1. Controlled Assessment BU2.4 – Diffusion

2. Dissolved substances
Oxygen required for respiration passes through cell membranes by diffusion.
Dissolved substances can move into and out of cells by diffusion
Diffusion is the spreading of the particles of a liquid or a gas. The particles move from an area of higher concentration to an area of lower concentration.
3 ways to speed up diffusion
1 BIG difference in concentration
2 LARGE surface area
3 SHORT distance (ie THIN membrane)
High concentration outside
Low concentration inside
Same concentration inside and outside

3. Controlled Assessment BU2.4 – Diffusion
Diffusion is the spreading of the particles of a gas, or of any substance in solution, resulting in a net movement from a region where they are of a higher concentration to a region with a lower concentration.
The greater the difference in concentration, the faster the rate of diffusion

4. Controlled Assessment BU2.4 – Diffusion
Topic of investigation: the effect of a factor that may affect the rate of diffusion?
Investigate a factor that affects the rate of diffusion.
Develop your OWN hypothesis
Research possible methods to investigate it
Develop a detailed plan for ONE method
Fill in the RESEARCH NOTES sheet (BOTH sides) and hand in to your teacher.

5. Candidate Research Notes
Fill in both sides of the sheet. Make sure you SIGN and DATE the front page.
It is important you put as much detail as you can BUT do not write outside the boxes.
When you have finished, your teacher will check your notes and sign the front if everything is complete. If they are handed back to you unsigned, you MUST make the improvements before you start the next stage of the assessment.

6. Hypothesis Not a guess Based on prior observations
A statement not a question
States that changing an independent variable will affect a dependent variable
A good hypothesis describes the direction of the expected relationship if there is theory to support it
Explain WHY you made this hypothesis – use the statements ‘I think that ….’ and ‘This is because …’
Show your teacher a DRAFT on lined paper BEFORE you write on your Research Notes sheet

7. HINT
Which three factors affect the rate of diffusion? D…
S…. a....
C…. difference
Which factor did you investigate? What was the relationship between this and the rate of diffusion?
Which part of the drug patch influences the factor you investigated?
For fast drug delivery, what should be done with this part of the patch?
Context
Nicotine patches are made of an artificial membrane which delivers drugs to the blood stream.
The patch will need to have certain features enable the drug to get into the blood quickly (shorten the delivery time).

8. Risk assessment Hazard Risk Control
Name of the HAZARD, not just the object.
For example, water is not hazardous.
Water on the floor is a hazard.
Possible outcome: how could somebody be HARMED?
AND
How likely? Write low, medium or high risk
How to reduce the risk.
“Be careful” is NOT enough!
How could you prevent the risk from happening in the first place? NOT how you would deal with it after it happens
We recommend you use this table format, it saves a lot of space!
Show your draft to your teacher before writing on the Research Notes sheet.

9. Research
Read at least 2 sources. Look for descriptions of experiments that investigate factors affecting the rate of diffusion, or explanations of how to speed up diffusion.
PLAN AHEAD! You have to squeeze FOUR lines of writing into a very small space! Draft it on another piece of paper first.
Select the most useful source and write down its Title, Author, Publisher and Date OR its Title and Web address.
Write WHY you thought this one was the most useful. Don’t judge by appearance, read what it says. It could explain the theory, or it includes clear safety information or the method shows the steps in detail.
Choose ONE source to reject and write down its Title, Author, Publisher and Date OR its Title and Web address.
Write clearly WHY you rejected it.
Show your teacher a DRAFT on lined paper BEFORE you write on your Research Notes sheet

10. Equipment list List every item with sizes
Where possible include the range and resolution of the measuring instruments

11. Method in note form. Don’t write full sentences.
Variables
Method
Step by step instructions
It is a good idea to number the steps
Make sure they are in a logical order
Finish with an instruction to repeat the whole thing again and calculate a mean.
Independent variable Name AND how it will be measured AND the RANGE and INTERVAL of its values Dependent variable Name AND how you will measure it Control variables At least TWO RELEVANT ones named AND for EACH one, how it will be controlled. Say what value it will be when you keep it constant.
PLAN AHEAD!
Not enough space in the Method section?
Put the Variables beside the Equipment list

13. It is difficult to work out the end point – the time at which all the dye has turned clear
Think about how you might overcome this

14. Writing a Method: practice
20/04/2017
Writing a Method: practice
In Paper 1, you need to be able to turn your notes into a clear, ordered Method.
You have limited space to write, so practise writing it on ONE side of A4 ONLY
Divide the space into sections and include all the details you have in your notes.
Use the Writing a Method Medal Sheet to help you.
Show your work to your teacher and make any changes they suggest.
Equipment
Variables
Method
Hazard
Risk
Control
There should be no need for extra sheets in the exam! Poor organisation is marked down in this question, so it is a good idea to practise it. Peer assess by all means, but it is definitely worth checking yourself as well, particularly for organisation, spg and EVERY detail on the Research Notes should be in the answer. Marvellous Methods is an alternative help sheet which has good and bad exemplars F tier pupils might get on better with.
EK/RHS/2013

