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 biology food and it's constituents functions and principal sources of lipids chemical organization in living beings lipids

During symbiotic biological nitrogen fixation. The recognition of rhizobiahost interaction involves two classes of molecules there are _______________.

  1. Lectins an lipids

  2. Lectins and Polysaccharides

  3. Flavonoids and lipids

  4. Lectins and Alkaloids
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the symbiotic relationship between legumes and rhizobia, the initial recognition involves lectins (on the plant side) and specific polysaccharides or lipids on the bacterial surface.

Multiple choice biology interdependence in living beings - plants and animals animals as consumers scavengers and decomposers interdependence between plants and animals

Which of the following microorganisms convert nitrogenous waste into nitrogen compound?

  1. Bacteria and Fungi

  2. Fungi and Protozoan

  3. Protozoan and Algae

  4. Protozoan and Bacteria
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Bacteria and fungi belongs to the class of decomposers. They act on the waste materials and converts the nitrogen present in the waste to useful nitrogenous compounds. It also increases the nitrogen content of the soil and increases the fertility of the soil.

So, the correct answer is option A.

Multiple choice biology interdependence in living beings - plants and animals animals as consumers scavengers and decomposers interdependence between plants and animals

Which one of the following is genetically improved bacteria for pollution control.

  1. Pseudomonas

  2. Rhlzobium

  3. N!trobacter

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

Pseudomonas species, particularly Pseudomonas putida, have been genetically modified to degrade various environmental pollutants including hydrocarbons, pesticides, and heavy metals. This makes them valuable for bioremediation efforts to clean up contaminated sites. The other options are important soil bacteria but not primarily known for pollution control.

Multiple choice botany energy flow in an ecosystem biogeochemical cycle nutrient cycles species, communities and ecosystems

Which of the following are the examples of biogeochemical cycle?

  1. Nitrogen cycle

  2. Krebs cycle

  3. Electron cycle

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

A biogeochemical cycle involves biological, geological and chemical factors. The circulation of chemical nutrients like carbon, oxygen, nitrogen, phosphorus, calcium, and water, etc. between biotic and abiotic components of the biosphere is known as a biogeochemical cycle.
So, the correct option is option A.

Multiple choice botany energy flow in an ecosystem biogeochemical cycle nutrient cycles species, communities and ecosystems

The conversion of $\displaystyle $ is known as

  1. Denitrification

  2. Nitrification

  3. Nitrogen fixation

  4. Ammonification
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The process of conversion of free nitrogen from the atmosphere into soluble nitrates by microorganisms is  known as biological nitrogen fixation. 
When plants and animals die, the nitrogenous compounds present in their bodies are broken down into  ammonia. This process is known as ammonification.  Ammonia is converted to nitrates by nitrifying bacteria, such as Nitrosomonas and Nitrobacter, through a  process called nitrification.
Nitrification is followed by denitrification, wherein nitrates are converted into nitrogen gas (N2), by the  action of denitrifying bacteria such as species of Nitrosomonas, Pseudomonas, Alcaligenes and Bacillus.  The nitrogen gas is then released into the atmosphere.
Multiple choice biology environmental factors soil-nature climate factors abiotic components

Which of the following fixes atmospheric ${ N } _{ 2 }$?

  1. Nostoc

  2. Algae

  3. Methanogens

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Nostoc is a genus of cyanobacteria that are involved in nitrogen fixation. They are commonly found in the form of a gelatinous sheath that is composed of microfilaments.
So, the correct answer is 'Nostoc'.
Multiple choice botany living world mycorrhiza classification of fungi kingdom monera, protista and fungi useful and harmful microbes

A phosphate solubilising symbiotic association is :

  1. Rhizobium

  2. Mycorrhiiza

  3. Azolla

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

Roots of most terrestrial plants are colonized by symbiotic mycorrhizal fungi. These fungi are capable of mobilizing inorganic phosphates or compound phosphates present in the soil to the plant an a source of Phosphorus.

So, the correct answer is 'Mycorrhiiza'

Multiple choice evs earth - our home need to conserve biodiversity protecting our environment rules are for everyone

Find the odd one out:

  1. Methanobacteria

  2. Pseudomonas

  3. Clostridium

  4. E.coli
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Biogas constitutes 50-80% methane and rest carbon dioxide. Methane is produced by anaerobic degradation of organic matter. Methanobacteria is responsible for production of methane. Pseudomonas and Clostridium is responsible anaerobic degradation of complex organic polymers. E.coli is not involved in the production of biogas.

