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 evs a seeds tells a farmer's story manure manures and fertilisers water absorption organ

Leguminous plants are able to fix atmospheric nitrogen through the process ofsymbiotic nitrogen fixation. Which one of the following statements is not correct for this process of nitrogen fixation?

  1. Leghaemoglobin scavenges oxygen and is pinkish in colour.

  2. Nodules act as sites for nitrogen fixation.
  3. The enzyme nitrogenase catalyses the conversion of atmospheric $N _2$ to $NH _3$.

  4. Nitrogenase is insensitive to oxygen.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The nitrogenase enzyme is extremely sensitive to oxygen and is inactivated by it. Therefore, the statement that it is 'insensitive to oxygen' is incorrect.

Multiple choice evs a seeds tells a farmer's story manure manures and fertilisers water absorption organ

Leguminous plants are important in agriculture because

  1. They are disease resistant

  2. They have high amounts of proteins

  3. They require less nitrogen for growth

  4. Nitrogen fixing bacteria are symbiotically associated in them
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Leguminous plants are important in agriculture because they contribute to nitrogen fixation. They contain symbiotic nitrogen-fixing bacteria within the nodules that produce nitrogen compounds that help the plant to grow. When the plant dies, the fixed nitrogen is released, making it available to other plants and this helps to fertilize the soil.
So the correct answer is 'Nitrogen-fixing bacteria are symbiotically associated in them'.
Multiple choice evs a seeds tells a farmer's story manure manures and fertilisers water absorption organ

The pigment protein present in nodulated roots inhabited by Rhizobium is

  1. Nitrate reductase

  2. Hydrogenase

  3. Leghaemoglobin

  4. Plastocyanin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Rhizobium is symbiotic nitrogen-fixing bacteria present in the roots of leguminous plants. This bacteria is responsible for the formation of root nodules in legumes roots. The nodule contains a biochemical pigment protein called leg-haemoglobin that function as an oxygen scavenger.
so the correct answer is 'Leghaemoglobin'.
Multiple choice evs a seeds tells a farmer's story manure manures and fertilisers water absorption organ

Function of leghaemoglobin during biological nitrogen fixation in root nodules of legumes is to

  1. Convert atmospheric nitrogen to ammonia

  2. Convert ammonia to nitrite

  3. Transport oxygen for activity of nitrogenase

  4. Protect nitrogenase from oxygen
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Root nodules of a leguminous plant contain all the biochemical components required for nitrogen fixation including enzymes nitrogenase and a pink-coloured pigment called leghaemoglobin. Nitrogenase is highly sensitive enzyme to molecular oxygen as it functions under anaerobic conditions. To protect this enzyme from oxygen leghaemoglobin act as an oxygen scavenger.
So the correct answer is 'Protect nitrogenase from oxygen'.
Multiple choice evs a seeds tells a farmer's story manure manures and fertilisers water absorption organ

Which one is correct about the free living Rhizobium sp. and its enzyme?

  1. Bacteria are aerobic and nitrogenase are active

  2. Bacterial are anaerobic and nitrogenase is active (operational)

  3. Bacteria aerobic and nitrogenase is inactive

  4. Bacteria are anaerobic and nitrogenase is inactive
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Rhizobium, is a rod shaped, aerobic, nitrogen fixing bacterium present in the root nodules of leguminous plants. It performs symbiotic nitrogen fixation in the root nodules of leguminous plants, in presence of an enzyme dinitrogenase.

So, the correct option is ‘bacteria are aerobic and nitrogenase are active’.

Multiple choice chemistry nitrogen and sulfur nitrogen gas component of air - nitrogen nitrogen

Fixation of nitrogen means :

  1. reaction of nitrogen with oxygen

  2. conversion of free atmospheric nitrogen into

    nitrogen compounds

  3. the action of dentrifying bactria on nitrogen

    compounds

  4. decomposition of nitrogenous compounds to

    yield free nitrogen
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Fixation  - conversion of free atmospheric nitrogen into nitrogen compounds.

