Pre-Lab Questions Of the four major types of microscopes, give an example of a s

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Pre-Lab Questions

Of the four major types of microscopes, give an example of a scenario in which each would be the ideal choice for visualizing a sample. (10 points)

What is the difference between the coarse adjustment knob and the fine adjustment knob? When is it appropriate to use each of them? (10 points)

If you are using a compound microscope with an ocular lens with a magnification of 10x and an objective lens with a magnification of 40x, what is the total magnification? (5 points)

In this lab, we discussed preparation of a wet mount slide. Research and describe another slide preparation and an example of when it would be used. (10 points)

Experiment 1 Post-Lab Questions

What is the first step normally taken when you look through the ocular lenses? (5 points)

What does it mean that the image is inverted when you look through the ocular lenses? (5 points)

What new details are you able to see on the slide when the magnification is increased to 10x that you could not see at 4x? What about at 40x? (5 points)

.What were your calibration measurements for the following objectives? (5 points)

4x:

10x:

40x:

What were your objective and measurement estimates for the following specimens? (5 points)

Sand dollar juvenile:

Sand dollar larva:

Sand dollar embryo:

Human hair:

Blade of grass:

Why is it important to be able to properly calibrate and measure objects viewed through a microscope? (10 points)

Describe the qualitative difference you notice with the different types of microscope views in the “Microscope Compare” and “Specimen Compare” exercises. (10 points)

Experiment 2 Post-Lab Questions

The nuclei (the structure inside a cell that contains DNA) of the cheek cells have been stained using a special dye so that they appear purple. What shape are they? (5 points)

At high magnification, you may notice that not all of the nuclei in the onion root tip slide appear as the shape you described in Question 1. What do they look like? (5 points)

After completing the m1 exercise in the “Try This” section, how tall is the letter e? (10 points)

Explanation / Answer

1. Four Different types of microscope:

Simple microscope: It can be used to see striations in leaves or symptoms of skin diseases

Compound microscope: It uses two lenses to give greater magnified image. Blood sample can be tested using this microscope to identify presence of microorganisms.

Electron microscope: Transmission Electron Microscope: To visualise crosssections of a tissue

Scanning Electron Microscope: To visualise topological feature of a cell organelle

Phase contrast microscope: It is used to visualise liviing cells without staining it, The different cellular processes ongoing in a transparent cell can be observed.

2. Coarse adjustment knob is used to move the experimental stage up/down in centimeters range to bring the object closer to focus quickly.

Fine adjustment knob: It is used to move the experimental stage up/down in micrometer range to do more sharp focus of an image.

1st the coarse adjustment knb is used to bring the object closer to focal point, then the fine adjustment knob is used to increase its focus giving the image more accuracy.

3.Occular lens magnification: 10X

Objective lens magnification: 40X

Total magnification: Occular magnification X objective lens magnification

= (10X40)X

= 400X

4. Slide preparation: Heat fixing an stain: Used for bacterial smears which has a tendency to move around. To see the structure of the bacterial cells, 1st the bacterial culture is smeared on a slide and air dried. After air drying, the slide, the smeared side up is passed over a bunsen burner flame for 3 to 4 times to fix the bacterial cells onto the slide. Here care should be taken to not overheat the slides which can cause breakdown of the cells.

After heat fixing, the slides are stained with different stains depending on the type of bacteria and then after air drying the stain, it is seen under microscope.

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