Question 1

Explain biogas plant with a labelled diagram.

Accepted Answer

Biogas or gobar gas is a combustible gas.It is produced through the anaerobic breakdown of waste biomass.The biogas plant consists of the following parts:- 1) Inlet or charge pit:- for passage of slurry into the digester.The raw material used is cattle dung, farm refuse, organic waste.2) Digester:- cylindrical tank which is airtight, above which is present a  floating gas holder of metal with an outlet of gas and pit for removal of sludge.Here the organic wastes get solubilized into simpler substances called monomers (solubilisation).Monomers change to organic acid by fermenting microbes (acidogenesis).Organic acid mostly formed is acetic acid.Methanogens become active and act on components of microbial digestion and form methane gas (methanogenesis).3) Outlet:- consists of sludge which is used as manure.The methane gas formed in this process is used for cooking and lighting.

Question 2

Match the following list of bacteria and their commercially important products. Bacterium Product(i) Aspergillus niger(A) Lactic acid(ii) Acetobacter aceti (B) Butyric acid(iii) Clostridium butylicum(C) Acetic acid(iv) Lactobacillus(D) Citric acid Choose the correct match.

Accepted Answer

Bacterium  Product (i) Aspergillus niger (D) Citric acid  (ii) Acetobacter aceti &#9; (C) Acetic acid (iii) Clostridium butylicum (B) Butyric acid (iv) Lactobacillus (A) Lactic acidSo, the correct answer is 'i-(D), ii-(C), iii-(B), iv-(A)'

Question 3

Write the name of bacteria which converts milk to curd.

Accepted Answer

Lactobacillus converts milk to curd by producing lactic acid and reducing the pH of the milk. These bacteria convert the lactose into lactic acid, which imparts the sour taste to curd.

Question 4

Describe the role of microbes in sewage treatment plant.

Accepted Answer

After the primary treatment of sewage water, primary effluent is passed into large aeration tanks, where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh like structures). While growing, these microbes consume the major part of the organic matter in the effluent. This significantly reduces the BOD or Biochemical Oxygen Demand of the effluent. BOD refers to the amount of oxygen that would be consumed if all the organic matter in one litre of water is oxidised by bacteria. The sewage water is treated till the BOD is reduced. The effluent is then passed into a settling tank, where the bacterial flocs are allowed to sediment. This sediment is called activated sludge. A small part of activated sludge is pumped back into the aeration tank to serve as the inoculum. The remaining major part of the sludge is pumped into large tanks called anaerobic sludge digesters. Here, other kind of bacteria which grow anaerobically, digest the bacteria and fungi in the sludge. During this digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and carbon dioxide.

Question 5

Study the following statements regarding lactic acid bacteria (LAB) which are used to convert milk into curd.(i) They produce adds that coagulate and partially digest the milk proteins. (ii) A small amount of curd added to the fresh milk as an inoculum contains millions of LAB, which at suitable temperature, multiply and convert milk into curd. (iii) Conversion of milk into curd improves its nutritional quality by increasing vitamin $B_{12}$. (iv) LAB may result in acidity in the stomach of human beings. Which of the given statements are correct?

Accepted Answer

Microbes such as. Lactobacillus and others commonly called lactic acid bacteria (LAB) grow in milk and convert it into curd. During growth, such bacteria produce adds (mainly lactic add) that coagulate and partially digest the milk proteins. A small amount of curd, known as starter, is added to the milk and kept at a suitable temperature, where lactic acid bacteria multiply in millions and converts milk into curd that also improves its nutritional quality by increasing vitamin BI2. It also checks the growth of disease-causing microbes in the stomach.So, the correct answer is '(i), (ii) and (iii)'

Question 6

Which one of the following is not a biofertilizer?

Accepted Answer

Agrobacterium is not a biofertilizer. It causes crown gall disease in plants because of which it is most extensively used in biotechnology for the gene transfer and its expression. Nostoc, Rhizobium and Mycorrhiza is associated with roots of plants and converts the atmospheric Nitrogen into nitrites and nitrates and make it available for the plants.So, the correct answer is option A.

Question 7

Yeast is used for the production of

Accepted Answer

Yeast is a eukaryotic and single-celled fungus. The commonly used species of yeast is Saccharomyces cerevisiae. It is also known as baker's yeast. The yeast is used in the production of fermented products like cakes, bread, and alcohol. The organism converts the fermentable sugars present in the substrate into carbon dioxide and ethanol. The carbon dioxide gas makes the dough of bread and cake soft and fluffy. There are pores in the bread and cakes which is due to the carbon dioxide gas bubbles which get trapped during the process of baking. Thus, the correct answer is option D.

Question 8

Write a short paragraph on the harmful effect of microorganism.

Accepted Answer

Microorganisms are useful as well as harmful also, in fact, some microbes are very helpful but most of them are harmful to living beings.  1. Some microorganisms are pathogens which cause diseases to human animals and plants.2. Bacteria and fungi are well known to cause food spoilage and make them unfit for eating.3 Bacteria cause some diseases like cholera, typhoid, and diarrhea through water and food.4. Virus scan causes smallpox, cold, hepatitis polio and soon.5. Some microorganisms show antibiotic resistance to certain diseases.

Question 9

Find out the name of the microbes from which cyclosporin A (an immunosuppressive drugs) and statins (blood cholesterol lowering agents) are obtained.

Accepted Answer

(i) Cyclosporin A is obtained from the fungus Trichoderma polysporum. (ii) Statins are produced by yeast Monascus purpureus

Question 10

Match the items in column 'A' and column 'B' and choose correct answer.  Column A Column B(i) Lady bird (A) Methanobacterium(ii) Mycorrhiza(B) Trichodema(iii) Biological control (C)  Aphids(iv) Biogas(D) Glomus The correct answer is:

Accepted Answer

Lady bird beetle function as a biological controlling agent against Aphids. Glomus is a genus of arbuscular mycorrhizal fungi and it form symbiotic relationship with plant roots which is called mycorrhiza. Tricoderma is used as a biological controlling agent against pathogenic fungi belonging to various genera. Methanobacterium produce methane which is the main component of Biogas.So, the correct option is '(I)-C, (ii)-D, (iii)-B, (iv)-A'