section 3: classification & evolution - topic 3: variation Flashcards
what is variation?
the differences that exist between individuals
what is variation within a species called?
intraspecific variation
what is variation between species called?
interspecific variation
what is continuous variation?
when the individuals in a population vary within a range (there are no distinct categories)
what is discontinuous variation?
when there are 2 or more distinct categories (each individual falls into only one of these categories and there are no intermediates)
what can variation be caused by?
genetic factors, environmental factors, or a combination of both
explain genetic factors.
- different species have different genes
- individuals of the same species have the same genes, but different versions (alleles)
- the alleles an organism has makes up its genotype
- the differences in genotype result in variation in phenotype
what are examples of variation caused by genetic factors?
- eye colour in humans
- blood type in humans
- antibiotic resistance in bacteria
explain environmental factors.
variation can be caused by differences in the environment i.e. climate, food, lifestyle
^ characteristics controlled by environmental factors can change over an organisms life
what are examples of variation caused by environmental factors?
- accents
- whether people have pierced ears
explain the combination of genetic and environmental factors.
genetic factors determine the characteristics an organism’s born with but environmental factors can influence how some characteristics develop
what are examples of variation caused by a combination of genetic and environmental factors?
- height
(genes determine how tall an organism can grow, but diet or nutrient availability affect how tall it actually grows) - flagellum
(teens determine if a microorganism can grow one, but some will only grow them in certain environments i.e. if metal ions are present)
