CBSE Class 12 Biology Microbes In Human Welfare Worksheet Set B

Read and download free pdf of CBSE Class 12 Biology Microbes In Human Welfare Worksheet Set B. Students and teachers of Class 12 Biology can get free printable Worksheets for Class 12 Biology in PDF format prepared as per the latest syllabus and examination pattern in your schools. Standard 12 students should practice questions and answers given here for Biology in Grade 12 which will help them to improve your knowledge of all important chapters and its topics. Students should also download free pdf of Class 12 Biology Worksheets prepared by school teachers as per the latest NCERT, CBSE, KVS books and syllabus issued this academic year and solve important problems provided here with solutions on daily basis to get more score in school exams and tests

Microbes In Human Welfare Class 12 Biology Worksheet Pdf

Class 12 Biology students should refer to the following printable worksheet in Pdf for Microbes In Human Welfare in standard 12. This test paper with questions and answers for Grade 12 Biology will be very useful for exams and help you to score good marks

Class 12 Biology Worksheet for Microbes In Human Welfare

Important Questions for NCERT Class 12 Biology Microbes in Human Welfare

Question. Which of the following is not an advantage of mycorrhiza
(a) Phosphorus absorption
(b) Resistance to root borne pathogens
(c) Nitrogen fixation
(d) Tolerance to salinity and draught

Answer: C

Question. Which of the following chemicals, used as an immunosuppressive agent in organ transplantation
(a) Streptokinase
(b) Cyclosporin - A
(c) Statins
(d) Citric acid

Answer: B

Question. Match the following
A. Pectinases i. Blood cholesterol lowering agents
B. Streptokinases ii. Immunosuppressive agents
C. Cyclosporin - A iii.Clot-busters
D. Statin iv.Clearifying agents
      A   B   C  D
(a) iv   iii   ii  i
(b) iv   iii   i  ii
(c) iii   iv   ii  i
(d) i     ii   iii iv

Answer: A

Question. Match the following
A. Citric acid          i. Haemolytic streptococcus
B. Streptokinase    ii. Aspergillus niger
C. Cyclosporin - A  iii.Monascus purpureus
D. Statins             iv.Trichoderma polysporum
A B C D
(a) i ii iii iv
(b) ii i iii iv
(c) ii i iv iii
(d) iv ii iii i

Answer: C

Question. Which of the following is one of the advantage of application of viruses as bioinsecticides
(a) They are less effective
(b) They are host specific
(c) They are costly
(d) They can not obtain easily

Answer: D

Question. In which of the following conditions use of baculoviruses is desirable
(a) When they are used as part of IPM
(b) When an ecologically sensitive area is being treated
(c) When beneficial insects are being conserved
(d) All of the above

Answer: D

Question. Which of the following is not a product of distillation
(a) Whisky
(b) Brandy
(c) Wine
(d) Rum

Answer: C

Question. Find out odd one with refrence to distillation
(a) Beer
(b) Wine
(c) Both 1 and 2
(d) Vodka

Answer: D

Question. Use of biofertilizer is the part of
(a) Inorganic farming
(b) Organic farming
(c) Energy cropping
(d) Energy plantation

Answer: B

Question. Cultivation of which of the following crop plant specially get benif itted by application of cyanobacteria
(a) Maize
(b) legumes
(c) Wheat
(d) Rice

Answer: D

Ques. Which bacteria is utilized in gobar gas plant?
(a) Methanogens
(b) Nitrifying bacteria
(c) Ammonifying bacteria
(d) Denitrifying bacteria

Answer: A

Ques. Gobar gas contains mainly
(a) CO2 + H2
(b) CO2 + H2O
(c) CH4 only
(d) CH4 + CO2.

Answer: D

Ques. Which of the following can be used as a biocontrol agent in the treatment of plant disease?
(a) Lactobacillus
(b) Trichoderma
(c) Chlorella
(d) Anabaena

Answer: B

Ques. Select the correct group of biocontrol agents.
(a) Nostoc, Azospirillium, Nucleopolyhedrovirus
(b) Bacillus thuringiensis, Tobacco mosaic virus, Aphids
(c) Trichoderma, Baculovirus, Bacillus thuringiensis
(d) Oscillatoria, Rhizobium, Trichoderma

Answer: C

Ques. A biocontrol agent to be a part of an integrated pest management should be
(a) species-specific and symbiotic
(b) free living and broad spectrum
(c) narrow spectrum and symbiotic
(d) species-specific and inactive on non-target organisms.

Answer: D

Ques. Microbe used for biocontrol of pest butterfly caterpillars is
(a) Saccharomyces cerevisiae
(b) Bacillus thuringiensis
(c) Streptococcus sp.
(d) Trichoderma sp. 

