Staining With Microscopes

Question 1

What stain can you use to show DNA and chromosomes?

Answer 1

Acetic Orcein (stains a dark red)

Question 2

What stain to you use to see the cytoplasm?

Answer 2

Eosin (stains a deep blue/purple)

Question 3

What stain do you use to see lipids?

Answer 3

Sudan red (stains red)

Question 4

What stain do you use to see starch?

Answer 4

Iodine (stains blue/black/purple)

Question 5

What stain do you use to see cellulose in plant cell walls?

Answer 5

Iodine (stains yellow)

Question 6

What is the common all purpose stain?

Answer 6

Methylene blue

Question 7

What are stains and why do we use them?

Answer 7

Stains are coloured molecules which bind to molecules on a specimen which increases the contrast

Question 8

What are the benefits of using stains?

Answer 8

•Increases the contrast
•Which allows for parts of the cell to be distinguished easier
•Clearer image allows for more internal structure to be seen

Question 11

What can microscopes be used to observe?

Answer 11

Cell structure

Microscopes are essential tools in biology for studying cells.

Question 12

What are the two main types of microscopes mentioned?

Answer 12

Light microscopes and electron microscopes

Each type has different capabilities and uses.

Question 13

What is the maximum resolution of a light microscope?

Answer 13

Around 0.2 micrometres (µm)

This limits the maximum useful magnification to about ×1500.

Question 14

What types of structures can light microscopes observe?

Answer 14

Entire cells, nuclei, mitochondria, chloroplasts

These are larger structures that can be visualized with light microscopes.

Question 15

What are some advantages of light microscopes?

Answer 15

• Small and relatively cheap
• Simple specimen preparation
• Can produce colour images
• Allow observation of living specimens

These benefits make light microscopes accessible for educational use.

Question 16

What is the maximum resolution of electron microscopes?

Answer 16

Around 0.0002 micrometres (0.2 nm)

This high resolution allows for detailed observation of cellular structures.

Question 17

What can electron microscopes be used to observe?

Answer 17

Cell membranes, ribosomes, endoplasmic reticulum, lysosomes

These structures are much smaller and require higher magnification.

Question 18

What are some limitations of electron microscopes?

Answer 18

• Very large and expensive
• Complex specimen preparation
• Specimens must be viewed in a vacuum
• Images are always black and white

These factors limit the usability of electron microscopes in certain situations.

Question 19

What are the two types of electron microscopes?

Answer 19

Transmission electron microscopes (TEMs) and scanning electron microscopes (SEMs)

Each type serves different purposes in imaging.

Question 20

How do transmission electron microscopes (TEMs) create images?

Answer 20

By transmitting a beam of electrons through a specimen

Denser parts of the specimen absorb more electrons, appearing darker.

Question 21

What are the characteristics of images produced by TEMs?

Answer 21

• High-resolution
• Allow internal structures to be seen
• Two-dimensional

TEMs are crucial for detailed cellular studies.

Question 22

How do scanning electron microscopes (SEMs) create images?

Answer 22

By passing a beam of electrons across the surface of a specimen

This technique detects how electrons bounce back.

Question 23

What are the characteristics of images produced by SEMs?

Answer 23

• Three-dimensional
• Show the surface of specimens
• Lower maximum resolution than TEMs

SEMs provide a different perspective on sample morphology.