What organelle allows cells to orient themselves toward or away from light?

The eyespot is a specialized organelle found in certain unicellular organisms, such as euglena, that allows them to detect and respond to light. This organelle contains photoreceptive pigments that enable the organism to sense the direction and intensity of light, facilitating a behavior known as phototaxis. When light is detected, the eyespot helps the cell orient itself either towards the light source (positive phototaxis) or away from it (negative phototaxis). This is crucial for organisms that rely on light for photosynthesis, enabling them to maximize light exposure for energy production.

In contrast, the other options serve different functions. Pseudopodia are extensions of the cell membrane used primarily for movement and food capture in amoebas and other similar cells. The pellicle is a flexible, supporting layer found in some protists but does not serve the purpose of light orientation. Cysts are dormant forms of some microorganisms that enable them to survive harsh conditions, but they do not play a role in light detection or orientation.