Body-building foods
Every living thing is a body builder ? not just people who exercise with weights. At this moment, billions of bodies are building themselves up on this planet. They may be as small as a weed growing in the cracks in the pavement or as large as a redwood tree growing on the North American coast. Every living thing goes through a stage of growth. It may only take a few minutes if it is a microbe or it may take up to twenty years if it is a human. Some living things, like trees, never stop growing and live for hundreds of years. That is why they become so large.

When a plant makes food in its leaves, it uses some of the food for building up its body. These foods travel through the plant to two places where its body grows. They travel to the tip of its shoot and the tips of its roots. At the shoot tip, the foods make the shoot longer and wider. They may make it stronger to hold more leaves and branches. At the root tips, the foods are used to make the roots grow longer and push their way through the soil. They make the roots grow tiny white hairs that you can see best with a magnifying glass. These hairs help the root take up water.

Even when the plant is fully grown, it goes on making body-building food. It does not make food for itself but for its offspring ? the seeds. In each seed is a tiny plant that has a store of food. In this store are body-building foods to help the tiny plant sprout and grow into a seedling.

The body-building foods in the plant are also used by other living things. These are the animals that feed on the plants. Some animals are so small that they make tunnels in the leaf. From the top of the leaf these tunnels look like squiggly lines. Slightly larger animals, like caterpillars, munch around the edges of the leaves while very large animals, like deer, eat the whole leaf.

When a plant loses its leaf it might not grow another one and if it were to lose all its leaves it might die. The grass plant does not have this problem. The food it makes in its leaves goes to the bottom of the leaf just above the soil. Here the food makes part of a new leaf and pushes the rest of the leaf upwards. Many animals including rabbits and cattle eat grass. When they eat the leaves they take the top part of the leaf and do not reach the part where the food has collected. This means that no sooner has a grass plant lost part of its leaf, it grows another part to replace it. A grass leaf is like a conveyer belt at a supermarket: it is always moving food along. The food does not move horizontally but vertically into the air where the animals can bite it off.

When body-building foods of a plant are eaten by an animal they are digested and turned into body-building foods for the animal. These foods are used to make bone, muscle and skin. They are even used to build up the brain and nerves.

But still the journey of body-building foods is not over. Many animals are eaten by other animals. For example, a fox feeds on rabbits. When a fox eats rabbit meat the body-building foods in it are digested by the fox and turned into new body-building foods for the fox. Many wild animals, like the fox, have fleas. They are insects that live in the animal's fur and feeds on its blood. When a flea sucks up some blood in its needle-like mouth the body-building foods in the blood are used by the flea to make up its own body. This means that body-building foods can travel a long way. They can pass from the grass to a rabbit and then to a fox and finally help a flea grow long legs so it can leap from one fox to another when two foxes meet.

How long does it take a microbe to fully grow?
In ideal conditions it can grow and breed every twenty minutes. Usually conditions are too cold or too dry so microbes grow more slowly but they still grow faster than other living things.

What does a plant use to make body-building foods?
It uses air, water, sunlight and substances in the soil called minerals. When gardeners put fertiliser on a soil they are adding minerals that the plants can use to make body-building foods.

Do all plants give body-building foods to animals?
Yes, they do, but not all of them are useful to us. For example, grass only has small amounts of body-building foods in it leaves so animals like the cow have to eat large amounts of grass to get the nourishment they need. We can eat plants which are particularly packed with body-building foods. These plants are peas, beans and lentils. The plants in this group are called pulses. A pea, bean or lentil is a seed and when we eat them we eat the body-building food that was stored there for the tiny plant in the seed.

Can you see the tiny plant in a pea seed?
Yes, you can. If you open up a fresh pea you will see the tiny plant looking like a walking stick. When we eat peas or any pulse, we eat the food store and the tiny plants inside them.

Can people survive without eating meat?
Yes, they can. If they eat pulses and eggs and dairy products they can get all the body-building food they need. People who do not eat meat are called vegetarians. Some people do not eat any food such as milk or eggs from animals. They are called vegans. There are some people who do not even eat pulses or cereals. They eat mainly fruit but also nuts and honey and are known as fruitarians.


Is there a meat which is made from plants?
It is not really a meat, but a meat-like substance is made from soya beans. The scientific name for body building materials in food is called protein and the substance made from soya beans is called textured vegetable protein or TVP. It is a white spongy substance, which can be used to make the 'meaty' part of meals such as hamburgers.

What happens to the protein in an animal when it dies?
If the dead animal is eaten by a scavenger, like a vulture, the protein passes into the vulture's body and is digested and used to build up the vulture's body. If the body is broken down by microbes and rots away, the proteins break up and are destroyed. Some of the parts from which they were made go back into the soil and form minerals. These may be taken up by other plants and made into body building substances in the leaves again.