LT Microscope

Question 1

What are the functions of light microscope components?

Answer 1

• Magnification and resolution
• Focus adjustment (coarse and fine knobs)
• Specimen movement (mechanical stage)

Question 2

Differences between compound and stereoscopic microscopes?

Answer 2

Compound:
- Higher magnification (up to 400X)
- Thin specimen viewing
Stereoscopic:
- 3D images
- Thicker specimen viewing
- Lower magnification (50X)

Question 3

Total magnification calculation?

Answer 3

Ocular magnification × Objective magnification (e.g., 10X × 40X = 400X)

Question 4

Relationship between magnification and working distance?

Answer 4

As magnification ↑, working distance ↓

Question 5

How to calculate field diameter?

Answer 5

Use the equation:
Field Diameter1 × Magnification1 = Field Diameter2 × Magnification2

Question 6

Estimating object size under a microscope?

Answer 6

Measure fraction of field diameter occupied
Multiply field diameter by this fraction

Question 7

Plant vs. animal cells under a microscope?

Answer 7

Plant cells:
- Cell wall
- plasma membrane
- nucleus
- cytoplasm
- Stained with iodine or methylene blue
Animal cells:
- Plasma membrane
- nucleus
- cytoplasm
- Stained with methylene blue

Question 8

Why water for plant cells and saline for animal cells?

Answer 8

Plant cells need water for turgidity
Animal cells need isotonic saline to avoid damage

Question 9

Coarse vs. fine focus knobs?

Answer 9

Coarse Focus: For 4X objective only
Fine Focus: For 10X, 40X, and higher objectives

Question 10

Proper microscope storage?

Answer 10

Lower stage
Set to 4X objective
Turn off light, wrap cords
Store in assigned cabinet slot

Question 11

what is the plasma membrane and what is it made of

Answer 11

fatty boundary that surrounds all cells
made of phospholipids and proteins

Question 12

cell size (eukaryotic vs prokaryotic)

Answer 12

eukaryotic: 10-100 um
prokayotic: 1-10 um

Question 13

DNA in eukaryotes vs prokaryotes
AND
organelles
AND what does the cytoplasm contain in eukaryotes

Answer 13

• DNA in eukaryotes is enclosed in a membrane bound compartment called the nucleus
• eukaryotes have membrane bound organelles that help with various functions in the cell

Prokaryotes do not have a nucleus nor organelles

cytoplasm contains organelles and dissolved chemicals

Question 14

what are onion vs animal cheek cells stained with

Answer 14

a) animal cheek epithelial cell stained with methylene blue
b) onion epidermal cells stained with iodine

Question 15

what does mechanical stage do

Answer 15

clips slide into place and allows users to move the slide in the x plane (using stage control knob)

Question 16

what does sample stage do

Answer 16

provides a platform for the specimen + allows users to move the specimen in the y plane (front to back) (using stage control knob)

Question 17

what does the condenser do

Answer 17

collects and concentrates light onto the specimen
it can be controlled to optimize contrast and resolution of the image and reduce glare

Question 18

what does the condenser adjustment lever do

Answer 18

control the distance of the condenser to the sample stage

Question 19

condenser adjustment lever down does what to the condenser

Answer 19

it brings the condenser up (and vise versa)

Question 20

relationship between magnification and height of condenser

Answer 20

the lower the magnification the higher the condenser should be

Question 21

what do the iris diaphragm & lever do

Answer 21

controls the amount of light entering and leaving the condenser (can be used to optimize contrast and reduce glare)

Question 22

relationship between magnification and field of depth

Answer 22

higher magnification = thinnest focal plane = lowest depth of field

highest magnification is easiest because you are looking at the thinnest slice

Question 23

in what position should be the condenser lever when viewing a specimen with 10X and 40X objective

Answer 23

condenser should be brought down (lever up)