LIFE SCIENCE

Detailed explanation-1: -A tertiary consumer is an animal that obtains its nutrition by eating primary consumers and secondary consumers. Usually tertiary consumers are carnivorous predators, although they may also be omnivores, which are animals that feed on both meat and plant material.

Detailed explanation-2: -The bear is a primary consumer as it directly feeds on plants, berries in this case. The bear, when eats rodents, becomes a secondary consumer. Rodents feed on grass, so is a primary consumer.

Detailed explanation-3: -The number of tertiary consumers depends on secondary consumers for its food, and secondary consumers feed on primary consumers, and they depend on for its food. The tertiary consumers always have less than those of other consumers because of this inefficiency, only a few top-level consumers have enough food.