101. In a hydroponic experiment, one set of plants develops weak growth and older leaves with burned margins, while another set develops weak growth and general older-leaf yellowing without marked edge scorch. Which omitted nutrients most likely correspond to these two sets in that order?
ⓐ. Potassium, then nitrogen
ⓑ. Nitrogen, then potassium
ⓒ. Phosphorus, then nitrogen
ⓓ. Potassium, then phosphorus
Correct Answer: Potassium, then nitrogen
Explanation: Burned or scorched leaf margins in older leaves are a classic sign pointing toward potassium deficiency, especially when growth is also reduced. Potassium has major roles in osmotic balance and enzyme regulation, and its deficiency often affects tissue condition at the leaf edges. General older-leaf yellowing without prominent edge burn is more typical of nitrogen deficiency because nitrogen shortage reduces chlorophyll-related and biosynthetic activity throughout the leaf. Since both nutrients are mobile, both may affect older leaves first, but the visible pattern separates them. The order therefore matches potassium first and nitrogen second. That makes this the most likely identification.
102. Which statement best describes the major role of calcium in plants?
ⓐ. It mainly functions in ATP-based energy transfer reactions
ⓑ. It mainly acts in cell wall stability, membrane integrity, and growth of meristematic regions
ⓒ. It mainly forms the central atom of chlorophyll molecules
ⓓ. It mainly serves as a constituent of sulphur-containing amino acids
Correct Answer: It mainly acts in cell wall stability, membrane integrity, and growth of meristematic regions
Explanation: Calcium is an important structural and regulatory nutrient in plants. It contributes to the stability of the cell wall and helps maintain the integrity of cell membranes. It is especially important in actively growing regions such as root tips and shoot apices, where new cells are formed and organized. Because of this, calcium is closely linked with meristematic activity and normal tissue development. Its role is different from nutrients mainly associated with chlorophyll or amino acid formation. A shortage of calcium quickly affects delicate growing tissues. That is why calcium is best described through cell wall stability, membrane integrity, and meristem growth.
103. Which deficiency symptom is most typically associated with calcium deficiency in plants?
ⓐ. Marginal scorching first appearing in older leaves
ⓑ. General chlorosis beginning in older leaves with weak vegetative growth
ⓒ. Death of growing points and poor development of young tissues
ⓓ. Dark green stunting with delayed maturity in older plants
Correct Answer: Death of growing points and poor development of young tissues
Explanation: Calcium is relatively immobile in plants, so it cannot be redistributed easily from older tissues to young developing regions. As a result, deficiency symptoms usually appear first in growing points such as root apices, shoot tips, and young leaves. These tissues may show poor development, deformation, or even death in severe deficiency. This pattern reflects calcium’s importance in cell division, membrane function, and structural stability in newly forming cells. Unlike mobile nutrient deficiencies, the older leaves are not the earliest sites of clear symptoms. The damage is concentrated in actively growing parts. Therefore, death of growing points and poor young tissue development is most typical of calcium deficiency.
104. Which statement best explains the importance of magnesium in plants?
ⓐ. It is the main nutrient responsible for cell wall cementing in middle lamella
ⓑ. It is a central component of chlorophyll and also activates many enzymes
ⓒ. It is required mainly for sulphur-rich amino acid synthesis only
ⓓ. It is involved chiefly in the formation of stomatal waxes
Correct Answer: It is a central component of chlorophyll and also activates many enzymes
Explanation: Magnesium has a very important role in plant metabolism because it forms the central atom of the chlorophyll molecule. This directly links it with photosynthesis and green coloration of leaves. In addition, magnesium also participates in enzyme activation, making it useful in several metabolic reactions. Thus, magnesium contributes both as a constituent of a vital pigment and as a regulator of biochemical processes. This dual role makes it a major nutrient for healthy plant growth. It is not primarily a cell wall nutrient or a sulphur-substitute nutrient. Hence, magnesium is best known as a chlorophyll component and enzyme activator.
