into the effect of light intensity on the rate of photosynthesis in algae.

Lesson details

Key learning points

  1. Process data and plot a graph of appropriate results to identify and describe patterns or trends in the results.
  2. Explain the results using ideas about the requirement of light for photosynthesis.
  3. Identify sources of systematic and random error that could affect the accuracy of the measurements.
  4. Suggest improvements (e.g. ways to measure the pH change and/or the rate more accurately).
  5. Evaluate the precision, repeatability and reproducibility of the results.

Keywords

  • Accuracy - A measurement result is considered accurate if it is judged to be close to the true value.

  • Error - An error leads to measurements being different to what they would otherwise be (the true value).

  • Precision - Precision refers to how closely results are spread around the mean value.

  • Repeatability - Measurements are similar when repeated by the same person or group using the same equipment and method.

  • Reproducibility - Similar results are obtained when an investigation is repeated by another person or group using different equipment.

Common misconception

Pupils often struggle with the difference between repeatability and reproducibility.

The lesson outlines the difference between these two aspects of working scientifically and checks pupils understanding of these in relation to the investigation.

Spend time talking about accuracy and precision. Precision is where all results are in close agreement. It doesn't infer accuracy. Use a dartboard analogy. The 'true value' is the bullseye. Throwing darts here is both precise and accurate. Hitting double 1 with 5 darts is precise but not accurate.
Teacher tip

Content guidance

  • Risk assessment required - equipment

Supervision

Adult supervision 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).

Lesson video

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6 Questions

Q1.
Plants produce glucose and during photosynthesis.
Correct Answer: oxygen, O2
Q2.
What is the role of chlorophyll in photosynthesis?
to absorb carbon dioxide
Correct answer: to absorb energy from light
to absorb oxygen
to absorb water
Q3.
What is the gas taken in by plants for photosynthesis?
Correct Answer: carbon dioxide, CO2
Q4.
In which cell organelle does photosynthesis occur?
Correct Answer: chloroplast
Q5.
What is the formula for glucose?
C₂H₆O
Correct answer: C₆H₁₂O₆
H₂O
CO₂
Q6.
How can gas production be measured in photosynthesis experiments?
using a pH meter
using a ruler
Correct answer: counting bubbles
using a thermometer

6 Questions

Q1.
What is the purpose of evaluating an experiment?
to compare it with other experiments
to confirm the results
Correct answer: to identify errors and suggest improvements
to repeat the experiment exactly
Q2.
What does precision in an experiment refer to?
the closeness to the true value
Correct answer: the spread of results around the mean value
the consistency of results by different groups
the consistency of results by the same group
Q3.
How can you improve the accuracy of pH measurement in photosynthesis experiments?
Use a gas syringe.
Correct answer: Use a pH probe.
Use a stopwatch.
Use a thermometer.
Q4.
What does reproducibility in an experiment mean?
obtaining different results by different people or groups
obtaining different results by the same person or group
Correct answer: obtaining similar results by different people using different equipment
obtaining similar results by the same person or group
Q5.
How can systematic errors be identified in an experiment?
by changing the experimental method
Correct answer: by comparing results to known standards or controls
by ignoring outliers
by repeating the experiment multiple times
Q6.
How can you reduce random errors in your data collection?
by ignoring inconsistent data
by relying on a single measurement
Correct answer: by taking multiple measurements and averaging them
by using different equipment each time

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