Microscopy-Experiment Flashcards
Explain the microscopy experiment
.This experiment is about using a microscope to look at onion skin cells and estimate their size
What are the parts of the microscope?
.There are two focus controls. The top one is used to get an initial focus. The lower “fine focus” control is used with high magnification to make small adjustments to the focus
.The mirror is used to reflect light upwards through the slide to obtain a bright image. The stage has a hole under the slide to allow the light though
How do you prepare a slide?
1) Place a drop of water on the slide
2) Using a forceps remove a thin layer of onion
3) Place the specimen on the slide gently
4) Using a pipette add 2-3 drops of stain e.g. iodine to the specimen
5) Slowly and at 90 angle lower the cover slip to cover the specimen. Avoid air bubbles
Explain the stages of using a light microscope
1) Gently, carry the microscope with one hand under the base and one hand on the arm
2) Plug in and switch on the light source
3) Clip in the prepared slide onto the stage
4) Select the lowest power objectives lens first
5) Look down the eyepiece. Turn the coarse focus wheel to move the stage upwards and get a rough image
6) Turn the fine focus wheel to get a more precise image
7) Select higher power objective lens and repeat step 5
How do you draw your observations?
1) Draw what you see under a microscope using a pencil with a sharp point
2) Make sure your drawing takes up at least half of the space available that is drawn with clear, unbroken lines
3) The drawing should not include any colouring or shading
4) If you are drawing cells, the sub cellular structures should be drawn in proportion
5) Remember to include a title and include the magnification it was seen under
6) Label the important features
What is the equation for finding image, magnification and actual size?
Image=actual size x magnification
How do you estimate the size of a cell using a calculation?
Average cell size(mm)= field of view/number of cells
