Biology · Environmental Studies

Microbiology and Nitrogen Cycle

950 Questions

This hub focuses on microbiology and the nitrogen cycle, covering essential concepts about bacteria and soil microbes. Topics include nitrogen fixation, bacterial structures, and soil microbial processes. These concepts are frequently tested in general science sections of various competitive exams.

Nitrogen fixing bacteriaGram-positive bacteriaBacterial flagellaDenitrifying bacteriaAmmonia conversion processBacterial resting spores

Microbiology and Nitrogen Cycle Questions

Multiple choice botany the living world archaebacteria the three domains of life classification of microbes

Food poisoning and gas forming rod-shaped bacterium is

  1. Shigella

  2. Salmonella

  3. Clostridium

  4. Escherichia coli
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Clostridium bacteria is one of the most cause of food poisoning. It is a rod-shaped Gram-positive bacteria. It is a causative agent of botulism disease. It is a gas forming bacteria. It causes causative agent of botulism Gas gangrene by producing gas in tissues in gangrene.

Thus, the correct answer is 'Clostridium.'

Multiple choice botany the living world archaebacteria the three domains of life classification of microbes

An obligate anaerobe is

  1. Ulothrix

  2. Spirogyra

  3. Methane bacteria

  4. Onion
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Obligate anaerobes are organisms which grow in absence of oxygen. In presence of oxygen, they cannot survive. The example includes methane producing bacteria or methanogens.  They obtain their energy without consumption of oxygen. Other examples include Clostridium species.

Thus, the correct answer is 'Methane bacteria.'

Multiple choice botany the living world archaebacteria the three domains of life classification of microbes

Archaebacteria found in salt pans and salt marshes are

  1. Methanogens

  2. Thermoacidophiles

  3. Ruminant symbionts

  4. Halophiles
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Halophiles are organisms that thrive in high salt concentrations. They are also called as salt-loving microorganisms. Majority of halophiles belongs to Archaebacteria group. They are found in hypersaline environments like in arid, coastal, deep‐sea, underground salt mines. They can comfortably live in evaporation ponds or salt lakes, salt pans and salt marshes. 

Thus, the correct answer is 'Halophiles.'

Multiple choice botany the living world archaebacteria the three domains of life classification of microbes

Bacteria that survive high salt concentration and temperature belongs to

  1. Cyanobacteria

  2. Archaebacteria

  3. Eubacteria

  4. Actinomycetes

  5. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

There are three major known groups of Archaebacteria, namely methanogens, halophiles and thermophiles. Halophiles are organisms that thrive in high salt concentrations. They are found in hypersaline environments like in arid, coastal, deep‐sea, underground salt mines. Thermophiles are organisms that thrive extreme temperatures. 

Thus, the correct answer is 'Archaebacteria.'

Multiple choice botany the living world archaebacteria the three domains of life classification of microbes

Bacteria useful in biogas fermentation are

  1. Methanogens

  2. Halophiles

  3. Vibrio

  4. Thermoacidophiles

  5. Cyanobacteria
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Marsh gas is also called as biogas. It is also called as methane gas as it primarily consists of methane gas along with hydrogen sulfide and carbon dioxide in minor composition. It is a produced by the decomposition of vegetable matter under water by anaerobic bacteria. Bacteria useful in biogas fermentation are Methanogens. They are found in marshes.

Thus, the correct answer is 'Methanogens.'

Multiple choice botany the living world archaebacteria the three domains of life classification of microbes

Cyanobacteria (Nostoc) is

  1. Oxygenic with nitrogenase

  2. Oxygenic without nitrogenase

  3. Non-oxygenic with nitrigenase

  4. Non-oxygenic without nitrogenase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Nostoc is a genus of Cyanobacteria. It is oxygenic photosynthetic bacteria. It has ability to synthesize their own food in presence of oxygen. It has ability to fix atmospheric nitrogen. It converts nitrogen into ammonia. The heterocysts present in it are specialized cyanobacterial cells for nitrogen fixation. It contains enzyme nitrogenase. Nitrogenase is inactivated by oxygen. Hence, the heterocyst creates a micro anaerobic environment.
Thus, the correct answer is 'Oxygenic with nitrogenase.'
Multiple choice botany the living world archaebacteria the three domains of life classification of microbes

