Food Chain Worksheet with a detailed food web diagram illustrating the relationships between different organisms in an ecosystem.

Final Answer:
① A food chain starts with a producer and ends with a top predator. Green plants are called producers because they use the light energy of the sun to produce food using carbon dioxide and water through a process called photosynthesis. Animals cannot make their food and thus are called consumers.
② There are four main trophic levels in a food chain. They are producers, primary consumers, secondary consumers, and tertiary consumers. Apart from the said trophic levels, top predators have no natural predators except humans. Then, decomposers, like fungi and bacteria, turn dead organisms into inorganic materials in the soil.
Longest food chains (two examples):
1. Grass → Grasshopper → Shrew → Snake → Hawk
2. Tree → Deer → Mountain Lion