105. Which symptom is most characteristic of magnesium deficiency in plants?
ⓐ. Interveinal chlorosis beginning in older leaves
ⓑ. Death of shoot apex with root tip injury first
ⓒ. Uniform chlorosis limited to the youngest leaves
ⓓ. Water-soaked lesions appearing on mature fruits only
Correct Answer: Interveinal chlorosis beginning in older leaves
Explanation: Magnesium is a mobile nutrient in plants, so when deficiency occurs, the plant can move magnesium from older leaves to younger actively growing tissues. Because of this, the older leaves show symptoms first. One of the most characteristic signs is interveinal chlorosis, in which the tissue between veins turns yellow while the veins may remain relatively greener for some time. This pattern is especially useful in distinguishing magnesium deficiency from other nutrient shortages. Since magnesium is directly related to chlorophyll and photosynthetic function, its deficiency quickly affects leaf colour. Therefore, interveinal chlorosis in older leaves is the most typical symptom.
106. What is one major role of sulphur in plant metabolism?
ⓐ. It mainly controls guard cell turgor through ionic balance
ⓑ. It mainly stabilizes root cap cells through calcium pectate formation
ⓒ. It mainly functions as the central atom of chlorophyll
ⓓ. It is a constituent of certain amino acids and proteins
Correct Answer: It is a constituent of certain amino acids and proteins
Explanation: Sulphur is essential because it forms part of certain amino acids, especially sulphur-containing ones, and through them becomes part of proteins. This makes sulphur important in growth, metabolism, and synthesis of vital cellular compounds. It is therefore a true constituent nutrient rather than only a regulator. Its role in amino acids links it with enzyme formation and general metabolic activity. Because proteins are indispensable in living cells, sulphur becomes an important macronutrient even though its requirement is lower than nitrogen or potassium. The key idea is that sulphur is built into important organic compounds. That is why its major role is as a constituent of certain amino acids and proteins.
107. Which deficiency symptom is most commonly associated with sulphur deficiency in plants?
ⓐ. Chlorosis first appearing in young leaves
ⓑ. Marginal leaf burn in older leaves only
ⓒ. Necrosis of root tip before any leaf change
ⓓ. Dark green leaves with delayed flowering
Correct Answer: Chlorosis first appearing in young leaves
Explanation: Sulphur is comparatively less mobile within the plant, so when external supply becomes low, it is not readily shifted from older tissues to newer growing leaves. As a result, the youngest leaves often show deficiency symptoms first. A common symptom is chlorosis, because sulphur is important in protein formation and normal metabolic functioning that supports chlorophyll development. This pattern resembles the logic of other immobile or less mobile nutrients, where young tissues are the earliest sites of injury. The symptom is therefore not mainly older-leaf scorching or dark green stunting. Thus, chlorosis first appearing in young leaves is most typical of sulphur deficiency.
108. Which of the following is correctly matched?
ⓐ. Calcium — central atom of chlorophyll molecule
ⓑ. Magnesium — interveinal chlorosis in older leaves when deficient
ⓒ. Sulphur — first deficiency symptom mainly in older leaves because of high mobility
ⓓ. Calcium — major constituent of sulphur-containing amino acids
Correct Answer: Magnesium — interveinal chlorosis in older leaves when deficient
Explanation: Magnesium is correctly matched here because its deficiency commonly produces interveinal chlorosis in older leaves. This happens because magnesium is mobile and can be shifted to younger tissues, leaving older leaves deficient first. Calcium is not the central atom of chlorophyll; that role belongs to magnesium. Sulphur deficiency usually appears first in younger leaves rather than older ones because sulphur is not highly mobile. Calcium also does not serve as the major constituent of sulphur-containing amino acids. Therefore, among the given pairs, only magnesium with interveinal chlorosis in older leaves is correct.
109. Which nutrient among calcium, magnesium, and sulphur is most directly associated with the chlorophyll molecule itself?
