B2

• Define cells


  basic building block of all living organisms
• define tissues


  a group of cells with a similar function
• define organs


  a group of tissues that works together to form a function
• define systems


  a group of organs which perform a particular function
• deine organism


  group of organ systems working together
• What happens in mouth?

  • Mechanical digestion- teeth break down food into smaller pieces (increasing surface area)
  • Chemical digestion- amylase digests starch into glucose
• What happens in the oesophagus?

  peristalsis

  muscles contract the mixture of food and saliva to push food through the oesophagus to stomach
• What happens in stomach?

  HCl- kills bacteria, creates right conditions for enzymes to work

  Mucus stomach lining- protects wall of stomach from HCl, gap causes stomach ulcer

  Mechanical digestion- walls churn down the food

  Chemical digestion- pepsin digests protein into peptides, enzymes digest large insoluble molecules into soluble molecules to be absorbed into blood
• Define what happens in bile?

  neutalises the stomach

  emulsifies fats which increases surface area
• In the small intestine...

  all digestible molecules are now soleuble and can be absorbed through walls of small intestine into blood by diffusion
• What is the role of the pancreas?

  make all enzymes and released into small intestine
• What happens in large intestine?

  waste is removed to rectum then anus

  remaining water absorbed into bloodstream
• What are enzymes?


  they are biological catalysts
• What are enzymes made of?

  protein
• What is an example of carbohydrase

  amylase
• what does carbhydrase break down?

  starch into glucose
• where is carbohydrase made in?

  pancreas, small intestine, salivary gland
• What is an example of protease?

  pepsin and trypsin
• what does protease break down?

  protein into amino acids
• where is protease made in?

  small intestine, pancreas, stomach
• what does lipase break down?

  fats into fatty acids and glycerol
• where is lipase made in?


  small intestine, pancreas
• What is a substrate?

  a substance that is broken down by an enzyme
• where does a substrate bind to an enzyme?

  active site
• why are enzymes specific?

  each enzyme has a complementary shape of the active site that can bind to one type of substrate?
• Where do enzymes work best?

  optimum conditions of pH and temp
• Lock and key theory

  1 only one type of substrate binds to complimentary shape of active site

  2 bonds break in the substrate

  3 2 smaller products are released
• Define denature


  When an enzyme cannot work because its active site has lost its specific shape so the substrate no longer fits
• What causes enzymes to denature?

  Extreme heat (above 40oC) and extreme pH
• What is the purpose of digestion?

  To break down large insoluble molecules into small soluble molecules so they can be absorbed into the bloodstream
• Where is bile made?

  liver
• Where is bile stored?

  gall bladder
• Why must hydrochloric acid from the stomach be neutralised by bile in the small intestine?

  so that enzymes arent denatured
• What equipment is used to control temperature in an investigation?

  water bath
• What is the structure of the lungs?

  trachea, bronchus alveoli, bronchioles
• What side of the heart is thicker and why?

  left because it has to pump blood at a higher pressure to all parts of the body
• What are blood vessels made up of?

  artery, vein, capillary
• What are the features of an artery?

  small lumen, thick outer wall, smooth lining, thick layer of muscles and elastic fibres
• What is the role of the artery?

  take blood away from the heart and it is thick to cope with high pressures of blood
• What are the features of a vein?

  large lumen, thin outer wall, smooth lining, thin layer of muscles and elastic fibres