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Organism level systems

OCR GCSE BiologyTopic 3 of 627 lessons

Revision notes for Organism level systems in OCR Biology A (J247). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

  1. Structure of the nervous systemThe nervous system detects changes and sends electrical impulses to bring about a response.
  2. How the nervous system coordinates a responseA coordinated response means the right effectors act together, at the right time, in a way that suits the stimulus.
  3. The reflex arcA reflex is a fast, automatic response to a stimulus.
  4. Structure of the eyeThe eye detects light and focuses it so the brain can form a clear picture.
  5. Defects of the eyeSome people have eyes that cannot focus properly, or that cannot detect colour normally.
  6. Structure and function of the brainThe brain is part of the CNS and controls what the body does.
  7. Difficulties of investigating brain functionThe brain controls everything we think, feel and do, but it is very hard to study.
  8. Limitations in treating nervous system damageDamage and disease in the brain, spinal cord and other parts of the nervous system are very hard to treat.
  9. Hormonal coordination and the endocrine systemThe body has two coordination systems.
  10. Thyroxine and adrenalineThyroxine is made by the thyroid gland in the neck.
  11. Hormones in human reproductionAt puberty the sex hormones cause the secondary sexual characteristics.
  12. Control of the menstrual cycleThe menstrual cycle is controlled by four hormones that affect one another.
  13. Hormones and contraceptionContraception is used to prevent pregnancy.
  14. Hormones and infertility treatmentA woman is infertile if she cannot become pregnant.
  15. Auxins in phototropism and gravitropismPlants respond to their surroundings by changing the direction in which they grow.
  16. The effects of auxins, gibberellins and ethenePlant hormones control many processes besides bending.
  17. Uses of plant hormones in agriculture and horticultureFarmers and gardeners use plant hormones to control how plants grow.
  18. Maintaining a constant internal environmentYour body is always dealing with change.
  19. The skin and body temperature controlThe skin plays a key part in controlling body temperature.
  20. Insulin and blood sugar levelThe sugar in blood is glucose, and cells need it for respiration.
  21. Glucagon and insulin working togetherBetween meals, or during exercise, cells keep using glucose and the blood glucose level starts to fall.
  22. Type 1 and type 2 diabetesDiabetes is a condition in which the blood glucose level cannot be controlled properly.
  23. Osmotic changes and body cellsCells in the body are surrounded by body fluids such as blood plasma and tissue fluid.
  24. The kidneys and water balanceWater enters the body in drink and food and leaves in sweat, in breath and in urine.
  25. Structure of the kidney and the kidney tubuleBlood reaches each kidney in the renal artery, which brings blood containing urea, and leaves in the renal vein.
  26. ADH and the kidney tubulesADH is a hormone released into the blood by the pituitary gland.
  27. Responses to temperature and osmotic challengesThe body keeps its internal conditions steady using negative feedback.

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