10.5 - Quantitative Investigations of Variation

Created by

Pietra Magagnin

Cards (16)

variation
differences between individuals
interspecific variation
variation from one species to another
intraspecific variation
variation between members of the same species
what causes variation?
genetic factors: mutations, meiosis, fertilisation
environmental factors: light, soil acidity, temperature, food availability
discontinuous variation
distinct categories
tends to be qualitative
controlled by a few genes
unaffected by the environment
continuous variation
no distinct categories
tends to be quantitative
controlled by a few genes
influenced by the environment
random sampling - method
divide study area into a grid with coordinates
use a random number generator to select coordinates at random
use a quadrat on selected grid to collect data
why might a sample not be representative?
sampling bias: selection process may be biased
chance
how can chance be removed from sampling?
use a larger sample size: smaller probability results are due to chance and less affected by anomalies
analyse data using statistical tests to see if variation is due to chance
mean
in normal distribution curve: maximum height of the curve
provides an average that can be used to compare samples
standard deviation
measure of spread of data around the mean
greater standard deviation = data is more spread out/varied
in normal distribution curve: width of the curve
68-95-99.7 rule
68% of data lies within 1 standard deviation of the mean
95% of data lies within 2 standard deviations of the mean
99.7% of data lies within 3 standard deviations of the mean
point of inflection on normal distribution curves
when curve changes concavity
what's used to plot error bars?
standard deviation
what does it mean when error bars overlap?
results are due to chance
changing the variable most likely doesn't affect the population
what does it mean when error bars don't overlap?
results aren't due to chance
changing the variable most likely affects the population