How would a houseplant typically respond to sunlight that comes from only one direction?

• A. The plant's leaves would turn away from the light source.
• B. The plant's stem would bend toward the light source.
• C. The plant's roots would grow toward the light source.
• D. The plant would stop growing entirely.

Answer: (B)

Verified step by step guidance

1. Understand the concept of phototropism: Phototropism is a plant's growth response to light. It occurs when certain parts of the plant grow toward or away from a light source.
2. Identify the role of auxins: Auxins are plant hormones that regulate growth. When light is unevenly distributed, auxins accumulate on the shaded side of the plant, causing cells on that side to elongate more than those on the light-exposed side.
3. Analyze the plant's response: Due to the uneven elongation of cells, the stem bends toward the light source, allowing the plant to maximize its exposure to sunlight for photosynthesis.
4. Eliminate incorrect options: The plant's leaves turning away from the light source, roots growing toward the light source, or the plant stopping growth entirely are not consistent with the biological process of phototropism.
5. Conclude the correct response: The plant's stem bends toward the light source as a result of phototropism, driven by the redistribution of auxins.