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First read the questions carefully using the Read section. Use the Details button to understand concepts clearly. After completing reading, click Practice Quiz to test yourself.
📘 Study MCQs
Q1. Which of these is not a micro-organism?
• Algae
• Bacteria
• Virus
• Ant
Answer: Ant
An ant is an insect visible to the naked eye, while algae, bacteria, and viruses are microscopic organisms.
Q2. Micro-organisms that cause diseases are called?
• Carriers
• Pathogens
• Antibodies
• Vaccines
Answer: Pathogens
Pathogens are harmful micro-organisms that cause diseases in plants, animals, and humans.
Q3. Which micro-organism is used in making bread and cake?
• Virus
• Yeast
• Lactobacillus
• Plasmodium
Answer: Yeast
Yeast is a fungus used in baking. It releases carbon dioxide during fermentation, making the dough rise.
Q4. Malaria is caused by which micro-organism?
• Bacteria
• Protozoa
• Fungus
• Virus
Answer: Protozoa
Malaria is caused by a protozoan named plasmodium, which is transmitted through the bite of a female anopheles mosquito.
Q5. The process of conversion of sugar into alcohol by yeast is called?
• Pasteurization
• Fermentation
• Nitrogen fixation
• Vaccination
Answer: Fermentation
Fermentation is the chemical process by which yeast breaks down sugars to produce alcohol and carbon dioxide.
Q6. Which bacteria convert atmospheric nitrogen into soil compounds?
• Lactobacillus
• Rhizobium
• Streptococcus
• E. coli
Answer: Rhizobium
Rhizobium bacteria live in the root nodules of leguminous plants and convert atmospheric nitrogen into usable nitrogen compounds for plants.
Q7. What is the common name of the fungus ‘penicillium’ used in medicine?
• Mushroom
• Mould
• Yeast
• Bread mould
Answer: Mould
Penicillium is a blue-green mould that grows on fruits and is used to produce the antibiotic penicillin.
Q8. Which disease is prevented by the BCG vaccine?
• Polio
• Tuberculosis
• Cholera
• Typhoid
Answer: Tuberculosis
The BCG vaccine is given to provide immunity against tuberculosis (TB), a bacterial disease.
Q9. Which of these is a viral disease?
• Typhoid
• Cholera
• Common cold
• Tuberculosis
Answer: Common cold
The common cold is caused by a virus, while typhoid, cholera, and tuberculosis are bacterial diseases.
Q10. What is the process of heating milk to kill harmful bacteria called?
• Fermentation
• Vaccination
• Pasteurization
• Preservation
Answer: Pasteurization
Pasteurization is the process of heating milk to a high temperature for a short time to kill harmful microbes, named after louis pasteur.
Q11. Which of these is a friendly microbe used to make curd from milk?
• Yeast
• Lactobacillus
• Rhizobium
• Penicillium
Answer: Lactobacillus
Lactobacillus bacteria promote the formation of curd by converting lactose in milk to lactic acid.
Q12. Dengue fever is spread by which carrier?
• Housefly
• Female anopheles mosquito
• Female aedes mosquito
• Amoeba
Answer: Female aedes mosquito
The dengue virus is transmitted to humans through the bite of an infected female aedes mosquito.
Q13. What do we call the medicine that kills or stops the growth of bacteria?
• Antibiotic
• Vaccine
• Antiseptic
• Antibody
Answer: Antibiotic
Antibiotics are medicines that kill or inhibit the growth of bacteria. They are not effective against viruses.
Q14. Which of these helps in increasing soil fertility?
• Virus
• Nitrogen-fixing bacteria
• Algae
• Pathogen
Answer: Nitrogen-fixing bacteria
Bacteria like rhizobium increase soil fertility by converting atmospheric nitrogen into nitrogenous compounds that plants can use.
Q15. Micro-organisms can be seen with the help of a?
• Telescope
• Microscope
• Periscope
• Kaleidoscope
Answer: Microscope
A microscope is an instrument used to see objects that are too small to be seen by the naked eye, like micro-organisms.
Q16. Which gas is produced during fermentation by yeast?
• Oxygen
• Nitrogen
• Carbon dioxide
• Hydrogen
Answer: Carbon dioxide
During fermentation, yeast converts sugars into alcohol and carbon dioxide gas.
