Flashcards in Microscope Deck (12):
1
What are the rules for biological drawing?
Observe the specimen and record what you see clearly and accurately. Labelled drawings and diagrams can be used.
2
What are some points you need to remember when observing through a microscope?
- Draw what you see, not what you think you should be seeing.
- Always use a sharp pencil
-Make your drawings large
-Make the lines clear and sharp
-Do not shade or colour in any areas
-Make sure the different parts of the drawing are in proportion
-Labels should be spaced neatly around the drawing
3
What is the difference between electron and light microscopes?
Electron microscopes have a higher resolution and magnification than light microscopes.
4
What is magnification?
Magnification is how much bigger a sample appears to be under the microscope than it is in real life.
5
What is resolution?
Resolution is the ability to distinguish between two points on an image i.e. the amount of detail
6
Pros and cons of electron microscopes
- Expensive to buy
-Expensive to produce electron beam.
-Large and requires special rooms.
-Lengthy and complex sample prep.
-Preparation distorts material.
-Vacuum is required.
-All images in black and white.
-Magnifies over 500 000 times.
-Specimens are dead, as they must be fixed in plastic and viewed in a vacuum
-The electron beam can damage specimens and they must be stained with an electron-dense chemical (usually heavy metals like osmium, lead or gold).
7
Pros and cons of light microscopes
-Cheap to purchase
-Cheap to operate.
-Small and portable.
-Simple and easy sample preparation.
-Material rarely distorted by preparation.
-Vacuum is not required.
-Natural colour of sample maintained.
-Magnifies objects only up to 2000 times
-Specimens can be living or dead
-Stains are often needed to make the cells visible
8
What are the main limitations of the electron microscope?
The inability to observe living specimens, difficulty of preparation of samples and expensive equipment are the main limitations.
9
What are the main limitations of the light microscope?
Low resolution and as a result cannot magnify above x1500 and still give a clear image
10
What is cell division? (mitosis)
The division of a cell into two daughter cells with the same genetic material.
11
Magnification
x 1000 x1000
mm μm nm
Example: 1mm 1000μm 1,000,000nm
12