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

Which of the following sentences about mycophages is untrue?

  1. All mycophages of higher fungi possess dsRNA.

  2. Killer system in Saccharomyces cerevisae is induced by mycophages.

  3. Cytopathic effect is not produced by mycophages in Agaricus.

  4. Some viruses of lower fungi have dsDNA.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This is untrue. Mycophages do not produce cytopathic effect in many fungi.

Multiple choice

Which of the following is a free-living anaerobic nitrogen fixing bacteria?

  1. Clostridium

  2. Rhizobium

  3. Azotobacter

  4. Nitrobacter
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Clostridium is a free-living anaerobic nitrogen-fixing bacteria. It lives in soil and fixes nitrogen without requiring oxygen or a host plant. Rhizobium is symbiotic (requires legume host), Azotobacter is aerobic (requires oxygen), and Nitrobacter is a nitrifying bacteria that converts nitrite to nitrate but does not fix nitrogen.

Multiple choice

Chemosynthesis occurs in

  1. green plants

  2. non-green herbs

  3. floating hydrophytes

  4. colourless aerobic bacteria
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Chemosynthesis occurs only in colourless aerobic bacteria such as, Nitrosomonas, Nitrobacter etc.

Multiple choice

Which of the following features characterises Gram-positive genus Brocothrix?

  1. Aerobic filament forming non-motile rods

  2. Facultatively anaerobic non-motile rods occurring as long kinked filaments

  3. Aerobic non-motile short rods

  4. Aerotolerant long to very short non-motile rods often in chains
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Correct Answer: Facultatively anaerobic non-motile rods occurring as long kinked filaments

Multiple choice

Which of the following are included in phylum Fibrobacteres?

  1. Phosphate solubilising bacteria

  2. Rumen bacteria

  3. Glycan utilising bacteria

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

Fibrobacteres is a small bacterial phylum which includes many of the major rumen bacteria. They allow the degradation of plant-based cellulose in ruminant animals.