Page 16 - CB1.3 Genetic Varation sciPAD

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16 CB 1.3 GENETIC VARIATION
PRINCIPLES OF GENETIC VARIATION
Variation and Normal Distribution
The study of a measurable trait (such as height) in a large population usually reveals that very few
individuals possess extreme characteristics (e.g. very tall or very short), and that more individuals
are found nearer the average value for that population. This type of distribution is called a ‘normal
distribution’ and is characterised by a bell-shaped graph as shown below.
Number of boys
Height (cm)
Height of 15-Year-Old Boys in New Zealand
Short
(low frequency) Average
(high frequency)
Tall
(low frequency)
Measuring Height
Method: 1. Your teacher will set up a measuring station for you to measure your height.
Results: My height: cm.
Share the class’s results on the board to get data for the entire class. Record results in
the table below and draw a line graph of your data.
Height
(cm) < 140 140
-145
146
-150
151
-155
156
-160
161
-165
166
-170
171
-175
176
-180 > 180
Tally
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