CONTROLLED ASSESSMENT BU1.3 VITAMIN C

Topic of the investigation: How much vitamin C is in food depends upon the time the food is cooked for

Research ONE possible method to investigate the hypothesis

Develop a detailed plan for this method Fill in the RESEARCH NOTES sheet (BOTH sides)

and hand in to your teacher.

CANDIDATE RESEARCH NOTES Fill in both sides of the sheet. Make sure you SIGN the

front page. Use the information from the source you found most

useful, but you can use information from the other sources too.

It is important you put as much detail as you can BUT do not write outside the boxes.

CONTEXT A food scientist needs to explain

to hospital cooks how long to cook vegetables so that they contain as much vitamin C as possible

How could the results of this investigation help to show the amount of cooking time needed or the different methods of cooking to retain vitamin C content?

Explain in your own words.

HINT

Vitamin C is needed for healthy skin and blood vessels

Vitamin C is soluble in water so it can be found in the juices and extracts of certain fruits and vegetables

Cooking vegetables by boiling in water is likely to reduce their vitamin C content

Measuring the vitamin C content

• This is done using a chemical called DCPIP• DCPIP has a blue colour • In the presence of vitamin C DCPIP goes colourless• The more vitamin C present the more drops of DCPIP

need to be added to the food extract before a blue colour remains. (When this happens all the vitamin C has reacted with the DCPIP)

• Problems:• It may be difficult to determine the end point• The drops of DCPIP may not all be the same size

RESEARCH Find at least 3 sources. Look for descriptions of experiments that

tell you how to extract the vitamin C from the vegetable and how to test for it. A diagram is not essential but may be useful.

PLAN AHEAD! You have to squeeze FOUR lines of writing into a very small space! Draft it on another piece of paper first.

1. Select the most useful source and write down its Title, Author, Publisher and Date OR its Title and Web address.

2. Write WHY you thought this one was the most useful. It could be because it helps you with the theory, or maybe it has a good diagram, includes clear safety information or the method shows the steps in detail.

3. Choose ONE of your rejected sources and write down its Title, Author, Publisher and Date OR its Title and Web address.

4. Write WHY you rejected it.

RISK ASSESSMENT

RISK ASSESSMENT

HazardName (for example broken glass)

RiskHow likely? (low/medium/high risk) ANDPossible outcome

ControlHow to reduce risk. (“Be careful” is NOT enough!)

EQUIPMENT LIST

You can draw a labelled diagram but this will take a while.

A clear list with sizes stated would be quicker.

METHOD IN NOTE FORM. DON’T WRITE FULL SENTENCES HERE.

VARIABLES METHOD

Independent variable Name AND how it will be measuredDependent variableName AND what you will measure Control variablesAt least TWO RELEVANT ones named AND for EACH one, how it will be controlled.

1. Step by step2. 3. 4. 5. Don’t forget repeats and

calculating means. Say HOW a mean is calculated.

* HINT Use all the sources or a textbook to find out two factors that will affect the values used.

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.

My response is …

Strengths, weaknesses and next steps

EK Range High School 2013

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?

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?

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?

Investigations: Writing a Method

This is what you need to doto get the full 9 marks in the Part 1 CAU exam

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?

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 in the column headings

PAPER 1 STRUCTUREQuestion 1 Research sources 3 marksUSE your Research Notes• Identify two sources. • Say why you found one better than the

other.

Question 2 Control variables 3 marksSee the next slide

Question 3 Plan 9 marksUSE your Research Notes• Write an equipment list • Name the variables• Say how the control variables should be

kept the same• Write instructions for the method in a

logical order• What are you going to measure or count?• Write a 3-part Risk Assessment (Hazard,

risk, how to control the risk)• Spelling, punctuation and grammar

MATTER for this question!

Question 4 3 marks Will ask about one of the Key Terms, for example comparing results, Zero error, Repeatability, Anomalous results.Make sure you know what the words on the AQA Glossary of Terms mean and can explain why they are important.Question 5 Results table 2 marksYour 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

Question2 Control variables 3 marks

You will need to name a variable you are going to control

THEN

You will need to describe how you would carry out a preliminary investigation to determine the value (size) of this control variableAND Explain how the results of this investigation will help you to decide on the best value for the control variable

For example:How will you know the volume of vegetable extract to test?

Too small a volume - the results may be very close together and you will not see a trend

Too large a volume and you could spent too much time collecting your results so you do not finish the experiment

Can you design an experiment which will give you an idea of the best volume to choose?

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 might be provided with a results table or the teacher can tell you how to arrange it.

TAKE PART! Make sure the teacher sees you take some measurements and taking care to keep the control variables the same.

PROCEDURE

You should be given a photocopy of instructions to follow.

If you do not understand what to do, make sure you ask for help.

ANALYSING RESULTS

You MUST do this by yourself 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.

The teacher cannot help you.

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 Draw a conclusion Match your results to the hypothesis Evaluate the method and quality of data Analyse further secondary data Report your findings in the context set.

PAPER 2 STRUCTURE

Question 1 Your investigation 12 marksUSE your Research Notes, Results and GraphWill ask about your investigation for example:• What were the names of your variables?• What were the uncertainties in your investigation

and how could you reduce them?• Did you repeat any of the readings? If yes then say

why. Refer back to your graph: are all your points on or near the line of best fit?

• Do your results support your hypothesis? Say yes they do or no they don’t because … quote some figures from your data to support what you are saying

• Do other results show that the investigation is reproducible? If they do then they show a similar trend to your results. Quote some figures to support your answer

Question 2 Secondary Data 11 marksa) Sketch graph. Name and label both axes but NO

numbers. SHAPE of line only, no points plotted.b) Case studies 1, 2, 3. Explain whether each one

supports the hypothesis (one does, one does but has an error, one has a different IV) Write about ALL of them, IDENTIFY each one clearly.

c) Case study 4. Relationshipsd) Justification using the information given about

case study 4.

Question 3 Context 3 marksUSE your Research Notes.Explain how your investigation could be useful in context given.

Question 4 Graph 4 marksYou may 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