Question

A student is asked to prepare a microscope slide to show the contents of the cells from onion skin and animal tissue. Describe how the student should carry this out, include the equipment that should be used.

Answer 1

Explanation:

Method:

1. First add a few drops of water or solution on the microscope slide to avoid dryness and wilting
2. Take a small piece of onion and using tweezers, peel off the membrane from the underside (the rough side).
3. Place the membrane flat on the surface of the slide.
4. Add a drop of Iodine solution to the onion skin
5. Using a pin, lower the thin glass cover slip or cover glass onto the slide. Make sure there are no air bubbles (Fig. 1).
6. Make sure the lowest power objective lens (the shortest lens if there are several present) is in line with the optical tube, and the microscope light is turned on. Then place the prepared slide onto the stage of the microscope.
7. Looking from the side (NOT through the eyepiece), lower the tube using the coarse focus knob until the end of the objective lens is just above the cover glass. Do this carefully so as not to crack the cover glass (and possibly damage the objective lens).
8. Now look through the eyepiece and turn ONLY the smaller, fine focusing knob to move the optical tube upwards until an image comes into focus. The cells should look something like lizard skin.
9. Swap the objective lens for a higher powered one so that you can see the cells at greater magnification. You should be able to make out a nucleus in each cell.
10. Be very careful; these dyes can stain your skin and clothes.Could be dangerous if it is on you.

Answer 2

In this process insoluble impurities are removed from water by passing the impure water through a filter paper. A circular piece of filter paper is taken and folded twice to make a cone and this is kept inside a funnel. A flask is kept below the funnel and the mixture is houred into the flask through the funnel. Sand is retained on the filter paper and clean water is obtained in the flask

The mixture of insoluble impurities for example, (mud ) and water is allowed to stand undisturbed in a beakker.

After some time the mud settles down at the bottom of the container as sediments. This process is called sedimentation.

Clean water can then be poured out into a seperate container without disturbing the sediments. This process is called decantation.