bio paper 2

• Thyroxine


  Controls the metabolic rate of the body.
• Insulin


  Controls glucose levels in the blood.
• Oestrogen


  Development of sexual characteristics in females and in the menstrual cycle inhibits FSH production, stimulates LH production and maintains lining of the uterus
• Testosterone


  Development of sexual characteristics in males and sperm production.
• Growth hormone (GH)


  Controls growth in children.
• Thyroid stimulating hormone (TSH)


  Stimulates thyroid gland to produce thyroxine.
• Antidiuretic hormone (ADH)


  Influences the absorption of water by kidneys, regulating the amount of water in the body.
• What are the 5 conditions that are regulated in the body by homeostasis?

  - Carbon dioxide levels

  - Water levels

  - Blood sugar concentration

  - Urea concentration

  - Internal body temperature
• What are neurotransimtters and what do they do?

  They are chemicals that diffuse across synapses and bind to receptors on the next nerve cell.
• What are gaps between nerve cells called?

  Synapses.
• What are the 5 components of a reflex arc?

  1. Stimulus

  2. Receptor

  3. Nerve cells

  4. Effector

  5. Response
• What are the 5 components of a reflex arc? (hard)

  1. Receptor

  2. Sensory neurone

  3. Relay neurone

  4. Motor neurone

  5. Effector
• How are electrical impulses transported across between nerve cells?

  The arrival of the electrical impulse at the end of the nerve cell triggers the release of neurotransmitters, which diffuse across the synapse and bind to receptors on the next nerve cell. This triggers the production of an electrical impulse in the next nerve cell.
• What are 3 examples of reflex actions?


  Sneezing, blinking, dropping hot objects.
• What is a sense organ involved in a reflex coordinated by the spinal cord?

  The skin.
• What are the cerebellum, cerebral cortex and medulla responsible for?

  - The cerebellum is responsible for muscle coordination

  - The cerebral cortex is responsible for conscious thought

  -The medulla is responsible for unconscious activities
• Where are the cerebellum, cerebral cortex and medulla in the brain?

  Cerebral cortex is the top hemisphere, cerebellum is the part below at the back and the medulla is in the stem part.
• What is accomodation in the eye?

  The process of changing lens shape in order to focus on an object as its distance from the eye changes.
• What is hyperopia?


  Long-sightedness.
• What is myopia?


  Short-sightedness.
• What does short-sightedness mean?

  You can only see clearly at short distances.
• What is vasodilation?

  Widening of blood vessels near the surface of the skin to release heat loss through the blood.
• What is vasoconstriction?

  Narrowing of blood vessels near the surface of the skin to decrease heat loss through the blood.
• Which 3 things happen when body temperature becomes too high?

  Sweating, hairs lie flat, vasodilation.
• What is the technical term for body temperature control?

  Thermoregulation
• Which 3 things happen when body temperature becomes too low?

  Shivering, hairs stand on end, vasoconstriction.
• In what region of the brain are the receptors that detect internal body temperature?

  Thermoregulatory centre
• What are the 2 main difference between the central nervous system and the endocrine system?

  The CNS uses electrical impulses whereas the endocrine system uses hormones in the blood. The CNS is much faster.
• Which hormone does the pancreas release if there is too little glucose in the body?

  Glucagon
• Which hormone does the pancreas release if there is too much glucose in the body?

  Insulin
• How does kidney dialysis work?

  The patient's blood flows through the machine and passes over a partially permeable membrane which the dialysis fluid is on the other side of. This fluid contains the optimum concentrations of glucose and salts in a healthy person's blood. A concentration gradient is formed and excess ions and urea diffuse from the blood to the fluid.
• What are 2 risks of dialysis?

  Blood clots, infections.
• How is urine produced? (What is the function of the kidney?)

  The blood is filtered removing all water, urea and salts. Some water and some salts are reabsorbed into the bloodstream and all urea and the remaining water and salts form urine.
• What part of the brain monitors the volume of water in blood?

  The hypothalamus
• What do gibberellins do?


  Initiate seed germination.
• What does ethene do in plants?

  Controls cell division and ripening of fruits.
• What do auxins do?

  Change growth patterns to allow plants to move towards or away from a stimulus.
• What do auxins do in shoots and roots?

  - In roots, auxins prevent elongation of cells.

  - In shoots, auxins promote elongation of cells.
• Why can auxins be used as weed killers?

  They can make weeds grow so fast they use all their resources and die.
• What does meiosis produce?

  Four genetically non-identical daughter cells.