Phototropism | Plant Biology | Khan Academy

TL;DR

Plants exhibit phototropism, where they turn and grow towards light, and this is controlled by a hormone called auxin.

Transcript

• [Instructor] You've probably seen plants, either in your house or if you go for a walk. You've seen parts of the plants twist and turn in all sorts of directions. And if you observe closely, you'll see that oftentimes, it looks like the plant is twisting or turning towards the light. And what we're gonna do in this video is study that phenomenon ... Read More

Key Insights

• 🙂 Tropism refers to the phenomenon of plants changing direction due to external stimuli, and phototropism specifically relates to light.
• 🌱 Auxin is a plant hormone that controls plant growth and is responsible for phototropism.
• ⚡ Cells with a higher concentration of active auxin elongate, causing the plant to bend towards the light source.

Questions & Answers

Q: What is phototropism?

Phototropism is the phenomenon where plants turn or grow towards or away from light.

Q: What is auxin?

Auxin is a plant hormone that plays a crucial role in controlling plant growth and development, including phototropism.

Q: How does auxin cause plants to bend towards light?

Auxin acts by increasing the concentration of active auxin on the side of the plant away from the light, causing cells on that side to elongate and bend the plant towards the light source.

Q: What is positive and negative phototropism?

Positive phototropism occurs when plants turn or grow towards the light, while negative phototropism is when plants move away from the light.

Summary & Key Takeaways

• Plants exhibit tropism, where they change direction due to external stimuli, such as light.

• Phototropism is the specific term for plants turning or growing in response to light.

• Auxin, a plant hormone, is responsible for controlling the growth and direction of plants in response to light.