Chapter 10: Microbes in Human Welfare

Ans: Aerobic degradation is more significant than anaerobic degradation for the treatment of large volumes of organic-rich wastewaters because: 

i) The majority of the organic sludge is digested in the wastewater during aerobic degradation.

ii) The decomposers are removed from the organic waste, which is rich in nutrients, after aerobic decomposition.

iii) During aerobic degradation, the biological oxygen demand (BOD) is lowered, making the water more favorable for aquatic species.

iv) Activated sludge is formed during aerobic decomposition, which creates gases such as methane and carbon dioxide, which are the major components of biogas.

Ans: (a) The Ministry of Environment and Forests, Government of India has initiated two plAns:

i. Ganga Action Plan

ii. Yamuna Action Plan

These plans were planned to involve a large number of sewage treatment plants. Ganga and Yamuna are very important rivers in terms of flora, fauna and as a tourist and religious attraction spot.

Ans: (b) The Ganga is India's greatest river, flowing across India and Bangladesh for around 2520 kilometres and providing home for more than 140 different species of fish, 90 different species of frogs, and numerous endangered species. As a result, the Ganga is considered the world's greatest river and must be pollution-free.

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The primary concepts underlying biological pest and disease control are to reduce the population of pests by introducing natural predators into the ecosystem.

Examples are:

i) The Ladybird beetle is used to control the population of insects like Aphids.

ii. Nucleopolyhydro viruses (NPVs) are being used to kill insects such as caterpillars and butterflies which damage the plants and crops. This virus will damage the insect’s midguts.

Ans: The Biological Oxygen Demand (BOD) will increase, resulting in the mortality of species like fish owing to a lack of oxygen in the water. As people drink water directly from the river, illnesses like cholera and dysentery will spread.

Ans: Anaerobic sludge digestion is important in sewage treatment because it reduces Biological Oxygen Demand (BOD). Sludge digestion occurs in the presence of anaerobic bacteria, and when the sludge is digested, the anaerobic bacteria release a mixture of gases such as methane (\[CH_{3}\]), carbon dioxide (\[CO_{2}\]), and hydrogen sulphide (\[H_{2}S\]). Biogas is made up mostly of these components.

Ans: Lactic acid bacteria (LAB) is widely used to ferment or culture food products. Lactic acid bacteria (LAB) are found in curd. Its useful applications are:

i) Lactic acid bacteria (LAB) is a type of bacteria that can convert milk into curd by producing an enzyme called lactase.

ii) Some people will suffer from a condition called lactose tolerance which gets allergic to lactose. So the bacteria will help to remove or convert lactose.

iii) Lactic acid bacteria (LAB) increase the vitamin B12 content and they are present in our digestive system also.

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