Required Practical: Light Intensity and Photosynthesis

This lesson covers the AQA GCSE Combined Science Trilogy (8464) required practical on investigating the effect of light intensity on the rate of photosynthesis using an aquatic plant. You will be expected to describe the method, identify variables, apply the inverse square law and evaluate the experiment.

---

Overview of the Practical

You investigate how changing light intensity affects the rate of photosynthesis by counting the number of oxygen bubbles produced by an aquatic plant (e.g. Elodea / pondweed) at different distances from a lamp.

The Principle

• Oxygen is a by-product of photosynthesis.
• The more oxygen bubbles produced per minute, the faster the rate of photosynthesis.
• By moving the lamp to different distances, you change the light intensity reaching the plant.

---

Method