How do photosynthesis and cellular respiration relate in terms of energy flow?

• A. Photosynthesis stores energy in glucose; cellular respiration releases that energy to power cell activities.
• B. Photosynthesis consumes energy while respiration creates energy.
• C. Respiration stores energy in ATP; photosynthesis uses ATP.
• D. Both use energy to produce carbon dioxide.

Answer: (A)

Energy flow connects these two processes. Photosynthesis captures energy from sunlight and stores it in the chemical bonds of glucose. Later, cells release that stored energy by breaking down glucose during cellular respiration to make ATP, the energy currency used to power cell activities. In this way, the glucose created by photosynthesis becomes the fuel that respiration uses to run the cell.

Photosynthesis uses light energy to convert carbon dioxide and water into glucose and oxygen, while respiration uses oxygen to break down glucose into carbon dioxide and water, releasing energy as ATP. The oxygen produced by photosynthesis feeds respiration, and the carbon dioxide produced by respiration is used by photosynthesis, keeping the cycle going.

So the best description is that photosynthesis stores energy in glucose, and cellular respiration releases that energy to power cell activities. The other statements don’t fit because they misstate who uses or stores energy (photosynthesis doesn’t simply consume energy, and respiration doesn’t store energy as ATP at the organismal level in the way described; also both processes don’t both produce carbon dioxide).