Biology STAAR Practice Test 2026 - Free State of Texas Assessments of Academic Readiness Practice Questions and Study Guide

The formula for cellular respiration is represented as C6 H12 O6 + 6O2 → 6CO2 + 6H2O + ATP. This equation illustrates the process by which cells convert glucose and oxygen into carbon dioxide, water, and adenosine triphosphate (ATP), which is the energy currency of the cell.

In this process, glucose (a simple sugar) is oxidized, breaking down through a series of metabolic pathways, primarily glycolysis, the Krebs cycle, and oxidative phosphorylation. Oxygen serves as the final electron acceptor, facilitating the production of ATP and releasing carbon dioxide and water as byproducts. This transformation is essential for producing the energy required for various cellular activities.

The other options do not accurately represent cellular respiration. For instance, one option depicts photosynthesis, the reverse of respiration, by showing the conversion of carbon dioxide and water into glucose and oxygen. Others imply energy transfer without clearly articulating the reactants or byproducts involved, which do not encompass the complete and accurate biochemical process that cellular respiration entails. Recognizing the details of the respiration process is crucial for understanding how energy is utilized in biological systems.