Tag: introduction to microbiology

Questions Related to introduction to microbiology

Study the following statements regarding lactic acid bacteria (LAB) which are used to convert milk into curd.
(i) They produce adds that coagulate and partially digest the milk proteins.
(ii) A small amount of curd added to the fresh milk as an inoculum contains millions of LAB, which at suitable temperature, multiply and convert milk into curd.
(iii) Conversion of milk into curd improves its nutritional quality by increasing vitamin $B _{12}$.
(iv) LAB may result in acidity in the stomach of human beings.
Which of the given statements are correct? 

zoology introduction to microbiology commercial use of microorganism microbes in household and industry microbial products - food, medicines and industrial products food production and microorganisms

  1. (i) and (ii)

  2. (ii) and (iii)

  3. (i), (ii) and (iii)

  4. (i), (ii), (iii) and (iv)

Show answer
Correct Option: C
Explanation:

Microbes such as. Lactobacillus and others commonly called lactic acid bacteria (LAB) grow in milk and convert it into curd. During growth, such bacteria produce adds (mainly lactic add) that coagulate and partially digest the milk proteins. A small amount of curd, known as starter, is added to the milk and kept at a suitable temperature, where lactic acid bacteria multiply in millions and converts milk into curd that also improves its nutritional quality by increasing vitamin BI2. It also checks the growth of disease-causing microbes in the stomach.

So, the correct answer is '(i), (ii) and (iii)'

Statement 1 : Besides curdling of milk, LAB also improve its nutritional quality by increasing vitamin $B _{12}$.
Statement 2 : LAB, when present in human stomach, check disease causing microbes. 

zoology introduction to microbiology commercial use of microorganism microbes in household and industry microbial products - food, medicines and industrial products food production and microorganisms

  1. Both statements 1 and 2 are correct.

  2. Statement 1 is correct but statement 2 is incorrect.

  3. Statement 1 is incorrect but statement 2 is correct.

  4. Both statements 1 and 2 are incorrect.

Show answer
Correct Option: A
Explanation:
LAB improve its nutritional quality by increasing vitamin B$ _12$ besides curdling the milk.
LAB produce myriad beneficial effects for human beings include, alleviation of lactose intolerance, diarrhoea, peptic ulcer, stimulation of immune system, antiallergic effects, antifungal actions and prevention of colon cancer.
So, the correct option is 'Both statements 1 and 2 are correct'

Identify the bacteria that promotes the formation of curd.

zoology introduction to microbiology commercial use of microorganism microbes in household and industry microbial products - food, medicines and industrial products food production and microorganisms

  1. Vibrio cholerae

  2. Lactobacillus

  3. Mycobacterium leprae

  4. Clostridium tetani

Show answer
Correct Option: B
Explanation:

Lactobacillus acts on the lactose of the milk and converts it into lactic acid. The increased acidity causes the milk proteins (casein) to coagulate and form the curd. So, the correct answer is option B.

How is the lactic acid fermentation used in milk industry?

zoology introduction to microbiology commercial use of microorganism microbes in household and industry microbial products - food, medicines and industrial products food production and microorganisms

  1. To convert milk sugar to lactic acid

  2. Lactic acid coagulate the milk protein casein

  3. Lactic acid coagulate the milk fats

  4. All of the these

Show answer
Correct Option: A
Explanation:
  • Lactobacillus bacteria cause the fermentation of milk in which milk sugar lactose is converted into lactic acid. This produces yoghurt and curd.
  • Lactobacillus is acidophiles which best grow at a pH of 1 to 5.4.

Milk is converted into curd by 

zoology introduction to microbiology commercial use of microorganism microbes in household and industry microbial products - food, medicines and industrial products food production and microorganisms

  1. Bacteria

  2. Fungi

  3. Algae

  4. None of these

Show answer
Correct Option: A
Explanation:

Milk is converted into curd by the action of Lacto bacillus. It multiplies and promotes the formation of curd in milk.

Bacteria responsible for fermentation of dairy milk are

zoology introduction to microbiology commercial use of microorganism microbes in household and industry microbial products - food, medicines and industrial products food production and microorganisms

  1. Lactobacillus

  2. Hay Bacillus

  3. Acetobacter

  4. Rhizobium

Show answer
Correct Option: A
Explanation:

The most common bacteria responsible for fermentation of dairy milk are Lactobacillus species. Bacteria like Lactococcus and Leuconostoc are also used in production of fermented milk products. Lactobacillus produce lactic acid from lactose by the process of glucose fermentation. This also increases acidity and sours and thickens the milk.

Thus, the correct answer is 'Lactobacillus.'

Activated sludge should have the ability to settle quickly so that it can:

zoology introduction to microbiology microbial pollution control environmental use of microorganism microbes in waste treatment and biogas

  1. be rapidly pumped back from sedimentation tank to aeration tank

  2. absorb pathogenic bacteria present in wastewater while sinking to the bottom of the settling tank

  3. be discarded and anaerobically digested

  4. absorb colloidal organic matter.

Show answer
Correct Option: A
Explanation:

The activated sludge have to settle quickly so that it can be pumped back to the aeration tank. So, the correct option is 'be rapidly pumped back from sedimentation tank to aeration tank'

In the sewage treatment, bacterial flocs are allowed to sediment in a settling tank. This sediment is called as:

zoology introduction to microbiology microbial pollution control environmental use of microorganism microbes in waste treatment and biogas

  1. inactivated sludge

  2. activated sludge

  3. primary sludge

  4. secondary sluge

Show answer
Correct Option: B
Explanation:
In the secondary treatment, the effluent is passed into a settling tank where the bacterial flocs are allowed to sediment and the sediment is called activated sludge.
So, the correct option is 'activated sludge'

The primary treatment of removal of:

zoology introduction to microbiology microbial pollution control environmental use of microorganism microbes in waste treatment and biogas

  1. dissolved impurities

  2. stable particles

  3. toxic substances

  4. harmful bacteria

Show answer
Correct Option: A
Explanation:

The primary treatment involves physical removal of particles from the sewage through filtration and sedimentation. These are removed initially by sequential filtration which removes the floating debris and then grit is removed by sedimentation. 

So, the correct option is 'Option A' .

Wastewater treatment generates a large quantity of sludge, which can be treated by:

zoology introduction to microbiology microbial pollution control environmental use of microorganism microbes in waste treatment and biogas

  1. anaerobic digesters

  2. floc

  3. chemicals

  4. oxidation pond

Show answer
Correct Option: A
Explanation:

Wastewater treatment generates a large quantity of activated sludge during secondary treatment which is used as a inoculum and a small part of it is pumped back to the large aeration tanks whereas the remaining part of that sludge is treated by anaerobic sludge digesters anaerobically. During this digestion, bacteria produces a mixture of gases called biogas. 

So, the correct option is 'Option A' .