2.1.1(a)the use of microscopy t observe and investigate different types of cell and cell structure in a range of eukaryotic organisms

What is resolution?

The ability to distinguish separate points on an image as two separate objects

How do light microscopes work?

Use light to form an image

What is the disadvantages of light microscope?

Stains can kill cells

Only be used for larger structures (mitochondria or entire cells or nuclei)

What is the advantages of the light microscope?

Small and cheap

The preparation is easy for school labs

They produce colour images

Can be used on living or dead cells

(Can see cell division for living cells)

What are the disadvantages of electron microscope?

Large and expensive

Black and white images

Specimens prepared in a complex way

Specimens have to be viewed in a vaccum so can only see dead cells

What kind of structures can you see in an electron microscope?

Ribosomes

Endoplasmic reticulum

Cell membrane

How do TEMS WORK?

Transmission electron microscope

Transmit. Abeam of electrons to specimen

The denser areas of th specimen absorb more electrons and so appear darker

What is the ADVANTAGES of TEMS

Internal structures are sown

2 dimensional

High resolution

What is an SEM

Scanning electron microscope

Pass a beam of electrons over the surface of specimen and detect the rate at which electrons bounce back

What is the ADVANTAGES and DISADVNATGES of SEM

A : 3 dimensional

Show surface of specimens

D; lower maximum resolution