B7 Flashcards
Variation?
Differences in the characteristics of individuals in a population
3 causes of variation?
alleles - genetic e.g. hair and eye colour
Environment - language
a mix of both - height
Mutation?
random changes in dna
What can very rarely happen due to mutation?
a new phenotype leading to a change in species
what have all species of living things evolved from?
Simple life forms e.g. single cells
Called natural selection
what is the process of natural selection?
for example, rabbits that have inherited the allure for thicker and more light to survive in the cold temperature then rabbits with thinner fur which means they are more likely to go on to reproduce and they’re offspring could inherit the alleles for thicker fur and they are more likely to survive and reproduce
How do two separate species occur?
Sometimes two populations of one species can become so different in a phenotype that they can no longer into breed to produce fertile offspring
How did dogs occur and why?
thousands of years ago humans realise that wolves actually very useful animals as they provide protection, warmth and company. so humans took wolves and using the process of selective breeding over thousands of years created dogs. 
why have certain plants been selectively bred?
To produce large and unusual flowers
Why have domestic dogs been selectively bred?
To have a gentle nature
Why have food crops such as wheat been selectively bred?
To be resistant to disease
why have animals such as cows been selectively bred?
To produce more meat or milk
how is selective breeding carried out?
For example, if scientist wanted to breed large cows for meat, first we select the largest male and female, we then breed these together to produce offspring. We continue doing this over many generations until all the offspring are large.
what is a problem with selective breeding?
If we breed together closely related animals or plants, then we can get inbreeding
What could inbreeding lead to?
Disease or inherited defects
