Microbial Metabolism, Growth, and Genetics

Question 1

What are humans unable to do in their own bodies?

Answer 1

Alcohol fermentation.

Question 2

What is photosynthesis?

Answer 2

Conversion of light energy from the sun into chemical energy which is used for carbon fixation, cyanobacteria, algae, and green plants all contribute to this vital recycling of carbon.

Question 3

How are phototrophs different from chemotrophs?

Answer 3

Phototrophs use light energy while chemotrophs use chemical energy from oxidation-reduction reactions.

Question 4

How are autotrophs different from heterotrophs?

Answer 4

Autotrophs use inorganic carbon (CO2), while heterotrophs use organic carbon (organotrophs).

Question 5

Which microorganisms are the most medically important?

Answer 5

Chemoheterotrophs.

Question 6

Define psychrophils?

Answer 6

Cold loving microbes, maximal growth is at about 10°C.

Question 7

Define psychrotrophs?

Answer 7

Maximal growth at about 20°C.

Question 8

Define mesophils?

Answer 8

Moderate temp loving microbes, maximal growth at about 37°C.

Question 9

Define thermophiles?

Answer 9

Heat loving microbes, maximal growth at about 90°C.

Question 10

Define minimum growth temperature?

Answer 10

The lowest temperature at which a species will grow.

Question 11

Define optimum growth temperature?

Answer 11

The temperature at which a microbe grows the best.

Question 12

Define maximum growth temperature?

Answer 12

The highest temperature at which growth is possible.

Question 13

What is the range at which most bacteria grow?

Answer 13

Minimum and maximum temperature being 30°C apart.

Question 14

What is the pH most bacteria grow best at?

Answer 14

Between 6.5 and 7.5.

Question 15

What are obligate aerobes?

Answer 15

Require O2 to live.

Question 16

What are facultative anaerobes?

Answer 16

Use O2 when present but are able to continue growth in its absence.

Question 17

What are obligate anaerobes?

Answer 17

Are unable to use O2 and are harmed by its presence.

Question 18

What are aerotolerant anaerobes?

Answer 18

Can’t use O2 for growth but tolerate O2 fairly well.

Question 19

What are microaerophiles?

Answer 19

Grow only in O2 concentrations lower than in air.

Question 20

What is selective media?

Answer 20

By inhibiting unwanted microorganisms with salts, dyes, or other chemicals, selective media allow growth of only the desired microorganism.

Question 21

What is differential media?

Answer 21

Used to distinguish among different microorganisms.

Question 22

What is streak plate dilution?

Answer 22

Bacteria is smeared onto a place and continuously diluted until a single colony can be separated and looked at separately.

Question 23

How do you preserve a bacterial culture short term?

Answer 23

Refrigeration.

Question 24

How do you preserve a bacterial culture long term?

Answer 24

Deep freezing or lyophilization (freeze-drying).

Question 25

Define generation time?

Answer 25

The time required for a cell to divide or a population to double.

Question 26

What is the logarithmic progression of bacterial populations?

Answer 26

Bacterial division occurs according to logarithmic progression (2 cells to 4 cells to 8 cells etc.).

Question 27

What is the lag phase of growth?

Answer 27

Little or no change in the number of cells but metabolic activity is high.

Question 28

What is the log phase of growth?

Answer 28

Bacteria multiply at the fastest rate possible under the conditions provided.

Question 29

Which phase is most sensitive to antibiotics?

Answer 29

Log phase.

Question 30

What is the stationary phase of growth?

Answer 30

Cell division and cell death are equal.

Question 31

What is the death phase of growth?

Answer 31

Number of cell death exceeds the number of new cells formed.

Question 32

What is the best way to count cell numbers?

Answer 32

Spectrophotometer.

Question 33

What does a spectrophotometer do?

Answer 33

Measures the amount of light that passes through a suspension of cells.

Question 34

Define sterilization?

Answer 34

Process of destroying all forms of microbial life on an object or in a material, it is absolute.

Question 35

Define disinfection?

Answer 35

Process of reducing or inhibiting microbial growth by disinfectant.

Question 36

Define antisepsis?

Answer 36

Chemical disinfection of the skin, mucous membranes, or other living tissue.

Question 37

Define germicide?

Answer 37

Chemical agent that rapidly kills microbes but not necessarily their endospores.

Question 38

Define bacteriostasis?

Answer 38

A condition in which bacterial growth and multiplication are inhibited but bacteria are not killed (refrigeration).

Question 39

Define asepsis?

Answer 39

Absence of pathogens from an object or area, aseptic technique is deigned to prevent the entry of pathogens into the body (mask).

Question 40

Define degerming?

Answer 40

The removal of transient microbes from the skin by mechanical cleansing or by the use of an antiseptic (alcohol swabs).