Environmental Factors Influencing the Growth

Question 1

What are the 3 factors inffluencing the growth of bacteria?

Answer 1

-pH
-Temperature
- Gaseous composition of atmosphere

Question 2

T or F
Most bacteria grow best in neutral pH. (7.0-7.35)

Answer 2

True

Question 3

Types of bacteria grow best in cold temp (10-20°C) are called

Answer 3

Psychrophiles

Question 4

Bacteria that grow best in moderate temp. (20-40°C)

Answer 4

Mesophiles

Question 5

Bacteria grow best at high temperatures. (50-60°C)

Answer 5

Thermophiles

Question 6

T or F most bacteria grow in the human body are mesophiles

Answer 6

True- near the body temp (37°C)

Question 7

Diagnostic laboratories routinely incubate cultures for bacterial growth at what degree celsius?
A. 37
B. 36
C. 35
D. 38

Answer 7

C

Question 8

Fungal culture are incubated at what temp?

Answer 8

30°C

Question 9

Example of Thermophiles bacteria

Answer 9

Pseudomonas sp.

Question 10

Type of bacteria that require oxygen to grow.

Answer 10

Obligate aerobes

Question 11

Example of obligate aerobes bacteria.

Answer 11

M. tuberculosis

Question 12

It can survive in the presence of O but not used O in metabolism.

Answer 12

Aerotolerant anaerobes/ facultative aerobes

Question 13

Cannot grows in the presence of Oxygen. Common in body.

Answer 13

Obligate anaerobes

Question 14

Common spp. of aerotolerant anaerobes.

Answer 14

Clostridium spp.

Question 15

Can grow either with or w/o the presence of oxygen. Majoritiy in the body.

Answer 15

Facultative anaerobes

Question 16

Organisms grow best in increase of CO2

Answer 16

Capnophilic

Question 17

Examples of capnophilic

Answer 17

• Helicobacter
• campylobacter

Question 18

Type of bacteria that require a decrease in O2.

Answer 18

Microaerophilic

Question 19

Examplen of facultative anaerobes.

Answer 19

E. coli

Question 20

Bacteria replicates through what?

Answer 20

Binary fission

Question 21

The time required for one cell to divide into two cells is called

Answer 21

Generation time or doubling time

Question 22

T or F
The fast growing bacteria usually grow for about 20 mins.

Answer 22

True

Question 23

T or F
For slow-growing bacteria, it usually takes 12 hours to grow.

Answer 23

False- 24 hrs.

Question 24

Example of fast and slow growing bacteria.

Answer 24

Fast (E. coli)
Slow (M. tuberculosis)

Question 25

T or F If bacteria are in a balanced growth state, the increase in bacterial numbers is proportional to the increase of mass, protein content, nucleic acid content.

Answer 25

True

Question 26

What are the 4 phases of bacterial growth phase?

Answer 26

- lag phase - log phase - stationary phase - death phase

Question 27

In this phase, there is no multiplication of bacteria because they're only preparing to divide.

Answer 27

Lag phase

Question 28

Which is true about the log phase? A. High multiplication, low no. of bacteria, short period of time B. No multiplication, long period of time, low no. of bacteria C. High multiplication, high no. Of bacteria, short period of time D. No multiplication, low no. Of bacteria, short perdiod of time

Answer 28

C

Question 29

It is a phase in which nutrients are limited. The no. of bacteria is constant. (Equal no. of dead and living cells.)

Answer 29

Stationary phase

Question 30

Phase in which the no. of nonviable bacterial cells exceeds the no. of viable cells.

Answer 30

Death phase

Question 31

Adjustments phase: lag phase Plate phase:

Answer 31

Stationary phase

Question 32

It is a procedure done to maintain the living bacteria alive.

Answer 32

Subculture

Question 33

3 ways in determination of cell numbers.

Answer 33

- Direct microscope count - Direct plate count - Density measurement

Question 34

Which is/are true about Direct microscopic count? A. It distinguishes between live and dead cells B. All bacteria are already dead C. Estimate the no. of bacteria present in specimen D. Common in urine sample

Answer 34

B,C,D

Question 35

Which is/are not true about direct plate count? A. Can be done by growing dillution of broth cultures on agar plates. B. Can determine the no. of colony-forming units per milliliters (CFU/mL) C. Limit is 500 colonies D. Provides a count of viable cells only

Answer 35

C. Limit is only 300 colonies

Question 36

A measurement based on the density of bacterial broth culture in log phase.

Answer 36

Density measurement.

Question 37

The desity refers to what?

Answer 37

Turbidity/cloudliness

Question 38

This method is used to prepare a standard inoculum for antimicrobial susceptibility testing

Answer 38

Density measurement.

Question 39

method usually used in water analysis

Answer 39

Direct plate count

Question 40

What equipment is used in density measurement?

Answer 40

Spectrophotometer