NCERT solutions Biology Textbook for Class 12 chapter 10 Microbes in Human Welfare



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Chapter 10 - Microbes in Human Welfare

Pages 189 - 190

Bacteria cannot be seen with the 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?

Q 1 | Page 189 |

Give examples to prove that microbes release gases during metabolism.

Q 2 | Page 189 |

In which food would you find lactic acid bacteria? Mention some of their useful applications.

Q 3 | Page 189 |

Name some traditional Indian foods made of wheat, rice and Bengal gram (or their products) which involve use of microbes.

Q 4 | Page 189 |

In which way have microbes played a major role in controlling diseases caused by harmful bacteria?

Q 5 | Page 189 |

Name any two species of fungus, which are used in the production of the antibiotics.

Q 6 | Page 189 |

What is sewage? In which way can sewage be harmful to us?

Q 7 | Page 189 |

What is the key difference between primary and secondary sewage treatment?

Q 8 | Page 189 |

Do you think microbes can also be used as source of energy? If yes, how?

Q 9 | Page 189 |

Microbes can be used to decrease the use of chemical fertilisers and pesticides. Explain how this can be accomplished.

Q 10 | Page 189 |

Three water samples namely river water, untreated sewage water and secondary effluent discharged from a sewage treatment plant were subjected to BOD test. The samples were labelled A, B and C; but the laboratory attendant did not note which was which. The BOD values of the three samples A, B and C were recorded as 20mg/L, 8mg/L and 400mg/L, respectively. Which sample of the water is most polluted? Can you assign the correct label to each assuming the river water is relatively clean?

Q 11 | Page 189 |

Find out the name of the microbes from which Cyclosporin A (an immunosuppressive drug) and Statins (blood cholesterol lowering agents) are obtained

Q 12 | Page 190 |

Find out the role of microbes in the following

Single cell protein (SCP)

Q 13.1 | Page 190 |

Find out the role of microbes in the following 


Q 13.2 | Page 190 |

Arrange the following in the decreasing order (most important first) of their importance, for the welfare of human society. Give reasons for your answer.

Biogas, Citric acid, Penicillin and Curd

Q 14 | Page 190 |

How do biofertilisers enrich the fertility of the soil?

Q 15 | Page 190 |

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