Microbes in Household Products, Industrial Products & in Sewage Treatment

1 Mark Questions

1. Give the scientific name of the source organism from which the first antibiotic was produced. [Foreign 2014] Ans. The scientific name of organism, i.e. mould from which first antibiotic was produced is Penici Ilium notatum.
2. Which of the following is the baker's yeast used in fermentation? Saccharum barberi, Saccharomyces cerevisiae and Sonalika. [All India 2011,2009,2012] Ans. Saccharomyces cerevisiae is the baker's yeast used in fermentation.
3. Write the scientific name of the microbe used for fermenting malted cereals and fruit juices.[Delhi 2011] Ans. Saccharomyces cerevisiae also, commonly called brewer's yeast is the microbe used for fermenting malted cereals and fruit juices.11]

Mention the information that the health workers derive by measuring BOD of a waterbody. [All India 2010]

Ans. Higher the BOD of water body, more is its polluting potential and vice-versa. BOD indicates the presence of organic matter in the water.

1. Why is sewage water treated until the BOD is reduced? Give a reason. [Delhi 2010c]

Ans. The greater the BOD of sewage water, more is its polluting potential. So, the sewage water is treated, till its BOD is reduced to reduce the organic matter present in it.

1. Milk starts to coagulate when Lactic Acid Bacteria (LAB) is added to warm milk as a

starter. Mention any other two benefits LAB provides.[All India 2009]

Ans. Two benefits of LAB:

1. They improve the nutrient quality of curd by increasing the vitamin-B12 content.
2. LAB also check the growth of disease causing microbes in the stomach.

1. BOD of two samples of water A and B were 120 mg/L and 400 mg/L, Which sample is more polluted? [Foreign 2009] Ans. Sample B(BOD 400 mg/L) is more polluted as higher the BOD, more is the polluting potential
2. Given below are a few impurities in urban wastewater. Select two colloidal impurities: ammonia, faecal matter, silt, bacteria, calcium. [All India 2009c] Ans. Faecal matter and silt are the colloidal impurities in urban wastewater.

2 Marks Questions

1. Name two groups of organisms which constitute 'floes'. Write their influence on the level of BOD during biological treatment of sewage. [Delhi 2014c]

Ans. The groups of organisms that constitute mesh like structures called 'floes' are bacteria and fungi.

These bacterial masses associated with fungal filaments called floes, consume the major part of organic matter present in effluent, thereby reducing the BOD of the waste significantly during biological or secondary treatment of sewage.

10. Why is 'starter' added to set the milk into curd? Explain. [All India 2014c]

Ans. When a small amount of curd as starter is added to fresh milk, millions of Lactic Acid Bacteria (LAB) present in the starter grow in milk and convert it to curd. During this process, acids are produced by LAB that coagulate and partially digest the milk proteins (casein). LAB increases vitamin-B₁₂ content along with other vitamins in the curd

11. Name the bacterium responsible for the large holes seen in swiss cheese. What are these holes due to?

[All India 2013, Delhi 2008C]

Ans. Swiss cheese is produced by the bacterium Propionibacterium shermanii. The large holes in swiss cheese are due to the large amount of CO₂ production

12. Name the source of streptokinase. How does this bioactive molecule function in our body. [Delhi 2012]

or Name the enzyme produced by Streptococcus bacterium. Explain its importance in medical sciences.

[All India 2011]

Ans. Streptokinase enzyme is produced by the bacterium Streptococcus. It is modified by genetic engineering and is used as a clot buster for removing clots from the blood vessels of patients who have suffered from myocardial infarction.

13. Mention the importance of lactic acid bacteria to humans other than setting milk into curd.[Delhi 2012]

Ans. (i)Lactic Acid Bacteria (LAB) are used to produce an acid called lactic acid that is an important industrial product. It is also used in beverages, meat products, confectionary, dairy products, etc.

1. It also checks disease causing microbes in stomach.

14. Name the source of cyclosporin-A. How does this bioactive molecule function in our body? [All India 2012]

Ans. Cyclosporin-A is produced by the fungus Trichoderma polysporum. It is used as an immunosuppressive agent in organ-transplant patients.

15. Name the source of statin and state its action on the human body. [Foreign 2012] or

Give the scientific name of the microbes from which cyclosporin-A and statin are obtained. Write one medical use of each one of these drugs. [Foreign 2011]

Ans. Statin is produced by yeast Monascus purpureus. It is used as blood cholesterol lowering agent.

It acts by competitively inhibiting the enzyme responsible for synthesis of cholesterol. or

Cyclosporin-A is produced by the fungus Trichoderma polysporum. It is used as an