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Q1. Which of these is not a micro-organism?
An ant is a multicellular organism visible to the naked eye, belonging to the animal kingdom. Algae, bacteria, and viruses are all microscopic organisms that cannot be seen without a microscope, so they are classified as micro-organisms. Ants are arthropods and are not considered microorganisms.
Q2. Micro-organisms that cause diseases are called?
Pathogens are disease-causing microorganisms such as certain bacteria, viruses, fungi, and protozoa. They enter the body and multiply, causing infections and illnesses. Carriers spread diseases but are not the pathogens themselves, antibodies are proteins that fight infections, and vaccines are used for prevention.
Q3. Which micro-organism is used in making bread and cake?
Yeast is a fungus used in baking bread and cakes. During fermentation, yeast converts sugars into carbon dioxide gas, which causes the dough to rise and become soft and fluffy. Lactobacillus is used to make curd, Plasmodium causes malaria, and viruses are not used in food preparation.
Q4. Malaria is caused by which micro-organism?
Malaria is caused by a protozoan parasite called Plasmodium. It is transmitted to humans through the bite of an infected female Anopheles mosquito. The parasite multiplies in the liver and then infects red blood cells, causing fever, chills, and other symptoms.
Q5. The process of conversion of sugar into alcohol by yeast is called?
Fermentation is the process by which yeast converts sugar into alcohol and carbon dioxide in the absence of oxygen. This is used in the production of alcoholic beverages and in baking. Pasteurization is heat treatment, nitrogen fixation is done by bacteria, and vaccination is immunisation.
Q6. Which bacteria convert atmospheric nitrogen into soil compounds?
Rhizobium is a nitrogen-fixing bacterium found in the root nodules of leguminous plants (like peas and beans). It converts atmospheric nitrogen into usable compounds like nitrates, which enrich the soil and are absorbed by plants. This is essential for the nitrogen cycle and soil fertility.
Q7. What is the common name of the fungus ‘penicillium’ used in medicine?
Penicillium is a type of mould that produces the antibiotic penicillin. It is a filamentous fungus that grows on decaying matter and is commonly referred to as mould. The antibiotic penicillin was discovered from Penicillium and is used to treat bacterial infections.
Q8. Which disease is prevented by the BCG vaccine?
BCG (Bacillus Calmette-Guérin) vaccine is given to prevent tuberculosis (TB), which is caused by Mycobacterium tuberculosis. It is especially effective in children and is part of the universal immunisation program. Polio is prevented by polio drops, cholera and typhoid have different vaccines.
Q9. Which of these is a viral disease?
The common cold is caused by a virus (rhinovirus). It is highly contagious and affects the upper respiratory tract. Typhoid and cholera are bacterial diseases, and tuberculosis is caused by the bacterium Mycobacterium tuberculosis.
Q10. What is the process of heating milk to kill harmful bacteria called?
Pasteurization is the process of heating milk to a specific temperature (usually about 72°C for 15 seconds) and then quickly cooling it to kill harmful bacteria without affecting its taste or nutritional value. This process was developed by Louis Pasteur. Fermentation uses microbes, vaccination prevents diseases, and preservation includes other methods.
Q11. Which of these is a friendly microbe used to make curd from milk?
Lactobacillus is a beneficial bacterium that converts milk into curd by fermenting lactose (milk sugar) into lactic acid. This acid causes the milk to coagulate and gives curd its sour taste. Yeast is used in baking, Rhizobium fixes nitrogen, and Penicillium produces antibiotics.
Q12. Dengue fever is spread by which carrier?
Dengue fever is spread by the bite of an infected female Aedes mosquito (particularly Aedes aegypti). It breeds in clean stagnant water. Malaria is spread by Anopheles mosquitoes, houseflies transmit other diseases, and amoeba causes amoebiasis.
Q13. What do we call the medicine that kills or stops the growth of bacteria?
Antibiotics are medicines that kill or inhibit the growth of bacteria. They are used to treat bacterial infections like pneumonia and typhoid. Antibiotics are not effective against viral diseases. Vaccines prevent diseases, antiseptics are applied to wounds, and antibodies are immune proteins.
Q14. Which of these helps in increasing soil fertility?
Nitrogen-fixing bacteria like Rhizobium convert atmospheric nitrogen into nitrates, which are absorbed by plants as nutrients. This enriches the soil and increases fertility. Viruses are harmful, pathogens cause diseases, and algae may grow in water bodies but do not directly enrich soil.
Q15. Micro-organisms can be seen with the help of a?
Micro-organisms are too small to be seen with the naked eye and require a microscope for observation. Telescopes are used to see distant objects like stars, periscopes are used for seeing around obstacles, and kaleidoscopes produce colourful patterns.
Q16. Which gas is produced during fermentation by yeast?
During fermentation, yeast converts sugar into alcohol and carbon dioxide gas. This gas gets trapped in dough, causing it to rise and become soft. Oxygen is produced during photosynthesis, nitrogen is fixed by bacteria, and hydrogen is not produced in fermentation.
