Ch.3 Observing Organisms Through A Microscope

Question 1

Microorganisms are measured in — and —

Answer 1

1. Micrometers
2. Nanometers

Question 2

Light Microscopy:
~Any kind of microscope that uses — light to observe specimens
~Types of light microscopy:
*— light microscopy
*— microscopy
* —— microscopy
* — microscopy
* — microscopy

Answer 2

1. Visible
2. Compound
3. Darkfield
4. Phase-contrast
5. Fluorescence
6. Confocal

Question 3

In a compound microscope, the image from the — lens is magnified again by the — lens

Answer 3

1. Objective
2. Ocular

Question 4

Total magnification = — lens * — lens

Answer 4

1. Objective
2. Ocular

Question 5

Resolution is the ability of the lenses to distinguish ——

Answer 5

Two points

Question 6

The maximum resolution of a compound light microscope is ——

Answer 6

0.2 micrometers

Question 7

Shorter wavelengths of light provide — resolution

Answer 7

Greater

Question 8

The refractive index is a measure of the —— ability of a —

Answer 8

1. Light-bending
2. Medium

Question 9

Light may — after passing through a specimen to an that it doesn’t pass through the ——

Answer 9

1. Refract
2. Objective Lens

Question 10

—— is used to keep light from refracting

Answer 10

Immersion Oil

Question 11

Darkfield Microscopy:
~Light objects are visible against a — background
~ — disk placed in —
~ Only light reflected off the specimen enters the ——

Answer 11

1. Dark
2. Opaque
3. Condenser
4. Objective Lens

Question 12

Phase- Contrast Microscopy:
~ Allows examination of —— and — cell structures
~ Brings together two sets of — rays, — rays, and — rays to form an image

Answer 12

1. Living organisms
2. Internal
3. Light
4. Direct
5. Diffracted

Question 13

Fluorescence Microscopy:
~ Uses — (——) light
~ Fluorescenct substances absorb —— and emit —— (—) light
~ Cells may be stained with fluorescent dyes (—) if they do not naturally fluoresce

Answer 13

1. UV (short wavelength)
2. UV light
3. Longer wavelength (visible)
4. Fluorochromes

Question 14

Confocal Microscopy:
~ Cells are stained with fluorochrome dyes
~ ——(—) light is used to excite a single plane of a specimen
~ Each plane in a specimen is illuminate and a 3-d image is constructed with a computer

Answer 14

Short wavelength (blue)

Question 15

Electron Microscopy:
~ Uses — instead of light
~ The —— of electrons gives — resolution
~ Used for images too small to be seen with light microscopes, such as viruses

Answer 15

1. Electrons
2. Shorter wavelength
3. Greater

Question 16

Transmission Electron Microscopy:
~ A beam of electrons passes through — sections of a specimen, then through an — lens, then focused on a — lens
~ Specimens may be stained with heavy-metal salts for contrast
~ Magnifies — to —x; resolution of 10 nanometers

Answer 16

1. Ultra thin
2. Electromagnetic
3. Projector
4. 10,000 to 100,000

Question 17

Scanning Electron Microscopy:
~ An electron gun produces a beam of electrons that scans the surface of an entire specimen
~ —— emitted from the — produce a 3-d image
~ magnifies objects — to — X; resolution of 10 nanometers

Answer 17

1. Secondary Electrons
2. Specimen
3. 1,000 to 10,000

Question 18

Preparing Smears for Staining:
~ Stains consist of a — and — ion, one of which is colored
~ In a — dye, the chromophore is a cation
~ In an — dye, the chromophore is an anion
~ Staining the background instead of the cell is ——

Answer 18

1. Positive
2. Negative
3. Basic
4. Acidic
5. Negative Staining

Question 19

Simple Stains:
~ Simple Stain: use of a —— dye
~ Highlights the — microorganism to visualize cell shapes and structures
~ A mordant may be used to — the stain or — the specimen to — it

Answer 19

1. Single basic
2. Entire
3. Hold
4. Coat
5. Enlarge

Question 20

Differential Stains:
~ Unlike simple stains, differential stains react differently to different bacteria
~ Used to distinguish between bacteria
* ——
* ———

Answer 20

1. Gram stain
2. Acid-fast stain

Question 21

Gram Stain:
~ Classifies bacteria into gram-positive or gram-negative
* Gram positive bacteria have — peptidoglycan cell walls. They — the crystal violet stain and appear —
* Gram negative bacteria have — peptidoglycan cell walls and a layer of —. They do —— the crystal violet; they remain colorless until counterstained with safranin and then appear —

Answer 21

1. Thick
2. Retain
3. Purple
4. Thin
5. Lipopolysaccharides
6. Pink

Question 22

Gram Staining Steps:
1. Application of —— (purple dye)
2. Application of — (mordant)
3. —— (decolonization)
4. Application of — (counterstain)

Answer 22

1. Crystal Violet
2. Iodine
3. Alcohol Wash
4. safranin

Question 23

Acid Fast Stain:
~ Binds only to — that have a waxy material in their cell walls, which is not decolonized by acid-alcohol
~ Used for the identification of
* — & —

Answer 23

1. Bacteria
2. Mycobacterium
3. Nocardia

Question 24

Negative Staining for Capsules:
~ Capsules are a — converting that — accept most dyes
~ Suspension of India ink or nitro sim contrasts the background with the capsule, which appears as a — around the cells

Answer 24

1. Gelatinous
2. DO NOT
3. Halo

Question 25

Endospore Staining: ~Endospores are —, — structures inside some cells the cannot be stained by — methods ~ Primary Stain: ——, usually with — ~ Decolorize cells: — ~ Counterstain: — ~ Spores appear — within — or — cells

Answer 25

1. Resistant, dormant 2. Ordinary 3. Malachite green 4. Heat 5. Water 6. Safranin 7. Green 8. Red or pink