Class 12 Biology MCQ Chapter 10 Microbes in Human Welfare
Are you searching for Class 12 Biology MCQ Chapter 10 Microbes in Human Welfare English Medium? Then you have come to the right place. This article provides important multiple-choice questions (MCQs) with answers from Chapter 10: Microbes in Human Welfare for AHSEC Higher Secondary students.
This chapter explains the beneficial role of microorganisms in human life and the environment. Students will learn about microbes used in food production, industrial products, sewage treatment, biogas production, antibiotics, biofertilizers, and biocontrol agents. The chapter highlights how microorganisms contribute to agriculture, medicine, environmental management, and various industries.
All MCQs are prepared according to the latest AHSEC syllabus and examination pattern. Regular practice of these objective questions will help students understand important concepts, improve their revision, and perform better in examinations.
Whether you are preparing for class tests, model examinations, or the AHSEC Higher Secondary Final Examination, these MCQ solutions will help you strengthen your Biology preparation and score higher marks.
Unit VIII: Biology in Human Welfare
Microbes in Human Welfare
VSA & MCQ
I. Very Short Question-Answers
Q. What are microbes?
Ans: Microbes are microscopic organisms invisible to the naked eye.
Q. Name one useful bacterium used in curd formation.
Ans: Lactobacillus.
Q. What is fermentation?
Ans: Fermentation is the conversion of sugars into alcohol or acids by microbes.
Q. Which microorganism is used in bread making?
Ans: Yeast.
Q. Name the microorganism used in production of alcohol.
Ans: Saccharomyces cerevisiae.
Q. What are antibiotics?
Ans: Antibiotics are chemical substances produced by microbes that kill or inhibit other microbes.
Q. Who discovered penicillin?
Ans: Alexander Fleming.
Q. Which fungus produces penicillin?
Ans: Penicillium notatum.
Q. What are biofertilizers?
Ans: Biofertilizers are organisms that enrich soil fertility.
Q. Name one cyanobacterium used as biofertilizer.
Ans: Anabaena.
Q. What is biogas?
Ans: Biogas is a mixture of gases produced by microbial activity.
Q. Which gas is the major component of biogas?
Ans: Methane.
Q. Name the bacteria involved in biogas production.
Ans: Methanogens.
Q. What is sewage?
Ans: Sewage is wastewater containing domestic and industrial wastes.
Q. What is sewage treatment?
Ans: Sewage treatment is the process of removing contaminants from wastewater.
Q. What are activated sludge flocs?
Ans: They are masses of bacteria associated with fungal filaments in sewage treatment.
Q. What is biological oxygen demand (BOD)?
Ans: BOD is the amount of oxygen required by microbes to decompose organic matter.
Q. Name one bacterium involved in nitrogen fixation.
Ans: Rhizobium.
Q. What is primary treatment of sewage?
Ans: Primary treatment removes large and suspended particles physically.
Q. What is secondary treatment of sewage?
Ans: Secondary treatment uses microbes to degrade organic matter.
Q. What are probiotics?
Ans: Probiotics are beneficial microbes that improve intestinal health.
Q. Name one organic acid produced by microbes.
Ans: Citric acid.
Q. What is gobar gas?
Ans: Gobar gas is biogas produced from cattle dung.
Q. What are methanogens?
Ans: Methanogens are microbes that produce methane gas.
Q. Name one antibiotic-producing bacterium.
Ans: Streptomyces.
Q. What is biocontrol?
Ans: Biocontrol is the use of organisms to control pests and diseases.
Q. Name one fungus used in biocontrol.
Ans: Trichoderma.
Q. What is Bacillus thuringiensis (Bt)?
Ans: Bt is a bacterium used as biopesticide.
Q. What is mycorrhiza?
Ans: Mycorrhiza is symbiotic association between fungi and plant roots.
Q. Name one microbe used in production of statins.
Ans: Monascus purpureus.
