Why is a food web a more realistic way of portraying an ecosystem than a food chain?

Hi. Great question. A food web is more realistic as an ecosystem's stability is a product of it's biodiversity. The more biodiverse an ecosystem is the more stable it is. I'm this sense highly stable ecosystems are highly interdependent i.e. More species will rely on each other for food. The more feeding relationship there are the more realistic it is to represent the ecosystem as a diverse, interdependent food web.