Organisation

• Name the five levels of organisation in living organisms.

  Cells - Tissues - Organs - Organ systems - Organism
• What is a tissue?

  A tissue is a group of similar cells working together.
• What is an organ?

  An organ is a group of different tissues preforming specific functions.
• What is an organ system?

  An organ system is a group of different organs performing a specific function.
• What is digestion?

  The breakdown of large food molecules into smaller molecules which are then absorbed into blood.
• What is mechanical digestion?

  Mechanical breakdown of food into smaller pieces e.g. by the teeth.
• What is chemical digestion?

  Breaking down of larger molecules into smaller molecules by enzymes.
• Name the organs involved in the digestive system.

  Oesophagus, Stomach, Pancreas, Gall bladder, small intestines, large intestines, rectum.
• What is the function of the stomach?

  Organ which mixes and breaks down food by contracting and relaxing muscles.
• What is the function of the liver?

  Organ which makes and secretes bile.
• What is the function of the pancreas?

  Organ which makes and secretes digestive enzymes.
• What is the function of the small intestines?

  Organ where digested food is absorbed into the blood.
• What is the function of the large intestines?

  Organ which re-absorbs water from food.
• What is the function of bile in digestion?

  Neutralises hydrochloric acid from the stomach and emulsifies fat to form small droplets with a large surface area.
• What is the function of saliva in digestion?

  Lubrication to help swallowing - contains amylase to break down starch.
• What is an enzyme?

  A biological catalyst that breaks molecules down into smaller molecules.
• What is the name of the enzyme that breaks down carbohydrates?

  Carbohydrase (e.g. amylase).
• Where is this enzyme made?

  Salivary glands, pancreas and small intestine.
• Where does this enzyme act?

  Mouth, stomach, small intestine.
• What is carbohydrate broken down into?

  Starch.
• What is the name of the enzyme that breaks down protein?

  Protease.
• Where is this enzyme made?

  Protease is produced in the small intestine, stomach and pancreas.
• Where does this enzyme act?

  Stomach and small intestine.
• What is protein broken down into?

  Amino acids.
• What is the name of the enzyme that breaks down lipids?

  Lipase
• Where is this enzyme made?

  Lipase is made in the small intestine and pancreas.
• Where does this enzyme act?

  Small intestine.
• What are lipids broken down into?

  Glycerol and fatty acids.
• Explain the lock and key model for enzyme activity.

  The enzyme is the ‘lock’ and the substrate is the ‘key’. When the substrate bonds with the substrate this forms an enzyme-substrate complex. Only a specific key (substrate) will fit into the lock (active site of enzyme).
• What factors affect enzyme activity?

  pH, temperature.
• What does denaturing mean?

  When an enzyme is denatured it loses its shape, the active site can no longer bind to the substrate and no enzyme-substrate complexes are formed.
• What is the food test for starch?

  Iodine.
• What is a positive result for testing for starch?

  Blue-black.
• What is the food test for sugar?

  Benedict's.
• What is a positive result for testing for sugar?

  Red.
• What is the foot test for protein?

  Biuret.
• What is a positive result for testing for protein?

  Pink/purple.
• What is the food test for lipids?

  Ethanol.
• What is a positive result for testing for lipids?

  Cloudy layer.
• What are the adaptations of the villi for digestion?

  Large surface area, good blood supply, thin walls.