31 Years NEET Previous Year Questions: Mineral Nutrition - 1 (Old NCERT) - NEET MCQ

• Ammonia is first oxidised to nitrite by the bacteria Nitrosomonas and/or Nitrococcus.
• The nitrite is further oxidised to nitrate with the help of the bacterium Nitrobacter.
• Denitrification is carried by bacteria Pseudomonas and Thiobacillus.
• Both Rhizobium and Frankia are free-living in soil, but as symbionts, can fix atmospheric nitrogen.

Nitrogenase enzyme are responsible for the reduction of N₂ to ammonia the product of reaction catalized by nitrogenase in root nodule of leguminous plants are ammonia and hydrogen

Denitrification is the process opposite to nitrogen fixation in which nitrates (NO^-₃) get converted into N₂ gas by bacteria Pseudomonas denitrificans and Thiobacillus denitrificans.

In the process of denitrification, nitrates are reduced to gaseous compounds of nitrogen. Common bacteria causing denitrification of soil are Thiobacillus denitrificans, Pseudomous denitrificans, etc.

Potassium helps in the maintenance of cell turgidity and opening and closing of stomata.

From the given options, Option b has a better answer with macronutrients - Nitrogen, potassium and Phosphorus.
All other options have only micronutrients and thus 'b' turns the correct answer.
The primary macronutrients: nitrogen (N), phosphorus (P), potassium (K)
The three secondary macronutrients: calcium (Ca), sulfur (S), magnesium (Mg) the micronutrients/trace minerals: boron (B), chlorine (Cl), manganese (Mn), iron (Fe), zinc (Zn), copper (Cu), molybdenum (Mo), nickel (Ni).
In relatively large amounts, the soil supplies nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur; these are often called the macronutrients. In relatively small amounts, the soil supplies iron, manganese, boron, molybdenum, copper, zinc, chlorine, and cobalt, the so-called micronutrients. Nutrients must be available not only in sufficient amounts but also in appropriate ratios. So, the correct answer is option b.

Phosphorus, potassium, sulphur and calcium play an important role in plants growth. These minerals are required in large amount.
Phosphorus is required for all phosphorylation reactions and constitution of cell membrane, nucleic acids and some proteins.
Potassium is related to protein synthesis, closing and opening of stomata and activation of enzyme. 
Calcium regulates metabolic activities, function of cell membrane and stabilizes the structure of chromosomes.
Sulphur is the main constituent of the amino acids, cystine and methionine, coenzymes and vitamins.

The parts of the plants that show the deficiency symptoms also depend on the mobility of the element in the plant. For elements that are actively mobilised within the plants and exported to young developing tissues, the deficiency symptoms tend to appear first in the older tissues. 

For example, nitrogen, potassium and magnesium are visible first in the senescent leaves.

Biotin, also known as vitamin H, is a water-soluble B-vitamin. It is a coenzyme for carboxylase enzymes, involved in the synthesis of fatty acids, isoleucine, valine and in gluconeogenesis. Sulphur is a constituent of biotin. 

In the global nitrogen cycle, bacterial denitrification is recognised as important process that converts fixed nitrogen to atmospheric nitrogen gas, N₂. In marine nitrogen cycle, anaerobic oxidation of ammonium coupled to nitrate reduction, contributes substantially to N₂–production in marine sediments.

Ammonia is first stable compound produce in fixation of atmospheric nitrogen in leguminous plant. A molecule of nitrogen is change into two molecules of ammonia. It requires 16 ATP, a source of electron donor ferredoxin, hydrogen donor NADPH or FMNH₂ and dinitrogenase enzyme.

Nitrogenases are enzymes used by some organisms to fix atmospheric nitrogen gas. It is the only known family of enzymes that accomplish this process. Nitrogenase requires high input of energy & anaerobic condition.

Symbiotic nitrogen-fixing bacteria and Cyanobacteria are found in association to plant. The most common symbiotic bacteria is Rhizobium.
In dicot stem, the cambium present between xylem and phloem in vascular bundles is called fascicular or intrafascicular cambium. Besides this some cells of medullary rays also become meristematic and called interfascicular cambium.

