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Microbes in Human Welfare BIOLOGY - Microbes in Human Welfare

Maharashtra Board - STD 12 Science - BIOLOGY (MSBSHSE - English Medium). 582 questions in this chapter.

Question types

Microbes in Human Welfare question types

582 questions across 8 question groups — pick any mix to generate a BIOLOGY paper with step-by-step answer keys.

582
Questions
8
Question groups
5
Question types
Sample Questions

Microbes in Human Welfare questions

One sample from each question group in this chapter. Select any group above to see the full set with answer keys.

Q 1MCQ1 Mark
In cheese microorganisms are required for :
  • A
    Ripening only.
  • B
    Souring of milk only.
  • ✓
    Souring and ripening.
  • D
    Development of resistance to spoilage.

Answer: C.

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Q 2MCQ1 Mark
The bacterium that commonly lives in animal and human intestine is :
  • A
    Bacillus anthracis.
  • B
    Vibrio cholerae.
  • ✓
    Escherichia coli.
  • D
    Corynebacterium.

Answer: C.

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Q 3MCQ1 Mark
Match the items in Column $'A'$ and Column $'B'$ and choose correct answer.
 
Column $A$
 
Column $B$
$i.$
Lady bird
 $a.$
Methano bacterium
$ii.$
Mycorrhiza
 $b.$
Trichoderma
$iii.$
Biological control
 $c.$
Aphids
$iv.$
Biogas
 $d.$
Glomus
The correct answer is :
  • A
    $\text{i b, ii d, iii c, iv a}.$
  • ✓
    $\text{i c, ii d, iii b, iv a}$.
  • C
    $\text{i d, ii a, iii b, iv c.}$
  • D
    $\text{i c, ii b, iii a, iv d}.$

Answer: B.

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Q 4MCQ1 Mark
What would happen if oxygen availability to activated sludge flocs is reduced ?
  • ✓
    The center of flocs will become anoxic, which would cause death of bacteria and eventually breakage of flocs
  • B
    Flocs would increase in size as anaerobic bacteria would grow around flocs
  • C
    Protozoa would grow in large numbers
  • D
    It will slow down the rate of degradation of organic matter

Answer: A.

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Q 5MCQ1 Mark
Trichoderma harzianum has proved a useful microorganism for :
  • A
    Gene transfer in higher plants
  • ✓
    Biological control of soil-borne plant pathogens
  • C
    Bioremediation of contaminated soils
  • D
    Reclamation of wastelands

Answer: B.

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Q 21Answer the following questions in detail.5 Marks
As we know, our rivers Ganga and Yamuna are getting polluted day-by-day. Many factories discharge sewage effluents into these rivers. The load of pollution in these rivers also increases due to municipal sewage and many things thrown by people in the name of worship. The government has however taken some steps to save these rivers.
  1. What are the values shown by people who throw wastes in rivers?
  2. How could we help in decreasing pollution of rivers?
  3. State some advantages of saving the river
  4. State the action taken by the government to stop the pollution in these rivers.
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Q 23Answer the following questions in detail.5 Marks
Anukool is a big businessman in Delhi, but belongs to a small village. He went to his village during Christmas holiday. He was very disturbed to see women still using cowdung's cakes to prepare food there. He decided to set up a biogas plant so that people can use gas obtained from it for cooking. The villagers were very thankful to Anukool for his valuable help.
  1. What is biogas?
  2. What are the uses of biogas?
  3. Name some microorganisms involved in biogas production.
  4. What are the values shown by Anukool?
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Q 24Answer the following questions in detail.5 Marks
More than 25% of human population is suffering from hunger and malnutrition. Scientists have developed techniques where microbes are grown on industrial scale as a source of good protein which can be grown from waste water, animal manure and even sewage.
Based on the above information answer the following questions.
  1. In what ways would it be helpful to humans?
  2. What can be the response to such new ventures?
  3. What values have been manifested in the above case?
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Q 31Assertion (A) & Reason (B) MCQ1 Mark
Two statements are given$-$one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: Azolla is used as a biofertiliser in rice fields.
Reason: Azolla shows the presence of $N_2 -$ fixing bacteria in its leaf cavities.
  • ✓
    Both assertion and reason are true and reason is the correct explanation of assertion.
  • B
    Both assertion and reason are true but reason is not the correct explanation of assertion.
  • C
    Assertion is true but reason is false.
  • D
    Both assertion and reason are false.

Answer: A.

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Q 32Assertion (A) & Reason (B) MCQ1 Mark
Two statements are given$-$one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: Immobilised yeasts cause less fermentation.
Reason: Brewer's yeast produces beer not wine.
  • A
    Both assertion and reason are true and reason is the correct explanation of assertion.
  • B
    Both assertion and reason are true but reason is not the correct explanation of assertion.
  • C
    Assertion is true but reason is false.
  • ✓
    Both assertion and reason are false.

Answer: D.

