Cambridge International A Level Biology Revision Guide

Chapter P2: Planning, analysis and evaluation
End-of-chapter questions
1 a Calculate the standard deviation, s, for the fruit mass data on page 495. Use the formula:
∑(x −
s − x) =
2
n − 1
Show each step in your working. [4]
b Calculate the standard error, S M
, for this set of data. Use the formula:
S
s
M
= n
Show each step in your working. [2]
c A sample of lemon fruits was taken from a different population of lemon trees. The mean mass of this
sample of fruits was 84 g. The standard error was 0.52.
Draw a bar chart to show the means of the fruit masses for these two populations.
Draw error bars on your bar chart, and add a key to explain what the error bars represent. [5]
d Are the differences between the masses of the fruits in the two different populations significant?
Explain your answer. [3]
[Total: 14]
2 Using the data on page 497, carry out a t-test to determine whether the difference between petal lengths in
woodland and in a garden is significant. (The standard errors for these two data sets have already been calculated,
and are given on page 499.)
Show all of your working, and explain your conclusions fully. [10]
3 The standard deviations for the data in Table P2.4 have been calculated for you. Do these calculations for
yourself, showing your working fully. [5]
4 The scatter graphs show values for x plotted against values for y.
507
A
B
C
y
y
y
D
x
E
x
x
y
y
x
x
State the letter of any graph or graphs that:
a indicate there could be a positive correlation [1]
b indicate that there is probably no correlation [1]
c indicate that there is a linear correlation [1]
d indicate that Spearman’s rank correlation could be used [1]
e indicate that Pearson’s linear correlation test could be used [1]
[Total: 5]