Biology Core Practicals: 1 - Microscopes Flashcards
Where is the stage?
At the centre of the microscope
What is the purpose of the stage?
It is where the microscope slide is placed
What holds the microscope slide in place?
The clips either side
What is below the stage?
A lamp
What is the purpose of the lamp?
The light from the lamp passes up through the microscope slide to provide light shining through the coverslip and object in it
Instead of a lamp what do other microscopes have?
A mirror
What is the usage of a mirror?
It reflects the light up through the microscope slide
What is above the stage?
Lenses, objective lenses
How many objective lenses are there?
Three
Usually, what is the magnification of each three?
4x,10x,40x
What is at the top of the microscope?
The eyepiece
What does the eyepiece contain?
The eyepiece lens
Usually, what is the magnification of the eyepiece lens?
Magnification of 10x
Name the two dials?
Course focusing dial
Fine focusing dial
Where do you put the cells?
On a microscope slide
For plant cell what you add to the cell?
A drop of water or iodine, a chemical stain
Once your cell and stain is on the slide, what is next?
Lower your coverslip, gently to prevent trapping air bubble
For animal cells, how do you place them on the slide?
Using cotton bud, rub them on the inside of your cheek/animal
Once the cotton bud contains the cell DNA, what is next?
Smear the cotton bud onto the slide
What do you do once the slide contains cell/DNA from an animal cell?
You must add a drop of methylene blue, chemical stain
After the cell/DNA is on the slide, what is next?
Lower the coverslip, gently to prevent the trapping of air bubble
Why are chemical stains used?
To make cell parts more obvious
Why is a thin layer of a plant cell used under a microscope and not a thick one?
This is to make it easier to see the cell
When the slide is prepared, what is next?
Place the slide onto the stage and use the clips to hold it in place
Once the slide is in place, what is next?
You must select the lowest power objective lens and position is almost touching the microscope, usually 4x
How do you position the lens almost touching the microscope slide?
Turn the coarse focusing dial, looking from side on of the microscope
When do we stop turning the dial?
Once the objective lens is almost touching the slide
Why do we look at the microscope from the side?
As there is a risk damaging the slide if we look through the eyepiece lens
Once it is set up, what is next?
We look down the eyepiece lens
Once we look down the eyepiece lens, what is next?
Turn the coarse focusing dial
Why do we turn the coarse focusing dial?
BRINGS THE CELL INTO FOCUS, decreasing the distance between the objective lens and the slide
How are the cells brought into a CLEAR focus?
Use the fine focusing dial
How do you calculate the total magnification?
Total Magnification = Magnification of eyepiece X Magnification of objective lens
If the eyepiece lens has a magnification of 10x and the low-power objective lens has a magnification of 4x
What is the total magnification?
40x
After using the lower power objective lens, what can we now do?
Select the higher power objective lens
How do you include a magnification scale?
Place a clear plastic ruler over the stage, measure the diameter of the field view in mm
What do you do when you are showing a drawing of magnification?
Use a scale bar
What do you do when you are showing a drawing of magnification?
Show the magnification you are using
