Which term describes the rate at which an organism uses energy to sustain life?

Which term describes the rate at which an organism uses energy to sustain life?

• A. Metabolic Rate
• B. Growth Rate
• C. Oxygen Consumption Rate
• D. Heart Rate

Answer: (A)

Metabolic rate is the rate at which an organism uses energy to sustain life. It encompasses the energy needed for maintenance of cells and tissues, basic physiological processes like respiration and circulation, and the energy used during activities. That direct link to energy use makes it the best fit for describing how much energy an organism expends to stay alive. Growth rate describes how quickly an organism increases in size or mass, which is about energy used specifically for building new tissue rather than overall energy expenditure. Oxygen consumption rate is a common way to gauge metabolic rate because metabolism uses oxygen, but it’s a measurement, not the term itself. Heart rate reflects how often the heart beats and can rise with activity, but it doesn’t by itself define the total energy used to sustain life.

Metabolic rate is the rate at which an organism uses energy to sustain life. It encompasses the energy needed for maintenance of cells and tissues, basic physiological processes like respiration and circulation, and the energy used during activities. That direct link to energy use makes it the best fit for describing how much energy an organism expends to stay alive.

Growth rate describes how quickly an organism increases in size or mass, which is about energy used specifically for building new tissue rather than overall energy expenditure. Oxygen consumption rate is a common way to gauge metabolic rate because metabolism uses oxygen, but it’s a measurement, not the term itself. Heart rate reflects how often the heart beats and can rise with activity, but it doesn’t by itself define the total energy used to sustain life.