Cells + Microscopy

Question 1

What are the differences between Plant and Animal Cells

Answer 1

Plant cells:

• Large permanent Vacuole
• Cell wall
• Chlorosplasts
• amylosplast
• plasmosdesmata

Animal cells:

• Lysosomes
• Centrioles

Question 2

Equation Of magnification

Answer 2

I = AM

Question 3

Difference between Prokaryote and Eukaryotes

Answer 3

Prokaryote: (organisms include all bacteria)

• Nucleoid, free strand of DNA
• no membrane bound organelles
• Divide by binary fission
• Ribsomes : 70S (50, 30 sub units)
• anaerobic and aerobic

Eukaryote: organisms include all fungi, plant and animals.

• Nucleus
• Divide by mitosis and meiosis
• Ribosomes : 80S (60, 40 Sub units)
• aerobic

Question 4

Define resolution

Define Magnification

Answer 4

The extent to which two objects can be distinguoshed as two different structures

The extent to which thr actual size of the object is enlarged into the image seen through a microscope.

Question 5

Magnification and resolution of the 3 microscopes

Answer 5

Magnification

Light Microscope: up to x2000
Transmission em: up to x500,000
Scanning Em : up to 100,000

Resolution:
Light: 200nm
TEM: 0.5nm
SEM: 3-10nm

Question 6

What is the difference in micrsocopes (how they work)

Answer 6

TEM: Electron beams pass through the specimen

SEM: Electrons are reflected back from the specimen and detected

Light: Light shines through sample being observed.

Question 7

Advantages of EM

Answer 7

TEM: Higher magnification and resolution, enables intracellular details to be observed

SEM: High mag and resolution, 3D images of Surfaces.

Question 8

Disadvantages of EM

Answer 8

-Expensive
-complex preparation
-Images are black and white( artificial colour can be added)
Artefacts can be introduced during preparation.

Question 9

4 types of preparation of samples

And what does sectioning mean

Answer 9

Sectioned - cut into thin slices, fixed preserved and sterilised and stained

-Dry mount

• Wet mount
• Squash slide - pressure applied to slide- Root tops
• Smear slide - thin even coating on slide, cover slip place on sample e.g. blood

Question 10

Structures of Nucleus and Functions

Answer 10

Nucleolus: Creates ribosomes from RNA- rRNA
Nucleus - Contains genetic coded information
Nuclear pores - Transfer of RNA/ ribosomes