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100 questions in this collection · Page 6 of 10
Question 51 of 100
📘 CLASS XI
Mineral Nutrition
Analyze the following statements about hydroponic plant production:
I. The plants are grown in a tube or trough placed on a slight incline to facilitate continuous flow of the nutrient solution. II. A pump continuously circulates the nutrient solution from a reservoir to the elevated end of the tube. III. Gravity is used to return the nutrient solution back to the reservoir. IV. The roots of the plants must be kept in a completely stagnant, non-aerated solution to prevent root damage.
Explanation: Statements I, II, and III are correct. Hydroponic systems use an inclined channel, a pump for circulation, and gravity for return flow. Statement IV is incorrect because nutrient solutions must be adequately aerated for optimum root growth.
Question 52 of 100
📘 CLASS XI
Mineral Nutrition
Regarding the quantitative requirements and categorization of essential mineral nutrients, consider the following statements:
I. Nitrogen, phosphorus, and sulfur are categorized as macronutrients because they are present in plant tissues in excess of 10 mmole Kg-1 of dry matter. II. Iron and manganese are categorized as micronutrients because they are required in very small amounts (less than 10 mmole Kg-1 of dry matter). III. Gold and selenium are absolutely essential elements because they are found in some plants and can be detected at low concentrations.
Explanation: Statements I and II are correct. Macronutrients occur in amounts greater than 10 mmole Kg-1 dry matter, whereas micronutrients are required in smaller quantities. Statement III is incorrect because gold and selenium are not among the 17 essential plant nutrients.
Question 53 of 100
📘 CLASS XI
Mineral Nutrition
The function of essential elements can be grouped into broad physiological categories. Analyze the statements below:
I. Carbon, hydrogen, oxygen, and nitrogen function as structural elements of cells because they are key components of biomolecules. II. Magnesium acts as an activator for both RuBisCO and PEPcase, which are critical enzymes in photosynthetic carbon fixation. III. Zinc (Zn2+) acts as an activator of alcohol dehydrogenase during metabolic processes. IV. Potassium is involved in altering the osmotic potential of cells, which is directly linked to the opening and closing of stomata.
Explanation: All four statements are correct. Carbon, hydrogen, oxygen, and nitrogen are structural components of biomolecules. Magnesium activates RuBisCO and PEPcase, zinc activates alcohol dehydrogenase, and potassium regulates osmotic potential and stomatal movement.
Question 54 of 100
📘 CLASS XI
Mineral Nutrition
Consider the following statements regarding nitrogen and phosphorus uptake in plants:
I. Nitrogen is absorbed mainly as NO3-, though some is taken up as NO2- or NH4+. II. Meristematic tissues and metabolically active cells require nitrogen in particularly high amounts. III. Phosphorus is absorbed by plants from the soil in the form of elemental phosphorus. IV. Phosphorus is an essential constituent of cell membranes, certain proteins, all nucleic acids, and nucleotides.
Explanation: Statements I, II, and IV are correct. Nitrogen is absorbed mainly as NO3-, though some is taken up as NO2- or NH4+. Nitrogen is required in high amounts by meristematic and metabolically active tissues. Phosphorus is an essential constituent of cell membranes, nucleic acids, nucleotides, and certain proteins. Statement III is incorrect because phosphorus is absorbed as phosphate ions (H2PO4- and HPO42-), not elemental phosphorus.
Question 55 of 100
📘 CLASS XI
Mineral Nutrition
Read the following statements about the role of Potassium (K+):
I. Potassium is required in abundant quantities in meristematic tissues, buds, leaves, and root tips. II. It helps maintain an anion-cation balance in cells. III. It is involved in protein synthesis and maintaining cell turgidity. IV. It acts as a structural component of the middle lamella during cell wall synthesis.
Explanation: Statements I, II, and III are correct. Potassium is abundant in actively growing tissues, maintains anion-cation balance, and is involved in protein synthesis and cell turgidity. Statement IV is incorrect because calcium, in the form of calcium pectate, is the structural component of the middle lamella.
