Tag: discoveries by louis pasteur

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Multiple choice evs louis pasteur contribution of louis pasteur discoveries by louis pasteur discovery of microorganisms

Micro-organisms having optimum temperature for growth below $15^0$ C which cannot grow above $20^0$ C are called

  1. Mesophiles

  2. Thermophiles

  3. Psychrophiles

  4. None of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

(A)Mesophile is an organism that grows in a moderate temperature from 20-45 degree Celcius.

(B)A thermophile is an organism that grows in a relatively high temperature from 41-122 degree Celcius.
(C) is an organism that grows in a relatively low temperature from below 15-degree Celcius.
So, the correct option is 'Psychrophiles'.

Multiple choice evs louis pasteur contribution of louis pasteur discoveries by louis pasteur discovery of microorganisms

With which of the following is the name of Louis Pasteur associated?

  1. Explanation of the formation of simple organic molecules in the early atmosphere of earth

  2. The proposition of the composition of gases in the early atmosphere of earth

  3. Disproving the theory of spontaneous generation of organisms

  4. Proposition that the first photosynthetic organisms were cyanobacteria
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Louis Pasteur famously used swan-neck flasks to disprove the theory of spontaneous generation, demonstrating that micro-organisms exist in the air and contaminate sterile broths. Options A and B relate to early Earth atmosphere experiments like Miller-Urey, while D refers to evolutionary theories of cyanobacteria. Thus, option C is correct.

Multiple choice biology production of food from animals contribution of louis pasteur discoveries by louis pasteur discovery of microorganisms

Which of the following statements holds good with pasteurization?

  1. Pasteurization removes all the bacteria from milk.

  2. Pasteurization is a synonym for sterilization.

  3. Milk needs to be refrigerated even after pasteurization.

  4. Pasteurized milk causes lactose intolerance.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

a) Pasteurization does not remove all bacteria from milk. It reduces the harmful active bacteria from the milk but it is unable to kill their spores which might erupt again under favourable conditions. 

b) Pasteurization is not a synonym for sterilization because of two processes are very different from each other when it comes to application. Pasteurization is the process where the milk is heated at to a specific temperature for a set period of time to reduce the bacterial population to prevent the spoilage and increase the shelf life. Sterilization kills all forms of living microorganism in the sample along with the spores of microorganism which cannot be done by the pasteurization.
c) Milk needs to be refrigerated even after pasteurization because refrigeration helps to keep the microorganism inactive for longer duration which increases the shelf life of the milk.
d) Pasteurized milk does not cause lactose intolerance because it does not affect or degrade the lactase enzyme which is responsible for lactose digestion in the humans.
So, the correct answer is 'Milk needs to be refrigerated even after pasteurization'.

Multiple choice biology production of food from animals contribution of louis pasteur discoveries by louis pasteur discovery of microorganisms

The technique of developing pure culture of bacteria was developed by

  1. J. Lister

  2. L. Pasteur

  3. R. Koch

  4. A. V. Leeuwenhoek
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A pure culture is a laboratory culture containing a single species of microorganisms. A pure culture was usually derived from a mixed culture (culture containing many species of organisms) by transferring a small sample into a new, sterile growth medium. Robert Koch developed solid culture media and the methods for obtaining pure cultures of bacteria.

So, the correct answer is 'R. Koch'.
Multiple choice biology production of food from animals contribution of louis pasteur discoveries by louis pasteur discovery of microorganisms

Which famous biologist propounded the 'germ theory of disease'?

  1. Joseph Lister

  2. Thomas Syndenham

  3. Robert Koch

  4. Louis Pasteur
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The more formal experiments on the relationship between germ and disease were conducted by Louis Pasteur between the year 1860 and 1864. He discovered the pathology of the puerperal fever and the pyrogenic vibrio in the blood, and suggested using boric acid to kill these microorganisms before and after confinement.

So, the corect option is D. ( Louis Pasteur)

Multiple choice biology production of food from animals contribution of louis pasteur discoveries by louis pasteur discovery of microorganisms

Which of the following processes are used for increasing the shelf life of milk?

  1. Boiling

  2. Refrigerating

  3. Pasteurizing

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • Boiling increases the temperature of milk and kills many bacteria and thus increases the shelf life of milk when compared to raw milk.
  • Refrigeration lowers the temperatures of the growth medium ( milk) making it not suitable for bacterial growth and keeps milk fresh for a particular period of time.
  • Pasteurization is heating milk to high temperatures and cooling down quickly. This process kills many possible pathogens and increases the shelf life of milk to a better extent. (1 day to 2 days)
  • So the correct answer is 'Boiling, Refrigerating, and Pasteurizing'.