Microbes in Human Welfare

Previous Years' CBSE Board Questions

8.1 Microbes in Household Products

MCQ

1. Large holes in "Swiss Cheese" are due to
2. Propionibacterium shermanii
3. Saccharomyces cerevisiae
4. Penicillium chrysogenum

(2020) R

1. Acetobacter aceti.

VSA (1 mark)

Why do we add an inoculum of curd to milk for curdling it? (AI 2015C) U

1. How is lactic acid bacteria beneficial to us other than helping in curdling the milk? (AI 2015C)

SAII (3 marks)

1. Explain the changes that milk undergoes when suitable starter/inoculum is added to it. How does the end product formed prove to be beneficial for human health? (2020) Ap

8.2 Microbes in Industrial Products

1. Trichoderma (ii) Ethanol

MCQ

polysporum

1. Given below are the list of the commercially important products and their source organisms. Select the option that gives the correct matches.
2. Why does 'Swiss Cheese' develop large holes? (Delhi 2019) U

List-A List-B S.No. Bioactive Microbes (Source Products Organism)

1. Cyclosporin A (i) Streptococcus
2. Statins (ii) Trichoderma polysporum
3. Streptokinase (iii) Penicillium notatum
4. Penicillin (iv) Monascus purpureus

Options:

1. A-(i), B-(ii), C-(iii), D-(iv)
2. A-(iii), B-(iv), C-(ii), D-(i)
3. A-(iv), B-(iii), C-(ii), D-(i)

Scientific Product produced Use in human

name of the welfare

organism Streptokinase

Streptococcus that was later a

modified

ь Cyclosporin A C

Monascus d е

purpureus Sets milk into

Lactobacillus f

curd

(2023) R

1. A-(ii), B-(iv), C-(i), D-(iii)

1. The bioactive molecule used as an immunosupp- ressive agent during organ transplant is
2. tetracyclin (b) cyclosporin A
3. statin (d) streptomycin.

SAI (2 marks)

Describe the contributions of Alexander Fleming,

Ernest Chain and Howard Florey in the field of

microbiology. (2020)

Name the microbes that help production of the

following products commercially.

1. Statin (b) Citric acid
2. Penicillin (d) Butyric acid (AI 2017)

Mention a product of human welfare obtained with

the help of each one of the following microbes: (d)

1. LAB
2. (c) Propionibacterium shermanii

10. Bottled fruit juices are clearer as compared to those

made at home, Explain. (Foreign 2015)

SAII (3 marks)

Match the microbes listed under column-A with

the products mentioned under column-B.

Column-A Column-B (H) (J)

1. Saccharomyces cerevisiae (iv) Cyclosporin-A
2. State the medicinal value and the bioactive molecules produced by Penicillium notatum, Monascus purpureus and Trichoderma polysporum. (AI 2019)
3. State the medicinal value and the bioactive molecules produced by Streptococcus, Monascus and Trichoderma. (AI 2015)
4. Identify a, b, c, d, e and f in the table given below:

(2020) R (Foreign 2014) EV

8.3 Microbes in Sewage Treatment

VSA (1 mark)

What are 'flocs', formed during secondary treatment of sewage? (NCERT Exemplar, Delhi 2019)

SAI (2 marks)

1. What are flocs ? State their role in biological treatment of sewage. (Term II, 2021-22)

Mention the common bacterium found in the anaerobic sludge during sewage treatment and also in the rumen of cattle. How is this bacterium commercially useful? (Term II, 2021-22) U

Study the given diagram of Sewage Treatment Plant (S.T.P.) and answer the questions that follow:

Municipal Sewage 8.4 Microbes in Production of Biogas

1. (X) VSA (1 mark) Biological Sedimentation River treatment and filtration

S.T.P. (Sewage treatment plant) (A)

29. Explain the role of microorganisms in the following:

: Municipal Sewage (a) Reducing the sugar content in grape juice

1. (Y) (Z) Sequential Biological River Filtration treatment

S.T.P. (Sewage treatment plant) (B)

1. Which one of the two 'S.T.P.' (A) or (B) will be more effective in treating the human excreta in the municipal waste?

SAII (3 marks)

1. Write the steps followed in carrying the treatment of the sewage in step (Z), once the BOD of sewage is reduced significantly till it is passed on to the "anaerobic sludge digesters".

(Term II, 2021-22) [An]

List the events that reduce the Biological Oxygen Demand (BOD) of a primary effluent during sewage treatment. (Delhi 2016) Gas Distinguish between the roles of flocs and anaerobic sludge digesters in sewage treatments. (Delhi 2016)

Gas Holder

Sludge

Explain the different steps involved during primary treatment phase of sewage. (AI 2015)

1. Explain the process of secondary treatment given to the primary effluent up to the point it shows significant change in the level of biological oxygen demand (BOD) in it. (Al 2015) Ap

Digester

1. Name two groups of organisms which constitute 'flocs'. Write their influence on the level on BOD during biological treatment of sewage. (AI 2014C)

SAII (3 marks)

Describe how do 'flocs' and 'activated sludge' help in

sewage treatment. (Delhi 2017) U

Secondary treatment of the sewage is also called

biological treatment. Justify this statement and

explain the process. (Al 2017)

LA (5 marks)

1. (a) Explain the process of sewage water treatment before it can be discharged into natural water bodies.
2. Why is this treatment essential? (Al 2014)
3. (a) Name the category of microbes occurring naturally in sewage and making it less polluted during the treatment.
4. Explain the different steps involved in the secondary treatment of sewage. (Foreign 2014)
5. Write any two places where methanogens can be found. (Delhi 2019)

SAI (2 marks)

Why is a slurry of cattle dung (gobar) added to bio-

wastes in the tank of a gobar gas plant for generation

of biogas? (2019 C)

1. List the events that lead to biogas production from waste water whose BOD has been reduced significantly. (Delhi 2016)
2. (a) Write the scientific name of methanogen bacteria. Where are these bacteria generally found? Explain their role in biogas production.
3. Name the components of biogas. (2020)
4. Study the picture of biogas plant given below and answer the questions that follow.
5. Name the components gaining entry from A into the chamber.