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

Methyl-accepting chemotaxis proteins of bacteria ________.

  1. help to guide the bacterium since they are directly connected to the flagellar motor

  2. can only sense conditions that are favorable for bacterial growth

  3. tell the bacterium which way to go

  4. integrate multiple signals through a two component phospho-relay system
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Integrate multiple signals through a two component phospho-relay system. The methyl-accepting chemotaxis proteins are present on the outer surface of the bacteria. They are chemical sensors that help the bacteria to sense components present in its surroundings.

Multiple choice

Most of the Legionellas are pathogenic to amoeba. Which species of legionella was isolated from the biopurification systems of wood processing plants in 2015 that has no significant negative effect on growth or replication of the amoeba?

  1. Legionella pneumophila

  2. Legionella norrlandica

  3. Lactobacillus moravica

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

Legionella norrlandica isolated in 2015 from the biopurification systems of wood processing plants that has no significant negative effect on the growth or replication of the amoeba.

Multiple choice

Following bacteria were discovered in 2016. Match them against the source from which they were isolated ||| |---|---| |Bacterium|Source| |1. Streptomyces alfalfae|a. Peat swamp forest| |2. Streptomyces actinomycinicus|b. Wolfram mine| |3. Psychroflexus planctonicus|c. Rhizophere soil| |4. Massilia putida|d. Lake Xiaochaidan|
  1. 1. Streptomyces alfalfae c. Rhizosphere soil
    2. Streptomyces actinomycinicus b. Wolfram mine
    3. Psychroflexus planctonicus a. Peat swamp forest
    4. Massilia putida d. Lake Xiaochaidan
  2. 1. Streptomyces alfalfae b. Wolfram mine
    2. Streptomyces actinomycinicus d. Lake Xiaochaidan
    3. Psychroflexus planctonicus c. Rhizosphere soil
    4. Massilia putida a. Peat swamp forest
  3. 1. Streptomyces alfalfae c. Rhizophere soil
    2. Streptomyces actinomycinicus a. Peat swamp forest
    3. Psychroflexus planctonicus d. Lake Xiaochaidan
    4. Massilia putida b. Wolfram mine
  4. 1. Streptomyces alfalfae d. Lake Xiachaidan
    2. Streptomyces actinomycinicus c. Rhizosphere soil
    3. Psychroflexus planctonicus a. Peat swamp forest
    4. Massilia putida b. Wolfram mine
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This is the correct match Streptomyces alfalfae has been isolated from rhizosphere soil from an alfalfa field in Jingyang in China, Streptomyces actinomycinicus has been isolated from soil from a peat swamp forest in the Rayong Province in Thailand. Psychroflexus planctonicus has been isolated from the Lake Xiaochaidan in Qaidam Basin in the Qinghai Province in China. Massilia putida has been isolated from a wolfram mine in Dayu County in the Jiangxi Province in China.

Multiple choice

Enterobacter cloacae is associated with normal gut flora of humans. What does it cause in liliac plants?

  1. Bacterial rot

  2. Bacterial wet wood

  3. Bulb decay

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

Enterobacter bulb decay is a recently described storage disease of onion (Allium cepa), member of liliaceae family that is caused by Enterobacter cloacae. The disease was reported in 2011. In this disease, the exterior of the bulb remains asymptomatic while the inner scales show a brown to black discoloration and decay.

Multiple choice

Rhizobium lives in the root nodules of the leguminous plants and fixes atmospheric nitrogen in their roots and in turn, derives its nutrition from the plants. What is the relation between rhizobium and leguminous plants called?

  1. Symbiotic

  2. Parasitic

  3. Heterotrophic

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

Rhizobium and leguminous plants share a mutual relation with each other, which includes benefiting each other and getting benefited from each other.