1/10
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
what is selective breeding?
when humans artificially select the plants or animals that are going to breed → so that the genes for particular characteristics remain in the population
what are examples of selective breeding?
animals that produce more meat or milk
crops with disease resistance
dogs with a good, gentle temperament
decorative plants with big or unusual flowers
describe/explain the process of selective breeding
1) from your existing stock → the ones that have the characteristics that are wanted, are selected
2) breed them together
3) select the best offspring and breed them together
4) continue this process over several generations → the desirable trait gets stronger and stronger → eventually all of the offspring will have the characteristic
what else has selective breeding been used for?
in agriculture, selective breeding has been also used to improve yields
e.g. to improve meat yields → a farmer could breed together the cows and bulls with the best characteristics for producing meat → doing this for several generations then means the farmer would get a high meat yield
how long as selective breeding been going on for? And what has it led to?
it has been used for thousands of years
it’s how we’ve ended up with edible crops from wild plants and how we got domesticated animals like cows and dogs
what is the main problem with selective breeding?
it reduces the gene pool
what is the gene pool?
it is the number of different alleles in a population
why does the gene pool become reduced as a result of selective breeding?
this is because the farmer keeps on breeding the ‘best’ animals or plants → which are all closely related → this is known as inbreeding
what is inbreeding?
when closely related animals or plants are bred together
what can inbreeding lead to? And why?
inbreeding can cause health problems
as there is a higher chance of the organisms inheriting harmful genetic defects when the genes pool is limited
e.g. some dog breeds are more susceptible to certain defects, for instance pugs often have breathing problems
what is another problem as a result of inbreeding?
if a new disease appears, this can cause serious problems
as there is not a lot of variation in the population
all the the stock are closely related → and so if one of them is going to be killed by a disease → the others are likely to succumb to it too