Q17. Which micro-organisms decompose dead plants and animals?
Fungi and bacteria are decomposers that break down dead organic matter (plants and animals) into simpler substances. This process recycles nutrients back into the soil, making them available for plants. Algae photosynthesise, protozoa are single-celled consumers, and viruses are parasites.
Q18. Antibiotics are not effective against diseases caused by?
Antibiotics are effective only against bacterial infections, not against viral infections like the common cold, AIDS, or dengue. This is because viruses reproduce inside host cells, and antibiotics cannot target them without harming the host cells. Antiviral drugs are used for viral infections.
Q19. Edward Jenner discovered the vaccine for which disease?
Edward Jenner discovered the first vaccine in 1796 for smallpox by using cowpox material. This was a breakthrough in immunology. The polio vaccine was developed by Jonas Salk, rabies vaccine by Louis Pasteur, and chickenpox vaccine came much later.
Q20. What is the carrier of the malaria parasite called?
The malarial parasite, Plasmodium, is transmitted by the bite of an infected female Anopheles mosquito. The Aedes mosquito transmits dengue, houseflies spread other diseases, and tsetse flies transmit sleeping sickness.
Q21. Which of these is a single-celled micro-organism?
Amoeba is a single-celled protozoan that moves with pseudopodia and feeds on bacteria and other microorganisms. Mushroom and Penicillium are multicellular fungi, and Spirogyra is filamentous algae (though each filament is made of many cells). So Amoeba is the correct single-celled example.
Q22. Foot and mouth disease in cattle is caused by a?
Foot and mouth disease (FMD) is a highly contagious viral infection that affects cattle, sheep, and pigs. It causes fever and blisters in the mouth and on the feet. It is not caused by bacteria, fungi, or protozoa.
Q23. Which of these is a method of food preservation?
Fermentation, refrigeration, and adding salt are all effective food preservation methods. Fermentation produces acids/alcohol, refrigeration slows microbial growth, and salt draws moisture out of food, preventing spoilage. All these methods help preserve food for longer periods.
Q24. The first antibiotic, penicillin, was discovered by?
Alexander Fleming discovered penicillin in 1928 when he observed that the mould Penicillium killed bacteria in his culture plate. This was the first antibiotic discovered. Louis Pasteur worked on pasteurisation and vaccines, Robert Koch proved the germ theory, and Jenner discovered the smallpox vaccine.
Q25. Citrus canker is a plant disease caused by?
Citrus canker is a bacterial disease caused by Xanthomonas species. It affects citrus plants, causing lesions on leaves, stems, and fruits. It spreads through wind and rain and can reduce fruit yield. Fungal diseases include rust, while viruses cause other plant diseases.
Q26. Which vitamin is produced by bacteria in our intestine?
Bacteria present in the human intestine, particularly in the colon, synthesize Vitamin K, which is essential for blood clotting. They also produce some B vitamins, but Vitamin K is the most notable one produced by intestinal bacteria. Vitamins A and C are obtained from diet, not synthesised by intestinal bacteria.
Q27. What do we call the small chemical substances added to vaccines to protect us from diseases?
Vaccines contain antigens, which are weakened or dead parts of a pathogen. These antigens trigger the immune system to produce antibodies, providing immunity without causing the disease. Antibodies are made by the body, antibiotics treat infections, and pathogens cause diseases.
Q28. Which of these diseases can spread through contaminated water?
Cholera is a waterborne disease caused by the bacterium Vibrio cholerae. It spreads through contaminated drinking water and food. Malaria and dengue are mosquito-borne, and the common cold spreads through air or contact.
Q29. Yeast belongs to which group of micro-organisms?
Yeast is a unicellular fungus. It belongs to the kingdom Fungi and is widely used in fermentation for baking and brewing. It is not a bacterium, protozoan, or alga.
Q30. The study of micro-organisms is called?
Microbiology is the branch of science that deals with the study of microorganisms, including bacteria, viruses, fungi, algae, and protozoa. Biology is the study of all living organisms, pathology studies diseases, and ecology studies interactions between organisms and their environment.
Q31. Which of these is not preserved by sugar?
Milk is preserved by pasteurization, not by sugar. Jam, jelly, and marmalade are fruit preserves made with high sugar content, which prevents microbial growth by drawing moisture out through osmosis. Sugar acts as a preservative in these products.
Q32. Alcohol is produced on a commercial scale using which microbe?
Yeast (Saccharomyces cerevisiae) is used commercially to produce alcohol through fermentation of sugars. Lactobacillus produces lactic acid, Rhizobium fixes nitrogen, and Penicillium produces antibiotics. Yeast is the main microbe for alcohol production.
Q33. Which of these is a communicable disease?
The common cold is a communicable (infectious) disease, meaning it can spread from person to person through air, droplets, or contact. Diabetes, asthma, and heart disease are non-communicable diseases caused by genetic, lifestyle, or metabolic factors.