ⓐ. Sulphur
ⓑ. Calcium
ⓒ. Magnesium
ⓓ. All three equally
Correct Answer: Magnesium
Explanation: Magnesium is directly associated with the chlorophyll molecule because it occupies the central position in its structure. This makes magnesium essential for the normal green colour of leaves and for photosynthetic function. While calcium and sulphur are both important nutrients, their main roles lie elsewhere. Calcium is more strongly linked with structural stability and meristematic growth, and sulphur is linked with amino acids and proteins. Magnesium therefore stands out among these three as the nutrient directly built into chlorophyll. This explains why magnesium deficiency often causes leaf chlorosis. Hence, magnesium is the nutrient most directly associated with the chlorophyll molecule.
110. Assertion: Calcium deficiency usually becomes evident first in young growing regions of the plant. Reason: Calcium is not readily redistributed from older tissues to actively developing parts.
ⓐ. Both Assertion and Reason are true, and the Reason correctly explains the Assertion
ⓑ. Both Assertion and Reason are true, but the Reason does not explain the Assertion
ⓒ. Assertion is true, but the Reason is false
ⓓ. Assertion is false, but the Reason is true
Correct Answer: Both Assertion and Reason are true, and the Reason correctly explains the Assertion
Explanation: Calcium is a relatively immobile nutrient in the plant body, so once it is deposited in older tissues it is not easily moved to newer growing regions. Because of this, shoot apices, root tips, and young developing leaves depend heavily on a fresh external supply. When calcium becomes deficient, these rapidly growing tissues suffer first. This is why calcium deficiency is commonly associated with injury to meristematic regions rather than with early symptoms in older leaves. The assertion is therefore correct. The reason is also correct and directly explains the symptom pattern. Hence, both are true and the reason properly explains the assertion.
111. Two deficient plants show chlorosis, but the first develops it mainly between veins in older leaves, while the second develops it first in young leaves. Which pair of deficiencies is the best match?
ⓐ. First: calcium deficiency; Second: magnesium deficiency
ⓑ. First: magnesium deficiency; Second: sulphur deficiency
ⓒ. First: sulphur deficiency; Second: calcium deficiency
ⓓ. First: magnesium deficiency; Second: calcium deficiency
Correct Answer: First: magnesium deficiency; Second: sulphur deficiency
Explanation: Magnesium deficiency is classically associated with interveinal chlorosis, and because magnesium is mobile, the symptoms appear first in older leaves. Sulphur deficiency, on the other hand, tends to show chlorosis in young leaves because sulphur is not readily redistributed to newly developing tissues in the same way as magnesium. The question tests both symptom type and symptom location together. Older-leaf interveinal yellowing points strongly toward magnesium shortage. Young-leaf chlorosis without the older-leaf pattern fits sulphur deficiency much better. Therefore, the first plant matches magnesium deficiency and the second matches sulphur deficiency.
112. Which statement best corrects the idea that calcium deficiency and magnesium deficiency should affect the same leaves first because both are macronutrients?
ⓐ. Both deficiencies usually appear first in fruits rather than leaves
ⓑ. Both deficiencies begin in the same tissues, but one becomes more severe later
ⓒ. The site of first symptom appearance depends on mobility, so calcium and magnesium deficiencies differ in pattern
ⓓ. Macronutrient deficiencies never show diagnostic differences in plants
Correct Answer: The site of first symptom appearance depends on mobility, so calcium and magnesium deficiencies differ in pattern
Explanation: The classification of nutrients as macronutrients tells us the amount required, not how they move within the plant. Calcium and magnesium are both macronutrients, but their internal mobility differs greatly. Calcium is relatively immobile, so its deficiency affects young tissues and growing points first. Magnesium is mobile, so it is withdrawn from older leaves and sent to younger ones when supply becomes limited, causing older leaves to show symptoms first. This is why the visible pattern is not the same despite both being needed in fairly large amounts. Thus, mobility, not simply macronutrient status, explains the difference.
