practical skills

Question 1

when should a student’s T test be used?

Answer 1

when you want to see if there is a significant difference between the means of two sets (categorical) data

Question 2

when should the Chi-Squared test be used?

Answer 2

when you want to compare your observed result with your expected result, between categorical sets of data

Question 3

when should a correlation coefficient be used?

Answer 3

when you want to determine to what degree two sets of continuous data are correlated

Question 4

which axis does the independent variable go on?

Answer 4

the x-axis (horizontal)

Question 5

describe a reaction which can be followed to investigate the rate of enzyme catalysed reactions, and suggest how the progress can be followed

Answer 5

hydrogen peroxide (substrate) + catalase (enzyme) 
measure the volume of Oxygen produced each 10s using a gas syringe

Question 6

describe how to stain and view a plant tissue under a microscope

Answer 6

1) place on microscope slide and use a mounted needle to spread cells
2) add a few drops of toluidine blue stain and leave for a few mins, rinse
3) place a cover slip on top and squash

Question 7

name some ethical issues that arise from the use of invertebrates in experiments

Answer 7

• less developed nervous system
• utilitarianism
• lack of ability to give consent

Question 8

what can be used to determine rate of respiration?

Answer 8

a respirometer

Question 9

why does the ‘red fluid’ in the respirometer move as respiration occurs?

Answer 9

there is a decrease in volume within the tube due to usage of oxygen in respiration, and CO2 being removed by the soda lime. this means that pressure decreases