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 are facultative anaerobic Gram-negative bacteria?

  1. Bordetella pertussis and Mycobacterium tuberculosis

  2. Mycobacterium tuberculosis and Klebsiella pneumoniae

  3. Bordetella pertussis and Vibrio cholerae

  4. Klebsiella pneumoniae and Vibrio cholerae

  5. Klebsiella pneumoniae and Vibrio cholerae
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Klebsiella pneumoniae is a Gram-negative, facultative anaerobic, rod-shaped bacterium. Vibrio cholerae is a Gram-negative, facultative anaerobic, comma-shaped bacterium.

Multiple choice

Which of the following bacteria causes holoblight of beans?

  1. Pseudomonas salomonii

  2. Pseudomonas syringae

  3. Pseudomonas savastanoi

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

Pseudomonas syringae is a rod-shaped, Gram-negative bacterium with polar flagella which causes holoblight of beans. This bacterium produces a toxin which causes systemic chlorosis.

Multiple choice

Which of the following groups of bacteria are called gliding bacteria?

  1. Mycobacteria and Myxobacteria

  2. Mycobacteria and Cytophagales

  3. Myxobacteria and Cytophagales

  4. Cytophagales and Rickettsiae

  5. Rickettsiae and Chlamydiae
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Myxobacteria and Cytophagales are called gliding bacteria on the basis of their gliding mobility on solid surfaces.

Multiple choice

Cholera bacillus is a bacterial species that produces a soluble exotoxin and causes cholera in humans. Who among the following scientists is credited with the first production of live, but non-virulent forms of chicken cholera bacillus?

  1. Sabin

  2. Montague

  3. Jenner

  4. Salk

  5. Pasteur
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

A culture of chicken cholera bacillus accidentally left on bench during warm summer months lost much of its ability to cause disease, but could protect birds from the effects of fresh virulent bacillus. Pasteur also obtained similar results for anthrax and rabies.

Multiple choice

VAM is an alternative to inorganic fertilizer. What is VAM?

  1. Azospirillum

  2. Mycorrhiza

  3. Phosphate solubilising bacteria

  4. Nitrogen fixing bacteria

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

VAM (Vesicular Arbuscular Mycorrhiza) is a symbiotic fungus that forms associations with plant roots, enhancing nutrient uptake (especially phosphorus) and water absorption. It's widely used as an organic alternative to inorganic phosphatic fertilizers. The other options are all bacteria: Azospirillum and Azotobacter are nitrogen fixers, PSB are phosphate solubilizers, but VAM refers specifically to mycorrhizal fungi.

Multiple choice

Which of the following bacteria would one find living in hot springs?

  1. Thermoacidophiles

  2. Cyanobacteria

  3. Methanogens

  4. Chemoautotrophs

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

Correct answer. Thermoacidophiles favour hot and acidic environments. Archaebacteria: There are three major known groups of Archaebacteria: methanogens, halophiles and thermophiles. The methanogens are anaerobic bacteria that produce methane. They are found in sewage treatment plants, bogs and the intestinal tracts of ruminants. Ancient methanogens are the source of natural gas. Halophiles are bacteria that thrive in high salt concentrations such as those found in salt lakes or pools of sea water. Thermoacidophiles are the heat-loving bacteria found near hydrothermal vents and hot springs.