Read the following passage and answer the next five questions:

In nature, populations of different species do not remain isolated in the habitat but interact in many ways. Based on the outcome, these interactions between two species are classified into competition, predation and parasitism, commensalism, interspecific parasitism and mutualism. These interactions facilitate the transfer of energy at the trophic level. Some predators help in controlling the prey population, while plants have evolved morphological and chemical defences to avoid herbivores.