II. Multiple Choice Questions (MCQs)
Q. Curd formation involves:
(a) Yeast
(b) Lactobacillus
(c) Rhizobium
(d) Penicillium
Ans: (b) Lactobacillus
Q. Bread is prepared using:
(a) Algae
(b) Bacteria
(c) Yeast
(d) Virus
Ans: (c) Yeast
Q. Alcohol is produced by:
(a) Rhizobium
(b) Saccharomyces cerevisiae
(c) Lactobacillus
(d) Penicillium
Ans: (b) Saccharomyces cerevisiae
Q. Penicillin was discovered by:
(a) Louis Pasteur
(b) Robert Koch
(c) Alexander Fleming
(d) Edward Jenner
Ans: (c) Alexander Fleming
Q. Penicillin is obtained from:
(a) Aspergillus
(b) Penicillium
(c) Rhizopus
(d) Saccharomyces
Ans: (b) Penicillium
Q. Organisms enriching soil fertility are:
(a) Antibiotics
(b) Biofertilizers
(c) Biopesticides
(d) Pathogens
Ans: (b) Biofertilizers
Q. Rhizobium helps in:
(a) Alcohol production
(b) Nitrogen fixation
(c) Curd formation
(d) Sewage treatment only
Ans: (b) Nitrogen fixation
Q. Major component of biogas is:
(a) Oxygen
(b) Nitrogen
(c) Methane
(d) Carbon monoxide
Ans: (c) Methane
Q. Methane-producing microbes are:
(a) Cyanobacteria
(b) Methanogens
(c) Viruses
(d) Protozoans
Ans: (b) Methanogens
Q. Wastewater is called:
(a) Sludge
(b) Sewage
(c) Compost
(d) Manure
Ans: (b) Sewage
Q. Secondary sewage treatment mainly involves:
(a) Physical process
(b) Chemical process
(c) Microbial activity
(d) Filtration only
Ans: (c) Microbial activity
Q. Activated sludge contains:
(a) Viruses only
(b) Bacterial flocs
(c) Algae only
(d) Plant roots
Ans: (b) Bacterial flocs
Q. BOD stands for:
(a) Biological Oxygen Demand
(b) Biochemical Organic Deposit
(c) Biological Organic Decomposition
(d) Bacterial Oxygen Deficiency
Ans: (a) Biological Oxygen Demand
Q. Higher BOD indicates:
(a) Clean water
(b) Less pollution
(c) More organic pollution
(d) Pure oxygen
Ans: (c) More organic pollution
Q. Gobar gas mainly contains:
(a) Hydrogen
(b) Methane
(c) Oxygen
(d) Nitrogen
Ans: (b) Methane
Q. Trichoderma is used in:
(a) Fermentation
(b) Biocontrol
(c) Nitrogen fixation
(d) Sewage treatment
Ans: (b) Biocontrol
Q. Bacillus thuringiensis is used as:
(a) Antibiotic
(b) Biofertilizer
(c) Biopesticide
(d) Vaccine
Ans: (c) Biopesticide
Q. Symbiotic association between fungi and roots is:
(a) Lichen
(b) Mycorrhiza
(c) Biofilm
(d) Nodule
Ans: (b) Mycorrhiza
Q. Citric acid is produced by:
(a) Microbes
(b) Animals
(c) Viruses
(d) Protozoans only
Ans: (a) Microbes
Q. Probiotics are:
(a) Harmful microbes
(b) Disease-causing microbes
(c) Beneficial microbes
(d) Viruses
Ans: (c) Beneficial microbes
Q. Statins are produced by:
(a) Lactobacillus
(b) Monascus purpureus
(c) Rhizobium
(d) Methanogens
Ans: (b) Monascus purpureus
Q. Fermentation converts sugar into:
(a) Protein
(b) Alcohol
(c) Vitamins
(d) Lipids
Ans: (b) Alcohol
Q. Which one is a biofertilizer?
(a) Penicillium
(b) Rhizobium
(c) HIV
(d) Yeast
Ans: (b) Rhizobium
Q. The fungus used in antibiotic production is:
(a) Rhizopus
(b) Penicillium
(c) Aspergillus only
(d) Mucor
Ans: (b) Penicillium
Q. Cyanobacteria are useful in:
(a) Alcohol production
(b) Nitrogen fixation
(c) Bread making
(d) Vaccine preparation
Ans: (b) Nitrogen fixation
Q. Which one is used in sewage treatment?
(a) Methanogens
(b) Activated sludge microbes
(c) Viruses
(d) Protozoans only
Ans: (b) Activated sludge microbes
Q. Antibiotics are produced by:
(a) Plants only
(b) Microorganisms
(c) Animals only
(d) Viruses
Ans: (b) Microorganisms
Q. Anabaena is a:
(a) Fungus
(b) Cyanobacterium
(c) Virus
(d) Protozoan
Ans: (b) Cyanobacterium
Q. The process of biogas formation is carried out under:
(a) Aerobic conditions
(b) Anaerobic conditions
(c) Dry conditions
(d) Sterile conditions
Ans: (b) Anaerobic conditions
Q. Microbes used to control pests are called:
(a) Pathogens
(b) Biocontrol agents
(c) Antibiotics
(d) Fermenters
Ans: (b) Biocontrol agents
Q. Assertion (A): Lactobacillus helps in curd formation.
Reason (R): Lactobacillus converts milk into lactic acid.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Ans: (b)
Q. Assertion (A): Methanogens are important in biogas production.
Reason (R): Methanogens produce methane gas during anaerobic decomposition.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Ans: (a)
Q. Assertion (A): Secondary sewage treatment reduces organic pollutants.
Reason (R): Microbes degrade organic matter during secondary treatment.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Ans: (b)
Q. Assertion (A): Penicillin is an antibiotic.
Reason (R): Penicillin is produced by Penicillium fungus.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Ans: (c)
Q. Assertion (A): Rhizobium improves soil fertility.
Reason (R): Rhizobium fixes atmospheric nitrogen in root nodules.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Ans: (a)
Q. Assertion (A): Bt is used as a biopesticide.
Reason (R): Bacillus thuringiensis produces toxic proteins harmful to insect pests.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Ans: (b)
Q. Assertion (A): Higher BOD indicates cleaner water.
Reason (R): High BOD means greater amount of organic matter in water.
(a) Both A and R are true, and R is the correct explanation of A.
(b) Both A and R are true, but R is not the correct explanation of A.
(c) A is true, but R is false.
(d) A is false, but R is true.
Ans: (d)