Q17. Which micro-organisms decompose dead plants and animals?
• Algae
• Protozoa
• Fungi and bacteria
• Viruses
Answer: Fungi and bacteria
Decomposer micro-organisms like certain fungi and bacteria break down dead organic matter, recycling nutrients back into the soil.
Q18. Antibiotics are not effective against diseases caused by?
• Bacteria
• Fungi
• Viruses
• Algae
Answer: Viruses
Antibiotics work only against bacteria. They do not work against viral infections like the common cold or flu.
Q19. Edward Jenner discovered the vaccine for which disease?
• Polio
• Rabies
• Smallpox
• Chickenpox
Answer: Smallpox
Edward Jenner discovered the world’s first vaccine, which was for smallpox, in 1796.
Q20. What is the carrier of the malaria parasite called?
• Housefly
• Female anopheles mosquito
• Female aedes mosquito
• Tsetse fly
Answer: Female anopheles mosquito
The female anopheles mosquito acts as a carrier (vector) for the malaria-causing protozoan, plasmodium.
Q21. Which of these is a single-celled micro-organism?
• Amoeba
• Mushroom
• Penicillium
• Spirogyra (algae)
Answer: Amoeba
Amoeba is a single-celled protozoan, while mushroom, penicillium, and spirogyra are multicellular fungi and algae.
Q22. Foot and mouth disease in cattle is caused by a?
• Bacteria
• Fungus
• Virus
• Protozoa
Answer: Virus
Foot and mouth disease is a highly contagious viral disease that affects cattle and other cloven-hoofed animals.
Q23. Which of these is a method of food preservation?
• Fermentation
• Refrigeration
• Adding salt
• All of the above
Answer: All of the above
Fermentation, refrigeration (low temperature), and adding salt (creates a hypertonic medium) are all common methods to preserve food by inhibiting microbial growth.
Q24. The first antibiotic, penicillin, was discovered by?
• Robert Koch
• Louis Pasteur
• Alexander Fleming
• Edward Jenner
Answer: Alexander Fleming
Sir Alexander Fleming discovered the antibiotic penicillin in 1928 from the fungus penicillium notatum.
Q25. Citrus canker is a plant disease caused by?
• Fungus
• Virus
• Bacteria
• Algae
Answer: Bacteria
Citrus canker is a contagious plant disease caused by the bacterium xanthomonas axonopodis.
Q26. Which vitamin is produced by bacteria in our intestine?
• Vitamin a
• Vitamin b
• Vitamin c
• Vitamin k
Answer: Vitamin k
Some useful bacteria in our large intestine help in the synthesis of vitamin k, which is essential for blood clotting.
Q27. What do we call the small chemical substances added to vaccines to protect us from diseases?
• Antibodies
• Antigens
• Antibiotics
• Pathogens
Answer: Antigens
Vaccines contain weakened or dead antigens (part of the disease-causing microbe) that stimulate our body to produce antibodies for future protection.
Q28. Which of these diseases can spread through contaminated water?
• Malaria
• Dengue
• Cholera
• Common cold
Answer: Cholera
Cholera is a bacterial disease that spreads through water or food contaminated with the bacterium vibrio cholerae.
Q29. Yeast belongs to which group of micro-organisms?
• Bacteria
• Protozoa
• Fungi
• Algae
Answer: Fungi
Yeast is a single-celled, non-mycelial fungus used in baking and brewing.
Q30. The study of micro-organisms is called?
• Biology
• Microbiology
• Pathology
• Ecology
Answer: Microbiology
Microbiology is the branch of science that deals with the study of micro-organisms.
Q31. Which of these is not preserved by sugar?
• Milk
• Jam
• Jelly
• Marmalade
Answer: Milk
Milk is preserved by pasteurization or boiling. Jams, jellies, and marmalades are preserved by adding sugar which reduces moisture content.
Q32. Alcohol is produced on a commercial scale using which microbe?
• Lactobacillus
• Yeast
• Rhizobium
• Penicillium
Answer: Yeast
Yeast (saccharomyces cerevisiae) is used in the fermentation process for the commercial production of alcohol (ethanol).
Q33. Which of these is a communicable disease?
• Diabetes
• Common cold
• Asthma
• Heart disease
Answer: Common cold
Communicable diseases spread from one person to another. The common cold (viral) is communicable, while diabetes, asthma, and heart disease are non-communicable.