113. In a hydroponic experiment, one set of plants develops death of root tips and poor shoot apex growth, while another set develops interveinal chlorosis in older leaves. Which omitted nutrients most likely caused these two conditions in that order?
ⓐ. Calcium, then magnesium
ⓑ. Sulphur, then calcium
ⓒ. Magnesium, then sulphur
ⓓ. Calcium, then sulphur
Correct Answer: Calcium, then magnesium
Explanation: Death of root tips and poor shoot apex development are highly characteristic of calcium deficiency because calcium is essential for membrane stability, cell wall function, and meristematic growth. Since calcium is not readily moved from older tissues, growing regions are affected early when supply is inadequate. Interveinal chlorosis in older leaves is a classic sign of magnesium deficiency. Magnesium is mobile and linked with chlorophyll, so older leaves lose it first and become chlorotic between the veins. These two symptom patterns are distinct and useful in experimental diagnosis. Therefore, the omitted nutrients are most likely calcium first and magnesium second.
114. Which functional comparison among calcium, magnesium, and sulphur is most accurate?
ⓐ. Calcium is mainly linked with chlorophyll, magnesium with cell wall stability, and sulphur with stomatal movement
ⓑ. Calcium and sulphur both mainly regulate guard cells, while magnesium mainly forms proteins
ⓒ. Magnesium mainly supports only root growth, while calcium and sulphur act only in mature leaves
ⓓ. Calcium is strongly linked with structural stability, magnesium with chlorophyll and enzyme-related activity, and sulphur with amino acid constitution
Correct Answer: Calcium is strongly linked with structural stability, magnesium with chlorophyll and enzyme-related activity, and sulphur with amino acid constitution
Explanation: Each of these nutrients has a distinct major functional identity in plant physiology. Calcium is especially important in structural stability, membrane integrity, and proper development of growing tissues. Magnesium is unique because it is a constituent of chlorophyll and also helps activate many enzymes. Sulphur contributes to certain amino acids and therefore becomes part of proteins and related metabolic systems. This comparison helps distinguish the three nutrients without treating them as interchangeable. Their different physiological roles also explain why their deficiency patterns differ. Hence, the most accurate functional comparison is the one given in option D.
115. A plant shows chlorosis in young leaves, but the shoot tip remains alive and there is no clear interveinal pattern in older foliage. Which deficiency is the most likely among calcium, magnesium, and sulphur?
ⓐ. Calcium deficiency
ⓑ. Sulphur deficiency
ⓒ. Magnesium deficiency
ⓓ. None of the three because chlorosis never appears in young leaves
Correct Answer: Sulphur deficiency
Explanation: Sulphur deficiency commonly causes chlorosis in young leaves because sulphur is not readily redistributed from older tissues to newer ones. The fact that the shoot tip remains alive makes severe calcium deficiency less likely, since calcium shortage typically damages meristematic regions and growing points. The absence of a clear older-leaf interveinal pattern also argues against magnesium deficiency, which usually appears in older leaves due to magnesium mobility. This question therefore depends on separating symptom location and type carefully. Young-leaf chlorosis with living growing points fits sulphur deficiency best. That is why sulphur deficiency is the most likely answer.
116. Which observation would be least consistent with calcium deficiency?
ⓐ. Poor development of young tissues
ⓑ. Injury to growing points
ⓒ. Weakening of root tip growth
ⓓ. Interveinal chlorosis first appearing in older leaves
Correct Answer: Interveinal chlorosis first appearing in older leaves
Explanation: Calcium deficiency is mainly associated with damage to young and actively growing tissues because calcium is relatively immobile in plants. Symptoms often include injury to shoot apices, poor root tip growth, and defective development of young regions. Interveinal chlorosis in older leaves, however, is much more characteristic of magnesium deficiency. That pattern depends on magnesium mobility and its link with chlorophyll. Since calcium deficiency does not typically begin as older-leaf interveinal chlorosis, that observation is the least consistent with it. Therefore, the non-matching observation is interveinal chlorosis first appearing in older leaves.
