B3 Questions

• Name the five levels of organisation.

  cells, tissue, organ, organ system, organism
• What is a tissue?

  Group of cells with similar structures and functions
• What is and organ?

  group of tissues working together to perform a specific function.
• What is the function of the liver in digestion?

  Produces bile, which 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.
• Name three enzymes produced in the pancreas.

  Amylase, protease, lipase
• What are enzyme?


  Protein molecules that catalyse specific reactions in organisms.
• Why are enzymes described as specific?

  Each enzyme only catalyses a specific reaction, because the active site only fits together with certain substrates (like a lock and key).
• Describe the function of amylase.

  To break down starch in glucose.
• Where is amylase produced?

  Salivary glands, pancreas, and small intestine.
• Describe the function of proteases.


  To break down proteins into amino acids.
• Where are protease produced?

  Stomach, pancreas, and small intestine.
• Describe the function of lipases.


  To break down lipids into fatty acids and glycerol.
• Where are lipases produced?

  Pancreas and small intestine.
• What are two factors that affect the rate of activity of an enzyme?

  Temperature and pH.
• What does denatured mean?

  Shape of an enzyme's active site is changed by high temperatures or an extreme pH, so it can no longer bind with the substrate.
• Describe the effect of temperature on enzyme activity.

  As temperature increases, rate of reaction increases until it reaches the optimum for enzyme activity- above this temperature enzyme activity decreases and eventually stops.
• Describe the effect of pH on enzyme activity.

  Different enzymes have a different optimum pH at which their activity is greatest- a pH much lower or higher than this enzyme activity decreases and stops.
• Why different digestive enzymes have a different optimum pHs?

  Different parts of the digestive system have very different pHs- the stomach is strongly acidic, and the pH in the small intestine is close to neutral.
• What is and organ system?

  A group of organs working together to perform a specific function.