Tag: bio-geo chemical cycles in nature

Questions Related to bio-geo chemical cycles in nature

Which of the following is a symbiotic nitrogen fixer?

zoology bio-geo chemical cycles in nature nitrogen cycle biogeochemical cycles - gaseous nutrient cycles

  1. Frankia

  2. Anabaena azollae

  3. Glomus

  4. Both A and B

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Correct Option: D

Which gene cluster is responsible for nitrogen fixation in bacteria?

zoology bio-geo chemical cycles in nature nitrogen cycle biogeochemical cycles - gaseous nutrient cycles

  1. Nod, Nif, Nfx

  2. Nod, Nif, Fix

  3. Nod, Ndf, Nfx

  4. Ndx, Nif, Fix

  5. Ndx, Nif, nix

Show answer
Correct Option: B
Explanation:
Nitrogen fixation is a process by which nitrogen present in the atmosphere is converted into ammonia. It is essential to life because fixed inorganic nitrogen compounds are required for the biosynthesis of all nitrogen-containing compounds. This process is done with the help of nitrogen-fixing bacteria that have Nod, Nif and Fix gene clusters responsible for nitrogen fixation.
So the correct answer is 'Nod, Nif, Fix'.

Match the columns and choose the correct option.

I II
(a) Free-living aerobic nitrogen fixers 1. Anabaena and Nostoc
(b) Anaerobic nitrogen fixers 2. Pseudomonas and Thiobacillus
(c) Nitrogen-fixing cyanobacteria 3. Nitrosomonas and Nitrosococcus
(d) Denitrifying bacteria 4. Azotobacter and Beijerinckia
(e) Nitrifying bacteria 5. Rhodospirillum
zoology bio-geo chemical cycles in nature nitrogen cycle biogeochemical cycles - gaseous nutrient cycles

  1. a - 4, b - 5, c - 1, d - 2, e - 3 

  2. a - 5, b - 4, c - 1, d - 3, e - 2

  3. a - 4, b - 5, c - 2, d - 3, e - 1

  4. a - 4, b - 3, c - 1, d - 2, e - 5

  5. a - 4, b - 5, c - 3, d - 2, e - 1

Show answer
Correct Option: A
Explanation:
a) Free-living aerobic nitrogen fixers - Azotobacter and Beijernikia
b) Anaerobic nitrogen fixers - Rhodospirillum
c) Nitrogen-fixing cyanobacteria - Anabaena and Nostoc
d) Denitrifying bacteria - Pseudomonas and Thiobacillus
e) Nitrifying bacteria - Nitrosomonas and Nitosococcus
So the correct answer is 'a-4, b-5, c-1, d-2, e-3'

Which one helps in absorption of phosphorus from soil by plants?

zoology bio-geo chemical cycles in nature nitrogen cycle biogeochemical cycles - gaseous nutrient cycles

  1. Frankia

  2. Anabaena

  3. Glomus

  4. Rhizobium

Show answer
Correct Option: C
Explanation:

Frankia, Anabaena and Rhizobium are nitrogen-fixing bacteria that absorbs nitrogen from the soil. Glomus is a myccorhizal fungi. The fungal symbiont in these associations absorbs phosphorus from soil and passes it to the plant.
Thus, the correct answer is option (C). 

Which of the following is the function of nitrifying bacteria?

zoology bio-geo chemical cycles in nature nitrogen cycle biogeochemical cycles - gaseous nutrient cycles

  1. Oxidise $NH _3$ to $NO^- _3$

  2. Oxidise $NH _3$ to $NH^+ _4$

  3. Convert $NO^- _3$ to $NH _3$

  4. Convert $NO^- _3$ to $N _2$

Show answer
Correct Option: A
Explanation:
Nitrifying bacteria is an aerobic bacteria that use inorganic chemicals as an energy source. They are important in the nitrogen cycle as converters of soil ammonia to nitrates by the process of oxidation.
So the correct answer is 'oxidise NH$ _3$ to NO$ _3$-'.