1. The answer is (b) Virus
Explanation:
The virus is considered as intermediate between living and non-living. Outside a host-virus remains inactive. It can perform its life processes and reproduction only when it is inside a host cell.
2. The answer is (b) Influenza
Explanation:
Typhoid is caused by bacteria Salmonella typhoid.
Dysentry is caused by an amoeba which is a protozoan.
Cholera is caused by Vibrio cholera bacteria.
3. The answer is (b) Antibiotics
Explanation:
- Pain Killers gives relief from pain.
- Antibodies are produced by our immune system which acts and elicit a specific immune reaction.
- Antibiotics that inhibit or kill certain bacteria.
- Vaccines provide acquired immunity against a particular disease.
Explanation:
Carbon-di-oxide is released due to the fermentation process conducted by yeast. CO2 causes rising of the dough and make the bread fluffy.
6. The answer is (b) Malaria
Explanation:
Malaria is caused by protozoan named Plasmodium vivax which is transmitted by mosquitos. Other options are viral diseases hence they are wrong answers.
7. The answer is (b) Waste in pit B degraded faster than that in pit A.
Explanation:
Waste in pit B degrades faster than waste in pit A because Polythene in pit B is open and receives oxygen for composting whereas polythene in closed in pit A and organisms don’t receive oxygen to compost the waste material in the polythene bag.
8. a. Antibodies
b. Tuberculosis
c. Anthrax
d. Fermentation
9. a. Preservatives
b. Rhizobium
c. Carrier/ vector
d. Antibiotics
10. (a) Louis Pasteur – (iii) Fermentation
(b) Robert Koch – (ii) anthrax bacterium
(c) Edward Jenner – (iv) small pox vaccine
(d) Alexander Fleming – (i) Penicillin
11. Yeast is used in making bread and they are used in the fermentation of alcohol.
12. Fermentation is the process in yeast that converts sugars into alcohol.
13. Blue-green-algae enriches Nitrogen in the soil.
14. Tuberculosis can spread through the air when the infected person coughs. Hence we avoid standing close to a tuberculosis patient while he/she is coughing.
15. If the children are suffering from diarrhoea oral polio drops will get excreted due to frequent motions. Hence children with diarrhoea are not given with polio drops.
16.Oils prevent the attack of bacteria which will help preserve the pickle for a long period of time.
17. Column A – Column B
(a) Lactobacillus – (iv) Bacteria
(b) Aspergillus – (iii) Fungi
(c) Spirogyra – (i) Algae
(d) Paramecium – (ii) Protozoa
18.
| Friendly | Harmful Microorganisms |
| Yeast | Malarial parasite |
| Lactobacillus | Bread mould |
| Rhizobium | Bacillus anthracis |
19. The probable reason is that the chaat was contaminated by pathogenic microbes due to unhygienic conditions near the shop or the utensil used for serving could have contaminated.
The reason may be the contamination of food by pathogenic microbes. Contamination may be due to the unhygienic conditions near the shop or the utensil used to serve the chaat.
20. a. Polio, HIV
b. A virus can reproduce only when it is inside the host cell.
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