Biology SNAB a-level practical write up - Membrane permeability (3)
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Course
Practical write up
Institution
PEARSON (PEARSON)
Alevel biology practical write up is a report of a laboratory experiment conducted by students. It is required as part of the assessment for the subject.
The a-level biology practical write up document is a professional report and should be organised in a clear and logical manner. It should inc...
The effect of ethanol concentration on Beetroot Permeability
To investigate the effect of ethanol on membrane permeability
Hypothesis:
As the concentration of ethanol increases,the higher the permeability and the lower the light
transmitted
The cell membrane separates the interior of the cell from the exterior, but the membrane is permeable in order to
allow the movement of molecules via diffusion, such as phospholipids.
Phospholipids consist of a hydrophilic head and hydrophobic tail, forming the phospholipid bilayer that is broken
down in the presence of ethanol. The permeability of a membrane can be measured by using beetroot cells,
which contain a purple pigment called betalain. When the cell-surface membrane has a higher permeability, more
pigment leaks out of cells, The permeability can therefore be measured by the amount of pigment leaked from
beetroot cells into an aqueous solution using a colorimeter[1].
Equipment:
● Raw beetroot
● Plastic beaker
● 8 boiling tubes
● Colorimeter
● 8 Cuvettes
● Stopwatch
● Distilled water
● Pipette
● Small measuring cylinder
● Knife
Variables:
Independent- Concentration of ethanol
Dependent- Percentage transmission of light through the resulting solution
Control- Size of beetroot pieces
Risk Assessment;
➔ Probability/severity of risk: 1-Low, 2-Medium, 3-High/Likely
➔ Total Risk: 1, 2,3, 4, 6, 9
Risk: Hazard: Probability: Severity: Total Risk: Precaution:
Ethanol Irritant 2 2 4 Wear eye protection
and gloves;wash
skin immediately if it
comes in contact;
keep away from
heat/sparks
Glass Smashing; 1 2 3 Take care when
Equipment Injuries to moving glass
hand equipment to ensure
it is not smashed or
dropped
Sharp Injuring 2 2 4 Take care when
objects yourself using this equipment,
(knife/cork always use safely
borer) and securely, do not
leave near edges of
table
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