B14 - Variation and Evolution Flashcards
What is variation?
Variation is the difference in characteristics between individuals.
What is variation caused by?
- genes they have inherited
- conditions they have developed under
- combination of genes and the environment
Do new genetics make much difference?
Largely no, however a new phenotype sometimes can make an organism better suited to the environment so may become more common in the population.
How does evolution happen?
- variation between organisms
- best adapted have advantage
- organisms more likely to survive and reproduce
- pass on useful alleles to offspring
- useful characteristics become more common in population
What is selective breeding?
It is the process by which humans
breed plants and animals for particular genetic characteristics.
What are the steps of selective breeding?
- parents with desired characteristics are chosen
- they are bred together
- from the offspring, the ones with desired characteristics are chosen
- continues over generations until all offspring show desired characters
Why are characteristics chosen?
- disease resistant in food crops
- animals produce more meat or milk
- domestic dogs with gentle nature
- large or unusual flowers
What is ‘inbreeding’?
Some breeds are particularly prone to disease or inherited defects.
What is genetic engineering?
Involves modify the genome of an organism by introducing a gene from another organism to give a desired characteristic.
why do plant crops get genetically engineered
to be resistant to disease/herbicides/pesticides, to produce bigger fruits, to give higher yields
why has and are bacteria getting genetically engineered
to produce useful substances, such as human insulin to treat diabetes
why are enzymes used in genetic engineering
to cut out the required gene
what is used to transfer the required gene into the new cell in genetic engineering
vector (e.g., bacterial plasmid or virus)
Describe the steps involved in adult cell cloning
- nucleus removed from unfertilised egg cell
- nucleus from adult body cell inserted into egg cell
- electric shock stimulates egg cell to divide to form an embryo
- embryo develops and is inserted into the womb of an adult female
what is tissue culture cloning
using small groups of cells from plants to grow identical new plants
