MICROSCOPY Flashcards
What is a microscope?
An instrument which enables you to magnify an object hundreds, thousands, or even hundreds of thousands of times
By making visible the individual cells which make multicellular organisms , microscopes allow us to do what?
Discover how details of their structures relate to their functions
What was the first microscope developed?
Light microscopes (mid 19th century)
What is cell theory?
It was first developed by the mid 19th century when scientists had access to microscopes with a high enough level of magnification to see individual cells
What are the three rules of cell theory?
- both plant and animal tissue is composed of cells
- cells are the basic units of all life
- cells only develop from existing cells
Why is light microscopy important?
- easily available
- relatively cheap
- observes living organisms as well as dead prepared specimens
What is the importance of microscopes in the study of living organisms?
We are able to see how their structures relate to their functions in multicellular organisms
Why was cell theory not fully developed before the mid-19th century?
Because previous microscopes had worse resolution and magnification
What two lenses does a compound light microscope have?
2 lense objective lens near the specimen and an eyepiece lens through which the specimen is viewed
Objective lens produces a magnified image, which is magnified again by the eyepiece lens. This provides grater magnification and lower chromatic aberration than in a simple light microscope
What is chromatic aberration?
An effect produced by the refraction of different wavelengths of light, failure to focus
Light microscope advantages
- enable observation of living specimens
- easy to use
- relatively inexpensive
- can be easily transported
Light microscope disadvantages
- limited resolution means most internal cellular structures cannot be seen
What is magnification?
The number of times an image is enlarged compared ton actual object
What is resolution?
The ability to distinguish between two separate objects/ points and therefore the ability to see detail
What is the advantage of having two lenses?
- objective lens magnifies the specimen
- eyepiece lens magnifies image (from objective lens)
- higher magnification
What do we need to think about when interpreting images?
Different planes of section will give different shapes
Explain Dry Mount
Solid specimens can be used whole or cut into sections (sectioning)
Specimen is placed on the centre of slide & cover slip
Eg hair pollen dust = whole or muscle tissue or plants are sectioned
What is a Wet Mount?
Specimens are suspended in a liquid (water/immersion oil)
Cover slip is placed at an angle eg aquatic animals
Describe Squash Slides
Wet Mount is prepared first, then lens tissue is used to press down. Damage to the cover slip can be prevented by squashing the sample between two microscope slides.
Careful so that the cover slip isn’t broken when pressed eg root tip squashes for cell division
Describe Smear Slides
Edge of slide used to smear sample
Thin even coating on another slide
Cover slip is placed over sample eg red blood cells
