Electrical and Chemical Signals

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Electrical and Chemical Signals
Aim Does the colour intensity of a drink affect
how sweet it tastes?
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Any Questions?
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Method

• Collect cups, lemonade (of a known sucrose
  concentration), red food dye, stirring rod and a
  measuring cylinder.
• Measure out 50ml of lemonade into a measuring
  cylinder.
• Label the containers A-E.
• Add 1 drop of red food colouring to cup A, 2 to
  cup B, 3 to cup C, 4 to cup D and 5 to cup E.
• Stir the different lemonade/dye solutions to
  ensure an even distribution of food colouring.
• Ensure that the person tasting the drink does not
  see the preparation of the drink.

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Method Continued.

• 7) Get the same person to try all of the drinks
  A-E, in between each drink they should rinse
  their mouth out with mineral water.
• Then they should put the drinks into the order of
  which one they think is sweetest (A-E).
• Collect the results in a table and repeat the
  experiment again with the same person 2 more
  times.
• Making sure that you use clean cups each time.
• Then get different people to do the same
  experiment and compare the different results.
• Ensure that no-one shares the same cup, cups are
  clean and that the equipment used has not been
  used for any other experiments.

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Results Table Lets Fill it in as a class
Number of drops of red food colouring in each drink. Number of volunteers who thought the drink was the sweetest.
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• How did you make your experiment reliable?
• We repeated our experiment 3 times for each
  individual.
• We ignored any odd results or repeated them.
• How did you make your experiment valid?
• We used the same amount of lemonade each time
  (50ml)
• We used the same lemonade each time (with the
  same amount of sucrose in it).
• We washed our mouths out with water after each
  taste to get rid of any sugary taste
• We used clean cups
• We measured the amount of food dye used each time
  and used the same food dye each time
• People should be in the same age range
• Same brand of lemonade should be used
• Only one colour of food dye is used as this could
  affect results
• Try not to use other senses like smell as this
  could affect the results.

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How could you make your experiment even better??
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How would you carry out an investigation to
investigate the effect of smell on taste?
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Method (in your own words)..

1. Collect cups, lemonade (of a known sucrose
   concentration), blindfold, sugar, stirring rod
   and a measuring cylinder.
2. Measure out 50ml of lemonade into a measuring
   cylinder.
3. Label the containers A-E.
4. To each bottle add a different amount of sugar.
5. Stir the different lemonade/sugar solutions to
   ensure an even distribution.
6. Ensure that the person tasting the drink does not
   see the preparation of the drink.
7. Blindfold a person.
8. Get the person to smell a cup of one of the
   drinks, then taste it.
9. Get the person to rank the drinks in order of
   sweetness.

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• One hundred volunteers were chosen to complete
  this task. The results are shown in the table.
  The remainder of the volunteers were unable to
  detect a difference in the sweetness of the
  drinks.
• How many volunteers were unsure?

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How would you draw a bar chart of your data?
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Look at your graph, what do you see?
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• Transfer your results onto the table issued to
  you.
• Put your name onto the table.
• I will collect these in.
• This table will be given to you during the IAA
  exam on Monday.

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Look at the table of data
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One hundred volunteers were chosen to identify
flavours of drinks. The results are shown in the
table.
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What is on each axis?
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Use the information from your graphs
and scientific principles to help you explain why
being able to see may have affected peoples sense
of taste?
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What does your investigation tell you about the
senses of sight and taste?
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How could you make an experiment looking at how
sight affects taste, reliable and valid?
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How could you make a future investigation more

• Reliable
• Test more people (repeat).
• Valid
• Use a wider range of people (age, gender).
• Use a placebo/ control to compare results to.
• Control other senses.
• Do under lab conditions.

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What are the advantages and disadvantages of
adding artificial food colourings to foods?
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What are the advantages and disadvantages of
adding artificial food colouring?
Advantages Disadvantages
Mainly to food manufacturers. Mainly to consumers.
Aesthetics (nice appearance). Adding man-made chemicals (unknown).
Make more profit. May be allergic to chemicals.
Influences us to spend money and buy them!
Stain fingers/ teeth.
Could use natural colourings. Hyperactivity.
Adverse effects on health.
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Any questions???