4.3.6 variation Flashcards
continuous variation
variation where there’s 2 extremes & full range of values in between eg. line graph
discontinuous variation
where there are distinct categories & nothing in between eg. bar chart
environmental variation
variation caused by response to environmental factors eg. light intensity
genetic variation
variation caused by possessing different combination of alleles
interspecific variation
differences between species
intraspecific variation
variation between members of the same species
variation
presence of variety - differences between individuals
the greater the…. the greater the intraspecific variation
genetic diversity of a population
where are most values in continuous variation
close to mean value
what is continuous variation often regulated by
more than 1 gene & can be influenced by environment in which organism lives
examples of continuous variation
- height in humans
- length of leaves on an oak tree
- length of stalk (reproductive hypha) of a toadstool
- number of flagella on bacterium
which variation is usually quantifiable
continuous
what’s the best type of graph to use for continuous variation
histogram
what is discontinuous variation often regulated by
single gene & not influenced by environment in which organism lives
examples of discontinuous variation
- gender –> mammals either female or male, plants either female/male/hermaphrodite
- some bacteria have flagella, others don’t
- human blood groups (either A, B, AB, O)
what’s the best type of graph to use for discontinuous variation
bar chart
2 general causes of variation
- genetic
- environmental
describe inherited/genetic variation
- inherit genes from parents which provide info to define our characteristics
- combination of alleles inherited aren’t the same as any other living thing (except if have identical twin)
- we may share alleles with other members of species/other species but never complete match
describe environmental variation
- characteristics impacted by environment
eg. skin will tan/get darker with exposure to sunlight
examples of characteristics affected by both environmental & genetic variation
- humans have become taller due to better diet however, you’re unlikely to grow very tall if the rest of your family are short as height is limited by genes
- not all genes active at any one time eg. when you reach puberty, changes occur as diff. genes are becoming active
- changes in environment can also directly affect which genes are active
