Saturday, January 2, 2021

Microbes in Human Welfare | Class 12 Zoology | Previous Years Questions and Answers (2018 to 2020)

 7. MICROBES IN HUMAN WELFARE


2020 SAY

1.   A free living nitrogen fixing bacteria in the soil. (1)

(a)    Rhizobium                       (b)  Azospirillum

(c)    Nostoc                              (d)  Anabaena

ü Answer:

(b) Azospirillum

2.   Match the following: (2)

(a)    Acetic acid

(b)   Citric acid

(c)    Cyclosporine A

(d)   Lactic acid

(i)  Trichoderma polysporum

(ii)  Acetobacter aceti

(iii) Lactobacillus

(iv) Aspergillus niger

(v)  Monascus purpureus

ü Answer:

(a)    Acetic acid

(b)    Citric acid

(c)    Cyclosporine A

(d)    Lactic acid

(ii)  Acetobacter aceti

(iv) Aspergillus niger

(i)  Trichoderma polysporum

(iii) Lactobacillus


2020 MARCH

1.     Microbe which helps in the production of Biogas. (1)

a.      Aspergillus niger                    

b.     Trichoderma polysporum

c.      Saccharomvces cerevisiae     

d.     Methanobacterium


ü Answer:

(d) Methanobacterium

2.   Some examples of microbes in human welfare are given. Classify them under the headings given below. (2)

[Rhizobium, Propionibacterium sharmanii, Azaspirillum, Lactic acid bacteria, Anabaena, Azotobacter, Aspergillus niger, Saccharomyces cerevisiae]


Microbes in Household Products

Microbes as Bio-fertilizers

 

 

ü Answer:

Microbes in Household Products

Microbes as Bio-fertilizers

Propionibacterium sharmanii

Lactic acid bacteria

Saccharomyces cerevisiae

Aspergillus niger

Rhizobium

Azospirillum

Azotobacter

Anabaena


2019 SAY June

1.   Match the following: (2)

A

B

(a) Citric Acid

(b) Acetic acid

(c) Lactic acid

(d) Butyric acid

I. Acetobactor aceti

Il. Clostridium butylicum

III. Aspergillus niger

IV. Lactobacillus

V. Trichoderma polysporum

VI. Saccharomyces cerevisiae

ü Answer:

A

B

(a) Citric Acid

(b) Acetic acid

(c) Lactic acid

(d) Butyric acid

III. Aspergillus niger

I. Acetobactor aceti

IV. Lactobacillus

Il. Clostridium butylicum

2.   Bio-fertilisers are organisms that enrich the nutrient quality of the' soil. How these bio- fertilisers enrich the soil nutrients? Give two examples. (2)

ü Answer:

They can fix nitrogen from the atmosphere. Also absorb phosphorous. E.g. Rhizobium, Cyanobacteria, Mycorrhiza etc.

2019 MARCH


1.  Microbes are useful to human beings in diverse ways. If so, name the following. (2)

a.      Microbe known as "Baker's Yeast".

b.     Lactic acid producing bacterium.

c.      Fungus which helps in the production of bio-active molecule - cyclosporine A.

d.     Symbiotic nitrogen fixing bacterium.


ü Answer:

a.      Saccharomyces cerevisiae.

b.      Lactobacillus.

c.      Trichoderma polysporum.

d.      Rhizobium.


2018 SAY


1.   In sewage treatment plants microbes play a significant role. Distinguish between primary and secondary treatment in sewage plants. (2)


ü Answer:

Primary treatment: It is the physical removal of material in sewage by sequential filtration and sedimentation.

Secondary treatment: It involves aeration and constant agitation of effluent that causes vigorous growth of aerobic bacteria. They consume organic matter in the effluent and reduces its BOD.


2018 MARCH


1.   Complete the table with appropriate terms: (2)


Organism

Scientific name

Bioactive product

Fungus

……..A…….

Citric acid

…..B…..

Acetobacter aceti

Acetic acid

Fungus

Trichoderma polysporum

……C…….

Yeast

……..D……..

stain


ü Answer:


A= Aspergillus niger.

B= Bacterium

C= Cyclosporine A

D= Saccharomyces cerevisiae.



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