Variation Flashcards
Define variation:
Differences in characteristics between organisms.
Define interspecific variation:
Between members of different species.
Define intraspecific variation:
Differences between organisms within a species
What 2 factors causes variation?
Organisms genetic material –> differences in genetic material inherited from parents = variation
Environment where organism lives
List all possible genetic variations present within a population:
- Alleles –> different alleles = different outcomes
- Mutations –> changes in DNA sequence = change in protein -= change in physical/metabolic characteristics.
- Meiosis –> gametes receive half genetic material of parent cell. Independent assortment + crossing over occurs
–> Leads to variation - Sexual reproduction
- Chance –> many diff gametes produced from parental genome. Random fertilisation –> unique combo of genetic material
How can genetic variation be increased in asexual reproduction?
Mutation
Describe environmental causes of variation:
Plants =immobile = more affected by environment
Presence/absence of scars on body = purely environmental.
Is variation purely genetic/environmental?
Combination of both
Difficult to draw conclusions of causes of variation ‘nature vs nurture’
Define discontinuous variation:
Characteristic only results in certain values = discontinuous/discrete.
No in-between values
Purely genetic factors
Normally represented in bar chart (Can be pie chart)
Define continuous variation:
Characteristic that can take any value within a range
Graduation in values from 1 extreme to other = Continuum
Controlled by number of genes = polygenic
Represented in histogram
What are normal distribution curves?
continuous data plotted on graph = result in bell shaped curve
State characteristics of a normal distribution:
Mean, mode, median = same
bell shape symmetrical around the mean
most values lie close to mean –> number of individuals on extremes = low
What is standard deviation?
Measure of how spread out data is around the mean.
^ standard deviation = ^ spread of data = ^ variation
68% of values = 1 SD from mean
95% of values = 2 SD from mean
Formula for standard deviation:
√∑(x - x-)2/n-1
∑= the sum (total) of
x = value measured
x = mean value
n = total number of values in the sample
Formula for standard deviation:
√∑(x - x-)2/n-1
∑= the sum (total) of
x = value measured
x = mean value
n = total number of values in the sample
