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100 questions in this collection · Page 9 of 10
Question 81 of 100
📘 CLASS XI
Mineral Nutrition
Consider the following statements regarding the role of magnesium in plants:
I. It is absorbed by plants as divalent Mg2+. II. It activates enzymes of respiration and photosynthesis. III. It is involved in the synthesis of DNA and RNA. IV. It is a structural constituent of the plant cell wall middle lamella.
Explanation: Statements I, II, and III are correct. Magnesium is absorbed as Mg2+, activates respiratory and photosynthetic enzymes, and participates in nucleic acid synthesis. Statement IV is incorrect because calcium forms the middle lamella as calcium pectate.
Question 82 of 100
📘 CLASS XI
Mineral Nutrition
Read the following statements about sulphur:
I. Plants obtain sulphur as sulphate (SO42-) ions. II. Sulphur is present in the amino acids cysteine and methionine. III. It is a main constituent of ferredoxin, thiamine, biotin, and Coenzyme A. IV. Sulphur is a highly mobile element whose deficiency symptoms appear first in older leaves.
Explanation: Statements I, II, and III are correct. Sulphur is absorbed as sulphate, forms part of cysteine and methionine, and is present in ferredoxin, thiamine, biotin, and Coenzyme A. Statement IV is incorrect because sulphur is relatively immobile and its deficiency symptoms first appear in younger tissues.
Question 83 of 100
📘 CLASS XI
Mineral Nutrition
Which of the following statements about iron are correct?
I. Iron is absorbed in the form of ferric (Fe3+) ions. II. It is required in larger amounts in comparison to other micronutrients. III. It is an important constituent of proteins involved in the transfer of electrons like ferredoxin and cytochromes. IV. It is reversibly oxidized from Fe2+ to Fe3+ during electron transfer.
Explanation: All statements I, II, III, and IV are correct. Iron is a unique micronutrient required in larger quantities than other micronutrients, is absorbed as ferric ions, serves as a constituent of electron transfer proteins such as ferredoxin and cytochromes, and undergoes reversible oxidation between Fe2+ and Fe3+ during electron transfer.
Question 84 of 100
📘 CLASS XI
Mineral Nutrition
Analyze the following statements regarding the role of manganese:
I. Manganese is absorbed as manganous (Mn2+) ions. II. Its best-defined function is the photolysis of water to liberate oxygen during photosynthesis. III. It activates enzymes of photosynthesis, respiration, and nitrogen metabolism. IV. Manganese is a structural constituent of the chlorophyll ring structure.
Explanation: Statements I, II, and III are correct. Manganese is absorbed as Mn2+, activates several enzymes involved in photosynthesis, respiration, and nitrogen metabolism, and plays a key role in photolysis of water. Statement IV is incorrect because magnesium, not manganese, forms the central atom of the chlorophyll molecule.
Question 85 of 100
📘 CLASS XI
Mineral Nutrition
Consider the following statements regarding zinc:
I. Plants obtain zinc as Zn2+ ions. II. It activates various enzymes, especially carboxylases. III. It is needed in the synthesis of auxin. IV. Zinc deficiency leads strictly to the delay in flowering rather than chlorosis.
Explanation: Statements I, II, and III are correct. Zinc is absorbed as Zn2+, activates carboxylases, and is essential for auxin synthesis. Statement IV is incorrect because zinc deficiency commonly causes chlorosis rather than delayed flowering.
Question 86 of 100
📘 CLASS XI
Mineral Nutrition
Read the following statements about copper in plants:
I. It is absorbed as cupric (Cu2+) ions. II. It is essential for the overall metabolism in plants. III. Like iron, it is associated with certain enzymes involved in redox reactions. IV. It is reversibly oxidized from Cu+ to Cu2+.
Explanation: All statements I, II, III, and IV are correct. Copper is absorbed as Cu2+, is essential for metabolism, participates in redox enzymes, and undergoes reversible oxidation between Cu+ and Cu2+.
Question 87 of 100
📘 CLASS XI
Mineral Nutrition
Analyze the following statements regarding the role of boron in plants:
I. Boron is absorbed as BO33- or B4O72-. II. It is required for membrane functioning and pollen germination. III. It is required for the uptake and utilization of calcium (Ca2+). IV. It is required for nitrogenase enzyme activation.
Explanation: Statements I, II, and III are correct. Boron is involved in calcium utilization, membrane functioning, pollen germination, cell elongation, and carbohydrate translocation. Statement IV is incorrect because molybdenum, not boron, is the cofactor required for nitrogenase activity.
Question 88 of 100
📘 CLASS XI
Mineral Nutrition
Consider the following statements regarding molybdenum:
I. Plants obtain it as molybdate (MoO22+) ions. II. It is a component of several enzymes, including nitrogenase and nitrate reductase. III. It is a macronutrient required in large quantities. IV. Its deficiency can lead to a delay in flowering.
Explanation: Statements I, II, and IV are correct. Molybdenum is absorbed as molybdate ions and functions as a cofactor of nitrogenase and nitrate reductase. Its deficiency may delay flowering. Statement III is incorrect because molybdenum is a micronutrient.
Question 89 of 100
📘 CLASS XI
Mineral Nutrition
Regarding the role and classification of chlorine, analyze the statements:
I. It is absorbed as chloride (Cl-) ion. II. Along with Na+ and K+, it helps in determining solute concentration and anion-cation balance in cells. III. It is essential for the water-splitting reaction in photosynthesis. IV. It is an immobile macronutrient.
Explanation: Statements I, II, and III are correct. Chlorine is absorbed as chloride ions, helps maintain osmotic and ionic balance, and is essential for photolysis of water during photosynthesis. Statement IV is incorrect because chlorine is an essential micronutrient, not a macronutrient.
Question 90 of 100
📘 CLASS XI
Mineral Nutrition
Identify the correct statements regarding the mobility of plant nutrients:
I. For elements that are actively mobilized, deficiency symptoms appear first in senescent organs. II. Nitrogen, potassium, and magnesium are highly mobile elements. III. Immobile elements (like calcium and sulphur) show deficiency symptoms first in younger tissues. IV. Calcium is readily mobilized from older leaves to growing tips when deficiency occurs.
Explanation: Statements I, II, and III are correct. Mobile elements show deficiency symptoms first in older (senescent) leaves because they are translocated to young tissues. Immobile elements such as calcium and sulphur show deficiency symptoms first in younger tissues. Statement IV is incorrect because calcium is an immobile structural element and cannot be readily mobilized from older leaves.