Q1. Match the following biofertilisers with their type:
Column I
Column II
A. Rhizobium
(I) Symbiotic fungus
B. Azospirillum
(II) Symbiotic bacterium
C. Glomus
(III) Free-living bacterium
Correct Answer: (a)
Rhizobium is a symbiotic bacterium (II), Azospirillum is a free‑living bacterium (III), and Glomus is a symbiotic fungus (I). This correctly classifies these biofertilisers.
Q2. Identify correct statements for 'Biofertilisers': (i) They enrich the nutrient quality of the soil. (ii) Rhizobium fixes atmospheric nitrogen into organic forms. (iii) Mycorrhiza absorbs phosphorus from the soil.
Correct Answer: (a)
All statements are correct. Biofertilisers improve soil fertility, Rhizobium fixes nitrogen, and mycorrhizal fungi enhance phosphorus uptake. They are eco‑friendly alternatives to chemical fertilisers.
Q3. The 'clot buster' enzyme used to remove clots from blood vessels of heart patients is:
Correct Answer: (c)
Streptokinase is a thrombolytic enzyme that dissolves blood clots by converting plasminogen to plasmin. It is used in treating myocardial infarction (heart attacks). Lipases break down fats, pectinases clarify juices, and proteases hydrolyse proteins.
Q4. Which insect is useful to get rid of aphids?
Correct Answer: (b)
Ladybird beetles (ladybugs) are natural predators of aphids, feeding on them and thus controlling their population. Dragonflies prey on mosquitoes, butterfly caterpillars are pests, and moths are generally not used for aphid control.
Q5. Assertion: Baculoviruses are excellent for integrated pest management (IPM).
Reason: They have no negative impacts on non-target insects, mammals, or birds.
Correct Answer: (a)
Both statements are true. Baculoviruses are species‑specific and do not harm beneficial organisms, making them ideal for IPM. The reason directly supports why they are excellent for IPM.
Q6. Which of the following describes 'Secondary Sewage Treatment' correctly? (i) It is primarily a physical process. (ii) Useful aerobic microbes grow into flocs. (iii) It continues until the BOD of the effluent is reduced.
Correct Answer: (a)
Secondary treatment is biological, not physical. Flocs formation and BOD reduction are key features. Hence, statements (ii) and (iii) are correct, while (i) is false.
Q7. Assertion: All microbes are harmful to human beings.
Reason: Microbes cause a large number of diseases in humans, animals, and plants.
Correct Answer: (d)
The assertion is false because many microbes are beneficial (e.g., LAB, yeast, antibiotic producers). The reason is true – many microbes do cause diseases, but this does not imply all are harmful. Hence, the assertion is false, but the reason is correct.
Q8. Identify correct features of 'Rhizobium': (i) It is a symbiotic bacterium. (ii) Found in nodules of leguminous roots. (iii) Fixes atmospheric nitrogen.
Correct Answer: (a)
Rhizobium is a symbiotic bacterium that lives in root nodules of legumes and fixes nitrogen. All three statements are correct and describe its key characteristics.
Q9. Which bacteria are found in the rumen of cattle and help in cellulose digestion?
Correct Answer: (b)
Methanogens, such as Methanobacterium, reside in the rumen and break down cellulose into simpler compounds, producing methane as a by‑product. They are also used in biogas plants. Lactobacillus, Streptococcus, and Aspergillus are not the primary cellulose‑digesting rumen bacteria.
Q10. Assertion: Staphlylococci could not grow around a certain mould in Fleming's experiment.
Reason: The mould Penicillium notatum produced a chemical called Penicillin.
Correct Answer: (a)
Both true. The mould secreted penicillin, which inhibited the growth of Staphylococci. The reason directly explains the observation, making it the correct explanation.
Q11. Statins, used as blood-cholesterol lowering agents, are produced by the yeast:
Correct Answer: (c)
Monascus purpureus is the yeast that produces statins, which competitively inhibit the enzyme HMG‑CoA reductase involved in cholesterol synthesis. Saccharomyces is used in baking and brewing, Trichoderma produces cyclosporin, and Acetobacter produces acetic acid.
Q12. Fermentors are used in industry to:
Correct Answer: (b)
Fermentors are large vessels designed to provide optimal conditions (temperature, pH, aeration) for the large‑scale growth of microbes. They are essential for commercial production of antibiotics, enzymes, and alcoholic beverages. They are not used for storage, cheese curing, or juice clarification.
