Plant Light Response — Sensing and Growing Toward Light
Start with a seedling in its environment. Light is the cue, the plant is the receiver, and growth is the response.
GROWTH RESPONSE
Stem Bending — Phototropism in Action
The plant does not walk toward light. It changes growth on different sides of the stem, causing the shoot to bend.
CELLULAR MECHANISM
Cell-Level Mechanism — Light, Auxin, and Unequal Growth
Inside the stem, light sensing and hormone redistribution help cells elongate unevenly, creating directional growth.
Plant Light Response — A Natural Signal-and-Response System
Begin at the organism scale. Explore how a young plant detects light direction and changes its growth pattern over time.
Text-Only Plant Light Response Explorer
Overview: This explorer shows how plants respond to light through phototropism. Light acts as an environmental cue. The plant receives the cue and responds by changing growth direction.
1. Macro: Plant + Light
The plant detects directional light and bends toward the light source. This helps position leaves for photosynthesis.
2. Growth: Stem Bending
The shoot bends because cells on one side elongate more than cells on the other side. The response is gradual but measurable.
3. Cell: Auxin + Unequal Growth
Inside the stem, light sensing and auxin redistribution help create unequal cell elongation. Small cellular changes produce a visible whole-plant response.
Science Connections
Biology: phototropism, photosynthesis, hormones, growth. Physics: light direction and intensity. Chemistry: auxin as a chemical messenger and photosynthesis as chemical transformation. Engineering: sensors, control systems, directional response, and feedback.
Signal Lab Transfer
Use the plant system as a model for designing signals and responses. Ask: What cue starts the system? What detects it? What internal process connects detection to action? What visible response shows that the system worked?