Carboxypeptidase is an exopeptidase enzyme secreted by the pancreas that acts only on the peptide linkage of a terminal amino acid containing a free carboxyl group. Zinc is a cofactor for carboxypeptidase. In digestion carboxypeptidase, requires zinc for its protein degrading action.

Active transport needs energy for the transport of molecules in the cells. Translocation occurs through the plasmodesmata. Bakanae disease affect the rice plant. 

Correct option (c) Potassium - Readily immobilisation

Explanation : Active transport of nutrients require ATP Symplast includes translocation through plasmodesmata. Bakane disease of rice was found by Hori (1918) to be caused due to Gibberella fujikuroi. None of the options is correct Option (c) may be correct if statement be read as "Potassium readily moibilisation" instead of "potassium readily immobilisation.

The best defined function of manganese is in the splitting of water to liberate oxygen during photosynthesis. It is absorbed in the form of manganous ions (Mn2+). It activates many enzymes involved in photosynthesis, respiration and nitrogen metabolism.

Photolysis is catalysed by the proteinbound inorganic complex containing manganese ions (oxygen evolving complex) of photosystem II.

Cadmium is not an essential element for 
plants. Phosphorus is macronutrient and iron and manganese are micronutrients for plants.

Leghaemoglobin is the haemoglobin like red pigments found in root nodules of legumes and reported to function as an oxygen-carrying pigment in symbiotic nitrogen fixation.

The nitrifying bacteria bring about transformations of ammonia to nitrite and of nitrite to nitrate.

Calcium is not remobilized from the leaves to the fruits, like potassium, phosphorus and sulphur. It occurs abundantly in a non-exchangeable form such as anorthite (CaAl₂Si₂O₈).

A prokaryotic autotrophic nitrogen fixing symbiont is found in Cycas.

Rhodospirillum is a free-living, anaerobic nitrogen fixer bacteria. It can synthesize its food in presence of light under anaerobic condition.
Beijernickia and Azotobacter are free living aerobic nitrogen fixing bacteria. Rhizobium is a symbiotic nitrogen fixing bacteria.

Magnesium is a macronutrient. Micronutrients are essential elements that are required by plants in small amount. They include Fe, Cu, B, Mo, Mn, Cl, and Ni. Macronutrients, on the other hand, are those essential elements that are required by plants in larger amount. The examples include C, H, O, N, S, P, K, Ca and Mg.

Molybdenum is a micronutrient that plays an important role in nitrogen fixation. It is a part of nitrate reductase enzyme that helps in nitrogen fixation.

Frankia is symbiotic nitrogen fixer in root nodules of several non-legume plants like Casurina and Alnus.

Alcohol and nitrogenase pair is wrongly matched. Ethanol produces alcohol.

Manganese is essential for many plant functions. Some of them are:

• The assimilation of carbon dioxide in photosynthesis.
• It is involved in the Hill Reaction where water is split during photosynthesis.  
• It aids in the synthesis of chlorophyll and in nitrate assimilation.  
• Manganese activates fat forming enzymes.
• It functions in the formation of riboflavin, ascorbic acid, and carotene.  
• It functions in electron transport during photosynthesis.

Nitrogen fixation in root nodules of Alnus is brought about by Frankia. Frankia is a symbiotic nitrogen fixing bacteria in root nodules of several nonlegune plants like Casuarina (Australian Pine), Myrica and Alnus (Alder). 

Essential micro elements are Fe, Mn, Zn, B, Cu, Mo and essential macronutrionts are C,H, N, P, S, Ca, K, Mg.

Phosphorus: Phosphorus is absorbed by the plants from soil in the form of phosphate ions (either as H PO 2 4 − or HPO4 2− ). Phosphorus is a constituent of cell membranes, certain proteins, all nucleic acids and nucleotides, and is required for all phosphorylation reactions.