Biology & Human Welfare Test - 5

Primary treatment of sewage treatment involves physical removal of large and small particles like paper, plastic, pebble by passing through screen.

During anaerobic decomposition of organic wastes by bacteria biogas is produced but lignin do not get decomposed by these bacteria and left over in biogas plants.

• Microbes can be grown on artificial cultures media where they form colonies.
• During their metabolism, microbes produce chemicals, some of which are used by human beings.
• Microbes can live in highly acidic as well as an alkaline medium.
• Microbes are certainly ideal for biotechnology.

Both assertion and reason are correct

Explanation: In the activated sludge process, a small portion of the activated sludge is pumped back into the aeration tank to serve as an inoculum, which helps in the growth and multiplication of microorganisms. The remaining part of the sludge is sent to anaerobic sludge digesters, where it undergoes further treatment and stabilization, reducing the volume of sludge and producing biogas as a byproduct.

Correct Answer : b

Explanation : S ewage mainly includes human excreta and contains large amounts of organic waste and pathogenic microbes. Thus it is necessary that waste should be made less polluted before discharging into water bodies. 

The process of sewage treatment is explained in the following steps:

a) Primary treatment- In this treatment, filtration and sedimentation process is applied to remove large and small particles. Filtration process removes the floating debris by passing it through mesh wire screens. Then sedimentation removes the soil and small pebbles. The sediment is known as primary sludge and the supernatant is known as primary effluent. The effluent then enters the secondary treatment. 

b) Secondary treatment- In this treatment, large aeration tanks containing primary effluent are constantly agitated with a continuous supply of air. Thus aerobic microbes grow vigorously consuming a major part of the organic effluent reducing Biological Oxygen Demand (BOD) of the effluent. The sewage is then passed into the settling tank where bacteria settle and now it is known as activated sludge. Some of the activated sludge is again passed into aeration tank to serve as inoculum while rest of it enters into large tanks called anaerobic sludge digesters. Here anaerobic bacteria grow to produce a mixture of gases such as methane, hydrogen sulphide and carbon dioxide to form biogas. This effluent can then be released into natural water bodies.

Microbes are diverse in nature and include- protozoa, bacteria, fungi and microscopic animal and plant viruses, viroids and also prions that are proteinaceous infectious agents.

Symbiotic association of fungi with angiosperm plant root is called mycorrhiza. Most of the plants have this kind of relation. The fungus obtains some sugar from the plant and plant get minerals and water absorbed by fungi.

Organic farming is the practice of agriculture in which on chemical substance is used as fertilizers, pesticides or insecticides. Biofertilizers are used to provide nutrient.

In organic farming snail is not used. Glomus is kind of fungi used in organic farming for maintaining fertility of soil. Earthworm the process of composting to form vermiform compost and Oscillatoria is an algae that fix the nitrogen.

Tiger beetle is a large group of beetles known for their aggressive predatory habits and running speed. They are used as biological insecticides in organic farming practices.

• A major component of this waste-water is human excreta.
• This municipal waste-water is also called as sewage.
• It contains a large amount of organic matter and microbes. Many of which are pathogenic.

• STP stands for sewage treatment plants.
• Before the disposal of waste-water into the natural water bodies, sewage is treated in STPs to make it less polluting.

The patient suffering from myocardial infraction is immediately given injection of Streptokinase. Streptokinase is an enzyme secreted by several species of streptococci that can bind and activate plasminogen used as effective and inexpensive thrombolysis medication in some cases of myocardial infraction.

Azolla is used as a biofertilizers because it has association of nitrogen fixing Cyanobacteria. They increase the fertility of soil without any chemical fertilizers.

Common cold is an infectious disease caused by virus. It cannot be controlled by antibiotics as antibiotics are not effective against viral disease.