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#	Question	Answer
1	What are microbes?	Microbes are microscopic organisms including bacteria, fungi, protozoa, viruses, viroids, and prions.
2	Which microbes can be grown on nutritive media to form colonies?	Bacteria and many fungi can be grown on nutritive media to form visible colonies.
3	Which bacteria are commonly involved in curd formation?	Lactic acid bacteria (LAB) such as Lactobacillus.
4	How do LAB convert milk into curd?	LAB produce acids that coagulate and partially digest milk proteins.
5	What improves the nutritional quality of curd?	LAB increase vitamin B12 content in curd.
6	What beneficial role do LAB play in the stomach?	They help check disease-causing microbes.
7	Why does idli or dosa dough become puffed up?	Due to the production of CO2 during fermentation.
8	What is toddy?	A traditional drink made by fermenting sap from palms.
9	Name foods prepared by microbial fermentation mentioned in the text.	Fish, soybean, and bamboo shoots.
10	Which bacterium produces the large holes in Swiss cheese?	Propionibacterium sharmanii.
11	Why does Roquefort cheese have a special flavour?	Because it is ripened using specific fungi.
12	What are fermentors?	Large vessels used for industrial-scale production of microbial products.
13	Name two industrial products produced using microbes.	Beverages and antibiotics.
14	Which alcoholic beverages are produced without distillation?	Wine and beer.
15	Which alcoholic beverages are produced by distillation?	Whisky, brandy, and rum.
16	What are antibiotics?	Chemical substances produced by microbes that kill or retard growth of harmful microbes.
17	Who discovered penicillin?	Alexander Fleming.
18	Penicillin was obtained from which mould?	Penicillium notatum.
19	Who established the full potential of penicillin as an antibiotic?	Ernest Chain and Howard Florey.
20	In which war was penicillin extensively used to treat wounded soldiers?	World War II.
21	Name some diseases effectively controlled using antibiotics.	Plague, whooping cough, diphtheria, and leprosy.
22	Are all microbes harmful?	No, several microbes are useful to humans in diverse ways.
23	Which microorganism converts milk into curd?	Lactobacillus and other lactic acid bacteria (LAB).
24	What do LAB produce during curd formation?	Acids that coagulate and partially digest milk proteins.
25	What acts as an inoculum or starter in curd preparation?	A small amount of curd containing millions of LAB.
26	Which vitamin content increases during curd formation?	Vitamin B12.
27	What beneficial role do LAB play in the human stomach?	They help check disease-causing microbes.
28	Which foods are prepared using fermented dough by bacteria?	Dosa and idli.
29	Why does idli or dosa dough appear puffed up?	Due to production of CO2 gas during fermentation.
30	Which yeast is used in bread making?	Saccharomyces cerevisiae.
31	What is toddy?	A traditional drink made by fermenting sap from palms.
32	Name some food materials fermented by microbes.	Fish, soybean, and bamboo shoots.
33	Which bacterium is responsible for holes in Swiss cheese?	Propionibacterium sharmanii.
34	What gives Roquefort cheese its characteristic flavour?	Specific fungi grown during ripening.
35	Name two important industrial products produced using microbes.	Beverages and antibiotics.
36	What are fermentors?	Very large vessels used for industrial-scale growth of microbes.
37	Which microorganism is mainly used in fermented beverage production?	Yeast.
38	Name alcoholic beverages produced without distillation.	Wine and beer.
39	Name alcoholic beverages produced by distillation.	Whisky, brandy, and rum.
40	What are antibiotics?	Chemical substances produced by microbes that kill or retard growth of disease-causing microbes.
41	Who discovered penicillin?	Alexander Fleming.
42	Which bacteria was Fleming working on when penicillin was discovered?	Staphylococci bacteria.
43	Penicillin was obtained from which mould?	Penicillium notatum.
44	Who established the full potential of penicillin as an antibiotic?	Ernest Chain and Howard Florey.
45	In which war was penicillin extensively used for wounded soldiers?	World War II.
46	Which diseases are mentioned as being controlled effectively by antibiotics?	Plague, whooping cough, diphtheria, and leprosy.
47	Name the section that discusses industrial production of chemicals and enzymes by microbes.	Chemicals, Enzymes and other Bioactive Molecules.
