Selective breeding

Overview

How the individuals showing a characteristic are chosen and bred over generations, the traits sought in crops and livestock, the gain in food production, and the loss of variation.

What you need to know

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Questions from this subtopic

Each one with the model answer underneath.

1. 1

   What is selective breeding?

   Model answer

   It is choosing the individuals that show a desired characteristic most strongly and breeding them together so their offspring inherit it.

2. 2

   Describe how cattle could be selectively bred for a higher milk yield.

   Model answer

   Cows giving the most milk are bred with bulls whose mothers were high yielders, the best daughters are kept and bred again, and this is repeated over many generations.

3. 3

   Give two characteristics that food crops are commonly selectively bred for.

   Model answer

   A larger yield of grain or fruit, and resistance to disease.

4. 4

   Give two characteristics that domesticated animals are commonly selectively bred for.

   Model answer

   Fast growth with a high meat or milk yield, and a gentle temperament that makes them easy to handle.

5. 5

   Explain why selective breeding takes many generations to produce a large change.

   Model answer

   Each round of breeding shifts the characteristic only slightly, so parents must be chosen again and again before the trait becomes strong and reliable.

6. 6

   Explain how selective breeding has helped feed a growing human population.

   Model answer

   Modern crop varieties and livestock breeds produce far more food from the same area of farmland than their wild ancestors did.

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