A system approach to the major functional categories of insect life: feeding, gas exchange, homeostasis, locomotion, reproduction, development, communication and their interrelations. The alimentary and circulatory systems; integument, respiratory and excretory systems; the sensory, nervous, muscular, endocrine and exocrine systems. The reproductive system and development; unusual modes of reproduction and other adaptive processes that enhance the success of insects. Introduction to structure and function of biomolecules: peptides and proteins, carbohydrates, lipids, nucleotides; enzymes – properties and classification. General introduction to metabolism: production of energy from carbohydrates, lipids and amino acids; Coenzyme and cofactors. Energy utilization for biosynthesis, light generation and flight: insect flight – flight muscle ultra-structure, mobilization and transport of fuels to flight muscle. Insect hormones and regulation: structure, modes of action and biochemical activities – adipokinetic and hypertrehalosemic hormones in energy metabolism; ecdysone, ecdysiotropic hormone, bursicon and juvenile hormones in moulting process and sclerotization; pheromones.