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# Microbes in Human Welfare

#### Multiple Choice Questions

1.

The pesticide used as preventive measure in buildings is :

• aldrin

• dieldrin

• endrin

• DDT

A.

aldrin

Aldrin is a pesticide used to control soil insects such as termites, grasshoppers etc. It has been widely used to protect crops such as corn and potatoes. It is used as a preventive measure in buildings to prevent attack of termites. It is a chlorinated hydrocarbon or organochlorine.

2.

Chloromycetin is obtained from

• Streptomyces venezuelae

• Streptomyces rimosus

• Bacillus subtilis

• Clostridium botulinum

A.

Streptomyces venezuelae

Chloromycetin or chloramphenicol is obtained from Streptomyces venezuelae.

3.

Curdling of milk in small intestine occurs due to the action of

• rennin

• erypsine

• trypsin

• chymotrypsin

A.

rennin

Rennin is an enzyme found in gastric juices responsible for the coagulation of milk. It acts by hydrolysing peptide links. Therefore, in small intestine, renin plays an important role in curdling of milk.

4.

Yeast is used in the production of :

• acetic acid

• citric acid

• ethyl alcohol

• curd

C.

ethyl alcohol

Yeast is used in the production of ethyl alcohol. Sugar is fermented by yeast into alcohol and CO2. Ethyl alcohol is the main product of beweries.

Citric acid is produced by Aspergillus niger (fungus) and acetic acid by Acetobacter aceti (bacterium) whereas curd is produced by Lactobacillus lactis (bacterium).

5.

Which of the following is the product of glucose fermentation by yeast?

• C6H12O6

• C2H5OH

• (C6H10O5)n

• CH2OH

B.

C2H5OH

C2H5OH and CO2 are the products of glucose fermentation by yeast

C6H12O$\underset{\mathrm{yeast}}{\overset{\mathrm{fermentation}}{\to }}$ 2C2H5OH + 2CO2

6.

Continued consumption of a diet rich in butter, red meat and eggs for a long period may lead to:

• vitamin toxicity

• kidney stones

• hypercholesterolemia

• urine laden with ketone bodies

C.

hypercholesterolemia

Cholesterol is a soft waxy substance that is a natural component of the fats in the blood stream and in all the cells of the body. In our body 8% - 10% of the saturated fatty acids are coming from animal product, such as butter, egg, red meat. Contiuous consumption of this type of diet leads to hypercholesterolemia due to presence of excess amount of saturated fatty acid.

7.

Assertion : Yeasts such as Saccharomyces cerevisiae are used in baking industry.

Reason : Carbon dioxide produced during fermentation causes bread dough to rise by thermal expansion.

• If both Assertion and Reason are true and the reason is the correct explanation of the assertion

• If both Assertion and Reason are true but the reason is not the correct explanation of the assertion

• If Assertion is true statement but Reason is false

• If both Assertion and Reason are false statements

C.

If Assertion is true statement but Reason is false

Yeast such as Saccharomyces cerevisiae is used in baking industry. The yeast ferments glucose to yield ethyl alcohol and carbon dioxide. This carbon dioxide is used in baking industry for raising dough. Kneading, stretching and folding of the dough develops the protein structure to improve its elastic properties and its ability to hold gas. This improved gluten properties enable better retention of the gases within the dough as the structure expands and the cell walls become thinner.

8.

Which of the following pesticides is an acetylcholinesterase inhibitor?

• Aldrin

• BHC

• Endosulfan

• Malathion

D.

Malathion

Organophosphate or Malathion kills insects by inhibiting enzyme cholinesterase. It is an organic ester of carbonic acid. Its structure is somewhat similar to acetylcholine and, therefore has strong affinity for the enzyme acetylcholinesterase, and inhibits its activity.

9.

Streptomycin was isolated first time by :

• A. Flemming

• Robert Koch

• N. Borlaug

• S. Waksman

D.

S. Waksman

Streptomycin was first isolated by S. Waksman from Streptomyces griseus in 1944.

Robert Koch discovered anthrax causing bacterium.

Alexander Flemming discovered Penicillin (first antibiotic).

N. Borlaug is known as the Father of Green Revolution.

10.

Which of the following micro-organism is used for conversion of milk into curd?

• Xanthomonas citri

• Bacillus megatherium

• Acetobacter aceti

• None of the above

D.

None of the above

Streptococcus lactis, S. cremoris, S. thermophilus, Lactobacillus lactis and L. bulgaricus are the micro- organisms responsible for the conversion of milk into curd. These produce lactic acid from lactose, lower the pH to 4.6 and leads to coagulation of milk.

Xanthomonas citri causes citrus canker disease in citrus.

Bacillus megatherium is used in flavouring of tobacco and tea leaves.