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Q16 (CDS-I/2006) Environment & Ecology › Ecology & Ecosystem Basics › Biogeochemical cycles Answer Verified

In nature, how is nitrogen of the atmosphere made available for the plant growth ?

Result
Your answer: —  Â·  Correct: D
Explanation

Atmospheric nitrogen (N2) is highly inert due to its triple covalent bond and is inaccessible to most organisms directly [t1, t2]. In nature, it is made available for plant growth primarily through biological nitrogen fixation (BNF), a process carried out by specialized prokaryotes known as bacteria [t1, t4]. These include symbiotic bacteria like Rhizobium, which form nodules on the roots of leguminous plants, and free-living bacteria such as Azotobacter and Clostridium [c1, c2, t3]. These bacteria utilize the enzyme nitrogenase to convert atmospheric nitrogen into ammonia (NH3) or nitrates, which plants can readily assimilate for protein and nucleotide synthesis [c5, t1, t6]. While fungi and earthworms play vital roles in nutrient cycling and soil structure, they do not possess the metabolic pathways to fix atmospheric nitrogen [c3, t5]. Viruses are non-cellular entities and do not participate in nitrogen fixation [t5].

Sources

  1. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 2: Functions of an Ecosystem > s r n r u l z N ,- / & f . -. : : u ' , \ S ACADEMY * d 6 # . , r '' t u f Y l ' ' J * w { d ) / u Y . / > p. 20
  2. [2] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > The Nitrogen Cycle > p. 20
  3. [3] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 5: Geomorphic Processes > Biological Activity > p. 45
  4. [4] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 20: Earths Atmosphere > Life-giving gases > p. 280
  5. [5] https://www.nature.com/scitable/knowledge/library/biological-nitrogen-fixation-23570419/
  6. [6] https://www.khanacademy.org/science/biology/ecology/biogeochemical-cycles/a/the-nitrogen-cycle
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SIMILAR QUESTIONS

CAPF · 2025 · Q103 Relevance score: -3.08

Consider the following statements: 1. The circulation of nitrogen from the inorganic compounds in the soil to form protein in plants and animals and back again is known as the nitrogen cycle. 2. The preparation of ammonia by Haber process is an endothermic reaction. 3. Urea is synthetically made by the action of ammonia and carbon dioxide under high temperature and high pressure. Which of the statements given above is/are **not** correct?

CDS-I · 2008 · Q78 Relevance score: -3.42

Which one among the following kinds of organisms resides in the roots of pulse plants to do nitrogen fixation ?

CDS-II · 2007 · Q23 Relevance score: -3.42

Which one among the following kinds of organisms resides in the roots of pulse plants to do nitrogen fixation ?

IAS · 2010 · Q57 Relevance score: -4.71

Which feature of some species of blue green algae helps promoted them as bio-fertilizers?

CAPF · 2009 · Q123 Relevance score: -5.47

Assertion (A) : Nitrogen gas is used to provide inert atmosphere in chemical reaction. Reason (R) : Nitrogen gas has a very little chemical reactivity at ordinary temperature.