Which pairing correctly matches a plant hormone with its primary growth-regulating role?

Which pairing correctly matches a plant hormone with its primary growth-regulating role?

• A. Auxins promote cell elongation and apical dominance; cytokinins promote cell division
• B. Gibberellins promote leaf abscission; Ethylene promotes root elongation
• C. Abscisic acid promotes fruit ripening; Auxins promote dormancy
• D. Brassinosteroids inhibit growth; Cytokinins promote photosynthesis

Answer: (A)

The main idea here is that plant hormones have distinct, well-defined roles in growth. Auxins drive cell elongation in stems and promote apical dominance, which keeps the main shoot growing upward while suppressing the growth of lateral buds. Cytokinins stimulate cell division and work with auxins to drive shoot growth and tissue development. So pairing auxins with promoting cell elongation and apical dominance, and cytokinins with promoting cell division, aligns with what these hormones do most prominently. Other options mix up these roles. Gibberellins are known for promoting stem elongation and seed germination, not leaf abscission. Ethylene is the hormone that promotes fruit ripening (and can promote leaf abscission), not root elongation. Abscisic acid is associated with dormancy and stress responses rather than promoting fruit ripening. Brassinosteroids promote growth rather than inhibiting it, and cytokinins are not primarily described as promoting photosynthesis.

The main idea here is that plant hormones have distinct, well-defined roles in growth. Auxins drive cell elongation in stems and promote apical dominance, which keeps the main shoot growing upward while suppressing the growth of lateral buds. Cytokinins stimulate cell division and work with auxins to drive shoot growth and tissue development. So pairing auxins with promoting cell elongation and apical dominance, and cytokinins with promoting cell division, aligns with what these hormones do most prominently.

Other options mix up these roles. Gibberellins are known for promoting stem elongation and seed germination, not leaf abscission. Ethylene is the hormone that promotes fruit ripening (and can promote leaf abscission), not root elongation. Abscisic acid is associated with dormancy and stress responses rather than promoting fruit ripening. Brassinosteroids promote growth rather than inhibiting it, and cytokinins are not primarily described as promoting photosynthesis.