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

Ideonella sakaiensis was identified in 2016 by a team of researchers from Kyoto Institute of Technology and Keio University. What is the potential importance of this bacterium?

  1. Degradation of PCBs (polychlorinated biphenyls)

  2. Recycling of PET (polyethylene terephthalate) plastics

  3. Production of methane

  4. Leaching of copper
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ideonella sakaiensis has potential of recycling of PET plastics. The bacterium was observed to utilise two distinct enzymes that reacted with water to break down PET (polyethylene terephthalate) plastics.

Multiple choice

Arthrobacter is a genus of bacteria which is generally found in soil. Which among the following species of Arthrobacter produces the enzyme inulase II?

  1. Arthrobacter chlorophenolicus

  2. Arthrobacter sp strain R1

  3. Arthrobacter sp H65-7

  4. Arthrobacter luteus

  5. Arthrobacter crystallopoietes
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Arthrobacter sp H65-7 produces the enzyme inulase II that converts inulin into difructose anhydride (DFA). DFA is a promising nutrient for fighting osteoporis, because it helps absorption of calcium in the intestines.

Multiple choice

Which of the following bacteria is used as a bioleaching agent?

  1. Acetrobacter aceti

  2. Bacillus thuringiensis

  3. Lactobacillus delbrueckii

  4. Thiobacillus ferrooxidans

  5. Xanthomonas campestris
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Thiobacillus ferrooxidans is used in a mining technique called bioleaching (as bioleaching agent) whereby metals are extracted from their ores through oxidation.

Multiple choice

Which of the following is/are example(s) of biofertilizers?

  1. Blue green algae
  2. Ammonium nitrate
  3. Azospirillium

  1. 1 and 2 only

  2. 1 and 3 only

  3. 2 and 3 only

  4. 1, 2 and 3
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Bio-fertilizers provide eco-friendly organic agro-input and are more cost-effective than chemical fertilizers. Bio-fertilizers such as Rhizobium, Azotobacter, Azospirilium and blue green algae (BGA) have been in use for a long time. Ammonium nitrate is an example of chemical fertilizer.

Multiple choice

Rhizosphere microflora represent

  1. atagonism

  2. mutualism

  3. commensalism

  4. protocooperation

  5. amensalism
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

It is where two species interact with each other beneficially without establishing a physical contact with each other. The rhizosphere is the zone surrounding the roots of plants in which complex relations exist among the plant, the soil microorganisms and the soil itself.

Multiple choice

Which of the following are free living aerobic asymbiotic nitrogen fixing bacteria? P. Azotobacter Q. Klebsiella R. Clostridium S. Rhizobium Select the correct answer using codes given below:

  1. P and Q

  2. P and R

  3. P and S

  4. Q and R

  5. R and S
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Bacteria which convert atmospheric nitrogen into compounds of nitrogen are called nitrogen fixing bacteria. Azotobactor and klebsiella are examples of free living aerobic asymbiotic nitrogen fixing bacteria.

Multiple choice

Which of the following is a pair of non-motile bacteria?

  1. Helicobacter pylori and Nisseria gonorrhoeae

  2. Nisseria gonorrhoeae and Yersinia pestis

  3. Helicobacter pylori and Yersinia pestis

  4. Helicobacter pylori and Alcaligenes faecalis

  5. Yersinia pestis and Alcaligenes faecalis
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Nisseria gonorrhoeae is a coffee bean-shaped Gram-negative, non-motile bacteria. Yersinia pestis is a Gram-negative, rod-shaped, non-motile bacteria.