Chapter 1: Transport (F5)

• Unicellular and multicellular organism require a constant supply of oxygen and nutrients.
• Waste products like carbon dioxide and urea have also to be eliminated from the cell.
• Unicellular organisms have a big total surface area to volume ratio and this allows the efficient diffusion of respiratory gases, nutrients and waste products into and out of the cell.
  
• Multicellular organisms need to have a circulatory system to transport materials throughout the body.
• The human circulatory system consists of blood, blood vessels and the heart.
• Blood consists of blood cells and plasma.
• Blood cells consist of red blood cells, white blood cells and platelets.
• Plasma consists of water, plasma proteins, nutrients, metabolic waste, hormones and antibodies.
• Blood vessels are of three types: arteries, veins and capillaries.
• The circulation of the blood in humans is maintained by the pumping of the heart and the contraction of the skeletal muscles around veins.
• The heart has 4 chambers: left and right atria, and left and right ventricle.
• The tricuspid valve separates the right atrium from the right ventricle.
• The bicuspid valve separates the left atrium from the left ventricle.
• The valves prevent backflow of blood.
  
• Humans, fish, amphibians and birds have a closed circulatory system.
• Insects have an open circulatory system.
• Fish have a single circulatory system.
• Amphibians, birds and humans have a double circulatory system.
• Our circulatory system has a blood clotting mechanism which stops blood loss at the site of the damaged blood vessels.
• Clotting prevent serious blood loss, entry of microorganisms and maintain blood pressure as well as circulation of blood.
  
• The circulatory system is involved in the body's defense mechanism.
• The first line of defense consists of physical and chemical barriers that prevent pathogens from entering the body.
• The second line of defense involves phagocytes which perform phagocytosis.
• The third line of defense involves our body's immune system.
• Active immunity means the body makes its own antibodies in response to stimulation by an antigen.
• Passive immunity means the body receives antibodies from an outside source.
• The lymphatic system consists of lymphatic cappilaries, lymphatic vessels, lymph nodes and lympatic ducts.
• Excess interstitial fluid is drained into the lymphatic vessels and returned to the circulatory system.
  
• Transport in plants is provided by the vascular tissues.
• Vascular tissues include xylem and phloem.
• Translocation is the transport of organic solutes in phloem.
• Transpiration is the loss of water vapour from the surfaces of plants through evaporation.
• Transpiration is affected by external condition such as light intensity, air movement, humidity and temperature.
• Root pressure, capillary action and transpirational pull cause movement of water from the roots to the leaves.
• The opening and closing of the stomata helps in the regulation of transpiration.
• Guttation is the process where there is an exudation of drops of a liquid containing water and dissolved substances from the tip of the leaves.
• Guttation happens at night when the atmosphere is hot and moist.