Essay
Unit 4 - M3 justify the choice of instruments in the practical exercises
- Institution
- PEARSON (PEARSON)
This is my M3 task for my distinction graded unit 4 assignment
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Unit 4 – scientific practical techniquesM3 – Justify the choice of instruments in the practical exercises
In the microscopy experiment, sterile cotton swabs were used. These were necessary to carry out
the experiment as it meant there was no contact with other people’s hands due to one or two being
in individual sterile plastic bags. The reason they must be sterile is because any contamination
they’ve come across, for example, being placed on a table, being in other people’s hands etc. it
means that all the debris then transfers onto the cotton swab, making it no longer sterile. So, when
it comes to swabbing it inside our mouths it is not very hygienic, and when transferring onto the
microscope slide, our cheek cells and debris from cross contamination will be mixed. And ultimately,
we think we could be looking at one of our cheek cells when in fact we could be looking at
someone’s cells from their fingers.
Another instrument used in the experiment was a light microscope. These were very important for
the carry out of the microscopy experiment as without them, the cells would not be visible via the
naked eye or even with a small magnification. The light microscope has four different objectives,
three of them which we can use and the other must be used with oil. The highest objective possible
for this experiment was a 40x objective and it allowed us to visually see the cell, and some of the key
components, for example, the nucleus, the cell membrane, the cytoplasm. By being able to see this
we were able to efficiently measure the size of an individual cell and therefore able to work out the
size of it.
In the pH experiments, beakers were used. There were a few reasons for using beakers, one
being that when using the pH probe the beaker was wide enough to fit the pH probe into it. If a test
tube was used instead, then specifically for the pH probe test the contents inside the test tube
would have to be transferred into beakers which ends up wasting liquid as a small layer sticks to the
glass. Another reason for using beakers is that if they were dirty, the larger circumference made it
easier for them to be washed out. If test tubes were used and they were dirty, it is a lot harder to
wash them out due to not being able to easily reach the bottom, which is where all the liquids would
sit.
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