Q13. The technology of biogas production in India was developed mainly due to the efforts of:
Correct Answer: (a)
The Indian Agricultural Research Institute (IARI) and the Khadi and Village Industries Commission (KVIC) played key roles in developing and promoting biogas technology in India. They designed the floating‑dome type biogas plants commonly used in rural areas.
Q14. Which of the following are correct regarding 'BOD'? (i) BOD measures the rate of oxygen uptake by micro-organisms. (ii) Higher BOD means the water is less polluting. (iii) BOD is a measure of organic matter present in water.
Correct Answer: (a)
Statements (i) and (iii) are correct: BOD measures oxygen uptake and organic matter. Statement (ii) is false because higher BOD indicates more pollution, not less.
Q15. Select correct statements for 'Organic Farming': (i) Uses biofertilisers instead of chemical fertilisers. (ii) Aim is to enrich the nutrient quality of soil. (iii) Prevents environmental pollution.
Correct Answer: (a)
Organic farming relies on biofertilisers, improves soil health, and reduces pollution. All three statements accurately describe its principles.
Q16. The 'puffed-up' appearance of dough used for making idli and dosa is due to the production of:
Correct Answer: (c)
During fermentation, LAB and other microbes produce carbon dioxide gas, which gets trapped in the dough. This causes the dough to rise and become fluffy. The gas is CO₂, not oxygen, methane, or nitrogen.
Q17. Correct statements for 'Mycorrhiza' include: (i) Many members of genus Glomus form it. (ii) Fungus provides phosphorus to the plant. (iii) Plant provides resistance to root-borne pathogens.
Correct Answer: (a)
All statements are true: Glomus is a common mycorrhizal fungus, it supplies phosphorus, and the association also helps plants resist root pathogens and tolerate stress.
Q18. Biological control of pests relies on ______ rather than chemicals.
Correct Answer: (b)
Biological control uses natural predators, parasites, or pathogens to manage pest populations, avoiding chemical pesticides. This method is eco‑friendly and sustainable. Herbicides are chemicals, distillation is a separation technique, and fermentation is a metabolic process.
Q19. Assertion: Secondary sewage treatment is also called biological treatment.
Reason: It involves the use of heterotrophic aerobic microbes to consume organic matter.
Correct Answer: (a)
Both are true. Secondary treatment relies on aerobic microbes that break down organic matter, hence it is termed biological treatment. The reason correctly explains why it is called biological.
Q20. Assertion: Prions are diverse microbes.
Reason: They are proteinaceous infectious agents.
Correct Answer: (d)
The assertion is false – prions are not diverse; they are a specific type of misfolded protein. The reason is true – they are proteinaceous infectious agents. So, assertion false, reason true.
Q21. Identify correct statements for 'Bt-toxin': (i) Produced by Bacillus thuringiensis. (ii) Available in sachets as dried spores. (iii) Kills insect larvae in their gut.
Correct Answer: (a)
Bt‑toxin comes from B. thuringiensis, sold as spore formulations, and kills larvae upon ingestion. All three statements are correct.
Q22. Rhizobium forms a symbiotic association with the roots of:
Correct Answer: (c)
Rhizobium bacteria form nodules on the roots of leguminous plants (e.g., peas, beans, clover) and fix atmospheric nitrogen. They do not associate with paddy (rice), wheat, or conifers, which have different symbiotic partners.
Q23. Which of the following describes 'Activated Sludge' correctly? (i) It is the sediment of bacterial flocs in the settling tank. (ii) A small part is used as an inoculum in the aeration tank. (iii) The rest is pumped into anaerobic sludge digesters.
Correct Answer: (a)
All three statements are correct. Activated sludge is the settled flocs, part is recycled as inoculum, and the remainder goes to anaerobic digesters for biogas production.
Q24. Cyclosporin A is used as an ______ agent.
Correct Answer: (c)
Cyclosporin A suppresses the immune system and is used to prevent organ rejection after transplantation. It is not an antibiotic, a cholesterol‑lowering drug, or an anti‑inflammatory drug, though it has some anti‑inflammatory properties.
Q25. Assertion: Curd is more nutritious than milk.
Reason: LAB increases the content of Vitamin B12 in curd.
Correct Answer: (a)
Both statements are true. LAB fermentation enriches curd with vitamin B12, which directly improves its nutritional value compared to plain milk. The reason correctly explains the assertion.
