A dog breeder wants to produce guide dogs that are calm in temperament and easy to train. Describe how the breeder would use selective breeding to produce a new generation of guide dogs with these characteristics.

Cambridge International IGCSE Biology (0610) — 18.3 Selection · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

1. Select dogs that display calm temperament and are easy to train.
2. Breed the selected dogs together (or cross the chosen individuals).
3. From the offspring, choose those that show calm temperament and ease of training.
4. Repeat the selection and breeding over many generations until the traits are reliably expressed.

Examiner tips

  • Use the word ‘select’ to show you understand the first step. Show the cycle of selection → breeding → selection of offspring. Mention that the process is repeated over several generations.
  • common_mistakes
  • :
  • Not specifying that the breeder must choose dogs that already have the desired traits. Failing to mention the need to repeat the process over many generations. Using vague terms like ‘improve’ instead of ‘select’ and ‘breed’.

Mark scheme (4 marks)

  1. Select/identify dogs that show the desired characteristics (calm temperament and ease of training)
  2. Breed the selected dogs together / cross the chosen individuals
  3. Select offspring that show the desired characteristics from the new generation
  4. Repeat the process over many generations until the desired characteristics are reliably expressed

Key terms in this question

selective breeding

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