Chapter 2 – Microorganisms
Very Important Questions Answers – Set 1
Q.1. Mention two human diseases that are transmitted by a carrier.
Ans: Malaria and dengue are transmitted by carrier to humans.
Q.2. Which pathogen causes anthrax?
Ans: Bacillus anthracis causes of anthrax.
Q.3. Where do we find Rhizobium bacteria commonly?
Ans: Rhizobium bacteria commonly live in the root nodules of leguminous plants.
Q.4. Two special chemicals are used as food preservatives. What are these?
Ans: Sodium benzoate and sodium metabisulphite are special chemicals used as food preservatives.
Q.5. Give the meaning of symbiotic relationship.
Ans: The relationship between two organisms in which both the organisms are benefitted is called symbiotic relationship.
Q.6. Mention the kind of organisms that are classified under algae. Give examples.
Ans: Simple plant-like organisms that contain chlorophyll are classified under algae, e.g. Spirogyra, Chlamydomonas.
Q.7. We are advised to avoid collection of Water anywhere. Why?
Ans: We should avoid collection of water anywhere because this water serves as breeding ground for mosquitoes.
Q.8. Use a word for disease causing microorganisms.
Ans: The disease-causing microorganisms are called pathogens.
Q.9. Name the vaccine which is used against tuberculosis.
Ans: BCG vaccine is used against tuberculosis.
Q.10. What scientific name is used for bread mould?
Ans: Rhizopus is the scientific name of bread mould.
Q.11. Vaccine is essential for what purpose? Mention two diseases for which vaccines are available.
Ans: Vaccine is essential to protect all children against several diseases. Polio and hepatitis are two diseases for which vaccines are available.
Q.12. Do we have a separate branch of biology for the study of microorganisms, what is it called as?
Ans: Yes, the study of microorganisms is called Microbiology.
Q.13. Write the name of device by which we can study microorganisms successfully.
Ans: Microscope is the device that has made the study of microorganisms successful.
Q.14. Yeast is used for commercial use. Write two commercial uses of yeast.
Ans: Baking bread and manufacturing of alcoholic drinks are the commercial uses of yeast.
Q.15. Identify protozoan from the list of microorganisms given:
Rhizopus, Rhizobium, Penicillium, Amoeba.
Ans: Amoeba is a protozoan in the list given.
Q.16. Mention a characteristic of viruses.
Ans: Viruses are cellular tiny microscopic organisms that can develop only inside the cells of host organisms.
Q.17. Write the name of two groups of microorganisms which live in colonies.
Ans: The groups of microorganisms which live in colonies are bacteria and fungi.
Q.18. Name the process in yeast that converts sugars into alcohol.
Ans: Fermentation is the process by which yeast converts sugars into alcohol.
Q.19. A popular vaccination programme was launched in India in 1995. Name it.
Ans: Pulse Polio Immunisation Programme was launched in India in 1995 for eradication of polio.
Q.20. A gas is responsible for increase in volume of dough. Name it.
Ans: Carbon dioxide (CO2) given out by yeast is responsible for increase in volume of dough.
Q.21. Apart from the action of microorganisms, how nitrogen is fixed?
Ans: Apart from the action of microorganisms, nitrogen gets fixed through the action of lightning.
Q.22. Give example of a disease that can spread through direct contact with infected person.
Ans: Chickenpox and ringworm are diseases that can spread through direct contact with infected person.
Q.23. In the soil, which nutrient is enriched by blue-green algae (cyanobacteria)?
Ans: In the soil, nitrogen is enriched by blue-green algae (cyanobacteria).
Q.24. Preservatives are used in kitchen on daily basis. List a few of them.
Ans: Vinegar and oil are common preservatives, used in kitchen.
Q.25. ‘Viruses can also infect animals.’ Give an example.
Ans: Viruses can also infect animals, e.g. foot and mouth disease in cattle are caused by a virus.
Q.26. Name the group of microorganisms which can photosynthesise.
Ans: Algae are group of microorganisms which can photosynthesise.
Q.27. Should antibiotics be used in cold and flu? Give reason for your answer.
Ans: No, antibiotics should not be used in cold and flu because these diseases are caused by viruses. And antibiotics are not effective against viruses.
Q.28. An ingredient added to idlis and bhatura to make them soft. What is it?
Ans: Curd is added to idlis and bhatura to make them soft.
Q.29. Ashish left an orange in his bag and forgot about it. After a week, when he looked in his bag, he found something growing on his orange.
(a) What was growing on Ashish's orange?
(b) What kind of organism is it?
Ans: (a) Mould (b) Fungi
Q.30. Who discovered the vaccine for smallpox?
Ans: Edward Jenner in 1798 discovered vaccine for smallpox.
Q.31. Name any two algae which helps in nitrogen fixation.
Ans: Anabaena and Nostoc are two blue-green algae which help in nitrogen fixation.
Q.32. We add a little curd to warm milk to set curd for the next day. Why?
Ans: Curd contains several microorganisms. Of these, the bacterium, Lactobacillus promotes the formation of curd. It multiplies in milk and converts it into curd.
Q.33. The process of heating milk to a high temperature and then cooling it quickly is given a particular name, what is it?