Multiple choice botany ecosystem energy flow in food chain food chain and energy flow energy flow in ecosystem

Phenomenon, by which some primarily bacteria utilize chemicals to generate energy rich compounds, known as

  1. Autosynthesis

  2. Polysynthesis

  3. Photosynthesis

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

Chemosynthesis is the process by which certain organisms (like bacteria) obtain energy by oxidizing inorganic chemical compounds rather than using sunlight.

Multiple choice evs farming brings prosperity agriculture and types of crops crop management management of crops in india

Which one of the following can be used as biofertiliser in cotton field ?

  1. Azolla-Anabaena

  2. Streptococcus

  3. Azosphillum

  4. Azotobacter chroocoocurn
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Cotton is a dicotyledonous crop. The best biofertiliser for cotton is Bacillus cereus and Azotobacter chroococcum. These are free-living $N _2$ fixing bacteria and enhance the fertility of the soil.

Multiple choice photosystems photosynthesis in plants metabolism, cell respiration, and photosynthesis photosynthesis in higher plants biology

The green and purple sulphur bacteria use .......... as electron donors.

  1. ${H _2 O}$
  2. ${H _2 S}$
  3. ${C O _2}$
  4. $Isopropanol$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Like most other photosynthetic bacteria, purple and green sulphar bacteria do not produce oxygen (anoxygenic), because the reducing agent (electron donor) involved in photosynthesis is not water. They use H$ _{2}$S or Elementary Sulphur as electron donor. In any photosynthetic organism, CO$ _{2}$ is not used as electron donor. Rhodopseudomonas uses isopropanol as electron donor.
So, the correct answer is option B.

Multiple choice botany know the plant world closely nutrition and its types types of nutrition in plants different modes of nutrition in plants

Relation between bacteria and legume having nodulated roots is that of

  1. Host-parasitism

  2. Commensalism

  3. Symbiosis

  4. Epiphytism
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The relation between the bacteria and legume having nodulated root is of symbiosis because it is a mutually beneficial relationship where the bacteria acquire food and accommodation, while the plant acquires nitrogen to make proteins.

So, the correct option is 'Symbiosis'.

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

The nodules present in the leguminous plants appear pink in colour due to the presence of 

  1. RBC.s

  2. leghaemoglobin

  3. nitrogenase enzyme

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

Leghaemoglobin is an oxygen-binding protein found in the root nodules of leguminous plants. It gives the nodules their characteristic pink or red color.

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

Which of the following statements is incorrect about leghaemoglobin?

  1. It acts as $O _2$ scavenger

  2. It imparts pink or red colour to the nodules
  3. It combines with $O _2$ and protects nitrogenase

  4. It is a Mo-Fe protein.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Leghaemoglobin is an iron-containing protein (a hemoprotein), not a Molybdenum-Iron (Mo-Fe) protein. Nitrogenase is the Mo-Fe protein involved in nitrogen fixation.

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

Read the following statements and select the correct answer: - 


(i) Rhizobium leguminosarum is also known as Bacillus radicicola.
(ii) Nitrifying bacteria (Nitrosomonas, etc) are chemoautotrophs.
(iii) Enzyme nitrogenase fixes $N _2$ under aerobic conditions.
(iv) Leghaemoglobin creates aerobic conditions for the enzyme nitrogenase. 

  1. Statements (i), (ii) and (iii) are correct

  2. Statements (i) and (ii) are correct

  3. Statements (iii) and (iv) are correct

  4. All statements are correct
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Statements I and ii are correct. Rhizobium leguminosarum is also known as Bacillus radicicola. Nitrifying bacteria (Nitrosomonas, etc) are chemoautotrophs. They use inorganic energy sources. However, the enzyme nitrogenase is highly sensitive to oxygen and gets readily oxidised in it's presence and Leghaemoglobin creates anerobic conditions for the enzyme nitrogenase by scavenging the oxygen molecules.

Thus, the correct answer is 'Statements (i) and (ii) are correct.'