Final answer:
The primary source of energy in a food chain for animals is carbohydrates, specifically glucose, which can be traced back to photosynthesis. Energy is lost as heat when transferred through a food chain, with only about 10% of the energy being stored in each subsequent step.
Step-by-step explanation:
The primary source of energy for animals in a food chain is carbohydrates, specifically glucose. The digestible carbohydrates in an animal's diet are converted to glucose molecules through a series of catabolic chemical reactions. This energy can be traced back to photosynthesis, where the energy from the sun is used to convert carbon dioxide and water into glucose.
For example, in a simple food chain, plants produce glucose through photosynthesis. Herbivores then consume these plants, obtaining the energy stored in the glucose molecules. Carnivores that feed on the herbivores acquire the energy from the glucose molecules. Ultimately, all the energy in the food chain can be traced back to the photosynthetic vegetation that the initial plants consumed.
It is important to note that as energy is transferred along a food chain, some energy is lost as heat. This means that only about 10% of the energy from one step in a food chain is stored in the next step. The rest of the energy is lost or used for metabolic processes.