Question 56 of 100
📘 CLASS XI
Mineral Nutrition
Identify the correct statements regarding the role of Calcium (Ca2+) in plants:
I. Calcium is required by meristematic and differentiating tissues. II. During cell division, it is used in the synthesis of cell walls, particularly as calcium pectate in the middle lamella. III. It is needed during the formation of the mitotic spindle. IV. It is highly mobile and easily translocated from older senescing leaves to younger developing tissues.
Explanation: Statements I, II, and III are correct. Calcium is required in meristematic tissues, forms calcium pectate in the middle lamella, and is essential during mitotic spindle formation. Statement IV is incorrect because calcium is relatively immobile and therefore accumulates in older leaves.
Question 57 of 100
📘 CLASS XI
Mineral Nutrition
Consider the following statements regarding the roles of magnesium and sulphur:
I. Magnesium is a constituent of the ring structure of chlorophyll and helps maintain ribosome structure. II. Magnesium activates enzymes of respiration and photosynthesis, and is involved in the synthesis of DNA and RNA. III. Sulphur is present in all twenty standard amino acids. IV. Sulphur is the main constituent of coenzymes, ferredoxin, and vitamins like thiamine, biotin, and Coenzyme A.
Explanation: Statements I, II, and IV are correct. Magnesium forms the core of chlorophyll, stabilizes ribosomes, activates many enzymes, and participates in nucleic acid synthesis. Sulphur is present in ferredoxin, coenzymes, thiamine, biotin, and Coenzyme A. Statement III is incorrect because sulphur occurs only in cysteine and methionine.
Question 58 of 100
📘 CLASS XI
Mineral Nutrition
Analyze the following statements regarding Iron (Fe3+):
I. Iron is obtained by plants in the form of ferric (Fe3+) ions. II. It is required in smaller amounts compared to all other micronutrients. III. It is an important constituent of electron transfer proteins like ferredoxin and cytochromes. IV. It is reversibly oxidized from Fe2+ to Fe3+ during electron transfer, activates catalase, and is essential for chlorophyll formation.
Explanation: Statements I, III, and IV are correct. Iron is absorbed as ferric ions, forms part of cytochromes and ferredoxin, undergoes reversible Fe2+/Fe3+ oxidation during electron transport, activates catalase, and is essential for chlorophyll synthesis. Statement II is incorrect because iron is required in comparatively larger amounts than other micronutrients.
Question 59 of 100
📘 CLASS XI
Mineral Nutrition
With respect to Manganese (Mn2+), which of the following statements are correct?
I. It is absorbed in the form of manganous ions (Mn2+). II. It activates enzymes involved in photosynthesis, respiration, and nitrogen metabolism. III. Its best-defined function is the photolysis of water to liberate oxygen during photosynthesis. IV. It is a macronutrient required in concentrations exceeding 10 mmole Kg-1 of dry matter.
Explanation: Statements I, II, and III are correct. Manganese is absorbed as Mn2+, activates enzymes involved in photosynthesis, respiration, and nitrogen metabolism, and participates in photolysis of water during photosynthesis. Statement IV is incorrect because manganese is an essential micronutrient, not a macronutrient.
Question 60 of 100
📘 CLASS XI
Mineral Nutrition
Consider the roles of zinc and copper in plant physiology:
I. Plants obtain zinc as Zn2+ ions, which activate various enzymes, especially carboxylases. II. Zinc is actively involved in the synthesis of auxins. III. Copper is absorbed as cupric ions (Cu2+) and is essential for overall metabolism. IV. Copper, like iron, is associated with redox enzymes and is reversibly oxidized from Cu2+ to Cu3+.
Explanation: Statements I, II, and III are correct. Zinc activates carboxylases and is involved in auxin synthesis. Copper is absorbed as Cu2+ and plays an essential role in metabolism. Statement IV is incorrect because copper is reversibly oxidized between Cu+ and Cu2+, not Cu3+.