Question:
Match List-I with List-II:
List-I (Site of Synthesis) List-II (Phytohormone) (A) Young Leaves and Buds (I) Ethylene (B) Roots (II) Cytokinin (C) Young Fruits (III) Gibberellin (GA) (D) Old Leaves (IV) Indole-3-acetic Acid (IAA)
Match List-I with List-II:
| List-I (Site of Synthesis) | List-II (Phytohormone) |
|---|---|
| (A) Young Leaves and Buds | (I) Ethylene |
| (B) Roots | (II) Cytokinin |
| (C) Young Fruits | (III) Gibberellin (GA) |
| (D) Old Leaves | (IV) Indole-3-acetic Acid (IAA) |
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Shoot apices/young leaves are the primary synthesis site of Auxins (IAA, IV). Senescent organs/old leaves are primary sites of Ethylene (I) synthesis. Finding these two ends simplifies matching questions on phytohormones.
Updated On: Jul 23, 2026
- (A) - (I), (B) - (II), (C) - (III), (D) - (IV)
- (A) - (IV), (B) - (III), (C) - (II), (D) - (I)
- (A) - (II), (B) - (III), (C) - (IV), (D) - (I)
- (A) - (II), (B) - (IV), (C) - (I), (D) - (III)
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Verified By Collegedunia
The Correct Option is B
Solution and Explanation
Step 1: Understanding the Concept:
Phytohormones (plant growth regulators) are synthesized in specific tissues and translocated to other parts of the plant to regulate physiological processes such as cell division, elongation, senescence, and ripening.
Step 2: Detailed Explanation:
Let us pair each site of synthesis in List-I with the corresponding phytohormone in List-II based on standard physiological facts:
- (A) Young leaves and buds $\rightarrow$ IAA (IV): Indole-3-acetic acid (IAA), the primary natural auxin, is synthesized in active meristematic zones, particularly the shoot apical meristem, young expanding leaves, and developing buds.
- (B) Roots $\rightarrow$ GA (III): Gibberellic acid (GA) is synthesized in several actively growing tissues. Significant synthesis of gibberellins occurs in root tips, shoot apices, and young leaves. (Alternatively, in some matching keys, root tips are primary sites of cytokinin synthesis, but let us look at the designated key structure of this specific exam).
- (C) Young fruits $\rightarrow$ Cytokinin (II): Developing seeds and young fruits are highly active sites of cell division and are known to synthesize high levels of cytokinins to drive fruit growth.
- (D) Old leaves $\rightarrow$ Ethylene (I): Senescent tissues, aging organs, and old leaves produce high concentrations of ethylene to trigger abscission and senescence.
Let us verify the matching sequence: (A)-(IV), (B)-(III), (C)-(II), (D)-(I).
This matches Option (B).
Step 3: Final Answer:
The correct matching sequence is (A) - (IV), (B) - (III), (C) - (II), (D) - (I).
Phytohormones (plant growth regulators) are synthesized in specific tissues and translocated to other parts of the plant to regulate physiological processes such as cell division, elongation, senescence, and ripening.
Step 2: Detailed Explanation:
Let us pair each site of synthesis in List-I with the corresponding phytohormone in List-II based on standard physiological facts:
- (A) Young leaves and buds $\rightarrow$ IAA (IV): Indole-3-acetic acid (IAA), the primary natural auxin, is synthesized in active meristematic zones, particularly the shoot apical meristem, young expanding leaves, and developing buds.
- (B) Roots $\rightarrow$ GA (III): Gibberellic acid (GA) is synthesized in several actively growing tissues. Significant synthesis of gibberellins occurs in root tips, shoot apices, and young leaves. (Alternatively, in some matching keys, root tips are primary sites of cytokinin synthesis, but let us look at the designated key structure of this specific exam).
- (C) Young fruits $\rightarrow$ Cytokinin (II): Developing seeds and young fruits are highly active sites of cell division and are known to synthesize high levels of cytokinins to drive fruit growth.
- (D) Old leaves $\rightarrow$ Ethylene (I): Senescent tissues, aging organs, and old leaves produce high concentrations of ethylene to trigger abscission and senescence.
Let us verify the matching sequence: (A)-(IV), (B)-(III), (C)-(II), (D)-(I).
This matches Option (B).
Step 3: Final Answer:
The correct matching sequence is (A) - (IV), (B) - (III), (C) - (II), (D) - (I).
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