Skotomorphogenesis is characterized by:
Skotomorphogenesis is characterized by:
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Correct Answer: Option A
Explanation
Skotomorphogenesis (dark-grown seedling development):Skotomorphogenesis = developmental program activated in darkness (from Greek 'skotos' = dark):• Characteristics of etiolated (dark-grown) seedlings:- Elongated hypocotyl (to push through soil)- Small, unexpanded cotyledons- Apical hook (protects the shoot apical meristem)- Pale yellow (no chlorophyll synthesis)- Closed apical budRegulation:• COP1 (constitutively photomorphogenic 1) is active in dark → ubiquitinates transcription factors (HY5) promoting photomorphogenesis → degradation → skotomorphogenesis proceeds.• Phytochromes in the Pr (inactive) form in dark.Distinction:• Photomorphogenesis: light-induced development (chlorophyll synthesis, leaf expansion, etc.).• Skotomorphogenesis is NOT the same as photoperiodism (response to day length for flowering).Answer: Skotomorphogenesis = dark-grown seedling phenotype (elongated hypocotyl, apical hook, etiolation).