CBSE Class 11 Biology Mineral Nutrition Assignments

Important Questions for NCERT Class 11 Biology Mineral Nutrition

Ques. During biological nitrogen fixation, inactivation of nitrogenase by oxygen poisoning is prevented by
(a) carotene (b) cytochrome
(c) leghaemoglobin (d) xanthophyll.

Answer: C

Ques. The first stable product of fixation of atmospheric nitrogen in leguminous plants is
(a) NO3
(b) glutamate
(c) NO2
(d) ammonia. 

Answer: D

Ques. Which two distinct microbial processes are responsible for the release of fixed nitrogen as dinitrogen gas (N2) to the atmosphere?
(a) Aerobic nitrate oxidation and nitrite reduction
(b) Decomposition of organic nitrogen and conversion of dinitrogen to ammonium compounds
(c) Enteric fermentation in cattle and nitrogen fixation by Rhizobium in root nodules of legumes
(d) Anaerobic ammonium oxidation and denitrification 

Answer: D

Ques. Which one of the following is wrong statement?
(a) Anabaena and Nostoc are capable of fixing nitrogen in free-living state also.
(b) Root nodule forming nitrogen fixers live as aerobes under free-living conditions.
(c) Phosphorus is a constituent of cell membranes, certain nucleic acids and all proteins.
(d) Nitrosomonas and Nitrobacter are chemoautotrophs.

Answer: C

Ques. For its action, nitrogenase requires
(a) high input of energy
(b) light
(c) Mn2+
(d) super oxygen radicals. 

Answer: A

Ques. Nitrifying bacteria
(a) oxidise ammonia to nitrates
(b) convert free nitrogen to nitrogen compounds
(c) convert proteins into ammonia
(d) reduce nitrates to free nitrogen. 

Answer: A

Ques. The function of leghaemoglobin in the root nodules of legumes is
(a) inhibition of nitrogenase activity
(b) oxygen removal
(c) nodule differentiation
(d) expression of nif gene.

Answer: B

Ques. Leguminous plants are able to fix atmospheric nitrogen through the process of symbiotic nitrogen fixation. Which one of the following statements is not correct during this process of nitrogen fixation?
(a) Leghaemoglobin scavenges oxygen and is pinkish in colour.
(b) Nodules act as sites for nitrogen fixation.
(c) The enzyme nitrogenase catalyses the conversion of atmospheric N2 to NH3.
(d) Nitrogenase is insensitive to oxygen.

Answer: D

Ques. One of the free-living, anaerobic nitrogen-fixer is
(a) Beijerinckia (b) Rhodospirillum
(c) Rhizobium (d) Azotobacter. 

Answer: B

Ques. Which of the following is a flowering plant with nodules containing filamentous nitrogen-fixing microorganism?
(a) Crotalaria juncea
(b) Cycas revoluta
(c) Cicer arietinum
(d) Casuarina equisetifolia 

Answer: D

Ques. If by radiation all nitrogenase enzyme are inactivated, then there will be no
(a) fixation of nitrogen in legumes
(b) fixation of atmospheric nitrogen
(c) conversion from nitrate to nitrite in legumes
(d) conversion from ammonium to nitrate in soil.

Answer: A

Ques. Roots of which plant contains a red pigment which have affinity for oxygen?
(a) Carrot (b) Soybean
(c) Mustard (d) Radish 

Answer: B

Ques. What is true for cyanobacteria?
(a) Oxygenic with nitrogenase
(b) Oxygenic without nitrogenase
(c) Non oxygenic with nitrogenase
(d) Non oxygenic without nitrogenase 

Answer: A

Ques. Which aquatic fern performs nitrogen fixation?
(a) Azolla (b) Nostoc
(c) Salvia (d) Salvinia 

Answer: A

Ques. Enzyme first used for nitrogen fixation
(a) nitrogenase (b) nitroreductase
(c) transferase (d) transaminase. 

Answer: A

Ques. Which of the following is free-living aerobic nonphotosynthetic nitrogen-fixing bacterium?
(a) Nostoc (b) Azospirillum
(c) Rhizobium (d) Azotobacter 

Answer: D

Ques. A non-photosynthetic aerobic nitrogen fixing soil bacterium is
(a) Rhizobium (b) Clostridium
(c) Azotobacter (d) Klebsiella.

Answer: C