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 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

Which of the following pairs is mismatched?

  1. Azospirillum - Maize

  2. Mycorrhiza - Pine

  3. VAM - Mycoherbicide

  4. Rotenone - Natural insecticide
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Azospirillum inoculations are recommended mainly for sorghum, millets, maize, sugarcane and wheat.
Mycorrhizal biofertilizers can be used for pine trees.
Rotenone is an odourless, colourless, crystalline ketonic chemical compound used as a broad-spectrum insecticide, piscicide, and pesticide. It occurs naturally in the seeds and stems of several plants, such as the jicama vine plant and the roots of several members of Fabaceae.
VAM is a biofertilizer and not a mycoherbicide. 

So, the correct answer is option C.

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 botany living world mycorrhiza classification of fungi kingdom monera, protista and fungi useful and harmful microbes

Mycorrhiza is a symbiotic association between

  1. Bacteria and fungi

  2. Algae and fungi

  3. Fungi and roots of higher plants

  4. Blue green algae and roots of higher plants
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
  • Fungi present in the roots of the plants show a symbiotic relationship with each other. 
  • It helps the roots of the plants to absorb more nutrients and water from the soil. 
  • It also helps them obtain better resistance to environmental stresses. In return, plants provide shelter and nutrition to mycorrhiza.
So, option C is the correct answer.
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 botany ecosystem energy flow in food chain food chain and energy flow energy flow in ecosystem

Which bacteria consumes organic matter as their food, and thus oxidizing it to stable end product?

  1. Viruses

  2. Aerobic Bacteria

  3. Anaerobic Bacteria

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

Aerobic bacteria require oxygen to break down organic matter into stable end products like carbon dioxide and water. Anaerobic bacteria function in the absence of oxygen, and viruses are not organisms that consume organic matter in this way.

Multiple choice zoology biotechnology and its applications transgenic animals transgenic organisms applications of biotechnology

Which of the following is used as probiotic?

  1. Rhizobium

  2. Lactobacillus

  3. E. coli

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

Lactobacillus acidophilus is a type of bacteria found in your intestines.

 Lactobacilli, particularly L. acidophilus, are often used as probiotics. 
The World Health Organization defines probiotics as "live micro-organisms which, when administered in adequate amounts, confer a health benefit on the host."

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'.