Bio unit 14 Flashcards
variation
differences in the characteristics of individuals in a population
variation may be caused by
- the genes they have inherited (genetic causes)
- the conditions in which they have developed(environmental causes)
- a combination of genes and the environment
How often do mutations occur?
continuously
Can a mutation lead to a new phenotype?
rarely
What happens if the new phenotype is suited to an environmental change?
there can be a rapid change in the species
evolution
change in the inherited characteristics of a population over time through a process of natural selection which may result in the formation of a new species.
what does the theory of evolution by natural selection state?
all species of living things have evolved from simple life forms that first developed more than 3 billion years ago.
what happens if two populations of one species become so different in phenotype that they can no longer breed to produce fertile offsrpring?
they have formed two new species
selective breeding
process by which humans breed plants and animals for particular genetic characteristics.
how long have humans been doing selective breeding?
thousands of years since hey first bred food crops from wild plants and domesticated animals.
Process of selective breeding
- choosing parents with desired characteristic from a mixed population.
- they are bred together
- the offsrping that have the desired gene are bred together.
- This continues over many generations until the offspring show the desired characteristic.
examples of useful characteritsics
- disease resistance in food crops
- Animals which produce more meat or milk
- domestic dogs with a gentle nature
- large or usual flowers.
disadvantage of selective breeding
can lead to ‘inbreeding’ where some breeds are particularly prone to disease or inherited defects
genetic engineering
a process which involves modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic.
how have plant crops been geneticly engineered?
to be resistant to diseases or to produce bigger, better fruits.