Q34. The disease-causing microbe, mycobacterium tuberculosis, affects which organ?
• Liver
• Kidney
• Lungs
• Stomach
Answer: Lungs
Mycobacterium tuberculosis is the bacterium that causes tuberculosis (TB), primarily affecting the lungs.
Q35. Which of these helps in cleaning the environment?
• Viruses
• Decomposers
• Pathogens
• Carriers
Answer: Decomposers
Decomposer micro-organisms (bacteria & fungi) clean the environment by breaking down dead and decaying organic waste.
Q36. What is the full form of HIV?
• Human immunodeficiency virus
• Human infectious virus
• Human immune virus
• Highly infectious virus
Answer: Human immunodeficiency virus
HIV stands for human immunodeficiency virus. It weakens a person’s immune system.
Q37. What is the full form of ORS?
• Oral rehydration solution
• Oral recovery salt
• Oral rehydration salt
• Oral recovery solution
Answer: Oral rehydration solution
ORS stands for oral rehydration solution. It is given to prevent dehydration during diseases like cholera and diarrhea.
Q38. Which of these micro-organisms has chlorophyll?
• Fungi
• Bacteria
• Algae
• Virus
Answer: Algae
Algae are autotrophic micro-organisms that contain chlorophyll and can make their own food through photosynthesis.
Q39. Rust of wheat is a plant disease caused by a?
• Bacteria
• Virus
• Fungus
• Protozoa
Answer: Fungus
Rust of wheat is a common fungal disease that affects wheat plants.
Q40. Food poisoning can be caused by eating food spoiled by?
• Useful bacteria
• Harmful bacteria
• Yeast
• Nitrogen-fixing bacteria
Answer: Harmful bacteria
Certain harmful bacteria like salmonella can grow on food and produce toxins, causing severe food poisoning.
Q41. Which of these is an example of a fungus?
• Euglena
• Paramecium
• Bread mould
• Chlamydomonas
Answer: Bread mould
Bread mould (rhizopus) is a common fungus that grows on stale bread. The others are protozoa or algae.
Q42. What do we call the carrier of a disease-causing microbe?
• Host
• Pathogen
• Vector
• Antibody
Answer: Vector
A vector is an organism, like a mosquito or housefly, that carries disease-causing microbes from one host to another.
Q43. Polio drops given to children are a type of?
• Antibiotic
• Vaccine
• Antiseptic
• Antibody
Answer: Vaccine
Polio drops (oral polio vaccine or OPV) are a vaccine that provides immunity against the poliovirus.
Q44. Adding which substance is a common chemical method to preserve food?
• Sugar
• Salt
• Oil
• All of the above
Answer: All of the above
Sugar, salt, and oil are common preservatives. They create conditions where harmful micro-organisms cannot grow.
Q45. Which of these diseases is caused by a bacteria?
• Influenza
• AIDS
• Typhoid
• Measles
Answer: Typhoid
Typhoid is caused by the bacterium salmonella typhi. Influenza, AIDS, and measles are viral diseases.
Q46. What is the name of the micro-organisms that can live inside hot water springs?
• Pathogens
• Carriers
• Decomposers
• Thermophiles
Answer: Thermophiles
Some bacteria, called thermophiles, can survive in very high temperatures, like those found in hot water springs.
Q47. Which of these is not a communicable disease?
• Chickenpox
• Tuberculosis
• Diabetes
• Malaria
Answer: Diabetes
Diabetes is a non-communicable disease caused by a deficiency of insulin. It does not spread from person to person.
Q48. What do we call useful bacteria that help in digestion?
• Pathogenic bacteria
• Nitrogen-fixing bacteria
• Probiotics
• Antibiotics
Answer: Probiotics
Probiotics are live, beneficial bacteria (like lactobacillus) that help maintain a healthy digestive system.
Q49. Jams and pickles do not spoil easily because they have?
• No water content
• High salt or sugar content
• Both a and b
• None of the above
Answer: Both a and b
High sugar or salt content draws out moisture from microbes through osmosis, and the lack of free water prevents their growth.
Q50. The process of protecting the body from diseases with the help of vaccines is called?
• Immunization
• Fermentation
• Pasteurization
• Decomposition
Answer: Immunization
Immunization is the process by which a person becomes protected against a disease through vaccination.