Microbes in Human Welfare

NEET Biology · 80 questions · Page 7 of 8 · Click an option or "Show Solution" to reveal answer

Q61

The common nitrogen-fixer in paddy fields is:

A Azospirillum

B Frankia

C Rhizobium

D Oscillatoria

Correct Answer

Option A

Solution

Azospirillum is an anaerobic nitrogen fixing bacteria which forms loose association with roots of some plants.

Inoculation of paddy fields with these bacteria helps in increasing yield.

Q62

Which one of the following is not used in organic farming?

A Earthworm

B Oscillatoria

C Snail

D Glomus

Correct Answer

Option C

Solution

Glomus, earthworm and Oscillatoria can be used in organic farming while snail cannot.

Q63

A common biocontrol agent for the control of plant diseases is:

A Bacillus thuringiensis

B Trichoderma

C Glomus

D Baculovirus

Correct Answer

Option B

Solution

Free living fungus Trichoderma exerts biocontrol over several plant pathogens for the control of plant diseases.

Q64

Select the correct statement from the following:

A Methanobacterium is an aerobic bacterium found in rumen of cattle

B Activated sludge sediment in settlement tanks of sewage treatment plant is a rich source of aerobic bacteria

C Biogas, commonly called gobar gas, is pure methane

D Biogas is produced by the activity of aerobic bacteria on animal waste

Correct Answer

Option B

Solution

Activated sludge is rich in aerobic bacteria.

Methanobacterium is anaerobic.

Biogas contains methane, CO2, and traces of other gases - not pure methane.

Q65

Which of the following is not used as a biopesticide?

A Bacillus thuringiensis

B Trichoderma harzianum

C Nuclear Polyhedral Virus (NPV)

D Xanthomonas campestris

Correct Answer

Option D

Solution

Xanthomonas campestris is a plant pathogen that causes black rot. It is not a biopesticide.

Q66

Trichoderma harzianum has proved a useful microorganism for:

A biological control of soil-borne plant pathogens

B reclamation of wastelands

C gene transfer in higher plants

D bioremediation of contaminated soils

Correct Answer

Option A

Solution

Trichoderma harzianum is a fungus used for biological control of soil-borne plant pathogens.

Q67

Which one of the following pairs is wrongly matched?

A Methanogens - Gobar gas

B Yeast - Ethanol

C Streptomycetes - Antibiotic

D Coliforms - Vinegar

Correct Answer

Option D

Solution

Coliforms are bacteria found in feces. Vinegar is produced by Acetobacter, not coliforms.

Q68

Probiotics are:

A Cancer inducing microbes

B New kind of food allergens

C Live microbial food supplement

D Safe antibiotics

Correct Answer

Option C

Solution

Probiotics are defined as live microorganisms that may beneficially affect the host upon ingestion by improving the balance of intestinal microflora.

Q69

Dough kept overnight in warm weather becomes soft and spongy because of:

A Cohesion

B Absorption of carbon dioxide from atmosphere

C Osmosis

D Fermentation

Correct Answer

Option D

Solution

Yeast ferments sugars in dough producing CO2 which makes it soft and spongy.

Q70

A major component of gobar gas is:

A ethane

B methane

C butane

D ammonia

Correct Answer

Option B

Solution

Methane forms a major part of gobar gas (50-70%) which is produced by methanogenic bacteria.

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