Biology paper 2

• Homeostasis


  The maintenance of a constant internal environment
• Control systems


  • Common features
• Nervous system


  Function: Transmits information around the body
• Information passing through the nervous system

  1. Stimulus

  2. Receptor

  3. Sensory neurone

  4. Central nervous system

  5. Motor neurone

  6. Effector
• Reflex action


  Rapid, automatic response to a stimulus
• Required practical 7: plan and carry out an investigation into the effect of a factor on human reaction time
• Brain


  Function: Coordinates and controls the body
• Regions of the brain

  • Cerebral cortex
  • Cerebellum
  • Medulla
• Bio ONLY: Describe the functions of different regions of the brain
• Bio & HT ONLY: Explain how neuroscientists have been able to map regions of the brain to particular functions
• Eye


  Function: Allows vision
• Parts of the eye

  • Cornea
  • Iris
  • Pupil
  • Lens
  • Retina
  • Optic nerve
• Accommodation


  The process of changing the shape of the lens to focus light
• Bio & HT ONLY: Explain how the body's responses act to raise or lower temperature in a given context
• Endocrine glands


  • Pituitary
  • Pancreas
  • Thyroid
  • Adrenal
  • Ovary
  • Testis
• Blood glucose concentration is monitored and controlled by the pancreas
• Body's response when blood glucose is too high

  1. Insulin released

  2. Glucose stored as glycogen
• Type 1 diabetes


  Pancreas does not produce insulin
• Type 2 diabetes


  Body becomes resistant to insulin
• HT ONLY: Describe the body's response when blood glucose concentration is too low
• HT ONLY: Glucagon and insulin control blood glucose levels


  1. Glucagon raises blood glucose

  2. Insulin lowers blood glucose
• Ways water, ions and urea are lost from the body

  • Sweat
  • Urine
  • Breathing out
• HT ONLY: Recall that protein digestion leads to excess amino acids inside the body and describe what happens to these
• HT ONLY: Describe the effect of ADH on the permeability of the kidney tubules and explain how the water level in the body is controlled by ADH
• Treating kidney failure


  1. Organ transplant

  2. Dialysis
• Changes at puberty


  • Males
  • Females
• Hormones involved in the menstrual cycle

  • FSH
  • LH
  • Oestrogen
• HT ONLY: Explain how the different hormones interact to control the menstrual cycle and ovulation
• Methods of contraception


  • Hormonal
  • Non-hormonal
• HT ONLY: Explain how hormones are used to treat infertility, inc the steps in IVF
• HT ONLY: Evaluate the risks and benefits of fertility treatments
• Adrenaline


  Hormone produced by the adrenal glands
• Thyroxine


  Hormone produced by the thyroid gland
• HT ONLY: Thyroxine and adrenaline as negative feedback systems


  1. Thyroxine regulates metabolic rate

  2. Adrenaline prepares body for 'fight or flight'
• Bio ONLY: Describe hormone-linked plant responses, to include phototropism and gravitropism and the role of auxin
• Bio & HT ONLY: Describe the functions of gibberellins and ethene in plants
• Required practical 8: investigate the effect of light or gravity on the growth of newly germinated seedling
• HT ONLY: Explain the use of plant growth hormones are used in agriculture and horticulture (auxins, ethene and gibberellins)