Final answer:
The chloroplast is the structure unique to plant cells that enables them to capture sunlight for photosynthesis. This organelle contains chlorophyll, which is crucial for converting sunlight, along with water and carbon dioxide, into sugars for the plant's nourishment.
Step-by-step explanation:
The structure found only in plant cells that allows for the capture of energy from sunlight is the chloroplast. Plants use these specialized organelles to conduct photosynthesis, a process where sunlight, water, and carbon dioxide are transformed into sugars and oxygen.
Chloroplasts contain the pigment chlorophyll, which is essential for absorbing light energy. This light energy is then used to convert carbon dioxide and water into glucose, a process that also results in the release of oxygen as a byproduct. The glucose can be used directly for energy or converted into starch for storage, while oxygen is expelled into the atmosphere. Unlike animals, plants have the unique ability to create their own food using sunlight, which fundamentally differentiates them in terms of energy sources.