Respiration is the process through which the cells of our body produce the energy that is required for performing many important tasks. Each cell of our body utilizes the food we eat by respiration to break down the glucose present in the food into usable energy.
pest - any unwanted and destructive insect or other animal that attacks food or crops or livestock etc.; he sprayed the garden to get rid of pests; many pests have developed resistance to the common pesticides.
Systematic describes something that is planned out and careful. In your systematic search for your mother's car keys, you start in one room, looking everywhere from bottom to top before moving to the next room. Use the adjective systematic to describe things that are orderly and efficient. The Latin root of systematic is systema, an arrangement or system.