Where do people and other animals primarily obtain the energy needed for movement?

• A. By absorbing energy from the air
• B. By breaking down food molecules such as glucose
• C. From the minerals in their bones
• D. Directly from sunlight through photosynthesis

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the concept of energy acquisition in animals. Animals, including humans, are heterotrophs, meaning they obtain energy by consuming organic molecules rather than producing it themselves like autotrophs (e.g., plants).
2. Step 2: Recall the process of cellular respiration. Animals break down food molecules, such as glucose, through cellular respiration to produce ATP (adenosine triphosphate), the primary energy currency of cells.
3. Step 3: Eliminate incorrect options. Animals do not absorb energy from the air, as energy must come from chemical bonds in food molecules. They also do not obtain energy directly from sunlight, as they lack the ability to perform photosynthesis. Minerals in bones provide structural support, not energy.
4. Step 4: Focus on glucose as a key molecule. Glucose is a carbohydrate that serves as a primary energy source. During cellular respiration, glucose is broken down in a series of steps: glycolysis, the citric acid cycle, and oxidative phosphorylation.
5. Step 5: Summarize the correct answer. The energy needed for movement and other activities is obtained by breaking down food molecules, such as glucose, through cellular respiration to produce ATP.