Answers and bookmarks are saved in this browser, across visits. They do not sync to your account.
100 questions in this collection · Page 10 of 10
Question 91 of 100
📘 CLASS XI
Mineral Nutrition
Analyze the following statements regarding chlorosis:
I. Chlorosis is the loss of chlorophyll leading to yellowing of leaves. II. It is caused by the deficiency of elements N, K, Mg, S, Fe, Mn, Zn, and Mo. III. It occurs because these minerals are directly or indirectly involved in chlorophyll synthesis or maintenance. IV. Chlorosis only occurs in younger leaves, never in older leaves.
Explanation: Statements I, II, and III are correct. Chlorosis is the yellowing of leaves due to loss of chlorophyll and results from deficiencies of N, K, Mg, S, Fe, Mn, Zn, and Mo. Statement IV is incorrect because chlorosis may occur in either older or younger leaves depending on the mobility of the deficient element.
Question 92 of 100
📘 CLASS XI
Mineral Nutrition
Consider the following statements regarding necrosis:
I. Necrosis is the localized death of tissue, particularly leaf tissue. II. It is caused by the deficiency of Ca, Mg, Cu, and K. III. Necrosis is caused by the toxicity of molybdenum.
Explanation: Statements I and II are correct. Necrosis refers to the localized death of plant tissue and commonly results from deficiencies of calcium, magnesium, copper, and potassium. Statement III is incorrect because molybdenum toxicity is not the cause of necrosis.
Question 93 of 100
📘 CLASS XI
Mineral Nutrition
Analyze the statements regarding cell division inhibition and delayed flowering:
I. Low levels of N, K, S, and Mo cause inhibition of cell division. II. Some elements like N, S, and Mo delay flowering if their concentration in the plant is low. III. Calcium deficiency always accelerates flowering.
Explanation: Statements I and II are correct. Low concentrations of N, K, S, and Mo inhibit cell division, while deficiencies of N, S, and Mo delay flowering. Statement III is incorrect because calcium deficiency causes structural defects and necrosis rather than accelerating flowering.
Question 94 of 100
📘 CLASS XI
Mineral Nutrition
Read the statements regarding the toxicity of micronutrients:
I. Any mineral ion concentration in tissues that reduces the dry weight of tissues by about 10 per cent is considered toxic. II. Toxicity levels for any element vary among different plants. III. An excess of an element may inhibit the uptake of another element. IV. Micronutrient toxicity symptoms are identical to macronutrient deficiency symptoms in all cases.
Explanation: Statements I, II, and III are correct. Toxicity is defined by about a 10% reduction in tissue dry weight, toxicity thresholds vary among plant species, and excess of one element can inhibit the uptake of another. Statement IV is incorrect because micronutrient toxicity symptoms are variable and do not always resemble macronutrient deficiency symptoms.
Question 95 of 100
📘 CLASS XI
Mineral Nutrition
Consider the following statements regarding the mechanisms of manganese toxicity:
I. Manganese toxicity is characterized by brown spots surrounded by chlorotic veins. II. Manganese competes with iron and magnesium for uptake. III. Manganese competes with magnesium for binding with enzymes. IV. Manganese inhibits calcium translocation in the shoot apex.
Explanation: All statements I, II, III, and IV are correct. Manganese toxicity causes brown spots with chlorotic veins, competes with iron and magnesium for uptake, competes with magnesium for enzyme binding, and inhibits calcium translocation to the shoot apex, thereby inducing multiple nutrient deficiencies.
Question 96 of 100
📘 CLASS XI
Mineral Nutrition
Analyze the following statements regarding the absorption mechanism of minerals:
I. The initial rapid uptake of ions into the apoplast is passive. II. The apoplast is the "free space" or outer space of cells. III. The passive movement of ions into the apoplast occurs through ion-channels (selective pores). IV. The second phase of uptake into the symplast is passive and does not require energy.
Explanation: Statements I, II, and III are correct. The first phase of mineral absorption is passive and occurs through the apoplast via selective ion channels. Statement IV is incorrect because movement into the symplast is an active process requiring metabolic energy (ATP).
Question 97 of 100
📘 CLASS XI
Mineral Nutrition
Regarding the translocation of mineral salts and the properties of soil:
I. Minerals are translocated through the xylem along with the ascending stream of water. II. Xylem sap analysis shows the presence of mineral salts. III. Soil not only supplies minerals but also harbors nitrogen-fixing bacteria, holds water, and supplies air to roots. IV. Minerals are transported through the phloem during the day and xylem during the night.
Explanation: Statements I, II, and III are correct. Mineral salts move through the xylem with the transpiration stream, xylem sap contains dissolved minerals, and soil serves as a reservoir of minerals, water, air, and beneficial microorganisms. Statement IV is incorrect because minerals are transported primarily through the xylem, not alternately through phloem and xylem.
Question 98 of 100
📘 CLASS XI
Mineral Nutrition
With respect to biological nitrogen fixation, consider the following statements:
I. The enzyme nitrogenase is a Mo-Fe protein. II. It is highly sensitive to molecular oxygen. III. The reaction is: N2 + 8e- + 8H+ + 16ATP → 2NH3 + H2 + 16ADP + 16Pi. IV. Biological nitrogen fixation is an energy-cheap process requiring only 1 ATP per NH3.
Explanation: Statements I, II, and III are correct. Nitrogenase is a molybdenum-iron (Mo-Fe) protein that is highly sensitive to oxygen and catalyzes nitrogen fixation according to the given reaction. Statement IV is incorrect because approximately 8 ATP are required for each NH3 molecule produced.
Question 99 of 100
📘 CLASS XI
Mineral Nutrition
Consider the following statements regarding the synthesis and transport of amides in plants:
I. Asparagine and glutamine are structural parts of proteins. II. They are formed from aspartic acid and glutamic acid respectively by the addition of another amino group. III. Amides contain more nitrogen than amino acids. IV. They are transported to other parts of the plant via xylem vessels.
Explanation: All statements I, II, III, and IV are correct. Asparagine and glutamine are important amides derived from aspartic acid and glutamic acid, contain a higher nitrogen content than amino acids, and are transported through xylem vessels to other parts of the plant.
Question 100 of 100
📘 CLASS XI
Mineral Nutrition
Analyze the following statements regarding nitrogen metabolism in plants like soybean:
I. Nodules of some plants, like soybean, export fixed nitrogen as ureides. II. Ureides have a particularly high nitrogen-to-carbon ratio. III. Ureides are transported via the phloem.
Explanation: Statements I and II are correct. Soybean nodules export fixed nitrogen mainly as ureides, which possess a high nitrogen-to-carbon ratio. Statement III is incorrect because ureides are transported through the xylem along with the transpiration stream rather than through the phloem.