48	Which fungus is used for commercial production of citric acid?	Aspergillus niger.
49	Which bacterium produces acetic acid?	Acetobacter aceti.
50	Which bacterium produces butyric acid?	Clostridium butylicum.
51	Which bacterium produces lactic acid?	Lactobacillus.
52	Which yeast is used for commercial production of ethanol?	Saccharomyces cerevisiae.
53	What are lipases used for?	They are used in detergent formulations to remove oily stains.
54	Why are bottled fruit juices clearer than homemade juices?	They are clarified using pectinases and proteases.
55	Which bacterium produces streptokinase?	Streptococcus.
56	Which bioactive molecule is used as an immunosuppressive agent in organ-transplant patients?	Cyclosporin A.
57	Which fungus produces Cyclosporin A?	Trichoderma polysporum.
58	Which yeast produces statins?	Monascus purpureus.
59	What is the function of statins?	They lower blood cholesterol levels.
60	How do statins reduce cholesterol synthesis?	By competitively inhibiting the enzyme responsible for cholesterol synthesis.
61	What is municipal waste-water commonly called?	Sewage.
62	What are the major components of sewage?	Human excreta, organic matter, and microbes.
63	Why cannot sewage be directly discharged into rivers and streams?	Because it contains pollutants and pathogenic microbes.
64	Where is sewage treated before disposal?	In sewage treatment plants (STPs).
65	Which microbes carry out sewage treatment?	Heterotrophic microbes naturally present in sewage.
66	What are the two stages of sewage treatment?	Primary treatment and secondary (biological) treatment.
67	What is the main purpose of primary sewage treatment?	Physical removal of particles through filtration and sedimentation.
68	What is removed first during primary treatment?	Floating debris by sequential filtration.
69	What is grit in sewage treatment?	Soil and small pebbles removed by sedimentation.
70	What is primary sludge?	The solids that settle during primary treatment.
71	What is effluent?	The supernatant liquid remaining after sedimentation.
72	What happens during secondary or biological treatment?	Primary effluent is aerated to promote growth of aerobic microbes.
73	What are flocs?	Masses of bacteria associated with fungal filaments forming mesh-like structures.
74	What is BOD?	Biochemical Oxygen Demand.
75	Define BOD.	The amount of oxygen consumed if all organic matter in one litre of water is oxidised by bacteria.
76	What does the BOD test measure?	The rate of oxygen uptake by microorganisms in water.
77	What does a high BOD indicate?	Greater organic matter and higher polluting potential.
78	What is activated sludge?	Sedimented bacterial flocs formed after secondary treatment.
79	Why is a small portion of activated sludge pumped back into the aeration tank?	To serve as inoculum.
80	Where is the remaining activated sludge pumped?	Into anaerobic sludge digesters.
81	Which gases are produced during anaerobic digestion of sludge?	Methane, hydrogen sulphide, and carbon dioxide.
82	What is biogas?	A gaseous mixture produced during sludge digestion that can be used as fuel.
83	Why can biogas be used as a source of energy?	Because it is inflammable.
84	Where is treated effluent generally released after secondary treatment?	Into natural water bodies like rivers and streams.
85	How long has microbial sewage treatment been practiced worldwide?	For more than a century.
86	Why is untreated sewage dangerous?	It pollutes rivers and increases water-borne diseases.
87	Which two river-cleaning programmes were initiated by the Ministry of Environment and Forests?	Ganga Action Plan and Yamuna Action Plan.
88	What is the main aim of the Ganga Action Plan and Yamuna Action Plan?	To prevent pollution by ensuring only treated sewage is discharged into rivers.
89	What is biogas?	A mixture of gases, predominantly methane, produced by microbial activity and used as fuel.
90	Which gas is mainly present in biogas?	Methane.
91	What determines the type of gas produced by microbes?	The microbes involved and the organic substrates they utilise.
92	Which gas is mainly produced during fermentation of dough, cheese making, and beverage production?	Carbon dioxide (CO2).
93	Which bacteria produce large amounts of methane?	Methanogens.
94	Name a common methanogen bacterium.	Methanobacterium.
95	On what type of material do methanogens grow anaerobically?	Cellulosic material.
96	Which gases are produced by methanogens along with methane?	CO2 and H2.
97	Where are methanogens commonly found during sewage treatment?	In anaerobic sludge.
98	In which part of cattle are methanogens present?	Rumen.
99	What is the role of methanogens in the rumen of cattle?	They help in breakdown of cellulose and aid cattle nutrition.
100	Why is cattle dung rich in methanogens?	Because methanogens are present in the rumen and pass out with dung.
101	What is gobar gas?	Biogas produced from cattle dung.
102	What is the depth of a typical biogas plant tank?	About 10–15 feet deep.
103	What is fed into the biogas plant tank?	Bio-wastes and slurry of dung.
104	Why does the floating cover in a biogas plant rise upward?	Due to accumulation of gas produced by microbial activity.
