Page 175 - Big Ideas Year 10 sciPAD 2025

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SCIPAD - BIG IDEAS - BOOK 2
THE BASIS OF HEREDITY
Artificial Selection
Artificial selection is when people use selective breeding to produce new varieties of a species.
Selective breeding means that humans control which organisms are able to reproduce, i.e. only
those individuals that have the desired trait (characteristic) you are looking for are allowed to
breed.
No animal has been more selectively bred than the dog. Ever since the domestication (taming)
of the wolf over 13 000 years ago, humans have been producing new varieties of dogs based on
different characteristics - small, short, tall, long-haired, short-haired, or curly-haired. Chihuahuas
to Labradors, Poodles to Rottweilers, all breeds of dogs have been selectively bred from the wolf.
1. Use the axes below to sketch a graph to show the variation in height within a population
of wolves.
Variation in Height of a Wolf Pack
Number of individuals
Short Average height Tall
2. Mark on the graph where you would select wolves from if your goal was to breed small
wolves suitable for hunting rabbits.
3. The statements below outline the steps required to selectively breed cattle that produce
more milk. Arrange the steps in the correct order by placing the appropriate number in
each box.
Select the cows in your herd that produce the most milk.
Keep repeating the process of selection and breeding until you achieve your goal.
Only let these cows reproduce.
Select the offspring that produce the most milk.
Only let these offspring reproduce.
4. Complete the table below by stating which traits would be desirable to be selectively
bred. The first one has been done for you.
Organism Possible traits which could be selectively breed
Chickens Number of eggs produced, egg size, breast size, fast growth rate.
Sheep
Apple trees
Pine Trees
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