Photosynthesis

In this lesson, you will be investigating how plants produce their own food. This process, called photosynthesis, is very important since animals rely on plants for food. Therefore, the study of plants (botany) is a very important one for the survival of all living things.

As well as investigating the process of photosynthesis, you'll be learning how to change the presentation of information from words into drawings. It is sometimes faster to get information from a picture than by having to read a lot of words, so this is a good thing to be able to do.

What is photosynthesis?

Photosynthesis is probably the most important process that occurs on Earth. All life depends on it. Our present knowledge of photosynthesis is the outcome of many experiments and theories, built up over at least 300 years.

Scientists are curious people, who like to investigate the world around them and suggest explanations for why things occur. The following investigations demonstrate this curiosity and the way that the scientific community has gone about answering questions about plants.

van Helmont's experiment

Johann Baptist van Helmont lived in Belgium and his findings were reported in 1648. At that time, most people thought that plants grew because they took materials out of the soil. Dr van Helmont devised a plan to test this idea.

Dr van Helmont was investigating plant growth. He placed 90.9 kg of dry soil in a pot. In this he planted a 2.3 kg willow shoot. He watered the plant. After five years he weighed the plant (now a tree). It weighed 77.0 kg. He also weighed the dry soil. It weighed 90.8 kg.