Which process involves chemical reactions that break down nutrient molecules in living cells to release energy?

Which process involves chemical reactions that break down nutrient molecules in living cells to release energy?

• A. Respiration
• B. Growth
• C. Ingestion
• D. Sensitivity

Answer: (A)

Respiration is the process that breaks down nutrient molecules in living cells to release energy. During respiration, enzymes drive a series of chemical steps that oxidize nutrients like glucose, releasing energy that is captured in ATP, the cell’s energy currency. This energy powers cellular activities such as movement, growth, and maintaining temperature. When oxygen is present, the reaction is aerobic and yields a large amount of energy, producing carbon dioxide and water as byproducts. Even without oxygen, cells can still release energy through anaerobic respiration, but it provides much less energy and produces different end products (like lactic acid in muscles or ethanol and carbon dioxide in yeast). Other options don’t focus on breaking down nutrients to release energy: growth uses energy to build larger molecules, ingestion is about taking in food, and sensitivity relates to responding to stimuli.

Respiration is the process that breaks down nutrient molecules in living cells to release energy. During respiration, enzymes drive a series of chemical steps that oxidize nutrients like glucose, releasing energy that is captured in ATP, the cell’s energy currency. This energy powers cellular activities such as movement, growth, and maintaining temperature. When oxygen is present, the reaction is aerobic and yields a large amount of energy, producing carbon dioxide and water as byproducts. Even without oxygen, cells can still release energy through anaerobic respiration, but it provides much less energy and produces different end products (like lactic acid in muscles or ethanol and carbon dioxide in yeast). Other options don’t focus on breaking down nutrients to release energy: growth uses energy to build larger molecules, ingestion is about taking in food, and sensitivity relates to responding to stimuli.