LIFE SCIENCE

Detailed explanation-1: -The first and lowest level contains the producers, green plants. The plants or their products are consumed by the second-level organisms-the herbivores, or plant eaters. At the third level, primary carnivores, or meat eaters, eat the herbivores; and at the fourth level, secondary carnivores eat the primary carnivores.

Detailed explanation-2: -Most food chains consist of three or four trophic levels. A typical sequence may be plant, herbivore, carnivore, top carnivore; another sequence is plant, herbivore, parasite of the herbivore, and parasite of the parasite.

Detailed explanation-3: -Producers, Herbivores (primary consumers), Carnivores (secondary consumers), Predators (tertiary consumers).