Multiple choice biology wastewater story basics of water pollution sewage treatment wastewater treatment - need and methods personal and public cleanliness who will do this? water borne disease hygiene - a key to healthy life

Which of the following statements is correct ?

  1. Activated sludge - sediment in settlement tanks of sewage treatment plant is a rich source of aerobic bacteria

  2. Biogas is produced by the activity of aerobic bacteria on animal feed

  3. Methanobacterium is an aerobic bacterium found in rumen of cattle.

  4. Biogas, commonly called gobar gas, is pure methane.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Activated sludge consists of a flocculent mass of aerobic bacteria and fungi that decompose organic matter in sewage. Biogas is produced by anaerobic bacteria, and Methanobacterium is an anaerobe.

Multiple choice biology wastewater story basics of water pollution sewage treatment wastewater treatment - need and methods personal and public cleanliness who will do this? water borne disease hygiene - a key to healthy life

Select the correct statement from the following.

  1. Activated sludge-sediment in settlement tanks of sewage treatment plant is a rich source of aerobic bacteria

  2. Biogas is produced by the activity of aerobic bacteria on animal waste

  3. Methano bacterium is an aerobic bacterium found in rumen of cattle

  4. Biogas, commonly called as global gas, is pure methane
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

1. The effluent from aeration tank is passed into a settling tank where the aerobic bacterial ‘flocs’ are allowed to sediment and the sediment is called activated sludge.

2. Biogas is produced by the activity of anaerobic bacteria on activated sludge.
3. Methano bacterium is an anaerobic bacteria found in rumen of cattle.
4. Biogas is a mixture of gases such as methane, hydrogen sulphide and carbon dioxide.
So, the correct option is 'Activated sludge-sediment in settlement tanks of sewage treatment plant is a rich source of aerobic bacteria'.

Multiple choice biology wastewater story basics of water pollution sewage treatment wastewater treatment - need and methods personal and public cleanliness who will do this? water borne disease hygiene - a key to healthy life

Select the correct statement from the following.

  1. Methanobacterium is aerobic bacterium found in rumen of cattle.

  2. Biogas, commonly called gobar gas, is pure methane.

  3. Activated sludge-sediment in settlement tanks of sewage treatment plant is a rich source of aerobic bacteria.

  4. Biogas is produced by the activity of aerobic bacteria on animal waste.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Methanobacterium  are anaerobic organisms.
Biogas refers to a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen.
Activated sludge-sediment in settlement tanks of sewage treatment plant is a rich source of aerobic bacteria.
Biogas can be produced by anaerobic digestion with anaerobic bacteria.
Thus, the correct answer is option (C), 'Activated sludge-sediment in settlement tanks of sewage treatment plant is a rich source of aerobic bacteria'.

Multiple choice zoology ecosystems decomposition in ecosystem ecosystem productivity and decomposition producers, consumers and decomposers

Which bacteria can flourish and carry out decomposition of organic matter, both in presence and absence of oxygen?

  1. Facultative Bacteria

  2. Aerobic Bacteria

  3. Anaerobic Bacteria

  4. Blue green algae
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Facultative bacteria are versatile organisms that can switch their metabolic pathways to survive and function in both the presence and absence of oxygen.

Multiple choice zoology ecosystems decomposition in ecosystem ecosystem productivity and decomposition producers, consumers and decomposers

Mark the correct statement
a) Microbes helps in decomposition process
b) They help in maintaining biogeochemical cycle
c) Microbes only helps in carbon cycle, they don't have any role in nitrogen cycle

  1. a, b

  2. a, c

  3. b, c

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

Microbes play important role in our lives and in the environment. They help in the decomposition process and in maintaining the biogeo-chemical cycles like carbon and nitrogen cycles.

So, the correct answer is 'a,b'