LESSON 9: BATERIAL GROWTH

Question 1

refers to increase in number of cells and not the size of cells.

Answer 1

Bacterial growth

Question 2

in which the bacteria undergo
asexual cell division to produce two daughter cells genetically identical to the parent cell.

Answer 2

Binary fission

Question 3

Begins with DNA replication and
segregation of nucleoids
(distribution between the future
daughter cells).

Answer 3

Cell division

Question 4

the time required for a bacterium to give rise to two
daughter cells under optimum conditions. A bacterium replicates and multiplies rapidly producing millions of cells within 24

Answer 4

Generation time

Question 5

Bacterial Concentration

Answer 5

(i) cell concentration
(the number of viable cells per unit volume of culture) or
(ii) biomass concentration
(dry weight of cells per unit volume of culture)

Answer 6

(i) cell concentration
(the number of viable cells per unit volume of culture) or (ii) biomass concentration
(dry weight of cells per unit volume of culture)

Question 7

denotes the total number of bacteria in the sample, irrespective
of whether they are living or dead.

Answer 7

Total count

Question 8

indicates the number of living or viable bacteria

Answer 8

Viable count

Question 9

This count can
be obtained by dilution method (series of sequential dilutions used to reduce a dense
culture of cells to a more usable concentration) or plating method (number of
colonies that grow after a suitable incubation time).

Question 10

FOUR PHASES OF GROWTH CURVE :

Answer 10

1. Lag phase
2. Log phase
3. Stationary phase
4. Decline phase

Question 11

The time between inoculation and beginning of multiplication is
known as

Answer 11

Lag phase

Question 12

This phase is characterized by rapid exponential cell growth of
bacteria at their maximum rate.

Answer 12

Log phase

Question 13

After log phase, the bacterial growth almost stops
completely due to depletion of essential nutrients, water oxygen, change in pH
of the medium, etc. and accumulation of their own toxic metabolic wastes
(exotoxin

Question 14

Death rate of bacteria exceeds the rate of replication of bacteria. Endospores start forming during this stage

Question 15

the bacterial population declines due to death of cells due to
(a) accumulation of toxic products and autolytic enzymes and
(b) exhaustion of nutrients

Question 16

is a method utilized for industrial and research purpose that
is achieved by using a special device for replenishing nutrients and removing
bacterial population continuously so that bacteria growth is not inhibited due to lack
of nutrients or due to accumulation of toxic bacterial metabolites

Question 17

REQUIREMENT FOR GRWOTH BACTERIAL

Answer 17

1. Physical requirement
2. Chemical requirement

Question 18

PHYSICAL REQUIREMENTS

Answer 18

1. Temperature
2. pH
3. Osmotic pressure

Question 19

most bacteria grow within a limited range of temperature, and the minimum and maximum temperatures are only 30°C apart.

Answer 19

Temperature

Question 20

1. Minimum temperature is the lowest
   temperature at which a species will grow.
2. Optimum temperature is
   when a species grow best.
3. Maximum temperature is the highest
   temperature at which a species can grow.

They grow poorly beyond
the minimum and maximum temperature

Question 21

refers to the alkalinity or acidity of a solution. Most bacteria grow
best near neutral pH (6.5 – 7.5).

Answer 21

pH

Question 22

the pressure required to stop water/solution from
diffusing through a barrier by osmosis

Answer 22

Osmotic pressure

Question 23

Microorganisms require water
for growth and are made up of

Answer 23

80-90%

Question 24

when solution outside the cell has higher concentration of solutes than
inside the cell, water is diffused outside of cell and the cell shrinks.

Answer 24

Hypertonic environment:

Question 25

: when solution outside the cell has lower concentration of
solutes than inside the cell, water is diffused inside of cell and the cell
swells.

Answer 25

Hypotonic

Question 26

: when concentrations in two solutions are same, so cell
will neither swells nor shrinks.

Answer 26

Isotonic

Question 27

: important for all organic compounds that make up a living cell;
consist half the dry weight of a typical bacterial cell.

Answer 27

Carbon

Question 28

helps form the amino group in amino acids

Answer 28

Nitrogen

Question 29

used to synthesize sulfur-containing amino acids and vitamins

Answer 29

Sulfur

Question 30

important in synthesis of ATP, nucleic acids and
phospholipids of cell membranes

Answer 30

Phosphorus

Question 31

minerals that are minimally required by microbes, and
are also essential in enzymatic reactions

Answer 31

Trace Elements

Question 32

is required by aerobic microorganisms, it is toxic to anaerobic bacteria like Clostridium tetanus

Answer 32

Oxygen

Question 33

Singlet oxygen: extremely reactive

ii. Superoxide free radicals: highly unstable, steals electron from
neighboring molecules thereby increasing free radicals

iii. Peroxide anion

iv. Hydroxyl radical: most reactive form of oxyge

Question 34

are essential organic compounds that cannot
be synthesized by an organism thus must be obtained from the
environment. Ex: vitamins

Answer 34

Organic growth factor