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.


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