Chapter 3: Culturing and Microscopy

Question 1

What is a medium in microbiology?

Answer 1

A nutrient-rich substance used to grow microorganisms in the lab.

Question 2

What is a culture?

Answer 2

The growth of microorganisms in or on a nutrient medium.

Question 3

What is inoculation?

Answer 3

Introducing microorganisms into a medium to initiate growth.

Question 4

What does sterile mean in microbiology?

Answer 4

Completely free of all living microbes, including spores and viruses.

Question 5

What is incubation?

Answer 5

Keeping cultures at specific temperatures to promote microbial growth.

Question 6

What is liquid media?

Answer 6

A broth-based medium used for growing large volumes of bacteria.

Question 7

What is semisolid media?

Answer 7

Media with a low concentration of agar, useful for testing motility.

Question 8

What is solid media?

Answer 8

Media containing enough agar to form a firm surface for colony growth.

Question 9

What is agar?

Answer 9

A complex polysaccharide derived from algae, used to solidify media.

Question 10

What is synthetic or defined media?

Answer 10

Media with precisely known chemical composition.

Question 11

What is complex media?

Answer 11

Media with at least one ingredient not chemically defined (e.g., blood, peptones).

Question 12

What is a general-purpose medium?

Answer 12

A media that supports growth of a wide range of microbes.

Question 13

What is an enriched medium?

Answer 13

Media supplemented with special nutrients to grow fastidious organisms.

Question 14

What are growth factors?

Answer 14

Organic compounds like vitamins or amino acids that some microbes require.

Question 15

What does fastidious mean in microbiology?

Answer 15

Organisms with complex nutritional requirements.

Question 16

What is a selective medium?

Answer 16

Media that allows growth of certain microbes while inhibiting others.

Question 17

What is a differential medium?

Answer 17

Media that distinguishes between microbial types based on biochemical traits.

Question 18

What is hemolysin?

Answer 18

An enzyme that breaks down red blood cells, often tested with blood agar.

Question 19

What is reducing medium?

Answer 19

Media that absorbs oxygen to grow anaerobic organisms.

Question 20

What is fermentation medium used for?

Answer 20

To detect microbial fermentation of specific carbohydrates.

Question 21

What is transport media?

Answer 21

Media used to preserve and transport specimens without allowing growth.

Question 22

What is assay media?

Answer 22

Media used to test effects of antibiotics, disinfectants, or drugs.

Question 23

What is enumeration media?

Answer 23

Media used to count the number of organisms in a sample.

Question 24

What is a colony in microbiology?

Answer 24

A visible mass of microbial cells derived from a single parent cell.

Question 25

What is an inoculating loop?

Answer 25

A wire tool used to transfer microbes to media.

Question 26

What is a pure culture?

Answer 26

A culture containing only one species of microorganism.

Question 27

What does axenic mean?

Answer 27

A culture that is completely free of all other living organisms.

Question 28

What is a subculture?

Answer 28

A culture made from an isolated colony to maintain or study it

Question 29

What is a mixed culture?

Answer 29

A culture that contains more than one species of microorganism.

Question 30

What is a contaminated culture?

Answer 30

A culture that has unwanted microbes introduced.

Question 31

What are contaminants?

Answer 31

Unwanted organisms that invade a culture or environment

Question 32

What is a streak plate?

Answer 32

A method used to isolate pure colonies by spreading cells across an agar surface.

Question 33

What is a pour plate?

Answer 33

A method where diluted samples are mixed with agar and poured into plates.

Question 34

What is a spread plate?

Answer 34

A technique where a diluted sample is spread evenly across the surface of an agar plate

Question 35

What is microscopy?

Answer 35

The use of microscopes to view small objects and microorganisms.

Question 36

What is refraction?

Answer 36

The bending of light as it passes through different substances.

Question 37

What is a real image in microscopy?

Answer 37

The image formed by the objective lens that is projected to the ocular lens.

Question 38

What is a virtual image in microscopy?

Answer 38

The magnified image seen through the ocular lens.

Question 39

What is a simple microscope?

Answer 39

A microscope with a single magnifying lens.

Question 40

What is a compound microscope?

Answer 40

A microscope with two lenses: objective and ocular.

Question 41

What is the ocular lens?

Answer 41

The eyepiece lens that further magnifies the image.

Question 42

What is the objective lens?

Answer 42

The lens closest to the specimen; provides primary magnification.

Question 43

How is total magnification calculated?

Answer 43

Objective lens magnification × ocular lens magnification.

Question 44

What is resolution in microscopy?

Answer 44

The ability to distinguish two close points as separate.

Question 45

What is resolving power?

Answer 45

The measurement of how well a microscope can separate two objects.

Question 46

What is refractive index?

Answer 46

A measure of how much a substance bends light.

Question 47

What is bright-field microscopy?

Answer 47

Standard light microscopy where light passes directly through the specimen.

Question 48

What is dark-field microscopy?

Answer 48

A technique that shows specimens as bright objects on a dark background.

Question 49

What is phase-contrast microscopy?

Answer 49

Enhances contrast in transparent specimens without staining.

Question 50

What is interference microscopy?

Answer 50

Uses two beams of light to produce detailed 3D images of living cells.

Question 51

What is fluorescence microscopy?

Answer 51

Uses UV light to excite fluorescent dyes that emit visible light.

Question 52

What is confocal microscopy?

Answer 52

Uses lasers and optical sections to build a 3D image.

Question 53

What is electron microscopy?

Answer 53

Uses electron beams to view structures at high magnification (TEM, SEM).

Question 54

What is a wet mount?

Answer 54

A preparation where a specimen is placed in a drop of liquid under a coverslip.

Question 55

What is a hanging drop mount?

Answer 55

A technique used to view live microorganisms and their motility.

Question 56

What is a stained smear?

Answer 56

A thin film of microbes on a slide that is fixed and stained.

Question 57

What does it mean to "fix" a specimen?

Answer 57

To preserve and attach cells to a slide by heat or chemicals.

Question 58

What is a basic dye?

Answer 58

A dye with a positive charge that binds to negatively charged cell components.

Question 59

What is an acidic dye?

Answer 59

A negatively charged dye that stains background rather than cells.

Question 60

What is a positive stain?

Answer 60

A stain that colors the specimen directly.

Question 61

What is a negative stain?

Answer 61

stain that colors the background but not the specimen.

Question 62

What is a simple stain?

Answer 62

Uses one dye to color all cells the same

Question 63

What is a differential stain?

Answer 63

uses multiple dyes to distinguish different cell types or structures.

Question 64

What is a Gram stain?

Answer 64

A staining method that differentiates bacteria by cell wall structure.

Question 65

What are Gram-negative bacteria?

Answer 65

Bacteria with thin peptidoglycan and an outer membrane; stain pink.

Question 66

What are Gram-positive bacteria?

Answer 66

Bacteria with thick peptidoglycan and no outer membrane; stain purple.

Question 67

What is an acid-fast stain used for?

Answer 67

To detect Mycobacterium species with waxy cell walls.

Question 68

What is an endospore stain?

Answer 68

A stain that highlights bacterial endospores.

Question 69

What does "vegetative" mean in microbiology?

Answer 69

Refers to actively growing and dividing cells.

Question 70

What is a capsule stain?

Answer 70

A staining method to detect the protective capsules around some bacteria.

Question 71

What is a flagella stain?

Answer 71

A stain used to visualize bacterial flagella.