The Video lecture from Gaseous Exchange (F.Sc. First Year Biology) covers the process of respiration in Hydra, Earthworm and Cockroach with diagrams.It explains how the complexity of respiratory system increases from simple organism as Hydra to relatively complex organism as Cockroach. Find more e-learning material and educational video lectures in Urdu at maktab.pk. These videos are free to use for promotional and commercial purpose by keeping the credits to Maktab.