Nitrogen Metabolism : 12th Class Biology Question Answer Lesson 10 – NIOS
INTEXT QUESTIONS 10.1
- What is the percent by volume of nitrogen gas in the atmosphere? – 78.03 percent
- Name two biomolecules that contain nitrogen in plants. – proteins and enzymes.
- Why nitrogen is a stable molecule? – Because it is triple bonded.
- What is the percentage of nitrogen in protein – 16 percent.
- What is the boiling point of nitrogen? – –195.8°C.
- Choose the correct option:
Nitrogen fixation is the conversion of :
(a) atmospheric Nitrogen ⎯⎯⎯into → Nitrates
(b) atmospheric Nitrogen ⎯⎯⎯into → Ammonia
(c) atmospheric Nitrogen ⎯⎯⎯into → Amino acids
(d) both (a) and (b)
Ans. b - Nitrogen content of biosphere remains constant because of :
(a) Nitrogen cycle
(b) Nitrogen fixation
(c) Industrial pollution
(d) Absorption of nitrogen
Ans. a - Nitrates are converted into nitrogen by microbes called ..- Denitrifying Bacteria
INTEXT QUESTIONS 10.2
- Define nitrogen fixation.
Ans. Conversion of molecular nitrogen to ammonia. - Which industrial process is utilized for converting nitrogen to ammonia?
Ans. Haber’s process - Distinguish between biological and abiological nitrogen fixation.
Ans. Biological nitrogen fixation takes place in a living cell and abiological
fixation without a living cell. - Name the enzyme that helps in nitrogen fixation in living cells.
Ans. Nitrogenase. - Which gas prevents nitrogen fixation?
Ans. Nitrogen
INTEXT QUESTIONS 10.3
- Match the following:
A B
(i) Azotobacter (a) anaerobic nitrogen fixer.
(ii) Clostridium (b) aerobic nitrogen fixer
(iii) Lichens (c) aerobic nitrogen fixing cyanobacterium
(iv) Anabaena (d) symbiotic nitrogen fixer.
Ans. (i) b (ii) a (iii) d (iv) c - Which Gymnospermous plant fixes nitrogen?
Ans. Cycas - Is there any other gas evovled during nitrogen fixation? If yes, name the gas evolved.
Ans. Yes, Hydrogen gas. - How many ATP molecules are required to reduce a single molecule of nitrogen?
Ans. 16 ATP - What is the major source of electrons for reduction of nitrogen?
Ans. Reduced coenzymes such as Ferrodoxin - Match the following:
A B
(i) Leghemoglobin (a) cyanobacterium
(ii) Anabaena (b) Legumes
(iii) Reductive process (c) nitrogen fixation
Ans. (i) b (ii) a (iii) c - Name the proteins that help in establishing symbiosis and maintain root nodule functioning in legumes.
Ans. Nodulins.
INTEXT QUESTIONS 10.4
- Which is the most reduced form of inorganic nitrogen – NH4
- Match the following:
AB
(i) Nitrate reductase (a) nitrogen fixation
(ii) Nitrite reductase b) nitrate reduction
(iii) Nitrogenase c) nitrite reduction
Ans. (i) b (ii) c (iii) a - In which part of the cell, reduction of nitrate to nitrite occurs?
Ans. Cytosol. - Which is the most oxidized form of inorganic nitrogen? – Nitrate
- In which plant organelle reduction of nitrite to ammonia is catlyzed by the enzyme nitrite reductase? – Chloroplast
INTEXT QUESTIONS 10.5
- Match the following:
A B
(i) Amino acid (a) keto acid
(ii) Glutamic acid (b) amino group and carboxyl group
(iii) α-ketoglutaric acid (c) amino acid
Ans. (i) b (ii) c (iii) a - Name two biochemical reactions for biosynthesis of amino acids in plants.
Ans. Reductive amination and transamination. - Which group of enzymes catalyzes transamination reaction?
Ans. Transaminases. - What is the source of amino group for amino acid synthesis in reductive
amination reaction?
Ans. Ammonia - Which keto acid is the source for synthesis of glutamic acid?
Ans. Alpha ketoglutaric acid.
TERMINAL EXERCISES
- Define nitrogen fixation.
- Which form of combined nitrogen may be formed during lightening storms?
- Name three biomolecules other than enzymes and proteins, which contain
nitrogen. - Name one aerobic and one anaerobic bacterium, which fixes nitrogen.
- Which amino acid is synthesized due to reductive amination of α-ketoglutaric
acid? - Differentiate between biological and abiological nitrogen fixation.
- What is required for biological nitrogen fixation?
- How does human hemoglobin differ from leghemoglobin?
- What is the function of leghemoglobin?
- What are the functional differences between nitrate reductase and nitrite
reductase? - What is the difference between nitrogen fixation and nitrogen assimilation?
Describe in brief the process of abiological nitrogen fixation. - Describe in brief various steps involved in biological nitrogen fixation.
- Enumerate various free living and symbiotic nitrogen fixing systems with suitable
examples. - What are the major differences between free living and leguminous nitrogen
fixing organisms? - Describe in brief nitrate and nitrite reduction in plants..
- Describe in brief the reductive amination reactions for synthesis of amino acids
in plants. - Describe the transamination reaction for synthesis of amino acids in plants. How
does this differ from reductive amination?
NIOS 12th class biology Q Ans
- Origin and Evolution of Life & Classification : 12th Class Biology Notes – NIOS
- The Kingdoms Monera, Protista & Fungi : 12th Class Biology Notes – NIOS
- Kingdoms Plantae & Animalia : 12th Class Biology Question Answer Lesson 3 – NIOS
- Cell Structure & Function : 12th Class Biology Question Answer Lesson 4 – NIOS
- Tissues & Others Level of Organization : 12th Class Biology Question Answer Lesson 5 – NIOS
- Root System : 12th Class Biology Question Answer Lesson 6 – NIOS
- Shoot System : 12th Class Biology Question Answer Lesson 7 – NIOS
- Absorption, Transport & Water Loss (Transpiration) in Plants : 12th Class Biology Q Ans Lesson 8 – NIOS
- Nutrition in Plants – Mineral Nutrition : 12th Class Biology Question Answer Lesson 9 – NIOS
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