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Q 33Assertion (A) & Reason (B) MCQ1 Mark
Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: Azotobacter fixes nitrogen in symbiotic form.
Reason: Azotobacter form root nodules in the roots of leguminous plants.
  • A
    Both assertion and reason are true and reason is the correct explanation of assertion.
  • B
    Both assertion and reason are true but reason is not the correct explanation of assertion.
  • C
    Assertion is true but reason is false.
  • ✓
    Both assertion and reason are false.

Answer: D.

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Q 34Assertion (A) & Reason (B) MCQ1 Mark
Two statements are given-one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: In ripening of cheese, insoluble proteins are cleaved to form soluble peptides.
Reason: Hard cheese and soft cheese, both are ripened by lactic acid bacteria. 
  • A
    Both assertion and reason are true and reason is the correct explanation of assertion.
  • B
    Both assertion and reason are true but reason is not the correct explanation of assertion.
  • ✓
    Assertion is true but reason is false.
  • D
    Both assertion and reason are false.

Answer: C.

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Q 35Assertion (A) & Reason (B) MCQ1 Mark
Two statements are given$-$one labelled Assertion and the other labelled Reason. Select the correct answer to these questions from the codes $(a), (b), (c)$ and $(d)$ as given below.
Assertion: The alcoholic content of fortified wines are high.
Reason: The fermentation is stopped before all the sugars are being converted.
  • A
    Both assertion and reason are true and reason is the correct explanation of assertion.
  • ✓
    Both assertion and reason are true but reason is not the correct explanation of assertion.
  • C
    Assertion is true but reason is false.
  • D
    Both assertion and reason are false.

Answer: B.