15. Investigations: Writing a Method
EK Range High School 2013
Investigations: Writing a Method
Bronze
Can you
List the equipment you need, including at least one measuring instrument?
Name the independent variable and the dependent variable?
Give one way to make it a fair test?
State at least one safety precaution?
Describe what to do during the practical?
This is what you
need to do
to get the full 9 marks
in the Part 1 CAU exam
Strengths, weaknesses and next steps
Silver
Can you
List all the apparatus, giving details of sizes or types?
Identify and give the range and intervals or values of the independent variable?
Identify and state how the dependent variable will be measured?
Name at least two control variables and say how they will be controlled?
Describe at least two hazards and link them to their control measures?
Describe the sequence of the practical work using correct English?
Gold
Can you
List all the apparatus, including the sizes or types and the range and/or precision of all measuring instruments?
Identify all relevant variables, stating how they will be measured and/or controlled?
Write a 3-part risk assessment, linking at least two hazards with their associated risks and control measures?
Describe the sequence of the practical work using almost faultless English?
My response is …
Gold
Can you
List all the apparatus, including the sizes or types and the range and/or precision of all measuring instruments?
Identify all relevant variables, stating how they will be measured and/or controlled?
Write a 3-part risk assessment, linking at least two hazards with their associated risks and control measures?
Describe the sequence of the practical work using almost faultless English?
THINK PINK FOR LITERACY – GO GREEN TO IMPROVE
Well done – in this task you have:
To GO GREEN! You should now:
Over to you – re-write the THINK PINK section correcting the highlighted errors.
Diamond
Can you explain
Your choice of key apparatus
How you selected the values of the independent variable
Why it is important to control extraneous variables?

16. Results Draw a blank table suitable for the method you have planned
It’s worth 2 marks
Don’t forget to label each column clearly and write the UNITS
You MUST do this in EXAM CONDITIONS. Your teacher should be able to mark it straight away but they CANNOT tell you what is wrong with it!
Make sure you write your NAME and hand it in.

17. Paper 1 structure USE your Research Notes. Write your hypothesis
Q1 Hypothesis marks
USE your Research Notes.
Write your hypothesis
Explain why you made it.
Q2 Research sources marks
USE your Research Notes
Identify two sources.
Say why you found one better than the other.
Q3 Plan marks
Equipment list with details
Name the independent and dependent variables, giving details of how they will be measured and the range and interval of the IV
Identify the control variables and say how they should be kept the same
Write instructions for the method in a logical order
Write a 3-part Risk Assessment
Spelling, punctuation and grammar MATTER for this question!
Q4 Methods marks
Why is identifying the end point difficult?
What could you do to overcome this?
Q5 Results table marks
Your blank results table. This should have been done in a lesson. Make sure it is handed in.
If you did not do one earlier, draw it in the space below the question.
Total 20 marks

18. The Practical You may work individually or in groups
You will be asked to use the equipment and follow the method provided (this might not be the same as your own plan)
You should be given a photocopy of instructions to follow.
If you do not understand what to do, make sure you ask for help.
You need to produce your own results table, with heading and units and any repeat readings etc.
TAKE PART! Make sure the teacher sees you take some measurements and taking care to keep the control variables the same.

19. Analysing results You MUST do this by yourself
Remember to use a SHARP PENCIL and a RULER
Decide if it should be a bar chart or a line graph
If the IV is categoric (labels), draw a BAR CHART
If the IV is continuous (numbers that have been counted or measured), draw a LINE GRAPH
The graph is worth 4 marks.
Remember to make the graph take up more than half the page. Label both axes with the name and units. Accurate plotting of all points and a line of best fit are worth a mark each.
Your teacher cannot help you.

20. Exam Part 2
You will have your Research Notes, table and graph with you.
There will be Secondary Data sheets for use with some questions.
You will be required to:
Analyse your own results and see if they support your hypothesis
Identify anomalous results and explain how you could make use repeat readings to make your results more accurate
Look at the variables in your experiment
Evaluate methods and quality of data
Report your findings in the context set.

21. Paper 2 structure Total 30 marks Q1 Your investigation 15 marks
USE your Research Notes, Results and Graph
Will ask about your own results and how they relate to some of the Key Terms, for example:
Can you see any patterns in your results? – include examples.
Identify IV, state range of IV and explain whether it was suitable. Examples from results
Repeated readings and anomalous results: (Explain HOW you calculate a mean). How do repeats improve the results?
Uncertainties: what are they and how can we reduce their effect?
Reproducibility: how do results from other methods show if investigations are reproducible?
Make sure you know what the words on the AQA Glossary of Terms mean and can explain why they are important.
Q2 Secondary Data marks
Sketch graph. Name and label both axes, draw the SHAPE of line. NO points or numbers needed.
Case studies 1, 2, 3. Explain whether each one supports the hypothesis. Write about ALL of them, identify each one clearly.
Case study 4. Does the data support the statement? You will need to quote data.
Q3 Context marks
USE your Research Notes.
Explain how your investigation could be useful in context given.
Q4 Graph marks
You should have already done this. Check it is ready to hand in: labels and units on both axes. ALL points accurate. LoBF smooth curve or ruled line as appropriate.
Total 30 marks