Required Practical 6: Photosynthesis
Ever wondered how you can actually measure photosynthesis happening in real time? This experiment lets you count oxygen bubbles as plants produce them during photosynthesis.
You'll place pondweed in sodium hydrogen carbonate solution (which releases CO₂ for the plant) and position it at different distances from an LED light. As you move the light further away, you'll see fewer oxygen bubbles being produced. This demonstrates how light intensity affects the rate of photosynthesis.
The inverse square law is crucial here - when you double the distance from the light source, the number of bubbles falls by four times. If counting bubbles gets too fast or sizes vary too much, you can measure the actual volume of oxygen produced instead using a gas syringe for more accurate results.
Quick Tip: Always use LED lights rather than normal bulbs because they don't produce heat, which would affect your results.