Q26. Regarding 'Lactic Acid Bacteria' (LAB): (i) Grow in milk and convert it to curd. (ii) Produce acids that coagulate milk proteins. (iii) Check disease-causing microbes in the stomach.
Correct Answer: (a)
LAB perform all these functions: ferment milk to curd, coagulate proteins, and inhibit pathogens in the gut. They are versatile beneficial microbes.
Q27. Match the following for biogas plant (Figure 8.8):
Structure
Description
A. Digester
(I) 10-15 feet deep tank
B. Gas-holder
(II) Floating cover
Correct Answer: (a)
In a typical biogas plant, the digester is a deep tank (I) where fermentation occurs, and the gas‑holder is a floating cover (II) that collects the produced gas. This matches the standard design.
Q28. Correct statements for 'Primary Sludge' include: (i) All solids that settle during primary treatment. (ii) It is taken for secondary treatment.
Correct Answer: (a)
Primary sludge is the settled solids from primary treatment (i). It is not taken for secondary treatment; the supernatant is. Hence, only (i) is correct.
Q29. Baculoviruses of the genus ______ are used as narrow-spectrum insecticidal agents.
Correct Answer: (b)
Baculoviruses, especially those in the genus Nucleopolyhedrovirus, are species‑specific viruses that infect insects. They are highly effective and safe for non‑target organisms, making them ideal for integrated pest management (IPM). Methanobacterium, Glomus, and Anabaena are not baculoviruses.
Q30. Regarding 'Statins', identify true statements: (i) Produced by Monascus purpureus. (ii) Competitively inhibit cholesterol synthesis enzyme. (iii) Act as blood-cholesterol lowering agents.
Correct Answer: (a)
All three statements are correct: statins are from Monascus purpureus, they competitively inhibit HMG‑CoA reductase, and thereby lower blood cholesterol.
Q31. Which of the following are proteinaceous infectious agents?
Correct Answer: (c)
Prions are infectious agents composed entirely of protein, unlike viruses or viroids which contain nucleic acids. They cause diseases like mad cow disease and Creutzfeldt‑Jakob disease. Protozoa and bacteria are cellular organisms, while viroids are RNA‑only pathogens.
Q32. Flocs in secondary sewage treatment consist of:
Correct Answer: (b)
Flocs are masses of aerobic bacteria growing on fungal filaments, forming a mesh that traps organic matter. They are formed during secondary treatment in aeration tanks. Sand and grit are removed in primary treatment, and anaerobic bacteria are not the main component of flocs.
Q33. Assertion: Ladybird is a biocontrol agent.
Reason: It helps get rid of mosquitoes.
Correct Answer: (c)
Assertion is true – ladybirds are biocontrol agents. But reason is false – they control aphids, not mosquitoes. Dragonflies control mosquitoes. Thus, assertion true, reason false.
Q34. Bt-cotton is a plant that has been genetically engineered to express toxin genes from:
Correct Answer: (b)
Bt‑cotton contains genes from the bacterium Bacillus thuringiensis, which produce insecticidal proteins (Bt toxins) that kill specific pests like bollworms. Trichoderma is a biocontrol fungus, Nucleopolyhedrovirus is a viral insecticide, and Rhizobium fixes nitrogen.
Q35. Assertion: Biogas is a mixture of gases containing predominantly carbon dioxide.
Reason: Methanogens produce methane during the breakdown of cellulosic material.
Correct Answer: (d)
The assertion is false because biogas consists mainly of methane (about 50‑70%), not carbon dioxide. The reason is true – methanogens produce methane from cellulose. So, assertion false, reason true.
Q36. In sewage treatment, primary treatment involves:
Correct Answer: (b)
Primary treatment is a physical process that removes suspended solids and floating debris through filtration and sedimentation. It does not involve biological activity or BOD reduction; those are part of secondary treatment.
Q37. Regarding 'Baculoviruses', identify the correct statements: (i) They belong to the genus Nucleopolyhedrovirus. (ii) They are excellent for species-specific insecticidal applications. (iii) They have negative impacts on non-target birds.
Correct Answer: (a)
Baculoviruses are in the genus Nucleopolyhedrovirus, are species‑specific, and do not harm non‑target organisms. Statement (iii) is false; they are safe for birds and mammals.
