複選題

17. Plant hormones (phytohormones) trigger significant physiological changes at extremely low concentrations. Their mechanism of action typically involves the binding of hormone molecules to specific receptors, which activates internal signal transduction pathways to regulate gene expression or enzymatic activity. Based on current understanding of plant hormone signaling, which of the following statements are correct?
(A) Each hormone triggers a single, specific physiological response that remains consistent across all tissues and plant species.
(B) The same hormone can produce different physiological outcomes depending on the tissue type, developmental stage, and receptor/signaling context.
(C) Hormone action is strictly independent of dosage; the physiological outcome is determined only by the presence or absence of the signal.
(D) Physiological outcomes are often the result of complex interactions—such as synergy or antagonism—between multiple hormone classes rather than a single isolated signal.
(E) Plant hormones act only locally at the site of synthesis and are incapable of functioning as long-distance systemic signals through vascular tissues.