Q34. The disease-causing microbe, mycobacterium tuberculosis, affects which organ?
Mycobacterium tuberculosis primarily affects the lungs, causing tuberculosis (TB). It spreads through air when an infected person coughs or sneezes. The bacteria can also affect other organs, but the lungs are the main site of infection.
Q35. Which of these helps in cleaning the environment?
Decomposers like bacteria and fungi break down dead organic matter, recycling nutrients and cleaning the environment. Pathogens cause diseases, carriers spread them, and viruses are parasites. Decomposers are essential for the ecosystem.
Q36. What is the full form of HIV?
HIV stands for Human Immunodeficiency Virus. It attacks the immune system, specifically CD4 cells, and can lead to AIDS (Acquired Immunodeficiency Syndrome) if untreated. The virus is transmitted through blood, semen, vaginal fluids, and breast milk.
Q37. What is the full form of ORS?
ORS stands for Oral Rehydration Solution. It is a mixture of sugar and salt in water given to patients suffering from dehydration due to diarrhoea or cholera. It helps replace lost fluids and electrolytes and is a simple, effective treatment.
Q38. Which of these micro-organisms has chlorophyll?
Algae contain chlorophyll and can perform photosynthesis to make their own food, just like plants. Fungi and bacteria do not have chlorophyll (some bacteria like cyanobacteria do, but general bacteria do not). Viruses are not living and do not have chlorophyll.
Q39. Rust of wheat is a plant disease caused by a?
Rust of wheat is a fungal disease caused by Puccinia species. It appears as reddish-brown pustules on wheat leaves and stems. It is a serious agricultural problem and reduces crop yield. Bacteria, viruses, and protozoa do not cause this specific disease.
Q40. Food poisoning can be caused by eating food spoiled by?
Food poisoning is caused by consuming food contaminated with harmful bacteria like Salmonella, E. coli, or Staphylococcus. These bacteria produce toxins that cause illness. Useful bacteria are safe, yeast is used in baking, and nitrogen-fixing bacteria are beneficial to plants.
Q41. Which of these is an example of a fungus?
Bread mould (Rhizopus) is a fungus that grows on bread and other organic matter. Euglena and Chlamydomonas are algae, and Paramecium is a protozoan. Bread mould is a classic example of a fungus.
Q42. What do we call the carrier of a disease-causing microbe?
A vector is an organism that carries and transmits disease-causing pathogens from one host to another. Examples include mosquitoes (malaria, dengue), houseflies (cholera), and ticks. The pathogen is the disease-causing agent, and antibodies are immune proteins.
Q43. Polio drops given to children are a type of?
Polio drops contain a vaccine (oral polio vaccine) that protects children from poliovirus. It is given as part of the immunisation program. Antibiotics treat bacterial infections, antiseptics are applied to wounds, and antibodies are produced by the body.
Q44. Adding which substance is a common chemical method to preserve food?
Sugar (in jams, jellies), salt (in pickles, meat), and oil (in pickles) are all common chemical preservation methods. They create conditions that inhibit the growth of microorganisms by either drawing moisture out or limiting oxygen. All three are effective preservation techniques.
Q45. Which of these diseases is caused by a bacteria?
Typhoid is a bacterial disease caused by Salmonella typhi. It spreads through contaminated food and water and causes high fever, abdominal pain, and weakness. Influenza and measles are viral diseases, and AIDS is caused by HIV (virus).
Q46. What is the name of the micro-organisms that can live inside hot water springs?
Thermophiles are microorganisms that thrive in extremely hot environments, such as hot water springs (temperatures above 45°C). They are adapted to high temperatures and are examples of extremophiles. Pathogens cause diseases, carriers spread them, and decomposers break down matter.
Q47. Which of these is not a communicable disease?
Diabetes is a non-communicable disease caused by metabolic or lifestyle factors, not by pathogens. It does not spread from person to person. Chickenpox, tuberculosis, and malaria are all communicable diseases transmitted through air, droplets, or vectors.
Q48. What do we call useful bacteria that help in digestion?
Probiotics are beneficial bacteria that help in digestion and maintain gut health. They are found in fermented foods like curd and buttermilk. Pathogenic bacteria cause diseases, nitrogen-fixing bacteria help plants, and antibiotics are medicines.
Q49. Jams and pickles do not spoil easily because they have?
Jams and pickles do not spoil easily because they have high sugar (in jams) or high salt and oil (in pickles) content. These reduce the water activity available for microbes, preventing growth. Many jams also have very low moisture content (not zero), but both conditions together prevent spoilage.
Q50. The process of protecting the body from diseases with the help of vaccines is called?
Immunization is the process by which a person becomes protected against a disease through vaccination. The body’s immune system is stimulated to produce antibodies, providing immunity. Fermentation is microbial conversion, pasteurisation is heat treatment, and decomposition is breakdown of matter.