Biology PAPER 2

• Give the name of the body’s coordination system which involves hormones ?

  The endocrine system
• what is a hormone ? 


  is a chemical messenger secreted by a gland. it travels in the blood to a target organ , where it causes a response
• what type of organ secretes hormones ?

  glands
• which gland controls many other glands in the body ?

  the pituitary gland
• which is the pituitary gland considered a ‘master gland?’


  it secretes a wide range of hormones some of which may stimulate other endocrine glands
• what is the role of the pituitary gland in the endocrine system ?

  • secretes human growth hormone , controls human growth =
• what is the role of the thyroid gland in the endocrine system ?


  secretes the hormone thyroxine , controls metabolism , heart rate and body temperature
• what is the role of the pancreas in the endocrine system ?

  secretes the hormone insulin , controls blood glucose levels
• what is the role of the adrenal gland in the endocrine system ?

  secretes adrenaline , controls the body’s fight or flight response
• what is the role of the ovaries in the endocrine system ?


  secrete oestrogen , which coordinates the menstrual cycle and the development of female secondary sexual characteristics
• what is the role of the testes in the endocrine system?


  secrete testosterone , which coordinates the production of sperm and the development of male secondary characteristics
• which organ monitors and controls blood glucose concentration ?

  the pancreas
• how does the pancreas respond when blood glucose levels are too high ?


  it secretes the hormone insulin
• what is type one diabetes?


  One diabetes is an autoimmune disorder in which the pancreas does not produce sufficient insulin to control the blood glucose concentration , as a result blood glucose levels are often very high leading to excessive tiredness and weight loss
• how can type one diabetes be treated ?

  • insulin injections before meals , allows glucose to be converted into glycogen
  • limiting carbohydrate intake
• what is type two diabetes ?

  type two diabetes is a disorder in which the body cells stop responding to insulin, leading to an uncontrolled blood glucose concentration. Its onset is linked with increasing age and obesity
• how can type two diabetes be treated ?

  • following a carefully controlled diet
  • doing regular exercise
  • losing weight
  • use of drugs which increases insulin production and effectiveness
• what is osmosis ?

  is the movement of water from a dilute solution to a concerntration solution through a partially permeable membrane
• in what ways is water lost from the body ?

  • during exhalation via the lungs
  • sweating
  • urine
• in what ways are ions lost from the body ?

  • sweating
  • urine
• how are excess amino acids excreted from the body ?

  excess amino acids deaminated in the liver to form ammonia

  ammonia is toxic , therefore it is converted into urea

  urea is excreted from the body via sweat and urine
• how do kidneys maintain the balance of water and other substances in the body ?

  • filter blood in the order to remove waste products eg , urea
  • selectively reabsorb useful molecules eg , glucose , water
• what are two main ways of treating kidney failure ?

  • dialysis
  • transplant