105	How is biogas supplied to nearby houses?	Through pipes connected to the biogas plant outlet.
106	What happens to the spent slurry removed from the biogas plant?	It is used as fertiliser.
107	Why are biogas plants commonly built in rural areas?	Because cattle dung is available in large quantities there.
108	What are the uses of biogas?	Cooking and lighting.
109	Which organisations mainly developed biogas technology in India?	Indian Agricultural Research Institute (IARI) and Khadi and Village Industries Commission (KVIC).
110	What is biocontrol?	The use of biological methods for controlling plant diseases and pests.
111	Which chemicals are commonly used in conventional pest control?	Insecticides, pesticides, and weedicides.
112	Why are chemical pesticides harmful?	They are toxic to humans and animals and pollute the environment.
113	What is the basic principle of biological pest control in agriculture?	Controlling pests through natural predation rather than chemicals.
114	According to organic farmers, what increases sustainability in agriculture?	Greater biodiversity.
115	Why are pests not completely eradicated in organic farming?	Because beneficial predatory and parasitic insects depend on them.
116	What is a major advantage of biocontrol measures?	Reduced dependence on toxic chemicals and pesticides.
117	What knowledge is important for successful biocontrol?	Understanding life cycles, feeding patterns, and habitats of pests and predators.
118	What is the main objective of biocontrol measures?	To reduce dependence on toxic chemicals and pesticides.
119	Why is eradication of pests considered undesirable in organic farming?	Because beneficial predatory and parasitic insects depend on them for food or hosts.
120	What understanding is essential for developing effective biocontrol methods?	Knowledge of life cycles, feeding patterns, habitats, predators, and pests.
121	Which insect helps control aphids naturally?	Ladybird beetle.
122	Which insect helps control mosquitoes naturally?	Dragonfly.
123	Which bacterium is used as a microbial biocontrol agent against butterfly caterpillars?	Bacillus thuringiensis (Bt).
124	In what form is Bacillus thuringiensis commercially available?	As dried spores in sachets.
125	How is Bt applied to plants?	Mixed with water and sprayed onto vulnerable plants.
126	Which plants are mentioned as vulnerable to Bt-treated caterpillars?	Brassicas and fruit trees.
127	How does Bacillus thuringiensis kill insect larvae?	Toxin is released in the larval gut, killing the larvae.
128	What is an advantage of Bt over chemical pesticides?	It kills caterpillars without harming other insects.
129	What has genetic engineering enabled scientists to do with Bt toxin genes?	Introduce them into plants to make plants insect-resistant.
130	Name one genetically modified crop containing Bt toxin genes.	Bt-cotton.
131	Which fungus is used as a biological control agent against plant pathogens?	Trichoderma.
132	Where are Trichoderma species commonly found?	In root ecosystems.
133	What type of fungi are Trichoderma species?	Free-living fungi.
134	What are baculoviruses?	Pathogens that attack insects and other arthropods.
135	Which genus contains most baculoviruses used as biocontrol agents?	Nucleopolyhedrovirus.
136	Why are baculoviruses considered excellent biological control agents?	They are species-specific and have narrow-spectrum insecticidal applications.
137	What is the effect of baculoviruses on plants, mammals, birds, fish, and non-target insects?	They have no negative impacts.
138	In which programme are baculoviruses especially useful?	Integrated Pest Management (IPM) programme.
139	Why are baculoviruses suitable for ecologically sensitive areas?	Because they do not harm non-target organisms.
140	Why is environmental pollution a major concern in modern lifestyles?	Due to overuse of chemical fertilisers.
141	What is organic farming?	Farming that uses biofertilisers instead of chemical fertilisers.
142	What are biofertilisers?	Organisms that enrich the nutrient quality of soil.
143	What are the main sources of biofertilisers?	Bacteria, fungi, and cyanobacteria.
144	Which bacterium forms symbiotic nodules on roots of leguminous plants?	Rhizobium.
145	What is the role of Rhizobium in leguminous plants?	It fixes atmospheric nitrogen into organic forms.
146	Name two free-living nitrogen-fixing bacteria.	Azospirillum and Azotobacter.
147	What is mycorrhiza?	A symbiotic association between fungi and plant roots.
148	Which fungal genus commonly forms mycorrhiza?	Glomus.
149	What nutrient does the fungal symbiont absorb from soil in mycorrhiza?	Phosphorus.
150	Name two benefits of mycorrhizal association to plants.	Resistance to root-borne pathogens and tolerance to salinity and drought.