Answer: B

Ques. Which one of the following is an example of carrying out biological control of pests/diseases using microbes?
(a) Trichoderma sp. against certain plant pathogens.
(b) Nucleopolyhedrovirus against white rust in Brassica.
(c) Bt-cotton to increase cotton yield.
(d) Lady bird beetle against aphids in mustard.

Answer: A

Ques. A common biocontrol agent for the control of plant diseases is
(a) baculovirus
(b) Bacillus thuringiensis
(c) Glomus
(d) Trichoderma. 

Answer: D

Ques. Which of the following is not used as a biopesticide?
(a) Trichoderma harzianum
(b) Nucleopolyhedrovirus (NPV)
(c) Xanthomonas campestris
(d) Bacillus thuringiensis 

Answer: C

Ques. Trichoderma harzianum has proved a useful microorganism for
(a) gene transfer in higher plants
(b) biological control of soil-borne plant pathogens
(c) bioremediation of contaminated soils
(d) reclamation of wastelands. 

Answer: B

Ques. Which one of the following proved effective for biological control of nematodal diseases in plants?
(a) Gliocladium virens
(b) Paecilomyces lilacinus
(c) Pisolithus tinctorius
(d) Pseudomonas cepacia 

Answer: B

Ques. A genetically engineered microorganism used successfully in bioremediation of oil spills is a species of
(a) Trichoderma
(b) Xanthomonas
(c) Bacillus
(d) Pseudomonas. 

Answer: D

Ques. Biological control component is central to advanced agricultural production. Which of the following is used as a third  eneration pesticide?
(a) Insect repellants
(b) Organophosphate and carbamates
(c) Pathogens
(d) Pheromones 

Answer: D

Ques. Cochineal insects have proved very useful for
(a) cactus prevention
(b) Eichhornia prevention
(c) weeds control
(d) Parthenium control.

Answer: A

Ques. When a natural predator (living being) is applied on the other pathogen organism to control them, this process is called
(a) artificial control
(b) confusion technique
(c) biological control
(d) genetic engineering.

Answer: C

Ques. The rotenone is
(a) a natural herbicide
(b) a natural insecticide
(c) an insect hormone
(d) a bioherbicide.

Answer: B

Ques. One of the major difficulties in the biological control of insect pest is that
(a) the method is less effective as compared with the use of insecticides
(b) the practical difficulty of introducing the predator to specific areas
(c) the predator develops a preference to other diets and may itself become a pest
(d) the predator does not always survive when transferred to a new environment. 

Answer: D

Ques. Biological control of agricultural pests, unlike chemical control, is
(a) self perpetuating
(b) polluting
(c) very expensive
(d) toxic. 

Answer: A

Ques. Select the mismatch.
(a) Rhodospirillum – Mycorrhiza
(b) Anabaena – Nitrogen fixer
(c) Rhizobium – Alfalfa
(d) Frankia – Alnus 

Answer: A

Ques. A nitrogen-fixing microbe associated with Azolla in rice fields is
(a) Spirulina
(b) Anabaena
(c) Frankia
(d) Tolypothrix. 

Answer: B

Ques. Which one of the following microbes forms symbiotic association with plants and helps them in their nutrition?
(a) Azotobacter
(b) Aspergillus
(c) Glomus
(d) Trichoderma 

Answer: C


Long Answer Questions

Question. Describe how do ‘flocs’ and ‘activated sludge’ help in sewage treatment. 
Answer.
 Flocs are masses of aerobic bacteria associated with fungal filaments to form mesh like structures.
These aerobic microbes consume the major part of the organic matter in the effluent. This significantly reduces Biological oxygen demand (BOD) of the effluent.
A small part of the activated sludge is used as inoculum and pumped back to aeration tank. The remaining major part of the sludge is pumped into anaerobic sludge digesters where microbes or bacteria grow anaerobically to produce CH4 or H2S or CO2 or biogas.

Question. Complete the given table.

Name of the organismProduct/Enzyme/Bioactive male cule
Aspergillus niger(i)
(ii)Ethanol
(iii)Cyclosporin-A
(iv)Acetic acid
Monascus purpureus(v)
Streptococcus(vi)


Answer. (i) Citric acid
(ii) Saccharomyces cerevisiae
(iii) Trichoderma polysporum
(iv) Acetobacter aceti
(v) Statin
(vi) Streptokinase

Question. Cow dung and water is mixed and this slurry is fed into the biogas plant for digestion by microbes. The person performing the process shares that there is no need to provide inoculum for it, why? What is the role of microbes at the source? Under which condition will they be most active and effective? 
Answer. There is no need to provide inoculum for it because the bacteria, methanogens are present in cow dung. The role of these microbes is breakdown of cellulose. These are most active in an anaerobic condition.

