250+ TOP MCQs on Biological Characteristic of Water and Answers

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Environmental Engineering Multiple Choice Questions on “Biological Characteristic of Water”.

1. Which type of bacteria has a rod shaped structure?
a) Bacilli
b) Cocci
c) Spirilla
d) Vibrio
Answer: a
Clarification: Bacilli (Singular-Bacillus) has a rod shaped structure. Cocci has a spherically shaped structure, Spirilla has a spiral shaped structure and Vibrio has a comma shaped structure.

2. ________ represents the bacterial density that is most likely to be present in water.
a) BOD
b) COD
c) MPN
d) Coliform index
Answer: c
Clarification: Most Probable Number is a number that indicates the bacterial density present in water.BOD and COD are the terms related to the oxygen required by microorganism to oxidize organic and inorganic matter.

3. Which of the following is a better test to identify Coliforms?
a) Coliform index
b) Multiple tube fermentation
c) MPN test
d) Membrane filter technique
Answer: d
Clarification: Membrane filter technique is a better and simpler technique to identify Coliforms. Various results are obtained in a shorter time than the multiple tube fermentation technique. MPN test and coliform index are not used now.

4. What is the temperature at which MPN test is performed?
a) 35oC
b) 37 oC
c) 40oC
d) 45 oC
Answer: b
Clarification: MPN test is performed at 37oC where different samples of water are mixed with lactose broth and incubated in test tubes for 48 hours.

5. Which of the following statement is/are correct regarding coliform bacteria?
i. It is gram negative
ii. It is rod shaped bacteria
iii. It is a harmless aerobic microorganism
a) i, ii, iii
b) ii, iii
c) i, iii
d) i, ii
Answer: a
Clarification: Coliform bacteria is a gram negative, rod shaped and harmless aerobic microorganism which is found in the intestine of warm blooded animals including human beings.

6. Which of the following is the disease caused by bacterial infections?
a) Amoebic dysentery
b) Infectious hepatitis
c) Typhoid fever
d) Poliomyelitis
Answer: c
Clarification: Amoebic dysentery is caused by protozoan infection, Infectious hepatitis and Poliomyelitis are caused by a viral infection and Typhoid fever is caused by a bacterial infection.

7. The number of bacterial colonies by Agar plate count test should not exceed ____ per ml for potable water.
a) 1
b) 10
c) 100
d) 1000
Answer: c
Clarification: Agar plate count test is a test to count the number of bacterial colonies growing on a specified medium and the permissible limit for the number of bacterial colonies is 100 per ml.

8. If the acid and gas are formed in the multiple tube fermentation technique, the test is _____
a) Positive
b) Continued
c) Negative
d) Discarded
Answer: a
Clarification: The acid and gas formation in the Multiple tube fermentation technique indicates that the test is positive and there are coliform bacteria in the sample.

9. Which bacteria cause the reddish brown deposits in the tank?
a) Escherichia coli bacteria
b) Bacterium coli bacteria
c) Iron bacteria
d) Sulphur bacteria
Answer: c
Clarification: The growth of Iron bacteria causes the discoloration of tank due to reddish brown deposits and turbidity in water.

10. Which bacteria results in the corrosion of iron and steel pipes embedded in soil?
a) Escherichia coli bacteria
b) Bacterium coli bacteria
c) Iron bacteria
d) Sulphur bacteria
Answer: d
Clarification: Sulphur bacteria cause the corrosion of iron and steel pipes embedded in soil. They are both aerobic and anaerobic and are more destructive in marshy or clay soils where anaerobic conditions prevails.

11. Gelatin liquefying bacteria are helpful in the manufacturing of photographic films.
a) True
b) False
Answer: a
Clarification: These bacteria are capable of producing proteolytic ferments that digest and liquefy gelatin. So, their presence in water is helpful in photographic films and glue industries.