Biology · Environmental Studies

Microbiology and Nitrogen Cycle

1,029 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

Which of the following bacteria is not an example of spirochetes?

  1. Treponema

  2. Spirillum

  3. Leptospira

  4. Borrelia

  5. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

An important morphological difference from the helical spirochetes is that Spirillum bacteria are motile by conventional polar flagella, rather than axial filaments. This is why Spirilum is not classified as spirochete.

Multiple choice

Which of the following is an example of gram-positive bacteria having ability to oxidise glucose by Entner–Doudoroff pathway?

  1. Bacillus subtilis

  2. Enterococcus faecalis

  3. Escherichia coli

  4. Xanthomonas campestris

  5. Zymomonas mobilis
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Very few gram-positive bacteria have the ability to oxidise glucose by Entner–Doudoroff pathway. Enterococcus faecalis is an example of gram-positive bacteria having the ability to oxidise glucose by Entner–Doudoroff pathway.

Multiple choice

Which of the following statements is correct about Aerotolerant anaerobes?

  1. They are completely dependent on atmospheric oxygen for growth.

  2. They are able to grow under anaerobic conditions, but develop most rapidly in an aerobic environment.

  3. They grow equally well in the presence or absence of oxygen.

  4. It does not tolerate oxygen and dies in its presence.

  5. They thrive in an environment low in oxygen.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Aerotolerant anaerobes grow equally well in presence or absence of oxygen.

Multiple choice

Which of the following is a genus of microaerophilic bacteria?

  1. Campylobacter

  2. Bacteroides

  3. Clostridium

  4. Bacillus

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

Campylobacter is a genus of bacteria that are gram-negative, spiral, and microaerophilic. Microaerophiles require oxygen levels in the range of 2 to 10% for their growth and are damaged by the normal atmospheric level of oxygen (20%).

Multiple choice

Which of the following is a sulphate reducing bacterium?

  1. Gallionella ferruginea

  2. Desulfotomaculum carboxydivorans

  3. Rhodospirillum rubrum

  4. Beijerinckia derxii

  5. Streptococcus thermophilus
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Desulfotomaculum carboxydivorans is a moderately thermophilic, anaerobic, chemolithoheterotrophic, sulfate-reducing bacterium.

Multiple choice

Which of the following statements is incorrect regarding pseudomonas syringae?

  1. Pseudomonas syringae is a gram negative bacterium.

  2. Pseudomonas syringae has a polar flagella.

  3. Pseudomonas syringae is a plant pathogen.

  4. Pseudomonas syringae tests positive for arginine dihydrolase and oxidase activity.

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Pseudomonas syringae tests negative, not positive, for arginine dihydrolase and oxidase activity. Therefore, this statement is incorrect.

Multiple choice

Which of the following is a false statement?

  1. All NH4+ seems to be converted first into the amide group of glutamine.

  2. Conversion of organic nitrogen to NH4+ by soil microbes is called ammonification.

  3. Cl– is required for photochemical reaction involved in photolysis of water.

  4. Plant roots absorb ions as well as the salts.
Reveal answer Fill a bubble to check yourself
D Correct answer