Q38. Match the product in Column I with the microbe in Column II:
Column I (Product)
Column II (Microbe)
A. Citric acid
(I) Acetobacter aceti
B. Acetic acid
(II) Aspergillus niger
C. Butyric acid
(III) Lactobacillus
D. Lactic acid
(IV) Clostridium butylicum
Correct Answer: (a)
Citric acid is produced by Aspergillus niger (II); acetic acid by Acetobacter aceti (I); butyric acid by Clostridium butylicum (IV); and lactic acid by Lactobacillus (III). This pairing matches standard industrial microbiology.
Q39. Select correct statements for 'Biogas': (i) It is a mixture of gases containing predominantly methane. (ii) It is inflammable. (iii) It is used as a source of energy for cooking and lighting.
Correct Answer: (a)
All statements are correct: biogas is mainly methane, is flammable, and is used as a renewable energy source in rural areas for cooking and lighting.
Q40. Match the biocontrol agent with its target:
Column I (Agent)
Column II (Target)
A. Ladybird
(I) Mosquitoes
B. Dragonflies
(II) Aphids
C. Bt-toxin
(III) Butterfly caterpillars
Correct Answer: (a)
Ladybird beetles feed on aphids (II); dragonflies prey on mosquitoes (I); Bt‑toxin kills butterfly caterpillars (III). These are classic examples of biological control.
Q41. Mycorrhiza is a symbiotic association between fungi and plants, where the fungus helps in absorbing:
Correct Answer: (c)
Mycorrhizal fungi, such as Glomus, enhance the absorption of phosphorus from soil by the plant roots. They also help in water uptake and provide resistance to pathogens. Nitrogen is fixed by bacteria, and carbon and iron are not the primary benefit.
Q42. Assertion: Streptokinase is called a 'clot buster'.
Reason: It is produced by the bacterium Streptococcus.
Correct Answer: (b)
Both assertions are true, but the reason does not explain why it is called a clot buster – its function is due to its ability to dissolve clots, not its source. The source (Streptococcus) is unrelated to its action.
Q43. Lactic acid bacteria (LAB) improve the nutritional quality of milk by increasing which vitamin?
Correct Answer: (b)
LAB fermentation not only converts milk to curd but also enhances the content of vitamin B12. This vitamin is essential for nerve function and red blood cell formation. Thus, curd becomes more nutritious than plain milk.
Q44. Regarding the 'Mould' in Fleming's experiment: (i) It was Penicillium notatum. (ii) It prevented the growth of Staphylococci. (iii) It led to the discovery of antibiotics.
Correct Answer: (a)
All three statements are correct: Fleming's mould was Penicillium notatum, it inhibited Staphylococci, and this led to the discovery of the first antibiotic.
Q45. Assertion: Ganga Action Plan was initiated to save rivers from pollution.
Reason: Untreated sewage often leads to water-borne diseases.
Correct Answer: (a)
Both are true. The Ganga Action Plan aimed to reduce pollution in the Ganga River, and sewage is a major source of pollution causing diseases. The reason explains why such a plan was needed.
Q46. Baker’s yeast used for making bread is:
Correct Answer: (b)
Saccharomyces cerevisiae, also known as baker's yeast, is the common yeast used in bread‑making because it ferments sugars to produce CO₂, which leavens the dough. Lactobacillus is used in curd, Propionibacterium in Swiss cheese, and Aspergillus niger in citric acid production.
Q47. Assertion: Anaerobic sludge digesters produce biogas.
Reason: Bacteria produce methane, hydrogen sulphide, and CO2 in these tanks.
Correct Answer: (a)
Both true. In anaerobic digesters, bacteria break down organic matter and produce a gas mixture (biogas) that includes methane, CO₂, and H₂S. The reason correctly describes the composition and origin of biogas.
Q48. Match the nitrogen fixers:
Group
Microbe
A. Symbiotic
(I) Azotobacter
B. Free-living
(II) Rhizobium
Correct Answer: (a)
Rhizobium is symbiotic (A‑II), while Azotobacter is free‑living (B‑I). This is the correct classification of these nitrogen‑fixing bacteria.
Q49. Assertion: Organic farmers do not aim to completely eradicate pests.
Reason: Without pests, beneficial predatory and parasitic insects could not survive.
Correct Answer: (a)
Both are correct. Organic farming maintains ecological balance, so it doesn't aim for total pest elimination because that would remove the food source for natural enemies. The reason explains this sustainable approach.
