[Campbell Biology P.836] Considering the Photosynthesis-Water Loss Compromise in plants, whi... | Practice Question

Considering the Photosynthesis-Water Loss Compromise in plants, which of the following leaf orientations is most advantageous for a plant growing in a sunny, dry grassland environment, and why?

  • A: Horizontally oriented leaves, because they maximize light capture for photosynthesis.
  • B: Vertically oriented leaves, because they reduce exposure to intense light and allow light to penetrate deeper.
  • C: Horizontally oriented leaves, because they minimize water loss by increasing shading.
  • D: Vertically oriented leaves, because they absorb more light directly due to their perpendicular alignment with sun rays.

Explanation

In sunny or high-light environments like grasslands, horizontally oriented leaves can be exposed to overly intense light, leading to injury and reduced photosynthesis. Vertically oriented leaves, however, allow light rays to be essentially parallel to their surfaces, meaning no single leaf receives too much light, and light can penetrate more deeply to lower leaves. This helps avoid damage from intense light and optimizes light distribution within the canopy.