General practical method questions (paper 3)

Question 1

Explain why student plotted standard deviation bars on the graph?

Answer 1

shows variation from the mean
therefore gives an indication of significant difference /
overlap gives indication of significant difference

Question 2

List possible improvements for a practical (general)

Answer 2

• use substrate with same SA:V ratio
• use same volume of solvent each time
• control temperature
• control time
• control speed at which lid/bung/solid is added

Question 3

Why do we do repeats

Answer 3

to identify anomalies (and to calculate a mean)

Question 4

What are some variables that may affect an experiment using humans?
(That should be controlled when the type of person is not the independant variable)

Answer 4

• age
• level of fitness
• diet
• sex
• health
• lifestyle
• mass