Page 53 - Science Coursebook

3.5 Selective breeding

Questions

A+I 1 Wheat is a crop that is grown in many different countries. The seed heads of

wheat plants are called ears. The seeds are called grain. Wheat grain is used to
make flour.

The first photograph shows one of the ancestors of modern wheat. The second

photograph shows a modern variety (breed) of wheat.

a What differences can you see between the old type of wheat and the
modern wheat?
b Explain how the modern variety of wheat could have been produced.
A+I 2 Imagine you are a farmer with a herd of goats, which you keep to produce milk.
You want to build up a herd of goats that produce more milk.
Describe what you would do. (Take care – remember that only females will
produce milk! Males do not produce milk.)

This scientist is trying to produce better varieties
of wheat. She is rubbing pollen from the flowers
of one plant onto the stigmas of another plant.
Can you suggest why she is keeping the plants in
a laboratory, rather than outside?

Summary
• When people breed animals and plants, they can choose which
ones they will allow to breed.
• Animals and plants with desired features are allowed to breed, but
those that do not have the desired features are not allowed to breed.
• This is done for many generations. This is selective breeding.

3 Variation and inheritance 51