Microscopy.

Draw a diagram of a light microscope.

Check book after.

What is the function of the Eyepiece?

This is where you observe the specimen from.

What is the function of the Objective lens?

Controls the magnification at which we observe the specimen.

What is the function of the Course focus knob?

Used to adjust the stage.

What is the function of the Fine Focus Knob?

Controls the objective lens.

What is the function of the Stage?

Where the specimen rests to be observed.

What is the function of the Clippers?

Used to hold the stage.

What is the function of the Diaphragm?

The diaphragm has a lever that controls the light intensity on the stage.

What is the function of the Mirror?

Where light reflects off and onto the stage.

What is the function of the Arm and Leg?

Where to hold and carry the microscope.

Write the steps for the Microscopy practical.

1. First, place the specimen onto the slide of the stage.

2. Next, set the objective lens to the lowest magnification.

3. Then, use the course focus knob to adjust the slide to the optimal position to observe the specimen. Do not use this feature for the remainder of the process.

4. Continually use the fine focus knob to adjust the objective lens to the optimal magnification to view the cell, and at different magnifications.

5. Continually use the diaphragm as well, so that the specimen can be viewed at the optimal light intensity, but also at different light intensities.

How do we set up a slide?

1. First, decide on the specimen that you want to observe( preferably plant or animal cells).

2. If you choose to observe a plant cell, an onion skin will be the specimen.

3. Firstly, peel a small layer of the onion skin.

4. Then, place a drop of water onto the slide, and rest the thin section of the onion skin onto it so that it can position its shape perfectly.

5. Next, place a drop of iodine onto the onion skin, and use a dissecting needle to lower the coverslip onto the blotch of iodine, at an angle. This will distribute the stain on the specimen evenly and reduce the number of air bubbles trapped, producing clearer images.

What cells do you observe if you choose animal cells?

If you choose animal cells, cheek cells are the specimen.

First, hold a cotton bud, and lightly rub the inside of your mouth with it.

Then, smoothly blot the cotton bud onto the slide of the stage.

The stain we use is methylene blue.

How do you identify plant cells?

1. Plant cells are stacked together.

2. The cell walls touch eachother.

How do you identify animal cells?

1. Animal cells are far apart

2. They overlap one another

Measurements

1mm --> 1000 micrometers

1 micrometer --> 1000 nanometers

1 nanometer --> 1000 picometers

What is the formula for magnification?

Magnification = Image size/ actual size.

What is the magnification of an electron microscope? What is the advantage of using this device?

x1,000,000

As the electron microscope has a greater magnification than a light microscope, the device is used to study smaller features of cells.

What is the magnification of a light microscope?

x1500