Simulic
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Variation lab – continuous vs discontinuous, genes vs environment

BiologyGeneticsAges 17–18

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A virtual practical on variation: measure height and hand span in a simulated year group (continuous variation: histogram with mean, sample standard deviation s using n − 1 and a normal curve) and record blood group and tongue rolling (discontinuous variation: bar chart). A twin study and four environment experiments (plant clones, hydrangea flowers, Himalayan rabbits, sea turtles) separate the effects of genes and environment.

Lesson: Variation: genetic and environmental causes

What it shows

This virtual practical lets students aged 11–16 investigate variation. In a simulated year group of 500 students they measure height and hand span, plot histograms, and calculate the mean and the sample standard deviation (n − 1), then compare them with blood groups and tongue rolling drawn as bar charts. A twin study compares identical twins, non-identical twins and unrelated people, and four experiments show the environment changing the phenotype. Data are simulated from realistic distributions; the heritability of height (about 80%), skin temperatures and the turtle sex curve are simplified models.

How to use

In Class survey, choose a Characteristic, set the Sample size, then press Measure 1, Measure 10 or Fill sample; change the Class width and compare the results table. In Twins, choose a Pair type and press +10 pairs. In Environment, choose an Experiment, change the light, soil pH or temperature, then press Grow 6 weeks, Record or Incubate 100 eggs.

Parameters you can change

  • Starting screen Class survey, Twin study, Environment
  • Characteristic Height, Hand span, ABO blood group, Tongue rolling
  • Sample size n 5–200 students
  • Draw a normal curve on the histogram
  • Pair type (Twins screen) Identical twins, raised together, Identical twins, raised apart, Non-identical twins, raised together, Unrelated people
  • Experiment (Environment screen) Plant clones: light and mineral ions, Hydrangea: soil pH, Himalayan rabbit: temperature, Sea turtle: incubation temperature

Questions to explore

  1. Why is height plotted as a histogram while ABO blood group is plotted as a bar chart?
  2. How do the sample mean and standard deviation change as the sample grows from 10 to 100 students?
  3. Identical twins raised apart still differ in height by a few centimetres. What causes this difference?

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