Q50. Which are correct for 'Cyanobacteria'? (i) They are autotrophic microbes. (ii) They add organic matter to the soil. (iii) They are used as biofertilisers in paddy fields.
Correct Answer: (a)
Cyanobacteria are autotrophic (photosynthetic), enrich soil with organic matter, and fix nitrogen, making them valuable biofertilisers in rice paddies.
Q51. Assertion: MTP is performed to get rid of unwanted pregnancy due to rapes.
Reason: Government of India legalised MTP in 1971.
Correct Answer: (b)
Both true, but the reason (legalization) does not explain why MTP is performed – it is done to terminate unwanted pregnancies, which may arise from rape, but the reason is about legal status, not the purpose. Hence, not the correct explanation.
Q52. Assertion: Bottled juices are clearer than home-made ones.
Reason: Bottled juices are clarified using lipases.
Correct Answer: (c)
The assertion is true – commercial juices are clearer due to clarification. However, the reason is false; clarification is done with pectinases and proteases, not lipases. Lipases break down fats, not pectin or protein.
Q53. The large holes in 'Swiss cheese' are due to the production of a large amount of CO2 by:
Correct Answer: (a)
Propionibacterium sharmanii ferments lactic acid to produce propionic acid and a large volume of CO₂ gas. This gas forms the characteristic big eyes or holes in Swiss cheese. Other microbes listed are associated with different products.
Q54. Which of the following is correct regarding 'Microbes in Household Products'? (i) Lactobacillus is used for making curd. (ii) Baker's yeast is used for bread making. (iii) Toddy is a fermented sap from palms.
Correct Answer: (a)
All three statements are correct. Lactobacillus ferments milk to curd, baker's yeast (Saccharomyces cerevisiae) leavens bread, and toddy is a traditional fermented beverage from palm sap.
Q55. Which of the following is used as a biofertiliser in paddy fields?
Correct Answer: (b)
Cyanobacteria (blue‑green algae) fix atmospheric nitrogen and are used as biofertilisers in rice paddies, where they enrich the soil with nitrogen. Mycoplasma is a pathogenic bacterium, baker's yeast is used in baking, and Lactobacillus is used in dairy.
Q56. Match the secondary metabolite with its category (Table 9.3):
Column I (Metabolite)
Column II (Category)
A. Morphine
(I) Toxin
B. Monoterpenes
(II) Alkaloid
C. Abrin
(III) Terpenoides
D. Curcumin
(IV) Drug
Correct Answer: (a)
Morphine is an alkaloid (II), monoterpenes are terpenoids (III), abrin is a toxin (I), and curcumin is a drug (IV). This matches the standard classification of secondary metabolites.
Q57. Assertion: Penicillin's full potential as an antibiotic was established by Alexander Fleming.
Reason: Fleming was awarded the Nobel Prize for his discovery in 1945.
Correct Answer: (d)
The assertion is false because Fleming discovered penicillin but it was Chain and Florey who established its therapeutic potential and mass production. The reason is true – Fleming shared the Nobel Prize in 1945. Thus, assertion false, reason true.
Q58. Assertion: Statins act as blood-cholesterol lowering agents.
Reason: They competitively inhibit the enzyme responsible for cholesterol synthesis.
Correct Answer: (a)
Both are true. Statins block HMG‑CoA reductase, reducing cholesterol production, which lowers blood cholesterol. The reason correctly explains the mechanism of action.
Q59. Assertion: Activated sludge is used as an inoculum in the aeration tank.
Reason: A small part of the activated sludge contains useful aerobic microbes.
Correct Answer: (a)
Both are true. Activated sludge is rich in active aerobic bacteria, and a portion is returned to the aeration tank to serve as inoculum, ensuring a high microbial population for efficient treatment. The reason correctly explains the use.
Q60. Which are true for 'Gobar Gas'? (i) Excreta of cattle is rich in methanogens. (ii) Can be used to generate biogas. (iii) technology was developed by IARI and KVIC.
Correct Answer: (a)
All statements are true: cow dung contains methanogens, can produce biogas, and the technology was promoted by IARI and KVIC in India.
Q61. Which of the following is correct for 'Biocontrol Agents'? (i) Dragonflies are used to get rid of mosquitoes. (ii) Ladybird is used to control aphids. (iii) Bt-spores are used to control butterfly caterpillars.
