Biology ยท 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

Leghemoglobin are

  1. Root nodule

  2. Leaf nodule

  3. Stem nodule

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

Leghemoglobin is a nitrogen- or oxygen-carrier hemoprotein found in the nitrogen-fixing root nodules of leguminous plants. It regulates oxygen concentration to protect the oxygen-sensitive nitrogenase enzyme.

Multiple choice

Function of Rhizobium are

  1. Soil

  2. Dicot

  3. Nitogen fixation

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

Rhizobium is a soil-dwelling bacterium that establishes a symbiotic relationship with dicotyledonous plants (specifically legumes) to perform biological nitrogen fixation. Thus, all the options describe aspects of its habitat, host, and function.

Multiple choice

Conversion of nitrogen to ammonia called

  1. Nitogen fixation

  2. Nitrifiy

  3. Denitrifcation

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

The biological or chemical process of converting atmospheric nitrogen (N2) into ammonia (NH3) is known as nitrogen fixation. This process is carried out by specialized diazotrophic microorganisms.

Multiple choice

Root nodule formation by

  1. Nod gene

  2. Nif gene

  3. Nitogenase

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

Nodulation (nod) genes are responsible for the initiation and formation of root nodules in symbiotic relationships between rhizobia and host legumes. Nif genes, on the other hand, encode the nitrogenase enzyme responsible for the actual fixation of nitrogen.

Multiple choice

Rhizobium is

  1. Gram positive

  2. Gram negative

  3. Both

  4. Gram positive and negative
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Rhizobium is a genus of Gram-negative, motile, rod-shaped bacteria that establish symbiotic relationships with the roots of leguminous plants.

Multiple choice

Example of non symbiotic is

  1. Azolla

  2. Rhizobium

  3. BGA

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

While Rhizobium and Bradyrhizobium are obligate symbiotic nitrogen fixers, and Azolla forms an obligate symbiosis with Anabaena, many Blue-Green Algae (BGA) can fix nitrogen in a free-living, non-symbiotic state.

Multiple choice

Which is nitrogen fixing bacteria

  1. Azolla

  2. Anabena

  3. Rhizobium

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

Anabaena and Rhizobium are well-known nitrogen-fixing bacteria. Although Azolla is a eukaryotic fern, it is frequently grouped with these organisms in agricultural contexts because it houses the nitrogen-fixing cyanobacterium Anabaena azollae.

Multiple choice

In biological nitrogen fixation

  1. N-ammonia

  2. N-Nitrite

  3. N-Nitrify

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

Biological nitrogen fixation is the process where atmospheric nitrogen gas (N2) is reduced to ammonia (NH3) by the enzyme nitrogenase, making ammonia the primary product.

Multiple choice

_________ is a bacteria found in poultry.

  1. Botulinum

  2. E. Coli

  3. Fecal Coliform

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

Salmonella is a genus of rod-shaped bacteria that is commonly associated with raw poultry and eggs, causing salmonellosis if food is undercooked.

Multiple choice

The enzyme Nitrogenase is a

  1. Mo- Fe protein

  2. Catalyses the conversion of atmospheric nitrogen to ammonia

  3. Both

  4. None
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Nitrogenase is a molybdenum-iron (Mo-Fe) protein that catalyzes the reduction of atmospheric nitrogen to ammonia.