Tag: bacteria; benefits and harmful effects

Questions Related to bacteria; benefits and harmful effects

The function of leghaemoglobin in the root nodules of legumes is

  1. Expression of nif gene

  2. Inhibition of nitrogenase activity

  3. Oxygen removal

  4. Nodule differentiation


Correct Option: C
Explanation:

Enzyme nitrogenase, that catalyses nitrogen fixation is oxygen labile. Leguminous plant proteins called leghaemoglobin act as oxygen scavenger facilitating Rhizobium in fixing nitrogen.
So answer is- 'O
xygen removal'.

Which one of the following is a wrong match of a microbe and its industrial product?

  1. Clostridium butylicum - lactic acid

  2. Aspergillus niger - citric acid

  3. Acetobacter aceti - acetic acid

  4. None of the above


Correct Option: A
Explanation:
  • Clostridium butylicum - lactic acid is a wrong match of a microbe and its industrial product because Clostridium butylicum forms butyric acid.
  • So, the correct answer is 'butyric acid'.

_______ is a free-living $N _2$ -fixing aerobic bacterium.

  1. Rhodospirillum

  2. Azotobacter

  3. Clostridium

  4. Rhizobium


Correct Option: B

Pasteurization is performed at

  1. 100$^o$C for 30 minutes

  2. 82$^o$C for 15 minutes

  3. 72$^o$C for 20 minutes

  4. 65$^o$C for 30 minutes


Correct Option: D
Explanation:

There are basically two methods of pasteurization in use today- batch and continuous flow. In the batch process (batch pasteurizer), a large quantity of milk is held in a heated vat at 149$^{0}$F/65$^{0}$C for 30 minutes, followed by quick cooling to about 39$^{0}$F / 4$^{0}$C. In the continuous flow process (continuous flow pasteurizer) also known as HTST, for high temperature, short time, milk is held at 161$^{0}$F / 72$^{0}$C for at least 16 seconds. Before being chilled back to 39$^{0}$F / 4$^{0}$C. 

Microorganisms are useful in 

  1. Preparation of food and food additives

  2. Production of alcoholic beverages

  3. Therapeutic compounds

  4. All of the above


Correct Option: D
Explanation:

Microorganisms are used in brewing, wine-making, baking, pickling and other food-making processes. They are also used to control the fermentation process in the production of cultured dairy products such as yogurt and cheese. The cultures also provide flavour and aroma, and inhibit undesirable organisms. Microbes are used in the biological treatment of sewage and industrial waste effluents. Microbes are used in fermentation to produce ethanol.

Curing of tobacco is done by

  1. Micrococcus candicans

  2. Bacillus subtilis

  3. Bacillus megaterium

  4. Bacillus ramosus


Correct Option: C
Explanation:

After tobacco has been harvested, it is necessary to cure it before consumption. Tobacco curing is also known as colour curing, because when tobacco leaves are cured, the intention is to change their colour and reduce their chlorophyll content. Bacillus megaterium is an endophyte and is a potential agent for the biocontrol of plant diseases. 

For retting of jute, the fermenting microbe used is 

  1. Helicobacter pylori

  2. Mesophilic bacteria

  3. Streptococcus lactis

  4. Butyric acid bacteria


Correct Option: D
Explanation:

Retting is a process employing the action of microorganisms and moisture on plants to dissolve or rot away much of the cellular tissues and pectins surrounding bast fibre bundles and so facilitating separation of the fibre from the stem. Butyric acid bacteria helps in the retting of jute fibre.

Which one causes food poisoning?

  1. Azotobacter

  2. Nitrosomonas

  3. Nitrobacter

  4. Clostridium botulinum


Correct Option: D

Citrus canker is a plant disease caused by a microorganism which belongs to group 'X'. The other microorganism of this group are responsible for causing human disease like

  1. Measkes and polio

  2. Hepatitis A and chicken

  3. Typhoid and polio

  4. Tuberculosis and cholera


Correct Option: D
Explanation:
  • Citrus canker is a disease that affects citrus species caused by the bacterium Xanthomonas axonopodis.
  • The bacteria causing diseases in humans are- Tuberculosis and cholera.
  • Cholera is caused by the bacterium Vibrio cholera.
  • Tuberculosis is caused by Mycobacterium tuberculosis. 

Wine turns sour because of

  1. Heat

  2. Aerobic bacteria

  3. Anaerobic bacteria

  4. Exposure to the light


Correct Option: B
Explanation:

Mycoderma aceti is an aerobic acetic acid bacterium that converts ethanol into acetic acid in presence of oxygen. The ethanol is first aerobically fermented into acetaldehyde which is then oxidized into acetic acid. The Mycoderma aceti present in wine and in the surrounding air produce acetic acid (vinegar) which imparts sour taste to the wine. The requirement of oxygen for the process. Heat exposure renders the bacteria inactive and acetic acid production is stopped. Long term exposure to UV light affect the phenolic and ester component of wine and render it tasteless; since acetic acid formation is not affected by light, wine is not turned sour in light.

Therefore, the correct answer is option B.