The molecule in the food we eat contain substances stored in chemical bonds. Which statement BEST explains how this energy is released?
A. Cells extract and capture the energy in food molecules all at once, then store it for later use
B. Chemical bonds in food molecules are broken, releasing energy and allowing cells to use the energy to make ATP.
C. Cells burn food molecules, releasing energy as heat that powers movement while keeping the body at the correct temperature.
The correct answer and explanation is :
The correct answer is B. Chemical bonds in food molecules are broken, releasing energy and allowing cells to use the energy to make ATP.
Explanation:
The energy stored in the food we eat is primarily stored in the chemical bonds between atoms within molecules like carbohydrates, proteins, and fats. To understand how this energy is released, it’s important to grasp how cells process these molecules for energy production.
When we eat food, our digestive system breaks down complex food molecules (like carbohydrates, proteins, and fats) into simpler molecules (such as glucose, amino acids, and fatty acids). Once these smaller molecules are absorbed into the bloodstream, they enter cells, where they are further processed in a series of metabolic pathways. One of the key pathways involved in energy extraction is cellular respiration, which occurs in the mitochondria of cells.
In cellular respiration, glucose (or other substrates derived from food) undergoes a series of reactions, starting with glycolysis in the cytoplasm, followed by the Krebs cycle and electron transport chain in the mitochondria. During these reactions, the chemical bonds in glucose are broken, releasing energy. This energy is used to produce adenosine triphosphate (ATP), which is the primary energy currency of the cell. ATP is then used by the cell to power various processes, such as muscle contraction, protein synthesis, and maintaining cellular structure.
Option A is incorrect because cells do not extract and store energy all at once. Energy is released progressively through biochemical reactions and is immediately used to produce ATP.
Option C is also incorrect because cells do not simply “burn” food molecules to release heat; instead, they undergo controlled biochemical reactions to release energy in a usable form (ATP), with only a small fraction of the energy lost as heat.
Therefore, B is the best explanation because it accurately describes the process of breaking chemical bonds in food molecules to release energy, which is then used to produce ATP, the energy carrier used by cells for their various functions.