Ans: Pasteurisation is heating milk to a high temperature and then cooling it quickly. By doing so, it prevents the growth of microbes.
Q.34. Give the term used for spherical bacteria.
Ans: Spherical bacteria are called as cocci.
Q.35. Take 1/2 kg wheat flour (atta or maida) add some sugar and mix with warm water. Add a small amount of yeast powder and knead to make a soft dough. What do you observe after two hours? Did you find the dough rising?
Ans: We will find the volume of dough has increased. Carbon dioxide produced by yeast has caused the dough to expand and rise.
Q.36. Ankur's mother told him to wash his hands with soap before eating because his hands might have bacteria. Ankur did not believe her because he could not see anything on his hands. Why couldn't Ankur see the bacteria on his hands? State how bacteria can be harmful to humans.
Ans: Bacteria are too small, cannot be seen with the naked eye. It can be seen only with a microscope. That's why Ankur could not see the bacteria on his hands. Bacteria can cause various diseases like dysentery, typhoid, cholera, etc.
Q.37. A person suffering from common cold sneezes, fine droplets of moisture carrying thousands of viruses spread in the air. Viruses enter the body of a healthy person while breathing. Give name of these type of diseases.
Ans: The microbial diseases that can spread from an infected person to a healthy person through air, water, food or physical contact are called communicable diseases, e.g. common cold, cholera, TB.
Q.38. (a) Name two diseases that are caused by virus.
(b) Write one important characteristic of virus.
Ans:
(a) Influenza and chickenpox are two diseases caused by virus in humans.
(b) Virus can reproduce only inside the cells of host of an infected person.
Q.39. Write category of the following microorganisms from which they belong.
Lactobacillus, Amoeba, Chlamydomonas, Penicillium.
Ans:
|
Organism |
Group |
|
Lactobacillus |
Bacteria |
|
Amoeba |
Protozoa |
|
Chlamydomonas |
Algae |
|
Penicillium |
Fungi |
Q.40. Microorganisms survive under adverse conditions. How?
Ans: Microorganisms survive under adverse conditions by forming a hard and protective covering called cyst around them. On return of favourable conditions, the cyst wall breaks and microorganisms resume their life cycles.
Q.41. How do vaccines work?
Ans: A vaccine consists of dead or weakened microbes which when introduced in a healthy body, produce suitable antibodies to fight and kill the disease-causing microbes. These antibodies remain in the body to protect from disease causing microbes, thus develop immunity.
Q.42. What will happen to ‘pooris’ and ‘unused kneaded flour’ if they are left in the open for a day or two?
Ans: The ‘unused kneaded flour’ if left in warm conditions, gets infected by microbes which cause fermentation and spoils the flour. The pooris would remain in relatively good condition because these were deep fried in heated oil that kills microbes.
Q.43. Polio drops are not given to children suffering from diarrhoea. Why?
Ans: If the child is suffering from diarrhoea, the polio drops that are orally given vaccine may be excreted out because of frequent motions and thus becomes ineffective.
Q.44. Sachin opened two packets of milo drink. He left one in the refrigerator and another on the table. Three days later, he got a bad smell from the packet left on the table. The packet of milo drink in the refrigerator did not have a bad smell. Why? Explain.
Ans: The packet which was put in the refrigerator did not have a bad smell because there was a cold temperature and bacteria cannot grow there. Decomposition by bacteria in the packet left on the table caused a bad smell.
Q.45. Do microorganisms play any useful role in environment? If yes, explain.
Ans: Yes, microorganisms play an important and useful role in environment by making it clean. They decompose dead organic waste of plants and animals into simpler substances. These simpler harmless substances contain nutrients and are used by plants as manures. Thus, microorganisms can be used for degradation and thereby cleaning the environment.
Q.46. Maya's mother has the following items in the kitchen.
(a) Hot corn soup (b) Frozen corn (c) Popcorn (d) Corn chips
In which food item will the bacteria start multiplying in two days?
Ans: The ideal conditions for bacteria to multiply are moisture, food and warmth. (b) is kept under cold temperature which prevents decomposing. (c) and (d) are under normal temperature but not as moist as (a).
So, only (a) has the most suitable conditions for bacteria to multiply.
Q.47. Why should we avoid standing close to a tuberculosis patient while he/she is coughing?
Ans: Tuberculosis is an air-borne disease which easily spreads when the infected person coughs as coughing spreads germs in the air. This is why, we should avoid standing close to a TB patient.
Q.48. Curd is formed from the milk. Explain how.
Ans: Lactobacillus bacterium present in curd converts milk into curd. It multiplies in milk and converts it into the curd.
Q.49. Classify the following into friendly and harmful microorganisms.
Yeast, Malarial parasite, Lactobacillus, Bread mould, Rhizobium, Bacillus anthracis.
Ans:
Friendly: Yeast, Lactobacillus, Rhizobium.
Harmful: Malarial parasite, Bread mould, Bacillus anthracis.
Q.50. Yeast is very useful for baking industry. Elucidate the role of yeast.
Ans: Yeast plays an important role in baking industry. It reproduces rapidly and produces CO2 during respiration. Bubbles of the gas fill the dough and increase its volume, making the products such as bread, cake and fluffy.
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