Which description properly describes a step involved in cellular respiration?
A. Glucose is created, then the energy gained is transferred to the energy molecule. B. Carbon dioxide and water are released after the energy molecule is charged. C. Water is divided into carbon dioxide and glucose. D. Oxygen is combined with ATP to energize it.
The Correct Answer and Explanation is :
The correct answer is B. Carbon dioxide and water are released after the energy molecule is charged.
Explanation of Cellular Respiration
Cellular respiration is a complex biochemical process that occurs in living organisms, allowing them to convert glucose (a sugar) into usable energy in the form of adenosine triphosphate (ATP). This process primarily takes place in the mitochondria of eukaryotic cells and can be divided into several stages: glycolysis, the Krebs cycle (or citric acid cycle), and oxidative phosphorylation (electron transport chain and chemiosmosis).
- Glycolysis: This is the first step, occurring in the cytoplasm, where one molecule of glucose (6 carbon atoms) is broken down into two molecules of pyruvate (3 carbon atoms each). During this process, a small amount of ATP is produced, and NADH is generated, which carries electrons.
- Krebs Cycle: The pyruvate then enters the mitochondria, where it is further broken down. This cycle generates electron carriers (NADH and FADH₂) and releases carbon dioxide (CO₂) as a waste product. Each turn of the Krebs cycle results in the release of CO₂ and the production of ATP.
- Oxidative Phosphorylation: The electrons carried by NADH and FADH₂ are transferred through a series of proteins in the inner mitochondrial membrane, known as the electron transport chain. As electrons move through this chain, they help pump protons (H⁺ ions) into the intermembrane space, creating a proton gradient. ATP synthase then utilizes this gradient to produce ATP from ADP and inorganic phosphate. In this final stage, oxygen acts as the final electron acceptor, combining with protons to form water (H₂O) and ensuring that the process continues efficiently.
Thus, option B accurately reflects the key steps involved in cellular respiration, emphasizing that carbon dioxide and water are released after ATP is synthesized and the energy is utilized. This not only captures the essential nature of energy production but also highlights the byproducts of the process, crucial for understanding the overall energy dynamics in biological systems.