46 WJEC Biology AS Level - Marianne Izen - 2nd Edition Flashcards
What will happen if the bulb of your microscope is Incandescent rather than flouroscent?
If the bulb of your microscope is Incandescent rather than fluorescent, its heat is likely to harm the Amoeba after a few minutes.
What is the magnification of the image if you use a x40 objective lens and a x10 eyepiece lens ?
If you use a x40 objective lens and a x10 eyepiece lens, the magnification of the image that you see is 40 x 10-400.
Compare the magnification of an image with a x40 objective lens vs a x10 objective lens.
A x10 objective lens magnifies an image 10 times.
A x40 objective lens magnifies an image 40 times.
So with a x40 objective lens, the image is 40/10 = 4 times bigger than with a x10 objective lens.
What are the requisites of a high power drawing?
A high power drawing should have two or three cells.
It a composite of all the structures that you can see as you focus down through a specimen.
They will not all be in focus simultaneously but should all appear in the drawing
How do you prepare amoeba for microscopic examination?
Pipette two drops from a liquid culture containing the Amoeba and place on a microscope slide.
Add one drop of glycerol.
This increases the viscosity to slow down the Amoeba’s movement but does not cause harm.
Place a cover slip on the slide.
What are the steps for viewing in the microscope?
Lower the microscope stage as far as possible.
Place the slide on the stage.
With the x10 objective lens in place, raise the stage slowly until the image is in focus.
Move the slide slightly so that a suitable portion of the specimen is in the centre of the field of view.
Adjust the light intensity with the sub-stage iris diaphragm.
Move the x40 objective lens into position and refocus with the fine focus control.
Readjust the light intensity.
While examining using the x40 objective lens, repeatedly rotate the fine focus control in both directions, so as to view the whole depth of the specimen.
What are the steps in drawing of microscopic images?
Hold a sharp HB pencil firmly and rest your forearm on the table on which you are working.
Look at your specimen and study its proportions very carefully.
When you are ready to draw, make bold lines in single strokes.
If an area is enclosed, ensure that your lines meet exactly.
Draw outlines and do not shade in.
Make your drawing take at least half the area of the page.
What is a low power plan?
A low power plan does not include any individual cells.
It is a tissue plan and the boundaries of all the recognisable tissues should be drawn in with single lines.
What does this picture show?
Draw a labelled high power drawing of three onion epidermis cells.
