variation Flashcards
variation definition
the differences in characteristics between organisms
interspecific variation
variation between members of different species
intraspecific variation
differences between organisms within a species
2 main causes of variation
- genetic material
- organism’s living environment
genetic causes of variation
- alleles (genes have different alleles. A gene for a particular characterisitc has alleles producing different effects)
- mutations (changes to DNA sequence/genes leads to change of proteins which changes physical/metabolic characteristics
- meiosis (genetic material of mother and father mixes up to produce varied gametes)
- sexual reproduction (offspring inherits genes from parents so each individual differs)
- chance (when 2 gametes combine)
discontinuous variation
when there are 2 or more distinct categories
e.g. blood group, plant colour/seed shape, antibiotic resistance
continuous variation
where the individuals in a population vary within a range
e.g. height, mass, milk yield, leaves SA, width and length of microorganisms
environmental causes of variation
- climate
- food
- lifestyle
e.g. accents, piercings
both genetic and environmental causes of variation examples
e.g.
- height (diet)
- flagellum (genes determine if it grows flagellum, but some will only grow them in certain environments)
how to represent discontinuous variation
- bar chart
- pie chart
how to represent continuous variation
- frequency table
- plotted onto histogram
normal distribution
- symmetrical bell shaped curve
- same mean, mode, median
standard deviation
measure of how spread out the data is
how to calculate standard deviation
√((∑ ( X − X ¯ ) ^2)/ n − 1)
Student’s t test
used to compare the mean values of the 2 sets of data
