NCERT Board Intermediate Biology Questions solution Microbes in Human Welfare
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NCERT Board Intermediate Biology Questions solution
Microbes in Human Welfare
Q1: Bacteria cannot be seen with naked eyes, but these can be seen with the help of a microscope. If you have to carry a sample from your home to your biology laboratory to demonstrate the presence of microbes under a microscope, which sample would you carry and why?
Answer: Curd can be used as a sample for the study of microbes. Curd contains numerous lactic acid bacteria (LAB) or Lactobacillus. These bacteria produce acids that coagulate and digest milk proteins. A small drop of curd contains millions of bacteria, which can be easily observed under a microscope.
Q2: Give examples to prove that microbes release gases during metabolism.
Answer: The examples of bacteria that release gases during metabolism are:
(a) Bacteria and fungi carry out the process of fermentation and during this process, they release carbon dioxide. Fermentation is the process of converting a complex organic substance into a simpler substance with the action of bacteria or yeast. Fermentation of sugar produces alcohol with the release of carbon dioxide and very little energy.
(b) The dough used for making idli and dosa gives a puffed appearance. This is because of the action of bacteria which releases carbon dioxide. This CO2 released from the dough gets trapped in the dough, thereby giving it a puffed appearance.
Q3: In which food would you find lactic acid bacteria? Mention some of their useful applications.
Answer: Lactic acid bacteria can be found in curd. It is this bacterium that promotes the formation of milk into curd. The bacterium multiplies and increases its number, which converts the milk into curd. They also increase the content of vitamin B12 in curd.
Q4: In which way have microbes played a major role in controlling diseases caused by harmful bacteria?
Answer: Several micro-organisms are used for preparing medicines. Antibiotics are medicines produced by certain microorganisms to kill other disease-causing micro-organisms. These medicines are commonly obtained from bacteria and fungi. They either kill or stop the growth of disease-causing micro-organisms. Streptomycin, tetracycline, and penicillin are common antibiotics. Penicillium notatum produces chemical penicillin, which checks the growth of staphylococci bacteria in the body. Antibiotics are designed to destroy bacteria by weakening their cell walls. As a result of this weakening, certain immune cells such as the white blood cells enter the bacterial cell and cause cell lysis. Cell lysis is the process of destroying cells such as blood cells and bacteria.
Q5: Name any two species of fungus, which are used in the production of antibiotics.
Answer: Antibiotics are medicines that are produced by certain micro-organisms to kill other disease-causing microorganisms. These medicines are commonly obtained from bacteria and fungi. The species of fungus used in the production of antibiotics are:
|
Antibiotic |
Fungus source |
1. |
Penicillin |
Penicillium notatum |
2. |
Cephalosporin |
Cephalosporium acremonium |
Q6: What is sewage? In which way can sewage be harmful to us?
Answer: Sewage is the municipal waste matter that is carried away in sewers and drains. It includes both liquid and solid wastes, rich in organic matter and microbes. Many of these microbes are pathogenic and can cause several waterborne diseases. Sewage water is a major cause of polluting drinking water. Hence, it is essential that sewage water is properly collected, treated, and disposed.
Q7: What is the key difference between primary and secondary sewage treatment?
|
Primary sewage treatment |
|
Secondary sewage treatment |
1. |
It is a mechanical process involving the removal of coarse solid materials. |
1. |
It is a biological process involving the action of microbes. |
2. |
It is inexpensive and relatively less complicated. |
2. |
It is a very expensive and complicated process. |