Bacteria found in hot acidic aerobic conditions are

  1. Halophiles

  2. Thermoacidophiles

  3. Methanogens

  4. Rickettsiae
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Halophiles are bacteria that are found in high salt concentration conditions. Examples include Halobacillus, Halococcus. Bacteria found in hot acidic aerobic conditions are called as thermoacidophiles. Examples include Thermoplasma, Thermococci. Methanogens are organisms that produces methane gas. Example includes Methanococcus. Rickettsiae are obligate intracellular, Gram-negative bacteria found in ticks, lice, fleas, mites, mammals. Example includes Rickettsia rickettsii.

Thus, the correct answer is 'Thermoacidophiles.'

Multiple choice botany the living world archaebacteria the three domains of life classification of microbes

Bacteria involved in production of methane gas are

  1. Actinomycetes

  2. Methanogens

  3. Methanotrophs

  4. Cyanobacteria
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Methanogens belongs to Archeabacteria groups. They are involved in the production of methane gas or marshy gas. They are capable of producing methange gas in marshy areas. Examples include Methanococcus, Methanobacterium.

Thus, the correct answer is 'Methanogens.'

Multiple choice botany the living world archaebacteria the three domains of life classification of microbes

The primitive prokaryotes responsible for the production of biogas from the drug of ruminant animals include

  1. Eubacteria

  2. Halophiles

  3. Thermoacidophiles

  4. Methanogens
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Methanogens belongs to Archaebacteria. They are primitive prokaryotes. They produce methane gas or biogas. They produce biogas or marshy gas from the drug of ruminant animals. They are found in marshy areas and digestive tract of ruminants.

Thus, the correct answer is 'Methanogens.'

Multiple choice botany the living world archaebacteria the three domains of life classification of microbes

Archaebacteria common in marshes and rice fields are

  1. Methanogens

  2. Halophiles

  3. Thermoacidophiles

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Methanogens belongs to Archaebacteria. The other members of Archaebacteria includes halophiles and thermophiles. These are primitive prokaryotes. Methanogens produce methane gas or biogas. They produce biogas or marshy gas in marshy areas, rice fields and digestive tract of ruminants.

Thus, the correct answer is 'Methanogens.'

Multiple choice botany the living world archaebacteria the three domains of life classification of microbes

Obligate anaerobic archaebacreria with chemoautotrophic mode of nutrition are ____________.

  1. Mathanocens

  2. Halphiles

  3. Thermoacidophiles

  4. More than one option is correct
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Methanogens are obligate anaerobic archaebacteria that use carbon dioxide as an electron acceptor in a chemoautotrophic mode of nutrition, producing methane. They cannot survive in oxygen-containing environments and are found in places like marshes, swamps, and animal digestive systems. Halophiles prefer high-salt environments while thermoacidophiles thrive in hot acidic conditions.

Multiple choice botany the living world archaebacteria the three domains of life classification of microbes

Choose the correct answers from the alternatives given.
Facultative anaerobes:

  1. are photosynthetic

  2. do not always need oxygen

  3. are killed in an oxygenated environment

  4. require a constant supply of oxygen
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A facultative anaerobe is an organism that makes aerobic respiration if oxygen is absent.

So, the correct option is 'do not always need oxygen'.

Multiple choice botany the living world archaebacteria the three domains of life classification of microbes

Read the following statements regarding methanogens and select the correct option.
(i) They are included in the group Archaebacteria.
(ii) They are responsible for the production of biogas in gobar gas plants.
(iii) They live in hot sulphur springs.
(iv) They are strictly anaerobic. 

  1. Statements (i) and (ii) are correct.

  2. Statements (i), (ii) and (iv) are correct.

  3. Statements (ii), (iii) and (iv) are correct.

  4. All statements are correct.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Archaebacteria differ from other bacteria in having a different cell wall structure and this feature is responsible for their survival in extreme conditions. Methanogens are present in the gut of several ruminant animals such as cows and buffaloes and they are responsible for the production of methane (biogas) from the dung of these animals. Methanogens are obligate anaerobes.

So the correct option is "Statement(i) and (ii) are correct".