The Krebs cycle provides a common pathway for the metabolism of nutrients by the body. The Krebs cycle forms two pyruvate molecules. Each of the two pyruvate molecules formed in the cytoplasm from one molecule of glucose yields another molecule of:

Explanation:

The ultimate source of energy in the ecosystem is the sun. When we take our dog for a walk, we are utilizing energy stored in our body that we obtained food. We must have obtained that from either plants or animals. The animal in turn must have obtained its food from plant. Plants are the organisms in the food chain who can convert the energy from the sun into the chemical energy. So, we can say that when we walk our dog we use energy from the sunlight to power this activity.