Growth Kinetics and Culture Systems - Microbial Growth - Life Sciences Previous Year Questions

1

2007 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2007

The specific growth rate (μ) of a microorganism in death phase is

A

0 (zero)

B

μmax

C

less than zero

D

greater than zero

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2

2007 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2007

The volume of culture at the end of second day (neglect loss due to vaporization) is

A

6 m³

B

8 m³

C

10 m³

D

12 m³

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3

2007 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2007

What would be the dilution rate of the system at the end of second day ?

A

2.00

B

0.20

C

0.02

D

0.01

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4

2007 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2007

What is the generation time of this bacterium?

A

15 min

B

20 min

C

25 min

D

30 min

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5

2007 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2007

If the initial inoculum was only 1 cell, then after 10 hours what will be the number of cells?

A

2²⁰

B

2²⁴

C

2³⁰

D

2⁴⁰

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6

2008 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2008

Diauxic pattern of biomass growth is associated with

A

multiple lag phases

B

sequential utilization of multiple substrates

C

simultaneous utilization of multiple substrates

D

absence of lag phase

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7

2008 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2008

In a chemostat, evaluate the dilution rate at the cell wash-out condition by applying Monod’s model with the given set of data: μ_max = 1 h^-1; Y_X/S = 0.5 g g^-1; K_s = 0.2 g L^-1; S₀ = 10 g L^-1

A

1.00 h^-1

B

0.49 h^-1

C

0.98 h^-1

D

1.02 h^-1

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8

2008 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2008

A bacterial culture having a specific oxygen uptake rate of 5 mmol O₂ (g-DCW)^-1hr^-1 is being grown aerobically in a fed-batch bioreactor. The maximum value of the volumetric oxygen transfer coefficient is 0.18s^-1 for the stirred tank bioreactor and the critical dissolved oxygen concentration is 20% of the saturation concentration (8 mg/ml). The maximum density to which the cells can be grown in the fed-batch process without the growth being limited by oxygen transfer is, approximately

A

14 g/l

B

26 g/l

C

32 g/l

D

65 g/l

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9

2008 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2008

The respective values of the Monod kinetic constants μ_max (hr^-1) and K_s (mg/l) are as follows:

A

0.08, 8

B

0.8, 0.8

C

0.8, 80

D

8, 8

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10

2008 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2008

The same culture (with the μ_max and K_s values as computed above) is cultivated in a 10-litre chemostat being operated with a 50 ml/min sterile feed containing 50 g/l of substrate. Assuming an overall yield coefficient of 0.3 g-DCW/g-substrate, the respective values of the outlet biomass and substrate concentrations are

A

15 g/l, 48 mg/l

B

15 g/l, 0.48 g/l

C

48 g/l, 15 g/l

D

4.8 g/l, 4.8 g/l

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11

2009 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2009

A culture vessel in which physical, physicochemical and physiological conditions, as well as cell concentration, are kept constant is known as

A

Cell concentrator

B

Biostat

C

Batch bioreactor

D

Incubator

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12

2009 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2009

Which of the following statements are true about bioreactors ?
P. Continuous bioreactors provide less degree of control and uniform product quality than batch bioreactors.
Q. Batch bioreactors are ideally suited for reaction with substrate inhibition.
R. Choice of a bioreactor is dictated by kinetic considerations.
S. Fed batch bioreactors are also called semibatch bioreactors.

A

P, Q

B

Q, S

C

R, S

D

P, R

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13

2009 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2009

Determine the correctness or otherwise of the following Assertion (a) and Reason (r) :
Assertion (a) : Bacterial growth is called synchronous when majority of the cells are in same stage of the bacterial cell cycle.
Reason (r) : Synchronous culture can be obtained by growing bacteria in an enriched medium

A

Both (a) and (r) are true and (r) is the correct reason for (a).

B

Both (a) and (r) are true but (r) is not the correct reason for (a).

C

is true but (r) is false.

D

is false but (r) is true.

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14

2009 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2009

Which one of the following approaches would be appropriate if one wants to cultivate microorganisms under constant physiological conditions ?

A

Fed batch culture

B

Batch culture

C

Continuous culture

D

Discontinuous culture

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15

2009 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2009

Initial density of a culture of bacteria with a generation time of 30 minutes was 1 × 10³ cells/ml. After 5 hours of incubation, what serial dilution will you have to plate out to get ~100 colonies per ml ?

A

10³

B

10⁴

C

10⁵

D

10⁶

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16

2010 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2010

A growing bacterial culture with a doubling time of 20 min reaches cell density of 2 × 10⁸ cells/ ml in 3 hours. How much time would it take to reach the cell density of 1 × 10⁹ cells /ml?

A

200 min

B

180 min

C

160 min

D

90 min

Check answer

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17

2011 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2011

In an actively growing (exponential phase) yeast culture, the cell concentration increased from 10⁵ cells per ml to 10⁸ cells per ml in 4 h. The doubling time of the yeast is

A

120 minutes

B

30 minutes

C

18 minutes

D

60 minutes

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18

2012 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2012

A rich medium is inoculated with a bacterium that divides every 30 minutes. The number of bacteria at the end of 50 hours is

A

\(2 \times 10^{10}\)

B

\(2 \times 10^{20}\)

C

\(1 \times 10^{50}\)

D

\(1 \times 2^{100}\)

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19

2012 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2012

Ten bacteria were inoculated into a rich medium. If at the end of ten hours the total number of cells is \(10^8\), then the number of elapsed generations and the generation time respectively is

A

10, 120 minutes

B

10, 60 minutes

C

20, 30 minutes

D

40, 15 minutes

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20

2013 · Life Sciences · Microbial Growth · Growth Kinetics and Culture Systems

Life Sciences (XL) 2013

Chemostat is a continuous culture system in which sterile medium is fed into the culture vessel at the same rate as the spent medium is removed. If in a chemostat culture, the flow rate is 30 ml h⁻¹ and volume of the medium inside the vessel is 100 ml, the dilution rate in h⁻¹ is

A

3.33

B

1.50

C

0.75

D

0.30

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