Chapter 20: Selective Breeding

Question 1

Selective breeding is…

and why is it beneficial?

Answer 1

…the traditional method for improving crops and livestock,

• higher yields
• disease resistant
• hardier (survive in harsher climates)
• have a better balance of nutrients in the crop (e.g. more types of amino acids needed by humans)

Question 2

Genetic engineering is…

Answer 2

…a faster way, which transplants genes for a desired characteristic into an organism.

However, genetic engineering offers many potential benefits but carries the risk of unexpected harmful effects.

Question 3

Four steps of selective breeding…

Answer 3

1. Decide which characteristics are important
2. Choose parents that show these characteristics
3. Select the best offspring from parents to breed the next generation
4. Repeat the process continuously

Question 4

Examples of selective breeding…

Answer 4

Wheat: Producing disease-resistant wheat by crossbreeding wheat plants with disease resistance and wheat plants with a high yield.

Dairy cattle: Increasing milk yield by selecting bulls from high yield herds and breeding them with cows that have the best milk production.

Cattle breeds: Selective breeding can also be used to modify other characteristics of cattle.

Question 5

Problems with selective breeding…

Answer 5

1. Future generations of selectively bred organisms will all share very similar genes. This could make some diseases more dangerous as all the organisms would be affected.
2. Some genes would be lost, making it more difficult to produce new varieties in the future: ‘inbreeding can lead to a reduction in the size of the gene pool’.

Question 6

Examples of genetic engineering…

Answer 6

Question 7

How genetic engineering is done…

Answer 7

Question 8

Can you answer these questions???

Answer 8