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 bacterium is present in the root nodules of the leguminous plants?

  1. Lactobacillus

  2. Rhizobium

  3. Clostridium

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

Rhizobium is the nitrogen fixing bacteria present in the root nodules of leguminous plants. This bacteria lives in symbiotic relation with the plants, gets shelter from plant and in return provides usable form of nitrogen to it.

Multiple choice

The ribosomes in the bacteria are of _____.

  1. 30S type

  2. 40S type

  3. 70S type

  4. 90S type

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Prokaryotic cells, including bacteria, contain 70S ribosomes. These are smaller than the 80S ribosomes found in eukaryotic cells.

Multiple choice

To convert the atmospheric nitrogen into usable nitrogen, five steps are involved. The two prominent bacteria namely Pseudomonas and Clostridium are responsible for _________________.

  1. nitrogen fixation

  2. nitrification

  3. assimilation

  4. ammonification

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

When the ammonia is converted back into inert nitrogen, the process is called as denitrification. Bacteria are involved in this process which takes place in anaerobic conditions. Pseudomonas and Clostridium are responsible for the step of denitrification.  

Multiple choice

Consider the following statements and find out the correct ones.I. One of the alternate sources of proteins for animal and human nutrition is Single Cell Protein (SCP).II. Microbes like Spirulina can be grown easily on materials like waste water from potato processing plants (containing starch), straw, molasses, animal manure and even sewage.III. Methylotrophus, because of its high rate of biomass production and growth, can be expected to produce 25 tonnes of protein.

  1. Only I and II

  2. Only II and III

  3. Only I

  4. Only I and III

  5. All I, II and III
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

This is the correct answer option as all the statements are correct.I. One of the alternate sources of proteins for animal and human nutrition is Single Cell Protein (SCP).II. Microbes like Spirulina can be grown easily on materials like waste water from potato processing plants (containing starch), straw, molasses, animal manure and even sewage.III. Methylotrophus, because of its high rate of biomass production and growth, can be expected to produce 25 tonnes of protein.

Multiple choice

Pneumatophores are

  1. positively geotropic

  2. plagio-geotropic

  3. diageotropic

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

Pneumatophores are negatively geotropic.