This video lecture from Coordination and Control (F.Sc. second year Biology) covers about responses produced by the plants to cover the environmental stress. This video lecture also include different type of defense mechanism shown by plants against pathogens. Furthermore it include about biological rhythms, types of biological rhythms and how they are connected with the environment of individuals. 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.