REMEMBER IT!

• Random sampling eliminates systematic bias in a sample.
• The average of the data can be calculated by finding the mean.
• Variation within a sample can be calculated by finding the normal distribution of the mean and the standard deviation.
• Causes of variation can be genetic, environmental or both.
• Genetic variation is usually a product of sexual reproduction.
• Environmental factors include diet, lifestyle, access to energy sources, and accidents.

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TEST IT!

1.

Variation can be due to genetic factors.

a) What is variation?

b) Name another reason for variation in a species and provide two examples.

i. _______________________________________________
ii. ______________________________________________

2.

A class carries out an experiment using frogs in a pond. They take a random sample of the frogs.
a) What’s important about taking a random sample?
b) Name two ways in which they could analyse the data they collect.
i. ___________________________________________________
ii. ___________________________________________________

ANSWERS

1.

a) Differences between organisms
b) Environmental factors.
Examples include:

i. diet
ii. lifestyle
iii. accidents
iv. access to energy sources

2.

a) It prevents systematic bias

b) Answers include:

i. mean
ii. normal distribution of the mean
iii. standard deviation