Biology Quiz: Microscopes & Parts of a Cell

-Main benefit is resolution, the ability to see fine detail

• Produced crude microscope • Used a 2-lens system

-Built crude compound microscope

• Built simple single lens microscope • 1st to see unicellular motion

• built compound microscope • First person to use the word “cell” (cork) • 3 lens system

-Built 1st electron microscope

-first scanning electron microscope

• Image produced by light through specimen • 1 eyepiece/ocular (0-4 objective lenses) • Transparent specimens used • 1000X

• 2 oculars/eyepieces • 2 light sources • To look at solid objects • 85X

Pros: -images produced in color, 3D, living materials can be used Cons: • low magnifacations • poor resolution at high magnifacations

Light passes through specimen

Light reflects off specimen

When microscope is focused on one power, it should still be in focus when swtiched

Upsidedown and backwards (‘e’)

Image is the same as it is

• Diameter of what you see • Measured in microns (μ) • Descreases as magnifacation increases • Forumla: known f.o.v/(unknown mag/ known mag)* *known mag= image ocular x objective for each*

1mm x 1000 = 1 micron

= field diameter/fit number

scale = actual size/ drawing

1.) number of times microscope enlarges specimen magnifacation= drawing/actual sizw

• Uses beam of electrons not lightwaves • No colour • Able to see great detail

-Beam of electrons pass through stained tissue imbedded in plastic Pros: • very high mag. • high resolution (internal detail seen) Cons: • 2D • B&W

• scans surface of specimen • image produced by electrons reflected off surface onto screen • Often coat specimen gold for sharp images Pros: • High magnifacation • 3D B&W Cons: -specimen has to be dead