BRAINCAKEPhotomorphogenesis
Photomorphogenesis is the control of plant growth and development by light, independent of photosynthesis. Light affects the shape (morphology) of the plant, not just how much food it makes.
The effect is clearest when seedlings grown in the dark are compared with seedlings grown in the light. A seedling grown in darkness is etiolated:
• a long, thin stem with long internodes
• small, unexpanded leaves
• a pale yellow colour, because no chlorophyll is made
• a hooked tip that protects the shoot tip as it pushes through the soil
• weak roots and little supporting tissue
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Key terms in this lesson
- phytochrome
- A blue-green plant pigment existing in two interconvertible forms sensitive to red and far-red light, controlling responses such as flowering and germination.
More in Chemical Control
- Long Day Plants
- Short Day Plants
- Day Neutral Plants
- Signal Detection
- Discovery
- Germination and Photomorphogenesis
- Phytochromes, Photomorphogenesis and Tropisms
- Phytochrome as a Transcription Factor
All 30 lessons in Chemical Control · All Edexcel A-level Biology topics