5.2 - Selective Breeding

Question 1

What characteristics are plants selectively bred for?

Answer 1

Disease resistance in food crops
Increased crop yield
Hardiness to weather conditions (eg. drought tolerance)
Better tasting fruits
Large or unusual flowers

Question 2

What are the problems with selective breeding?

Answer 2

Selective breeding can lead to ‘inbreeding’
This occurs when only the ‘best’ animals or plants (which are closely related to each other) are bred together
This results in a reduction in the gene pool – this is a reduction in the number of alleles (different versions of genes) in a population
As inbreeding limits the size of the gene pool, there is an increased chance of:
Organisms inheriting harmful genetic defects
Organisms being vulnerable to new diseases (there is less chance of resistant alleles being present in the reduced gene pool)

Question 3

What does selective breeding mean?

Answer 3

Selective breeding or artificial selection means to select individuals with desirable characteristics and breed them together
The process doesn’t stop there though because it’s likely that not all of the offspring will show the characteristics you want so offspring that do show the desired characteristics are selected and bred together
This process has to be repeated for many successive generations before you can definitely say you have a ‘new breed’ that will reliably show those selected characteristics in all offspring

Question 4

What are the differences between natural and artifical selection?

Answer 4

Question 5

How does selective breeding occour in animals?

Answer 5

Individuals with the characteristics you want are bred together (often several different parents all with the desired characteristics are chosen so siblings do not have to be bred together in the next generation)
Offspring that show the desired characteristics are selected and bred together
This process is repeated for many successive generations
Animals are commonly selectively bred for various characteristics, including:
Cows, goats and sheep that produce lots of milk or meat
Chickens that lay large eggs
Domestic dogs that have a gentle nature
Sheep with good quality wool
Horses with fine features and a very fast pace