variation and evolution - selective breeding

Question 1

wolves

Answer 1

• walk around in packs
• can alert you if a threat is approaching or protect you against attack
• keep you warm/company
• so humans took wolves and through the process of selective breeding over thousands of years produced dogs we see today

Question 2

how have domestic dogs been selectively bred?

Answer 2

to have a gentle nature

Question 3

how have food crops been selectively bred?

Answer 3

to be resistant to disease

Question 4

how have animals such as cows been selectively bred?

Answer 4

to produce more meat or milk

Question 5

how have certain plants been selectively bred?

Answer 5

to produce large or unusual flowers

Question 6

how is selective breeding carried out? example breed large cows for meat

Answer 6

• take a mixed population of cows and select the largest male and female
• breed these together. sexual reproduction produces variation so offspring will be a mixture of larger animals and smaller animals
• we then select the largest male and female offspring + breed these together
• continue doing this over many generations until all the offspring are large

Question 7

problem with selective breeding?

Answer 7

if we breed together closely related animals or plants then we can get inbreeding which can cause some breeds to be prone to disease or inherited defects
example: dog breeds have been selectively bred for hundreds of generations. many dog breeds develop inherited disorders such as join problems, heart disease or epilepsy