151	What overall effect does mycorrhiza have on plants?	Increased plant growth and development.
152	What are cyanobacteria?	Autotrophic microbes found in aquatic and terrestrial environments.
153	Name some nitrogen-fixing cyanobacteria.	Anabaena, Nostoc, and Oscillatoria.
154	Why are cyanobacteria important in paddy fields?	They serve as biofertilisers.
155	How do blue-green algae improve soil fertility?	By adding organic matter to the soil.
156	Why do farmers use commercial biofertilisers?	To replenish soil nutrients and reduce dependence on chemical fertilisers.
157	For how long have microbes been used in sewage treatment?	For more than a hundred years.
158	What process helps in recycling water during sewage treatment?	Activated sludge formation.
159	Which microbes produce methane during degradation of plant waste?	Methanogens.
160	What is the common use of biogas produced by microbes in rural areas?	As a source of energy.
161	What is biocontrol?	The use of microbes to kill harmful pests.
162	What is the advantage of biocontrol measures?	They reduce the heavy use of toxic pesticides.
163	Why is there a need to use biofertilisers instead of chemical fertilisers?	To reduce dependence on chemical fertilisers and environmental pollution.
164	What do the diverse uses of microbes indicate?	Microbes play an important role in human welfare.
165	Why can bacteria not be seen with naked eyes?	Because they are microscopic organisms.
166	Which instrument is used to observe microbes?	Microscope.
167	Which bacteria are commonly found in curd?	Lactic acid bacteria (LAB).
168	Mention one useful application of LAB.	Conversion of milk into curd.
169	Name some traditional Indian foods involving microbes.	Foods made from wheat, rice, and Bengal gram products.
170	How have microbes helped in controlling harmful bacteria?	By producing antibiotics.
171	Name any two fungal sources of antibiotics .	Penicillium notatum and Trichoderma polysporum.
172	What is sewage?	Municipal waste-water containing organic matter and microbes.
173	Why can sewage be harmful?	It contains pathogenic microbes and pollutants.
174	What is the key difference between primary and secondary sewage treatment?	Primary treatment removes particles physically, while secondary treatment uses microbes biologically.
175	Can microbes be used as a source of energy?	Yes, through production of biogas.
176	Which gas is mainly present in biogas?	Methane.
177	How can microbes reduce the use of chemical fertilisers?	By acting as biofertilisers.
178	What is measured in a BOD test?	Biochemical Oxygen Demand.
179	Which water sample has the highest pollution level in a BOD test?	The sample with the highest BOD value.
180	Which microorganism produces Cyclosporin A?	Trichoderma polysporum.
181	What is the function of Cyclosporin A?	It acts as an immunosuppressive drug.
182	Which microorganism produces statins?	Monascus purpureus.
183	What is the role of statins?	Lowering blood cholesterol.
184	What are biofertilisers?	Organisms that enrich soil nutrient quality.
185	Which microorganisms are major sources of biofertilisers?	Bacteria, fungi, and cyanobacteria.
186	Name a symbiotic nitrogen-fixing bacterium used as biofertiliser.	Rhizobium.
187	Name two free-living nitrogen-fixing bacteria.	Azospirillum and Azotobacter.
188	Name some nitrogen-fixing cyanobacteria.	Anabaena, Nostoc, and Oscillatoria.
189	What is the role of mycorrhiza in plants?	It helps absorb phosphorus and improves plant growth.
190	Which fungus commonly forms mycorrhiza?	Glomus.
191	Which microorganism converts milk into curd?	Lactobacillus.
192	Which yeast ferments bread dough?	Saccharomyces cerevisiae.
193	Which microorganism produces citric acid?	Aspergillus niger.
194	Which bacterium produces acetic acid?	Acetobacter aceti.
195	Which bacterium produces lactic acid?	Lactobacillus.
196	What role do microbes play in human society overall?	They contribute significantly to human welfare through food production, medicine, sewage treatment, biogas production, biocontrol, and biofertilisers.