Which of these statements best defines a characteristic of a cell?

The statement that cells require energy for respiration is a fundamental characteristic of all living cells. This process, known as cellular respiration, is crucial for converting nutrients into usable energy in the form of adenosine triphosphate (ATP). It occurs in both prokaryotic and eukaryotic cells, allowing them to perform essential functions such as growth, repair, and maintenance of homeostasis.

Energy is obtained from various sources depending on the organism—plants typically use photosynthesis to generate their own energy, while animals and many other organisms rely on consuming organic matter. The ability to derive energy is a core component of cellular life and serves as a unifying feature among all types of cells, highlighting their role in sustaining life.

In contrast, the other statements do not accurately reflect universal characteristics of cells. Not all cells have thick walls, as this feature is specific to certain types of cells, such as bacteria and plant cells, while animal cells have flexible membranes. Additionally, all cells possess membranes, which are critical for maintaining internal environments and separating cellular contents from their surroundings. Lastly, cells are a common feature in all forms of life, including animals, fungi, and bacteria, not just plants.