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Gaseous exchange and respiration

  GASEOUS EXCHANGE IN PLANTS AND ANIMALS Necessity for Gaseous Exchange in Living Organisms •              Most organisms use oxygen for respiration which is obtained from the environment. The energy comes from breakdown of food in respiration. Living organisms require energy to perform cellular activities. •              Carbon (IV) oxide is a by-product of respiration and its accumulation in cells is harmful which has to be removed. Photosynthetic cells of green plants use carbon (IV) oxide as a raw material for photosynthesis and produce oxygen as a byproduct. Gaseous exchange: •              The movement of these gases between the cells of organisms and the environment comprises gaseous exchange. •              The process of movi...
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Transport in animals

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  The Circulatory System •            Large and complex animals have circulatory systems that consist of tubes, a transport fluid and a means of pumping the fluid. Blood is the transport fluid which contains dissolved substances and cells. •            The tubes are blood vessels through which dissolved substances are circulated around the body. The heart is the pumping organ which keeps the blood in circulation. The types of circulatory system exist in animals: open and closed. •            In an open circulatory system: The heart pumps blood into vessels which open into body spaces known as haemocoel. Blood comes into contact with tissues. •            A closed circulatory system: Found in vertebrates and annelids where the blood is confined within blood vessels and does no...
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