Biology Paper 2

• What is homeostasis?


  The regulation of the conditions inside your body and cells to maintain a stable internal environment for optimum function
• What is a stimulus?


  A change in the environment
• What is does a receptor do?

  Detect a stimulus
• What does the coordination centre do?

  Organise a response to the stimulus with information from the receptor
• What does an effector do?

  Produce a response to the stimulus which counteracts the change happening
• What are some examples of receptors?

  • taste
  • smell
  • sound
• What are the effectors?

  • muscles
  • glands
• What is negative feedback?


  When the level of something gets too high or too low, the body attempts to turn it back to normal automatically
• What does the body attempt to control with homeostasis?

  • blood glucose concentration
  • body temperature
  • water levels
• What is the order of nervous system responses?

  Stimulus → Receptor → Coordinator → Effector → Response
• What factors affect reaction time?

  • tiredness
  • distractions
  • caffeine
  • alcohol
• Why are reflex actions important?

  They protect the body from harm unconsciously
• What is the order of reaction through the CNS?

  Stimulus → Receptor → Sensory neurone → Motor neurone → Effector → Response
• What is a synapse?

  The gap between neurones which allows electrical impulses to cross between them
• How do electrical impulses travel across a synapse?

  The impulses diffuse from electrical to chemical back to electrical and set of a new signal in the next neurone
• What does a neurone do?

  Carry electrical impulses around the body
• What are reflexes?


  Automatic responses to stimuli that don't involve the conscious part of the brain (CNS)
• What is the order of reaction in a reflex reaction?

  Stimulus → Sensory neurone → Synapse → Relay neurone → Motor neurone → Effector
• What is the practical used to measure reaction time?

  The ruler drop
• How is the ruler drop practical carried out?

  1. Hold the ruler between the thumb and forefinger
  2. Let go without warning
  3. Measure and record the number where the ruler has been caught
  4. Repeat the practical with a caffeinated drink
• What is an independent variable?


  The variable being changed in the experiment
• What is a dependant variable?


  The variable being measured or tested during the experiment
• What is a control variable?

  The variable being kept the same throughout the experiment
• What are some control variables in the ruler drop practical?

  • same hand to catch the ruler
  • ruler dropped from the same height
  • volume of caffeine
• Why do computers give a more accurate reaction time?


  They remove the possibility of human error
• How does the body attempt to control temperature when it's too hot?

  • Hair lies flat
  • Sweat
  • Blood vessels dilate
• How does the body attempt to control temperature when it's too cold?

  • Hairs stand up
  • Shivering
• What are hormones?


  Chemical messengers released by glands into the blood and carried to target organs
• What are the glands?

  • Pituitary gland
  • Thyroid gland
  • Adrenal gland
  • Pancreas
  • Ovaries
  • Testes
• Why is the pituitary gland known as the 'master gland'?

  It secretes several hormones which affect many organs and bodily functions
• What does the pituitary gland do?

  • stimulate thyroid gland
  • stimulate the ovaries to release eggs
  • stimulates the testes to make sperm and testosterone
• What does the thyroid gland do?


  Control the rate of metabolism
• What does the pancreas do?

  Control blood glucose levels
• What do the adrenal glands do?

  • prepare the body for fight or flight
  • prepares the body for stress
• What do the ovaries do?

  • develop female secondary characteristics
  • control the menstrual cycle
• What do the testes do?

  • develop the male secondary characteristics
  • produce sperm
• What are the characteristics of nerves?

  • fast action
  • act for a short time
  • act in a precise area
• What are the characteristics of hormones?

  • slower action
  • act for a long time
  • act in a general way
• What is type 1 diabetes?

  When the pancreas can no longer produce insulin
• How can you treat type 1 diabetes?

  • insulin injections
  • diet control
  • exercise