1. To Start - List the features which differ within these dog breeds

2. Types of Variation
Some variation is CONTINUOUS. This means that it may have any one of a large range of values. E.g. height. Some variation is DISCONTINUOUS. This means that it can only have one of a fixed number of options. E.g. eye colour

3. Continuous and Discontinuous Variation
Feature
Variation
Eye colour
Weight
Shoe size
Height
Skin colour
Tongue rolling
Fill in the table to indicate whether the variation is continuous or discontinuous

6. Selective Breeding
If an animal has a feature which is particularly useful, then farmers or breeders may allow that animal to breed in order to pass the useful feature onto the next generation.

7. Selective Breeding In Sheep
On your own List 5 features that might be important to breed into sheep. With your partner Compare your lists. Can you prioritise these features? As a class Can we agree on the important features?

8. Selecting Characteristics
On your own
Look at the table of
Information.
Which pairs of sheep
would you use to:
Breed sheep with good wool and good meat?
Breed sheep with good wool that can survive harsh winters?
Breed
Features
Balwen
Lives in cold, harsh conditions
Blue-faced Leicester
Good quality wool
Polled Dorset
Good quality meat
Fresian
Makes a lot of milk

9. Identical pollen different ovule
What About Plants?
Complete the following passage:
In plants two types of reproduction can take place.
Sexual – where the male ______ has to fertilise the female ______ to make a seed. This makes plants that have ________features to the parents
Asexual - where a new plant is grown from a root or stem cutting of one parent. This produces _________offspring to the parent
Identical pollen different ovule

10. Commercial Plant Growers
In large garden centres in the summer there are large numbers of identical plants
How have these plants been produced?
What advantages are there to the grower in doing this?
What disadvantages are there to doing this?

11. Is it all good news?
Sometimes breeding between close relatives makes genetic deformities more frequent.
British Bulldogs for example have such large heads that they are unable to be born without Caesarean Section. They are prone to breathing difficulties and heart problems.

12. The Future?
Cat breeders in Texas have deliberately crossed two cats with front paw deformities to produce a breed with tiny front paws.
They have called this the Twisty Cat or Kangaroo cat.
What do you think?

13. Questions to Finish What are your views on ;
Farmers using selective breeding to produce more valuable livestock more suited to today’s food market.
Breeders mating closely related pedigree animals despite the risks of deformities
Breeders producing new strains of animal which differ greatly from the natural variant.