Selective Breeding (T5) Flashcards
Other than food, what three things are animals bred for?
- to produce a range of medicines
- research into spare parts of surgery
- to research the action of drugs
Define selective breeding..
The breeding of only those individuals with desirable characteristics.
What else can selective breeding be known as?
Artificial selection.
Give an example of a plant that has been selectively bred for specific characteristics..
‘Brassica’ is a genus of cabbage-like plants
Crop plants are bred to produce strains that…
- give higher yields
- are resistant to certain diseases
- are resistant to certain insect / pest damage
- are better survivors
- have a better balance of nutrients in the crop
Farmers have selectively bred animals so that…
- produce more meat, milk or eggs
- produce more fur or better quality fur
- produce more offspring
- show increased resistance to diseases and parasites
Since the 1950’s the techniques of artificial insemination (AI) have become more available. How has this worked with bulls?
Bull’s with desirable features are kept and semen is obtained from them.
The semen
Since the 1950’s the techniques of artificial insemination (AI) have become more available. How has this worked with bulls?
Bull’s with desirable features are kept and semen is obtained from them.
The semen is diluted, frozen and stored.
Farmers can buy quantities for their cows.
The semen from one bull can inseminate 1000’s of cows.
Modern sheep are domesticated ……
Wild sheep
Farmed pigs come from ……
Wild boars
Describe the origins of the modern ‘dog’
All varieties of dog come from a single ancestor.
The original dog was a wolf, then it was domesticated and an animal capable of herding stock was created.
A sheep dog has all the wolf instincts except that of killing - this has been ‘selectively bred out’
What are the four steps of selective breeding?
1) decide which characteristics you want to keep
2) choose breeding pairs that show these characteristics
3) select the most suitable offspring from parents
4) repeat the process over generations
What are some problems with selective breeding?
- All future generations of selectively bred organisms will share very similar genes which could make some diseases more dangerous as all the animals would be affected.
- There is an increased risk of genetic diseases caused by recessive genes.
- Some genes would be lost in the crosses which could make it more difficult to produce new varieties in the future. In scientific language this is ‘inbreeding’ which can lead to a reduction in the size of the gene pool.
