Biology STAAR Practice Test 2025 – Comprehensive All-in-One Guide to Mastering the State of Texas Readiness Exam!

Cellular respiration is the primary process responsible for energy production in cells. During cellular respiration, glucose and oxygen are converted into carbon dioxide, water, and adenosine triphosphate (ATP), which is the energy currency of the cell. This process occurs in the mitochondria of eukaryotic cells and involves several stages, including glycolysis, the Krebs cycle, and the electron transport chain.

While diffusion and osmosis are important transport mechanisms in cells, they do not produce energy; rather, they facilitate the movement of substances across cell membranes. Photosynthesis, on the other hand, is the process by which plants, algae, and some bacteria convert light energy into chemical energy stored in glucose, which can then be utilized in cellular respiration. However, cellular respiration itself is the key process that directly generates energy for cellular functions.