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Q 36Case study (4 Marks)4 Marks
Microorganisms include bacteria, viruses, fungi and protozoa. In our mind, we presume, most of the time, that microbes are always harmful. Microbes are, of course, the causal agents of many infections diseases of plants and animals including humans but they also have lots of beneficial role. Lactic acid bacteria (LAB) are one of this kind of useful group. These are Gram positive, non-sporulating, either rod-shaped or spherical bacteria. They produce lactic acid in milk products as major metabolic end product of carbohydrate fermentation. LAB are considered as natural fermentors. Lactobacillus is a common LAB which converts lactose sugar of milk into lactic acid, that causes coagulation and partial digestion of milk protein casein. Milk is then changed into curd, yoghurt and cheese. Lactobacillus is also used in probiotics which have potentially beneficial effect on gut ecosystem of humans. Some other probiotic strain used belong to the Genus Bifidobacterium.
  1. Which of the following is not considered as microorganisms?
  1. Bacteriophage.
  2. Streptococcus.
  3. Porphyra.
  4. Staphylococcus.
  1. Select the incorrect option regarding the characteristics of lactic acid bacteria.
  1. They are rod-shaped or spherical.
  2. They are Gram positive.
  3. They take part in carbohydrate fermentation.
  4. They are acid intolerant.
  1. Which of the following is not a lactic acid producing bacteria?
  1. Streptococcus.
  2. Lactococcus.
  3. Saccharomyces.
  4. Enterococcus.
  1. Probiotics are:
  1. Gut friendly live bacteria.
  2. Acid balancing alternated bacteria.
  3. Beneficial amount of dead bacteria.
  4. Gram negative attenuated bacteria.
  1. Assertion: Lactobacillus bacteria do not retain crystal violet stain while staining.
Reason: Lactobacillus have a very thin layer of peptidoglycan layer in their cell wall.
  1. Both assertion and reason are true and reason is the correct explanation of assertion.
  2. Both assertion and reason are true but reason is not the correct explanation of assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false.
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Q 37Case study (4 Marks)4 Marks
Read the following and answer any four questions from (i) to (v) given below:
Enzymes are best known for their ability to catalise biochemical reactions without undergoing any change. A large number of enzymes are being used in biotechnological industry. Most of them are obtained from microbes. Proteases degrade proteins and polypeptides. Most of the commercially applicable proteases are alkaline and are biosynthesised mainly by bacteria such as Pseudomonas, Bacillus and some fungi like, Aspergillus. These enzymes are used in clearing beer, softening of bread and meat, degumming of silk, etc. Alkaline serine proteases have the largest applications in bio-industry. Alkaline proteases have shown their capability to work under high pH, temperature and in presence of inhibitory compounds. Another important group of enzymes is amylases. Amylolytic enzymes act on starch. These are obtained from Aspergillus, Rhizopus and Bacillus sp. These are used in softening and sweetening of bread, production of alcoholic beverages from starchy materials, clearing of turbidity in juices caused by starch, etc.
  1. Polypeptides are degraded by:
  1. Amylases.
  2. Proteases.
  3. Pectinases.
  4. Lipases.
  1. Amylolytic enzymes are not obtained from:
  1. Aspergillus.
  2. Aspergillus.
  3. Mucor.
  4. Bacillus.
  1. Clearing of turbidity in juices caused by starch is achieved by:
  1. Amylases.
  2. Proteases.
  3. Rennet.
  4. Both (a) and (b).
  1. Select the incorrect option from the following.
  1. Enzymes are proteinaceous substances.
  2. Enzymes are substrate specific.
  3. Enzymes are large sized molecules.
  4. Microbial enzymes can work only in normal temperature and pH.
  1. A farmer harvests corns and prepares corn starch. He wants to prepare some corn syrup from this. for the conversion he needs to use enzyme ______.
  1. Amylase.
  2. Glucoamylases.
  3. Glucoisomerases.
  4. All of these.
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Q 38Case study (4 Marks)4 Marks
Read the following and answer any four questions from (i) to (v) given below:
Green manuring is the fanning practice where a leguminous plant which has derived enough benefits from its association with appropriate species of Rhizobium, is ploughed into the field soil and then a non-legume is sown and allowed to get benefitted from the already present nitrogen fixer. Some legumes, such as, Crotolaria juncea, Sesbania rostrata, Lencaena leucocephala, etc. are used as green manure. Rhizobia, that fix atmospheric nitrogen in the form of nitrate, live in the roots ofleguminous plants. These nutrients are used by non-leguminous plants through the practice of green manuring.
  1. Green manures mainly provide nutrient enriched in:
  1. Magnesium.
  2. Sulphur.
  3. Nitrogen.
  4. Both (a) and (b).
  1. Which of the following plants is used as green manure in crop fields?
  1. Saccharum.
  2. Dichanthium.
  3. Phyllonthus.
  4. Crotolaria.
  1. Green manure plants belong to the Family:
  1. Lamiaceae.
  2. Papilionaceae.
  3. Liliaceae.
  4. Poaceae.
  1. Due to excess use of chemical fertilisers rich in nitrate, ________ disease occurred in children.
  1. Jaundice.
  2. Septicemia.
  3. Methemoglobinemia.
  4. Botulism.
  1. A green manure is:
  1. Rice.
  2. Maize.
  3. Sorghum.
  4. Sesbania.
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Q 39Case study (4 Marks)4 Marks
Read the following and answer any four questions from (i) to (v) given below:
When it comes to biopesticides, one of the most widely used fungi is Beauveria bassiana. It infects a range of insects like, pecan weevil, Colorado potato beetle, kudzu bug, etc. It causes a disease known as the white muscardine. Even after an insect is killed, the white mold continues to produce millions of new infective spores that are released into the environment. It is commercially formulated as products including Naturalis L, Mycotrol, BotaniGard, etc. Some other widely used molds are Trichoderma, Metarhizium, etc. Some of them release enzymes that dissolve potential pathogens, others form barriers around plant roots and make it impossible for harmful bacteria and pathogens to pass through.
  1. The key benefits of the biopesticides are that they are:
  1. Highly effective.
  2. Target specific.
  3. Reduced environmental risks.
  4. all of these.
  1. Naturalis-L is a conunercial formulation containing:
  1. Bacterial biopesticide.
  2. Fungal biopesticide.
  3. Fungal biofertiliser.
  4. Chemical pesticide.
  1. Which of the following is used as an effective bacterial biopesticide?
  1. Trichoderma.
  2. Beauveria.
  3. Bacillus thuringiensis.
  4. All of these.
  1. Baeuveria causes a disease called:
  1. White muscardine.
  2. Aspergillosis
  3. Green muscardine.
  4. Powdary mildews.
  1. Assertion: Trichoderma, found in root ecosystem, exerts biological control over several plant pathogens.
Reason: Trichoderma release enzyme which inhibits growth of several disease causing pathogens.
  1. Both assertion and reason are true and reason is the correct explanation of assertion.
  2. Both assertion and reason are true but reason is not the correct explanation of assertion.
  3. Assertion is true but reason is false.
  4. Both assertion and reason are false.
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Q 40Case study (4 Marks)4 Marks
Read the following and answer any four questions from (i) to (v) given below:
Disposal of untreated sewage into the river or freshwater pond causes huge water pollution. Four water samples from different sources (A, B, C, D) are collected and tested for BOD value in a lab to assess their quality. The BOD values are presented in the given table. Water samples are collected from primary effluent, secondary effluent, untreated sewage and river water. Study the given table and answer the following.
Sample BOD
A 20mg/ L
B 5mg/ L
C 300mg/ L
D 400mg/ L
  1. The source of sample 'C' is:
  1. River water.
  2. Primary effluent.
  3. Secondary effluent.
  4. Untreated sewage water.
  1. If sewage in untreated condition is disposed off in a freshwater body then.
  1. BOD and dissolved oxygen both will increase.
  2. BOD will increase and dissolved oxygen will decreas.
  3. BOD will decrease and dissolved oxygen will increase.
  4. BOD and dissolved oxygen both will decrease.
  1. A large number of pathogenic microbes can be present in water sample of:
  1. C
  2. A
  3. D
  4. Both (a) and (c).
  1. High value of BOD in sample O is due to:
  1. High amount of organic wastes and aerobic microbes.
  2. High amount of inorganic wastes and anaerobic microbes.
  3. High amount of organic wastes and anaerobic microbes.
  4. High amount of inorganic wastes and aerobic microbes.
  1. River water is represented by the sample.
  1. A
  2. B
  3. C
  4. D
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