Question. Explain the different steps involved in sewage treatment before it can be released into natural water bodies. 
OR
Describe the process of waste-water treatment under the following heads:
(a) Primary treatment
(b) Secondary treatment 
OR
Explain the process of sewage water treatment before it can be discharged into natural water bodies. Why is this treatment essential? 
Ans. Primary treatment or physical treatment
 It is the physical removal of large and small particles from sewage.
 First, the floating debris is removed by sequential filtration by passing through wire mesh screens.
 Then, the grit (soil and small pebbles) are removed by sedimentation in settling tanks. The sediment is called primary sludge and the supernatant is the effluent.
 The effluent is taken for secondary treatment.
The sewage treatment is essential before being released into water bodies so as to check water borne diseases or pathogenic organisms due to water pollution.

Question. Why should biological control of pests and pathogens be preferred to the conventional use of chemical pesticides? Explain how the following microbes act as biocontrol agents:
(a) Bacillus thuringiensis
(b) Nucleopolyhedrovirus
Answer. Biological control of pests and pathogens is preferred because:
(i) The chemicals cause pollution of water bodies as well as ground water, besides getting stored in the plants.
(ii) The chemicals are toxic thus extremely harmful to human beings and other animals.
(a) Bacillus thuringiensis: Bacillus thuringiensis is available in sachets as dried spores, which are mixed with water and sprayed onto vulnerable plants. When they are eaten by the insect larvae, the toxin is released in the gut where it becomes active and kills the larvae.
B. thuringiensis toxin genes when introduced into plant, develop resistance to attack by insect pests. Specific Bt toxin genes obtained from B. thuringiensis are used in several crop plants which make them resistant to insect pest.
(b) Nucleopolyhedrovirus: These viruses are excellent candidates for species-specific, narrow spectrum insecticidal applications. This is especially desirable when beneficial insects are being conserved to aid in an overall integrated pest management (IPM) programme.

Question. Name the genus to which baculoviruses belong. Describe their role in the integrated pest management programmes. 
Answer. Baculovirus belongs to the genus Nucleopolyhedrovirus. Baculoviruses are pathogens that attack insects and other arthopods. These viruses are very useful for species-specific, narrow spectrum insecticidal applications. Also, as they show no negative impacts on plants, mammals, birds, fish or even on non-target insects, they are beneficial in integrated pest management (IPM) programme in which beneficial insects are conserved.

Question. Explain the significant role of the genus Nucleopolyhedrovirus in an ecological sensitive area.
Answer. Baculoviruses are pathogens that attack insects and other arthropods. Baculoviruses of genus Nucleopolyhedrovirus are used as biological control agents. They are excellent candidates for species-specific, narrow spectrum insecticidal applications. They do not show negative impact on plants, mammals, birds, non-target insects. Therefore, they are used as biological control agents.
Importance in organic farming: It is desirable when beneficial insects are being conserved to aid in an overall Integrated Pest Management (IPM) programme. In organic farming, it is used to conserve beneficial insects and kills harmful ones.

ONE MARK QUESTION

1 Name the group of organisms and the substrate they act on to produce biogas.

2 What is the role of bacterium in the production of Swiss cheese?

3 How can small amount of curd added to fresh milk convert it to curd?

4  write the scientific name of baker’s yeast.

TWO MARK QUESTIONS

5 What are baculoviruses? Write their significance in agriculture. 

7 Mention the functions of LAB that are useful to man.

8 Name any four industrial products that employ microbes in their production.

9 Name any two alcoholic bewerages produced in each of the following ways:

a) With distillation

b) Without distillation

10 Mention any four diseases that can be treated by antibiotics.

3 MARK QUESTIONS

11 Name the three types of micro organisms acting as biofertilizers. How do they enrich the soil fertility?

12 Name any three organic acids and the microbes producing them.

13 Describe biogas plant.

14 Write the names of microbes from which Cyclosporin A, Statin and streptokinase obtained. Also write their importance.

5 MARK QUESTIONS

15 Dscribe the treatment of sewage before it is discharged into a water body like a river.

16 What are biofertilizers? Name the categories of organisms used as biofertilizers with an example for each. 

 

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Chapter 1 Reproduction in Organisms
CBSE Class 12 Biology Reproduction In Organisms Worksheet Set A
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Chapter 2 Sexual Reproduction In Flowering Plants
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Chapter 3 Human Reproduction
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Chapter 4 Reproductive Health
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Chapter 5 Principles of Inheritance and Variation
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Chapter 6 Molecular Basis of Inheritance
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Chapter 7 Evolution
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Chapter 8 Human Health and Disease
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Chapter 9 Strategies for Enhancement In Food Production
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Chapter 10 Microbes In Human Welfare
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Chapter 11 Biotechnology Principles and Processes
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Chapter 12 Biotechnology and Its Application
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