MICROBIAL WORLD
REVISION
CLASS VIII
1. Which of the following reproduces only inside a host cell?
(a) Bacteria (c) Amoeba (b) Virus (d) Fungus.
2. A disease in human beings caused by virus is _______.
(a) typhoid (c) dysentry (b) influenza (d) cholera
3. Pathogenic micro-organisms present in host cells are killed by medicines called
(a) pain killer (c) antibiotics (b) antibodies (d) vaccines
4. The two micro-organisms which live in symbiotic association in lichens are
(a) fungus and protozoa (c) bacteria and protozoa (b) alga and bacteria (d) alga and fungus
5. The gas released during the preparation of bread is
(a) oxygen (c) nitrogen (b) carbon dioxide (d) sulphur dioxide
6. The disease caused by a protozoan and spread by an insect is _________.
(a) dengue (c) polio (b) malaria (d) measles
7. Paheli dug two pits, A and B, in her garden. In pit A, she put a polyhtene bag packed with some agricultural waste. In pit B, she dumped the same kind of waste but without packing it in a polythene bag. She, then covered both the pits with soil. What did she observe after a month?
(a) Waste in pit A degraded faster than that in pit B.
(b) Waste in pit B degraded faster than that in pit A.
(c) Waste in both pits degraded almost equally.
(d) Waste in both pits did not degrade at all.
VERY SHORT ANSWER QUESTIONS
8. Unscramble the jumbled words underlined in the following statements.
(a) Cells of our body produce santiidobe to fight pathogens.
(b) curbossulite is an air-borne disease caused by a bacterium.
(c) Xanrhat is a dangerous bacterial disease.
(d) Yeasts are used in the wine industry because of their property of meronettinaf.
9. Suggest a suitable word for each of the following statements.
(a) Chemicals added to food to prevent growth of microorganisms. (b) Nitrogen-fixing microorganism present in the root nodules of legumes.
(c) Agent which spreads pathogens from one place to another.
(d) Chemicals which kill or stop the growth of pathogens.
10. Match the names of scientists given in Column A with the discovery made by them given in Column B.
Column A Column B
(a) Louis Pasteur (i) Penicillin
(b) Robert Koch (ii) anthrax bacterium
(c) Edward Jenner (iii) Fermentation
(d) Alexander Fleming (iv) small pox vaccine
(v) Typhoid
11. Name one commercial use of yeast.
12. Name the process in yeast that converts sugars into alcohol.
13. In the soil, which nutrient is enriched by blue-green algae (cyanobacteria)?
14. Why should we avoid standing close to a tuberculosis patient while he/she is coughing?
15. Polio drops are not given to children suffering from diarrhoea. Why?
16. Paheli watched her grandmother making mango pickle. After she bottled the pickle, her grand mother poured oil on top of the pickle before closing the lid. Paheli wanted to know why oil was poured? Can you help her understand why?
SHORT ANSWER QUESTIONS
17. Match the microorganisms given in the Column A to the group to which they belong in Column B.
Column A Column B
(a) Lactobacillus (i) Algae
(b) Aspergillus (ii) Protozoa
(c) Spirogyra (iii) Fungi
(d) Paramecium (iv) Bacteria
18. Classify the following into friendly and harmful microorganisms.
Yeast, malarial parasite, Lactobacillus, bread mould, Rhizobium, Bacillus anthracis
Friendly Harmful
________ ________
________ ________
________ ________
________ ________
19. While returning from the school, Boojho ate chaat from a street hawker. When he reached home, he felt ill and complained of stomach ache and fell ill. What could be the reason?
20. What will happen to ‘pooris’ and ‘unused kneaded flour’ if they are left in the open for a day or two?
21. (a) Name two diseases that are caused by virus.
(b) Write one important characteristic of virus.
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