117. Which statement best describes the major role of iron in plants?
ⓐ. It mainly acts as the central atom of chlorophyll molecules
ⓑ. It mainly functions in electron transfer and enzyme systems related to respiration and photosynthesis
ⓒ. It mainly maintains guard cell turgor during stomatal opening
ⓓ. It mainly forms sulphur-containing amino acids in proteins
Correct Answer: It mainly functions in electron transfer and enzyme systems related to respiration and photosynthesis
Explanation: Iron is an essential micronutrient that plays a major role in electron transfer reactions in plants. It is associated with cytochromes, ferredoxin, and other enzyme systems involved in respiration and photosynthesis. Although iron is necessary for chlorophyll formation, it is not itself the central atom of the chlorophyll molecule. Its importance lies in helping metabolic pathways that support energy transfer and redox activity. Because these processes are fundamental to plant growth, iron becomes indispensable even in small quantity. A deficiency quickly disturbs active metabolism in young tissues. That is why iron is best described through its role in electron transfer and related enzyme systems.
118. Which deficiency symptom is most commonly associated with iron deficiency in plants?
ⓐ. Interveinal chlorosis first appearing in young leaves
ⓑ. Marginal scorching first appearing in older leaves
ⓒ. Dark green leaves with delayed maturity
ⓓ. Death of root tips before any leaf symptom
Correct Answer: Interveinal chlorosis first appearing in young leaves
Explanation: Iron deficiency typically produces interveinal chlorosis in young leaves because iron is not readily redistributed from older tissues to new growing parts. As a result, the youngest leaves suffer first when external iron supply becomes inadequate. The veins may remain relatively greener for some time, while the tissue between them turns yellow. This symptom pattern is a classic diagnostic clue in plant nutrition. It reflects both the role of iron in chlorophyll-related metabolism and its limited mobility within the plant. The symptom is therefore different from older-leaf scorching or dark green stunting. Hence, interveinal chlorosis in young leaves is the most typical sign.
119. What is one important function of manganese in plants?
ⓐ. It mainly forms the backbone of nucleic acids
ⓑ. It mainly acts in enzyme activation and participates in photosynthetic processes
ⓒ. It mainly stabilizes the middle lamella through calcium pectate formation
ⓓ. It mainly serves as the major constituent of proteins and chlorophyll pigments
Correct Answer: It mainly acts in enzyme activation and participates in photosynthetic processes
Explanation: Manganese is an essential micronutrient known especially for its role in activating enzymes and assisting important metabolic reactions. It is also associated with photosynthetic processes, particularly those linked with the functioning of chloroplast-related systems. This makes manganese important in plant metabolism even though only a small amount is required. Its role is therefore more regulatory and catalytic than structural. It does not form the main backbone of nucleic acids or act like calcium in wall stabilization. Because enzyme-controlled reactions are central to plant life, manganese is functionally significant. Therefore, its correct major role is enzyme activation and participation in photosynthetic processes.
120. Which symptom is most characteristic of manganese deficiency in plants?
ⓐ. Uniform chlorosis of older leaves with strong leaf-edge burn
ⓑ. Interveinal chlorosis with small necrotic spots in young leaves
ⓒ. Swollen stem base with excessive water storage
ⓓ. General death of the shoot apex without leaf chlorosis
Correct Answer: Interveinal chlorosis with small necrotic spots in young leaves
Explanation: Manganese deficiency commonly appears as interveinal chlorosis, often accompanied by small necrotic or dead spots in the affected leaves. Because manganese is not freely redistributed to young tissues, the symptoms tend to be more visible in younger leaves. The presence of tiny necrotic specks along with chlorosis helps distinguish manganese deficiency from some other micronutrient disorders. Since manganese supports enzyme systems and photosynthetic functioning, its shortage quickly affects leaf tissue health. The symptom is not usually described as simple marginal burn or total apex death alone. This pattern is therefore a useful diagnostic feature. Hence, interveinal chlorosis with small necrotic spots in young leaves is most characteristic.
