Variation

• define variation?

  the differences between individuals
• intraspecific variation?

  Variation within a species.
• define interspecific variation?

  variation between different species
• define continuous variation + type of graph + cause?

  the data can take any value within a range - there are no distinct categories

  displayed in a histogram which forms a normal distribution (bell curve)

  characteristics are most likely controlled by multiple genes and influenced by environmental factors
• define discontinuous variation + type of graph + cause?

  values are in discrete categories, there are no intermediates

  displayed in a bar chart

  characteristics are most likely controlled by a single gene
• examples of continuous variation for plants, animals and microorganisms?

  Plants: number of leaves Animals: mass Microorganisms: length of flagellum
• what are the causes of variation?

  Genetic and environmental factors.
• describe variation caused by genetics?

  inheritance of specific combination of alleles

  meiosis

  random fusion of gametes at fertilisation

  mutations forming new alleles
• examples of environmental factors?

  climate, food
• define polygenic inheritance?

  one characteristic is caused by two or more genes e.g. height --> leads to continuous variation
• what is standard deviation?

  a measure of the spread of data around the mean

  it takes into account and reduces the effect of outliers

  shows where most of the data lies
• what can standard deviation be used for and how is this shown on a graph?

  how significantly different two sets of data are: on a bar chart with the bar as the mean, add and minus the standard deviation --> if they overlap, there's no significant difference