Which organism would be classified as a primary consumer?

A deer feeding on grass is classified as a primary consumer because it occupies the second trophic level in the food chain. Primary consumers are organisms that eat producers, which are typically plants or other autotrophs. In this case, the grass is a producer that converts sunlight into energy through photosynthesis. The deer, as a herbivore, directly consumes the grass and derives energy from it. This relationship exemplifies the flow of energy within an ecosystem, where primary consumers play a critical role by converting the energy stored in plants into a form that can be utilized by higher trophic levels, such as secondary consumers.

In contrast, lions and hawks are classified as secondary and tertiary consumers, respectively, as they feed on other animals. The tree's role is that of a producer, as it does not consume other organisms but rather creates its own energy through photosynthesis.