B14 - Variation and Evolution Flashcards
Variation?
the differences in the characteristics of individuals in a population
Phenotype?
physical characteristics
What is variation caused by? (3)
- differences in genes inherited (genetic causes)
- the conditions in which the organisms develop (environmental causes)
- or a combination of both
Theory of evolution by natural selection?
all species of living things have evolved from simple life forms that first developed over 3 billion years ago
Key steps in natural selection?
mutation of gene –> advantage to survival –> breed –> pass on genes
Very rarely do mutations lead to a new…
phenotype
D. Selective breeding?
speeds up natural selection by selecting animals or plants for breeding that have a required characteristic
Desired characteristics for selective breeding?
disease resistance
increased food production
domestic dogs with a gentle nature
heavily scented flowers
Problems with selective breeding?
- reduces number of alleles in population
- lack of variation could lead to whole population being wiped out if conditions change
- inbreeding - some breeds are prone to inherited defects or certain diseases or
Genetic engineering?
genes transferred to the cells of animals and plants at an early stage of development so they develop desired characteristics
Process of genetic engineering?
- genes from chromosomes of organisms ‘cut out’ by enzymes
- transferred o the cells of bacteria and other organisms using a vector ( usually bacteria plasmid or virus)
Genetically modified crops also known as…
GM crops
GM crops usually have…
improved resistance to insect attacks or herbicides and have a higher yield
Examples of GM crops? (3)
- potatoes modified to have more starch
- soybeans modified to produce healthier balance of fatty acids
- some GM grasses absorb and break down explosive residue in soil
Benefits of genetic engineering in agriculture? (3)
- improved growth rate in plants and animals
- crops can be designed to grow well in hot/cold/dry parts of the world
- increased food value of crops as GM crops usually have much bigger yields