Question

Why do most of the food chains consist of four steps

Answer 1

Well, the only way to explain this is to think mathematically. At the bottom level are plants. Let's say they absorb about 10% of the Sun's energy to convert to food. Then animals that eat the plants get only 10% of that energy. Carnivores, the next level, get only 10% of that (which is 0.1% of the energy from the Sun). As you can see, the higher an organism's level in the food chain, the fewer can exist. If you had 10 lions and 10 deer, all the deer would be killed and eaten and the lions would starve before the deer could have any babies. This means that if you go beyond about 4 levels, it is unsustainable to any organisms.

Answer 2

grass____》grasshoper》》》frog》》》snake