History and Scope of Microbiology

Question 1

Define a microorganism

Answer 1

organisms too small to be seen clearly by the unaided eye

Question 2

Define the theory of spontaneous generation

Answer 2

• living organisms could develop from nonliving matter. e.g. Maggots on meat
• supernatural forces cause disease

Question 3

How was spontaneous generation disproved

Answer 3

• Francesco Redi: well kept rotting meat won’t develop maggots
• Lazzaro Spallanzani: no bacterial growth in SEALED glass flasks that contained water and seeds after placing
  in boiling water for ~45 minutes
• Louis Pasteur: Used heat and air trapping to prevent growth (MAIN ONE)

Question 4

Selective culture (enrichment procedures)

Answer 4

Microbes can be
cultured selectively by providing nutrients
required by some but not all microorganisms in a
sample

Question 5

Sterilization

Answer 5

sterilization kills living organisms (pasteurisation)

Question 6

Aspectic Technque

Answer 6

practices that reduce contamination of sterile sites

Question 7

Pure Culture

Answer 7

isolation of single organisms

Question 8

Explain Koch’s postulates

Answer 8

1. microorganisms causing disease must be present in every case of disease
2. grow in pure culture
3. cause disease when inoculated into
   healthy animal
4. grow in pure culture from inoculated animal

Question 9

Explain how the enrichment procedure was developed.

Answer 9

• Isolated growth preferences for microbes
  Winogradsky column.

Question 10

Describe the interaction of plants with microbes giving specific examples

Answer 10

Disease: caused potato blight, rust and smut are fungal diseases in cereal ; tobacco mosaic virus; nitrogen fixation

Question 11

What were Pastuers experiments

Answer 11

Flask with swan neck is heated to destroy
microorganisms
A. Flask with air trap remains sterile
B. Flask with swan neck removed grows
bacteria
C. Flask tipped so liquid enters swan neck
grows bacteria

Question 12

Exceptions of Koch’s postulates

Answer 12

1. Asymptomatic carriers
2. Obligate human pathogens
   with no animal model (infects only humans)
3. Organisms that can’t be grown
   in pure culture (e.g. viruses)

Question 13

Autotrophic Growth (Enrichment procedures)

Answer 13

use chemicals as
the sole source of energy and carbon.

Question 14

List the technological advances that made microscopy possible and briefly describe the
people and experiments involved

Question 15

Describe an observation that supported spontaneous generation and explain the
experiment that disproved this theory.

Question 16

Explain how Koch’s postulates proved Pasteur’s “germ theory of disease”.

Question 17

How does selective culture work?

Question 18

Is it advisable to kill all microorganisms? Give your reasons why