Following are Microbes in Human Welfare Production Notes for Class 12 Biology. These revision notes have been prepared by expert teachers of Class 12 Biology as per the latest NCERT, CBSE, KVS books released for the current academic year. Students should go through Chater 10 Microbes in Human Welfare Production concepts and notes as these will help you to revise all important topics and help you to score more marks. We have provided Class 12 Biology notes for all chapters in your book. You can access it all free and download Pdf.

Chapter 10 Microbes in Human Welfare Production Notes Class 12 Biology

Important Questions Microbes in Human Welfare Class 12 Biology

Short Answer Questions

Question. Cyanobacteria(Nostoc,Anabaena)are used as biofertilisers in certain crop fields. Name such one crop. Also, mention the names of two other microorganisms which perform the same function.
Answer : Paddy (Rice Crop), Rhizobium and Azotobacter

Question. Why is secondary treatment of water in sewage treatment plant called biological treatment?
Answer : In this treatment Organic wastes of sewage water are decomposed by certain microorganisms in presence of water

Question. You have observed that fruit juice in bottles bought from the market is clearer as compared to those made at home. Give reason.
Answer : Bottle juices are clarified by the use of pectinase and proteases

Question. Fill in the blanks spaces a, b, c, d, e, and f given in the following table

Answer : a) to kill disease causing bacteria
(b) Lactobacillus
(c) remove clots from blood vessels
(d) Cyclosporin A
(e) Beverage
(f) Propionibacterium sharmanii

Question. Alexander Fleming discovered. Penicillin, but its full potential as an effective antibiotic was established by other scientists. Name the two scientists.
Answer : Ernest chain and Howard Florey

Question. How does a small amount of curd added to fresh milk convert it into curd? Mention a nutritional quality that gets added to the curd.
Answer : A large number of lactic acid bacteria are found in small amount of curd which multiply and convert the milk into curd by producing the lactic acid,The nutritional quality improves by increasing Vitamin B12

Question. Lactic Acid Bacteria(LAB)is commonly used in the conversion of milk into curd. Mention any two other functions of LAB that are useful to humans.
Answer : (i) LAB in human intestine synthesizes VitaminB12.
(ii) LAB in human stomach checks the growth of harmful microbes.

Question. What are statins? Name the microorganism that produces this substance. How is it medically important?
Answer : Statins are cholesterol reducing agents. They are produced by Monascus purpureus (Yeast) They act by Competitively inhibiting the enzymes responsible for synthesis of cholesterol and are used as blood cholesterol lowering agents.

Question. How do mycorrhizae function as biofertilisers? Explain with example.
Answer : Mycorrhiza are fungi associated with the roots of plants. Many members of genus Glomus form mycorrhiza. These fungal symbiont absorbs water
and minerals like phosphorus from the soil and provide them to the plant.

Question. An antibiotic called Wonder Drug was used to treat the wounded soldiers of America during World War-II. Name the drug and the scientist who discovered it.
Answer : Penicillin, Alexander Fleming

Question. Which Ministry of Govt. of India had initiated Ganga Action Plan and Yamuna Action Plan? What are the objectives of these plans?
Answer : The Ministry of Environment and Forests. The objective of Ganga Action Plan and Yamuna Action Plan is to save these rivers from pollution. It was proposed to build a large number of sewage treatment plants. So that only treated sewage may be discharged into these river

Question. What is biochemical oxygen demand (BOD) test? At what stage of Sewage treatment this test is performed? BOD level of three samples of water labelled as A, B and C are 30 mg/ L, 10mg/Land 500 mg/L respectively. Which sample of water is most polluted?
Answer : The BOD test measures the rate of uptake of oxygen by microorganisms in a sample of water. Biological treatment or Secondary treatment Sample € is most polluted because it has highest BOD level among the three samples of water.

Question. Name two alcoholic drinks produced in each of the following ways. (i) by distillation and(ii) without distillation.
Answer : (i) Whisky, brandy, rum_ by distillation
(ii) Wine, beer _ without distillation

Question. What are biofertilisers? A farmer is advised to add a culture of bacterium in the soil before sowing the crop. Name the bacterium in the culture. How is this bacterium useful to the crop? 
Answer : Biofertilisers are organisms that enrich the nutrient quality of the soil.
Azotobacter/Azospirillum (free living) This bacterium fixes atmospheric nitrogen into organic forms, which is used by the plants as nutrient.

Question. Name the plant whose sap is used in making Toddy. Mention the process involved in it.
Answer : Palm tree, by fermentation

Question. How does primary sludge differ from activated sludge? What type of changes in the sludge is carried out in anaerobic sludge digester? Give the composition of biogas produced in the wage treatment plant.
Answer : Primary sludge is all solids like soil, small pebbles that settle down in settling tank during primary treatment of sewage. Activated sludge is the sediment of bacterial ,flocs, in settling tank during biological treatment.Flocs are masses of bacteria held together by slime and fungal filaments. 
A part of activated sluge is used as inoculum in aeration tank and remaining is passed into a large tank called anaerobic sluge digester. In this tank, other kind of bacteria which grow an aerobically, digest the bacteria, fungi and biomass in the sludge. Biogas that produced in Sewage treatment plant is a mixture of methane, hydrogen and Carbon dioxide.