Practical 1 - Mircroscopes

Exercise 3: Following the video, take a clipping of a word from the newspaper, and mount this word on a clean slide, add some water and a coverslip.  Try to identify the letters at different magnifications.

Now prepare two more slides following the protocols below:

Cheek cells

• Take a clean cotton swab and gently scrape the inside of your mouth.

• Smear the cotton swab on the centre of the microscope slide

• Place the cotton bud in the bin

• Add a drop of methylene blue solution and place a coverslip on top - do not add too much solution.

• Remove excess solution by allowing a paper towel to touch one side of the coverslip

• Place the slide on the microscope with the low or medium magnification lens find a cell.

• Increase the magnification. What structures can you see?

Elodea cells

• Pick an entire healthy looking Elodea leaf using your fingers or cutting the leaf off with small scissors.

• Place the leaf on the microscope slide

• Add a drop of water and a cover-slip

• Increase the magnification. What structures can you see?

Write your initials on all the slides that you have prepared

Exercise 4: Taking measurements.

Using the eye piece scale:

• Can you use the measuring scale on the eye piece to measure the dimension of a letter? How do the units on this scale change as you change the magnification?

• Can you use the measuring scale on the eye piece to measure the length of your cheek and elodea cells? How do the units change as you change the magnification?

• Now mount the stage graticule, following the information given on the video below, work out how many mm one eye piece unit measures at each magnification.