Consider the following statements
1. Nitrification is a process in which nitrates are converted to nitrogen.
2. Denitrification is a process in which nitrogen is converted into nitrates.
3. Nucleic acids (DNA and RNA) contain nitrogen.
4. During atmospheric lightening, nitrogen in the air gets converted into oxides of nitrogen.
5. Nitrogen fixing bacteria are present in root legumes.
Choose the correct statement(s):
Options
A1, 2, 3 and v
B1, 3 and v
C3, 4.and v
D1, 2 and 4
Show AnswerHide Answer
Correct Answer
C3, 4.and v
Model Answer
Nitrogen Fixation
The chemical process known as nitrogen fixation, or biological nitrogen fixation, converts molecular nitrogen (N2), which has a strong triple covalent bond, into ammonia (NH3) or related nitrogenous compounds, typically in soil or aquatic systems but also in industry.
Molecular dinitrogen, the nitrogen in air, is a relatively nonreactive molecule that is metabolically ineffective for most microorganisms except a few.
Nitrogen-fixing bacteria are found in small nodules on the roots of legumes. Examples of a legume: alfalfa, pea, bean, clovers. Hence statement 5 is correct.
Nitrification: Nitrifying bacteria go through a natural process called nitrification. It is a crucial step in the soil's nitrogen cycle in which Ammonia is transformed into nitrites (NO2 -) and nitrates (NO3) during this aerobic process. Hence statement 1 is incorrect.
Denitrification: Denitrification is the process by which nitrate (NO3-) is converted into gaseous nitrogen (N) and the nitrogen compound is released back into the atmosphere. In the absence of oxygen, the soil's Thiobacillus species and Pseudomonas bacteria carry out the denitrification process. Hence, statement 2 is incorrect.
Nucleic acid
Nucleic acids are biopolymers and macromolecules that are necessary for all known forms of life.
Nucleotides are the monomers that make up nucleic acids. They are made up of three parts: a sugar with five carbons, a phosphate group, and a base with nitrogen. Hence statement 3 is correct.
Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are the two main types of nucleic acids.
The polymer is RNA if the sugar is ribose; The polymer is DNA if the sugar is the ribose derivative deoxyribose.
A nitrogen cycle diagram showing nitrogen fixation, ammonification, nitrification, assimilation and denitrification between air, soil, plants and bacteria.
