Unit C: Topic 1

Microscope functions

The base supports the microscope.

Ocular lens

Magnifies the image produced by the objective lens.

Objective lens

Captures and refracts the light reflected from the specimen.

Revolving nosepiece

Holds two or more objective lenses for easy switching.

Light source

Shines light on the specimen for visibility.

Diaphragm

Controls the amount of light entering the microscope.

Stage

Where the specimen is placed for observation.

Stage clips

Holds the slides in place on the stage.

Tube

Supports the eyepiece and lenses of the microscope.

Magnification formula

Multiply the power of the objective lens by the eyepiece.

Field diameter formula

Relates field diameter to magnification power.

Scale calculation formula

Ratio of drawing diameter to field diameter.

Contrast

Ability to differentiate based on light absorption and reflection.

Resolution

Ability to distinguish similar images or specimens.

SEM microscope

Provides 3D images with moderate magnification.

TEM microscope

Offers extreme magnification to see inside cells.

Spontaneous generation

The disproven theory of life arising from non-living matter.

Redi

Disproved spontaneous generation by showing flies lay eggs.

Needham

Conducted flawed experiments supporting spontaneous generation.

Spallanzani

Corrected Needham's errors in experiments on spontaneous generation.

Louis Pasteur

Disproved spontaneous generation with the S-shaped flask experiment.

Development of cell theory

Historical progression from microscope invention to cell observations.