Correct Answer: (a)
All three are correct examples: dragonflies prey on mosquitoes, ladybirds eat aphids, and Bt spores kill butterfly caterpillars. These are standard biocontrol applications.
Q62. Who discovered the first antibiotic, Penicillin?
Correct Answer: (c)
Alexander Fleming discovered penicillin in 1928 when he noticed that a mould (Penicillium notatum) inhibited the growth of Staphylococcus bacteria. Ernest Chain and Howard Florey later purified and mass‑produced it, but Fleming is credited with the initial discovery.
Q63. Assertion: Single Cell Protein (SCP) involves the use of microbes.
Reason: Microbes are used as a source of energy in rural areas.
Correct Answer: (c)
Assertion is true – SCP is protein from microbes. However, reason is false because microbes used as energy source are for biogas, not SCP. Thus, assertion true, reason false.
Q64. Regarding 'Methanogens', which statements are true? (i) They grow anaerobically on cellulosic material. (ii) They produce a large amount of methane. (iii) They are found in the rumen of cattle and anaerobic sludge.
Correct Answer: (a)
All three are correct. Methanogens are anaerobic archaea that break down cellulose and produce methane. They inhabit the rumen and anaerobic sludge digesters.
Q65. Match the bioactive molecule with its source:
Column I
Column II
A. Cyclosporin A
(I) Monascus purpureus
B. Statins
(II) Trichoderma polysporum
C. Streptokinase
(III) Streptococcus
Correct Answer: (a)
Cyclosporin A is from Trichoderma polysporum (II); statins from Monascus purpureus (I); streptokinase from Streptococcus (III). This matches the sources given in the chapter.
Q66. Which are correct for 'Azospirillum' and 'Azotobacter'? (i) They are symbiotic nitrogen fixers. (ii) They are free-living in the soil. (iii) They enrich soil nitrogen content.
Correct Answer: (a)
Both Azospirillum and Azotobacter are free‑living, not symbiotic. They fix nitrogen and enrich soil. Thus, statements (ii) and (iii) are correct.
Q67. Which of the following organisms is used for the production of citric acid?
Correct Answer: (b)
Aspergillus niger, a fungus, is widely used in the industrial production of citric acid through fermentation. Acetobacter aceti produces acetic acid, Clostridium butylicum produces butyric acid, and Lactobacillus produces lactic acid.
Q68. Assertion: High BOD of waste water indicates it is very polluted.
Reason: BOD measures the rate of oxygen uptake by micro-organisms in the water.
Correct Answer: (a)
Both statements are true. High BOD means more organic matter, leading to greater oxygen consumption by microbes, indicating severe pollution. The reason defines BOD and supports the assertion.
Q69. Which alcoholic beverages are produced without distillation?
Correct Answer: (c)
Wine and beer are produced by fermentation only; they are not distilled. Distillation is used to make spirits like whisky, brandy, rum, and gin, which have higher alcohol content. Thus, wine and beer are the correct pair.
Q70. Assertion: Cyanobacteria are autotrophic microbes.
Reason: They can fix atmospheric nitrogen in paddy fields.
Correct Answer: (b)
Both true, but autotrophy refers to photosynthesis (using light energy), while nitrogen fixation is a separate metabolic ability. The reason does not explain autotrophy; it describes another function. So, both true but reason not the explanation.
Q71. Assertion: Methanogens are found in anaerobic sludge.
Reason: They are also present in the rumen of cattle.
Correct Answer: (b)
Both statements are true, but the reason does not explain why methanogens are found in anaerobic sludge; they are found in both places because they thrive in oxygen‑free environments. The reason just gives another habitat, not a causal explanation.
Q72. Match the following for cheese specificity:
Cheese
Feature/Microbe
A. Swiss Cheese
(I) Specific fungi
B. Roquefort Cheese
(II) Bacterium / large holes
Correct Answer: (a)
Swiss cheese has large holes due to Propionibacterium (a bacterium) producing CO₂ (II). Roquefort cheese is ripened by specific fungi (Penicillium roqueforti) (I). Hence, A‑II, B‑I.
Q73. Identify the correct phylum/group being described: (i) They are narrow-spectrum insecticidal agents. (ii) Belong to the genus Nucleopolyhedrovirus. (iii) Desirable for Integrated Pest Management.
Correct Answer: (a)
These features describe baculoviruses – they are narrow‑spectrum, genus Nucleopolyhedrovirus, and used in IPM. Ladybirds are beetles, Bt‑cotton is a plant, and Trichoderma is a fungus.
