B14:VariationAndEvolution Flashcards
what is variation
the differences in characteristics of an individual in a population
genetic cause
differences in genes inherited
environmental cause
conditions in which individuals develop
what does the theory of evolution by natural selection state
that all species of living things have evolved from simple life forms that first developed over 3 billion years ago
what very rarely happens in mutation
a new phenotype
if a new phenotype is suited to an environmental change what can happen
a relatively rapid change in the species
what happens if two populations of the same species become so different
they can no longer interbreed to form fertile offspring, they have formed two new species
what is selective breeding
where humans breed plants and animals for the desired characteristics
what are some examples of desired characteristics
disease resistance, increased food production, domestic dogs with a gentle nature and heavily scented flowers
what can problems in selective breeding lead to
a lack of variation
what is genetic engineering
genes transferred to the cells of animals and plants at an early stage of their development so they develop the desired characteristics
how does genetic engineering work
genes can be “cut out “ using enzymes and transferred to the cells of bacteria and other organisms using a vector
what is a vector
usually a bacterial plasmid or a virus
what are crops that have had their genes modified called
GM (genetically modified) crops
what do GM crops usually have
improved resistance to insect attack or herbicides and generally produce a higher yield
