PHYSICAL REQUIREMENTS OF MICROORGANISMS

Question 1

Temperature meaning (3)

Answer 1

 Great influence on growth since growth is
dependent on chemical reactions that are
affected by temperature
 Also affects reproduction, morphology,
metabolic processes & nutritional
requirements
 Microorgs grow over a broad range of
temperature

Question 2

3 types of cardinal temperature for growth of microorganisms

Answer 2

Minimum
Optimum
Maximum

Question 3

lowest temp in which microbes can grow

Answer 3

Minimum

Question 4

temp in which microbes best grow

Answer 4

Optimum

Question 5

highest temp in which microbes can grow

Answer 5

Maximum

Question 6

Transport process slow growth cannot occur

Answer 6

Membrane gelling

Question 7

Collapse of cytoplasmic membrane ; thermal lysis

Answer 7

Protein denaturation

Question 8

Occuring at increasingly rapid rates

Answer 8

Enzymatic reactions

Question 9

Psychrophiles (3)

Answer 9

Cold-loving;

grow best at 15-20 °C

e.g. genera of Pseudomonas, Flavobacterium, Alcaligenes

Question 10

Mesophiles (3)

Answer 10

Moderate-temerature-loving

grow best at 25-40 °C

e.g. Most microorganisms

Question 11

Thermophiles 4

Answer 11

Heat-loving

grow best at 50-60°C

E.g. microbes in volcanic areas, compost heaps, hot springs

No eukaryotes grow at > 60 °C

Question 12

Group of microorganism based on tempt range

Answer 12

Psychrophiles Mesophiles Thermophiles

Question 13

Physiological Groups based on Responses to
Oxygen 4

Answer 13

Aerobes, Facultatives, Anaerobes, Microaerophiles

Question 14

Aerobes 2

Answer 14

Require O2
(21 % in a standard air)

e.g. Molds, Mycobacterium, Legionella

Question 15

Facultatives (2)

Answer 15


Can grow w/(aerobic) or w/o air (Anaerobic)



E.g. Enterobacteriaceae (e.g. E. coli), many yeasts
(e.g. Saccharomyces cerevisiaea)

Question 16

yielding processes; obtain
energy by fermentation under anaerobic condition

Answer 16

O2

Question 17

due to certain molecules
produced during reactions involving O2 (eg.
superoxide radical, hydrogen peroxide, hydroxyl
radicals – damage cells & destroy vital
components like DNA)

Answer 17

Toxicity to O2

Question 18

Cannot grow in air and do not use O2
for E
production
e.g. Clostridium

Answer 18

Anaerobes

Question 19

Limited tolerance due to susceptibility to
superoxide dismutase & hydrogen peroxide formed
in cultures under aerobic condition

Answer 19

Microaerophiles

Question 20

Can use O2
for E-yielding reactions but grow best
at 1-15% O2
in standard air

Answer 20

Microaerophiles

Question 21

Campylobacter jejuni as an example of

Answer 21

Microaerophiles

Question 22

Toxic forms of oxygen (4)

Answer 22

Superoxide, hydro perox, hydroxyl radical
Water

Question 23

The force with which water moves through the
cytoplasmic membrane from a solution of high
solute concentration to a solution of low solute
concentration

Answer 23

Osmotic pressure

Question 24

solute-loving microbes (eg.
Microbes in the ocean)

Answer 24

Halophiles

Question 25

pressure exerted by water
on cells by the weight of the water resting on top
of them

Answer 25

Hydrostatic Pressure

Question 26

pressure-dependent microbes (eg.
microbes in the ocean floor)

Answer 26

Barophiles