Updated on 9 Feb 2022 by BSJ @behlogy
Paper 5 Essentials
Time: 1 h 15m
Total: 30 marks
Always read and understand the questions first! In the question, find:
a. Aim or hypothesis
b. Independent variable
c. Dependent variable
d. Controlled variable
Defining the problem (~5m)
• Very basic questions like
hypothesis, variables etc.
Planning an Experiment (~10m)
• Write in full sentences in pen
• Be as specific as possible
• You can number your steps, but you CANNOT write in point form
• Your methods need not be described in chronological order – as long as all points are there
• If involves drawing, then drawing must be done in pencil (rules for drawing applies)
• You can use empty spaces for drafting in pencil (but please remember to erase it before handing it in)
6 points you must include:
1. Independent variable
a. List min 5 different values of the independent variable
E.g. 5 different concentrations with regular intervals apart/ 5 different temperatures
b. State how you are going to set up these independent variables
c. Remember to include the apparatus used
E.g. simple or serial dilution / use a thermostatically-controlled water bath
d. State how you make sure the experiment is well-controlled / less error-prone
E.g. randomise sampling to avoid bias / make sure participants do not know which drug they are
getting as results can be affected by subject expectation
2. Dependent variable
a. This must be something that’s measurable!
E.g. rate is not measurable, rate is ________ over time
You must state the variable that’s measured to calculate the rate
b. State how you are going to measure the dependent variables
E.g. take a reading every 10 minutes
c. Remember to include the apparatus used
E.g. length is measured using a ruler / dry the plant in an oven until the mass becomes constant.
measure dry mass using a weighing scale
d. State how you make sure the experiment is well-controlled / less error-prone
E.g. incubate enzyme and substrate separately, then start timer immediately after enzyme is added
to substrate / use yeast without methylene blue as a colour standard
e. State how you are going to analyse the results
E.g. compare between group A and B / plot a graph / calculate using this formula
1
, Updated on 9 Feb 2022 by BSJ @behlogy
3. Controlled variables
a. Min 3 constant variables
E.g. Temperature / pH / volume of solution
b. State how you are going to keep these variables constant
c. Remember to include the apparatus used
E.g. use pH buffer/ use a thermostatically-controlled water bath
4. Control
a. Control experiment ≠ controlled variable
b. Control experiment is important to ensure validity of the experiment. To make sure that the
independent variables are the ones causing the change in the dependent variable.
c. Two types:
Negative control = results should be always negative
E.g. use boiled enzyme, so no rate of reaction
Positive control = results should be always positive
E.g. have petri dish without antibiotics for bacteria, bacteria will definitely grow
5. Safety
a. State the hazard + why it is dangerous + precaution
E.g. Strong acid – corrosive – wear gloves and goggles
Enzymes / reagents – harmful– wear gloves and goggles
UV light – mutagen – wear goggles
Electrical appliances – danger of electrocution – wear rubber gloves / do not touch with wet hands
(In field experiments) Pollen / insect bites – allergies – wear mask / protective clothing
b. For human experiments, make sure they are aware of health risk, get consent before testing and
allow test subjects to stop if they fell unwell.
6. Repeat
a. Repeat experiment at least 3 times and obtain a mean to remove anomalies [R average]
List of common experiments:
• Simple and serial dilution
• Biological tests
• Enzyme experiments
• Potometer
• Respirometer
• Using redox indicators (DCPIP / methylene blue) to investigate the rate of respiration of yeast
• Using a gas syringe / photosynthometer to measure rate of photosynthesis in aquatic plants such as Elodea
• Chromatography to separate and identify chloroplast pigments
• Random sampling using frame quadrats
• Line or belt transects
• Mark-release-recapture technique
• Gel electrophoresis
Note: Some of these experiments have special procedures you have to remember!
The question can also describe to you an experiment you have never seen before and ask you to plan the
experiment accordingly.
2
Paper 5 Essentials
Time: 1 h 15m
Total: 30 marks
Always read and understand the questions first! In the question, find:
a. Aim or hypothesis
b. Independent variable
c. Dependent variable
d. Controlled variable
Defining the problem (~5m)
• Very basic questions like
hypothesis, variables etc.
Planning an Experiment (~10m)
• Write in full sentences in pen
• Be as specific as possible
• You can number your steps, but you CANNOT write in point form
• Your methods need not be described in chronological order – as long as all points are there
• If involves drawing, then drawing must be done in pencil (rules for drawing applies)
• You can use empty spaces for drafting in pencil (but please remember to erase it before handing it in)
6 points you must include:
1. Independent variable
a. List min 5 different values of the independent variable
E.g. 5 different concentrations with regular intervals apart/ 5 different temperatures
b. State how you are going to set up these independent variables
c. Remember to include the apparatus used
E.g. simple or serial dilution / use a thermostatically-controlled water bath
d. State how you make sure the experiment is well-controlled / less error-prone
E.g. randomise sampling to avoid bias / make sure participants do not know which drug they are
getting as results can be affected by subject expectation
2. Dependent variable
a. This must be something that’s measurable!
E.g. rate is not measurable, rate is ________ over time
You must state the variable that’s measured to calculate the rate
b. State how you are going to measure the dependent variables
E.g. take a reading every 10 minutes
c. Remember to include the apparatus used
E.g. length is measured using a ruler / dry the plant in an oven until the mass becomes constant.
measure dry mass using a weighing scale
d. State how you make sure the experiment is well-controlled / less error-prone
E.g. incubate enzyme and substrate separately, then start timer immediately after enzyme is added
to substrate / use yeast without methylene blue as a colour standard
e. State how you are going to analyse the results
E.g. compare between group A and B / plot a graph / calculate using this formula
1
, Updated on 9 Feb 2022 by BSJ @behlogy
3. Controlled variables
a. Min 3 constant variables
E.g. Temperature / pH / volume of solution
b. State how you are going to keep these variables constant
c. Remember to include the apparatus used
E.g. use pH buffer/ use a thermostatically-controlled water bath
4. Control
a. Control experiment ≠ controlled variable
b. Control experiment is important to ensure validity of the experiment. To make sure that the
independent variables are the ones causing the change in the dependent variable.
c. Two types:
Negative control = results should be always negative
E.g. use boiled enzyme, so no rate of reaction
Positive control = results should be always positive
E.g. have petri dish without antibiotics for bacteria, bacteria will definitely grow
5. Safety
a. State the hazard + why it is dangerous + precaution
E.g. Strong acid – corrosive – wear gloves and goggles
Enzymes / reagents – harmful– wear gloves and goggles
UV light – mutagen – wear goggles
Electrical appliances – danger of electrocution – wear rubber gloves / do not touch with wet hands
(In field experiments) Pollen / insect bites – allergies – wear mask / protective clothing
b. For human experiments, make sure they are aware of health risk, get consent before testing and
allow test subjects to stop if they fell unwell.
6. Repeat
a. Repeat experiment at least 3 times and obtain a mean to remove anomalies [R average]
List of common experiments:
• Simple and serial dilution
• Biological tests
• Enzyme experiments
• Potometer
• Respirometer
• Using redox indicators (DCPIP / methylene blue) to investigate the rate of respiration of yeast
• Using a gas syringe / photosynthometer to measure rate of photosynthesis in aquatic plants such as Elodea
• Chromatography to separate and identify chloroplast pigments
• Random sampling using frame quadrats
• Line or belt transects
• Mark-release-recapture technique
• Gel electrophoresis
Note: Some of these experiments have special procedures you have to remember!
The question can also describe to you an experiment you have never seen before and ask you to plan the
experiment accordingly.
2
