The food chain is the system where green plants make food in the presence of sunlight and from a few basic materials, such as water and co2. ALL food comes from the ground in the first instance. The food energy ,including protein can be taken directly from the plants ( vegetarian diet) which is direct and non wasteful and totally sustainable because it does not overuse earths limited resources. Everyone on earth would get a fair share. Man being an omnivore has the choice of eating in this sustainable way, in which there would be no starvation if all mankind ate a veggie diet. But people can and do eat the animals that have eaten the plant. Or eat the animals that have eaten the animals that have eaten the plant. At each higher rung in the food chain much more of the worlds resources are wasted as the animal consumed used up 90 pc in keeping it alive and growing and the return when slaughtered is only 10 pc. In this way meat eating is totally unsustainable Even more water is wasted on a carnivorous diet. So the food chain begins with the plants and ends with the top animals ,like the gentle herbivores,the grazers ,the cows and sheep. The food chain is very interesting to study! People go on about having to eat from the top of the food chain because they " have to have their protein" BUT they do not stop to work out where the vegetarian cow gets all its protein from or the strong Racehorse etc for that matter.
A food chain is a simple diagram that shows how the food or nutrients (the energy source) pass from one organism to another...
The transfer food energy from the producers, through a series of organisms (herbivores to carnivores to decomposers ) with repeated eating and being eaten is known as Food chain.