Here's why:

* Light is essential for photosynthesis: Plants need light to convert carbon dioxide and water into sugars, which they use for growth and energy.

* Without light, plants prioritize growth: In the absence of light, plants focus their energy on elongating their stems and reaching for a light source. This is why etiolated plants appear tall and spindly with pale, yellow leaves.

* Hormonal changes: Etiolation is also influenced by changes in plant hormone levels, specifically the increased production of the hormone auxin. Auxin stimulates stem elongation, further contributing to the characteristic etiolated appearance.

In summary: Etiolation is a survival mechanism that allows plants to reach for light when it's scarce.