Imaginative Teaching Resources & Inspirational Career Ideas from the Chilled Food Industry
Everything we eat is solar powered plants use the sun to create energy and grow, creating food that animals or humans eat. All animals, including humans, eat food that was, or is, a plant or animal.
Photosynthesis is a chemical process that occurs in plants, algae, and some types of bacteria, when they are exposed to sunlight. A by-product of this is oxygen which is released into the air and which we need to breathe.
This experiment lets you see the leaf photosynthesising.
What you will need:
Leaves
Dish/ bowl (glass is better)
Rock or weight to submerge the leaf
How to:
Pour some water in the bowl or dish with plenty to cover the leaf. Place the leaf in the water and weight it so its fully submerged (below).
Place the dish in direct sunlight.
After a few hours, you should be able to see bubbles forming on the leaf’s surface, showing that oxygen, a key product of of photosynthesis is being released.
The Science Behind It:
The bubbles are oxygen released by the plant during photosynthesis, which is the process of chlorophyll in plants (and algae) converting carbon dioxide and water into carbohydrates and oxygen (6CO2 + 6H20 = C6H12O6 + O2) using energy from sunlight.
You can also experiment with pondweed:
Gather materials: You’ll need pondweed (available at pet stores), a glass, water, and a light source.
Place pondweed in water: Put the pondweed in the glass of water.
Position light: Place a light source (like a lamp) 10 cm away from the pondweed.
Observe bubbles: After a few minutes, you should see bubbles forming on the pondweed, especially when it’s exposed to light.
Count bubbles: You can count the number of bubbles released over time to observe the rate of photosynthesis. Can you see the bubbles in the video below?
Why does this work?
Plants use sunlight, water, and carbon dioxide to produce glucose (their food and the basis of many carbohydrates) and oxygen through photosynthesis. The oxygen is released as bubbles when the plant is submerged in water.
Visit here for more variations of this experiment: Measuring photosynthesis experiment – Respiration and gas exchange – KS3 Biology – BBC Bitesize