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AS BIOLOGY
EXPERIMENT WRITE-UPS
Edexcel SNAB specification
Made by Nabilah Chowdhury

Copyrighted

References: SNAB Activity sheets + various internet resources




DAPHNIA EXPERIMENT
Topic: What affect does caffeine have on heart rate?

Aim: investigate how caffeine conc. can affect the heartbeat rate of daphnia

Background info:

If the environmental…

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Hypothesis:

The heart follows the atria-ventricular cycle. During systole the heart contracts whilst during diastole the
heart relaxes. This way the blood pressure is maintained.
However caffeine makes the heart constrict by making the ventricles contract more. This in turn narrows
the arteries and blood is spurted out…

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The results show a directly proportional trend ­ as the caffeine concentration increases so does the
number of heartbeats. Similar results are produces from each trial and therefore the results are repeatable
and reliable.




VITAMIN C EXPERIMENT
Topic: What is the Vitamin C content of different juices?

Aim:…

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DCPIP is a redox. Vitamin C (juice) is a reducing agent. The Vitamin C reduces the DCPIP and when it does,
the excess H+ from the acid in the juice binds to the DCPIP and changes it to a pale pink or colourless
solution.
If there is an…

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BEETROOT EXPERIMENT
Topic: Why does colour leak out of cooked beetroot?

Aim: use beetroot to examine the effect of temperature or alcohol on cell membranes.

Background info:

The dark red and purple pigments in beetroot are located in the cell vacuole and are chemical compounds
called betalains.

Prediction:…

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liquid like. The bilayer may separate so that two chains of phospholipids remain, and all the cells contents
will leak out.


Temperature:
At physiological, or body temperature, the cells function their best. As
temperatures increase, both the cell membrane and the proteins can
be affected. The fatty acid…

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Method for temperature
1. Use size 4 cork borer to cut sections of beetroot.
2. Cut x8 pieces of 1cm slices from these larger sections
3. Place slices in beaker of distilled water over night to wash away excess dye.

Next day...
4. Pour 5cm3 distilled water in…

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Method for alcohol
1. Use size 4 cork borer to cut sections of beetroot.
2. Cut x8 pieces of 1cm slices from these larger sections
3. Place slices in beaker of distilled water over night to wash away excess dye.

Next day...
4. Place one slice in a…

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If 100% light is transmitted, then no light has been absorbed.
If 80% of light is transmitted, then 20% has been absorbed thus some pigment must have leaked out of
the beetroot cell in order to have absorbed the light.

Temperature Observation Calorimeter
(degrees reading (%
Celsius) absorbency)…

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At first, the rate of reaction increased steeply because doubling the concentration means that it also
doubles the number of enzymes acting upon the surface of the substrate.
However, when adding a high conc. of enzymes the rate will not increase as quickly, as the surface of the…

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