Q74. Assertion: LAB play a very beneficial role in our stomach.
Reason: They help in checking disease-causing microbes in the stomach.
Correct Answer: (a)
Both are true. LAB present in the gut inhibit harmful pathogens by producing acids and bacteriocins. This beneficial role is correctly explained by their ability to check disease‑causing microbes.
Q75. Which are correct for 'Enzymes in Industry'? (i) Lipases are used in detergents. (ii) Pectinases are used to clarify bottled juices. (iii) Streptokinase is used as a clot buster.
Correct Answer: (a)
All three are correct uses of microbial enzymes: lipases in detergents, pectinases in juice clarification, and streptokinase as a thrombolytic agent.
Q76. Identify the correct statements regarding 'Antibiotics': (i) Anti means 'against' and bio means 'life'. (ii) They are 'pro-life' in the context of human beings. (iii) Penicillin was the first antibiotic discovered accidentally by Alexander Fleming.
Correct Answer: (a)
All statements are correct: antibiotic etymology is 'against life', they are beneficial (pro‑life) for humans, and penicillin was indeed the first antibiotic discovered accidentally by Fleming.
Q77. Match the following for sewage treatment:
Column I
Column II
A. Grit removal
(I) Secondary treatment
B. Flocs formation
(II) Primary treatment
C. Biogas production
(III) Sludge digester
Correct Answer: (a)
Grit removal is part of primary treatment (II). Flocs formation occurs during secondary treatment (I). Biogas production happens in the sludge digester (III). These steps are sequential in sewage treatment.
Q78. Match the following microbes with their descriptions:
Column I
Column II
A. Viruses
(I) Microscopic animal/plant parasites
B. Viroids
(II) RNA only infectious agents
C. Prions
(III) Protein only infectious agents
Correct Answer: (a)
Viruses are microscopic parasites (I); viroids consist only of RNA (II); prions are protein‑only infectious agents (III). This classification differentiates these infectious entities.
Q79. Assertion: Glomus helps plants tolerate salinity and drought.
Reason: The fungus absorbs phosphorus and passes it to the plant.
Correct Answer: (b)
Both statements are true, but the reason does not explain tolerance to salinity/drought – those are separate benefits of mycorrhizal association. Phosphorus absorption is a primary function, while stress tolerance is an additional advantage.
Q80. Microbes are present in which of the following environments?
Correct Answer: (d)
Microbes are found everywhere – in soil, water, air, inside other organisms, and even in extreme environments like hot springs and deep snow. Their distribution is ubiquitous across all ecosystems. This wide occurrence makes option 4 the correct choice.
Q81. Assertion: Roquefort cheese is ripened by fungi.
Reason: The fungi give the cheese a particular flavour.
Correct Answer: (a)
Both true. Roquefort cheese is ripened by the fungus Penicillium roqueforti, which imparts its characteristic flavour and texture. The reason correctly explains why fungi are used.
Q82. BOD refers to the amount of ______ consumed by bacteria in one liter of water.
Correct Answer: (c)
BOD (Biochemical Oxygen Demand) measures the oxygen consumed by microorganisms while decomposing organic matter in water. Higher BOD indicates more organic pollution, as more oxygen is required. CO₂, methane, and nitrogen are not directly measured by BOD.
Q83. Which of the following is correct? (i) Viruses, viroids and prions are microbes. (ii) Microbes like bacteria can form colonies on nutritive media. (iii) Antibiotics can treat diseases like plague and leprosy.
Correct Answer: (a)
All three statements are correct. Viruses, viroids, and prions are acellular microbes; bacteria can be cultured on media; antibiotics are effective against bacterial diseases like plague and leprosy.
Q84. Identify the correct phylum/microbe based on the statements? (i) It is a fungus used to produce citric acid. (ii) It can be grown on nutritive media to form colonies.
Correct Answer: (a)
Aspergillus niger is a fungus that produces citric acid and can be cultured on nutrient media. The other options are bacteria, not fungi, and are associated with different products.
Q85. Assertion: Trichoderma is used in the treatment of plant diseases.
Reason: They are free-living fungi very common in root ecosystems.
Correct Answer: (b)
Both are true, but the reason does not explain its use in disease treatment; it is used because it acts as a biocontrol agent against pathogenic fungi. Its common presence in roots is not the reason for its effectiveness, though it may help in colonization.