Microscopy experiment

Question 1

what are the aims of the microscopy experiment?

Answer 1

. to stain cells for examination with a light microscope
. to examine a range of cells and other structures with a microscope to understand their basic structure

Question 2

Preparing a slide

Answer 2

Animal cell

Question 3

Step 1

Answer 3

Put a small drop of water onto the middle of a clean microscope slide

Question 4

Step 2

Answer 4

gently swab the inside of your mouth with a clean cotton bud and then gently rub the cotton swab on the drop of water

Question 5

Step 3

Answer 5

stain them with methylene blue

Question 6

Step 4

Answer 6

place a coverslip on top by standing the slip upright on the slide next to the water droplet. Then, carefully tilt and lower it so it covers the specimen. A mounted needle can be used to hold the specimen in place as the coverslip is lowered (try not to get any air bubbles trapped in as they’ll obstruct the view of the specimen)

Question 7

What does the coverslip do

Answer 7

the coverslip protects the microscope and prevents the slide from drying out when it’s being examined

Question 8

Preparing the slide

Answer 8

Onion Epidermis cell

Question 9

Step 1

Answer 9

add a small drop of water to a clean microscope slide

Question 10

Step 2

Answer 10

use tweezers or forceps to peel some of the epidermal tissue from the skin of an onion. Using the tweezers/forceps place the epidermal tissue in the water on the slide

Question 11

Step 3

Answer 11

add 2 drops of iodine to stain the cells - this will highlight the structures in the cell by adding colour to them and make sure the onion skin lies flat on the slide and there are no air bubbles trapped

Question 12

Step 4

Answer 12

place a coverslip on top by standing the slip upright on the slide next to the water droplet. Then, carefully tilt and lower it so it covers the specimen. A mounted needle can be used to hold the specimen in place as the coverslip is lowered (try not to get any air bubbles trapped in as they’ll obstruct the view of the specimen)

Question 13

Step 5

Answer 13

remove any excess stain by soaking it with paper towels

Question 14

Using the microscope

Question 15

Step 1

Answer 15

Place the slip on the stage of the microscope and clip it into place

Question 16

Step 2

Answer 16

Turn the nosepiece to select the lowest power objective lens (x10)

Question 17

Step 3

Answer 17

Use the coarse adjustment knob to move the stage up so that the the slide is just below the objective lens (don’t look down the eyepiece whilst doing this)

Question 18

Step 4

Answer 18

Looking down the eyepiece use the coarse adjustment knob to move the stage downwards until the image is roughly in focus

Question 19

Step 5

Answer 19

Now use the fine focus knob to further focus the image

Question 20

Step 6

Answer 20

Repeat the process with higher magnifications for if a greater magnification is required

Question 21

Step 7

Answer 21

Observe the cells and make a labelled drawing of the cells that you see including any visible sub-cellular structures

Question 22

Risk assessment

Answer 22

. iodine solution - wear safety goggles when handling it
. care when handling coverslips, microscope slides and mounted needles
. care must be taken when looking down the microscope/eyepiece if the illumination is too bright