# Biology ISA - Section 2

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## Context

• The results could be useful to people who design drug delivery patches
• They will know thatas the concentration increases the rate of diffusion increases
• If they put a high concentration of drug into a patch the difference in in concentration is greater so the rate of diffusion is faster
• This would be good for painkiller
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## Sketch Graphs

Independent variable on the x axis.

Dependent variable on the y axis.

Boths axis need titles and units.

Do NOT draw points, only draw a line of best fit.

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## Case Studies

• Include data
• Check if the experiment has been repeated
• Look out for anomalies - have they been included in the mean?
• Is there a different independent variable?
• Possitive or negative correlation
• Is the effext proportional?
• Does the effect level out? (E.g. a curved line like limiting factors in photosynthesis)
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## Suggest why others might get different results

• They may have used a different method
• For example they could have used different values for their control variables.
• Also, they may have used a stronger alkali in the agar cubes which would have made the time taken for the cube to go colourless longer
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## Anomalous Results

• Yes I did get anomalous results
• They were at 0.4M and 0.6M
• They are not close to the line of best fit and do not follow the pattern
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## Independent Variable & Range

• Independent Variable - Concentration of acid
• Range - 0.2M to 1.0M
• This was a suitble range because there was a difference between the lowest concentration (0.2M) and the highest (1.0M)
• So my results agree with my hypothesis
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• Divide the sum by how many results there are
• This is how a mean value is calculated
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## Supporting The Hypothesis

• Yes my results do support my hypothesis
• As concentration of acid increases the rate of diffusion increases. The effect is less at higher concentrations
• For example, with 0.2M of acid the time taken to decolourise was 231 seconds, whereas when this was increased to 1.0M the tim take to decolourise was only 117 seconds
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## Uncertainties

• Difficult to decide when all the colour has gone
• Use the same person to judge the end point
• This will reduce random errorsand allows you to directly compare the cubes
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## Reproducible

• Compare with others who used the same independent variable
• Compare to see if they are similar
• If they are similar then the results are reproducible
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