Investigating Variation Flashcards
What is variation?
Variation is the differences that exist between individuals.
How do genetic factors lead to variation between species?
Different species have different genes, which creates genetic variation between species.
How could you eliminate bias from a population sample?
You can eliminate bias from a population sample by ensuring that the sample is chosen at random.
Why would you take samples when investigating a population?
You would take a sample because it is usually too time-consuming (or even impossible) to investigate every individual in an entire population.
A group of marine biologists was investigating the length of tusks in two populations of walrus (Odobenus rosmarus). The biologists recorded data from five walruses from each population. Calculate the mean tusk length for each population to 2 decimal places.
The mean of population A is 0.80 (to 2 d.p.). (0.64 +0.71 + 1.01 + 0.77 +0.89) ÷ 5 = 0.804 The mean of population B is 0.89 (to 2 d.p.). (0.82 +0.86 +0.97 + 0.90+ 0.91) ÷ 5 = 0.892
The standard deviation is 0.15 for population A and 0.06 for population B (to 2 decimal places). What does this tell you about the variation in the two samples?
E.g. the standard deviation of population A is higher than that of population B, suggesting that the values for population A are more spread out from the mean. This indicates that there is greater variation in tusk length in population A compared to population B. However, the standard deviation for both populations is quite low, which indicates there’s not much variation in either population.
