If you really feel that something in the realm of biology or ecology interests you, a general degree in either biology, ecology, botany, or zoology can afford you this background. Just as ecology focuses on interactions, all of these fields of study interact. Get involved in outside activities that reflect your interests. That is the best way to discover whether you really like to do something in the world outside of school, and a great way to make connections that can lead to jobs and a lot of fun. Simply put, a food chain moves food from organism to another providing energy to the organism digesting the food.
All food chains start with the sun.
The sun provides energy for plants. Plants are considered producers because they make their own food with the held of the sun. Animals, including humans, cannot make their own food. As a result they must get their energy from other sources, usually plants and other animals. As a result animals are considered consumers.