What major difference exists between the overall functions of plant and animal cells?

The distinction that plant cells perform photosynthesis while animal cells do not is a fundamental aspect of their physiology. This process occurs in the chloroplasts, which contain chlorophyll, allowing plants to capture sunlight and convert it into chemical energy in the form of glucose. This ability is crucial for plants as it enables them to produce their own food, making them autotrophic organisms. In contrast, animal cells are heterotrophic and rely on consuming other organisms for energy, lacking the cellular machinery for photosynthesis.

While animal cells are generally more flexible without a rigid cell wall, and typically smaller in size than many plant cells, neither of these statements defines the fundamental functional differences centered around energy production. Additionally, all eukaryotic cells, including both plant and animal cells, possess a nucleus, which rules out the possibility of plants lacking this organelle. Thus, the ability to perform photosynthesis stands out as a critical differentiating function between plant and animal cells.