 With all this background, we talk about the food chains. Food chains are a one way flow of energy. Food chain is a flow chart diagram that shows the flow of energy from one biotic component of an ecosystem to another and then to another and then to another and so on. So food chain is actually a relationship between different trophic levels or different biotic factors within an ecosystem. If we simply exemplify a food chain then this will be from producers eaten up by the consumers, consumers eaten up by the decomposers. In an ecosystem different types of food chains exist. This is actually a relationship of eating and being eaten. In an ecosystem we know that different types of organisms are present. Various types of plants, various types of animals and many of these animals are herbivores, many of these animals are carnivores, there are different types of plants and because different types of animals will eat upon different types of plants and some other types of animals will eat upon those animals. So in an ecosystem lot many types of food chains they do exist and as we know that ecosystems they are very different from each other and all those ecosystems have different types of biodiversity. So in different types of ecosystems, different types of food chains they do exist. We will talk about a few examples from various ecosystems of different types of food chains. Let us have a look on the slide of a food chain. You can see in the slide that initially there is a plant, there is a worm which eat upon this dead plant, then this worm is eaten up by the turtle, there are turtles in the environment which eat upon these worms and turtles are themselves eaten by the eagles. It makes a straight relationship that is producer the plant eaten by a worm, worm is a consumer that is eaten by the turtle, turtle itself is a consumer but a secondary consumer which is eaten by the eagle which is then in this way we call it a tertiary consumer. This is a straight generalized food chain. Now we talk about some specific food chains, food chains in some specific ecosystems. We talk about first a grassland ecosystem. We have to look at few properties of the grassland ecosystems. Grasslands which are other way, we can call them vast land, vast areas on which grass or grass like plants they do exist. The grassland ecosystems have some characteristics. The rainfall in these ecosystems is from 250 to 750 millimetres annually. This is not a sufficient rainfall. The result is that water is a crucial factor or we can call water a limiting factor. Water is a factor that limits life because water is required by the plants and animals. So specific group of plants or animals can grow here which can conserve water well and which have properties which help them to live with smaller quantities of water. Plants which live in the grassland which can flourish in the grasslands are tall and short grasses. We can say the grass family, plants from grass family, tall grasses, short grasses, then legumes, they grow well in these areas, the herbs, small plants, the mosses and lichens. These are the common inhabitants of a grassland ecosystem. They are present in these ecosystems which can survive with lesser quantities of water which have specific adaptations to conserve water and to live with fewer water.