Organisation

• What is a tissue?

  A group of specialised cells with a similar structure and function
• What makes up all living things?

  Cells
• Can tissues be made of more than one type of cell?

  Yes
• Give an example of a type of tissue.

  Muscular tissue
• What are organs formed from?

  A number of different tissues working together
• What is an example of an organ?

  The stomach
• What do organ systems do?

  Work together to perform a certain function
• What organ system is the stomach part of?

  The digestive system
• What is the function of the digestive system?

  To break down food for absorption by cells
• What do glands in the digestive system produce?

  Digestive juices containing enzymes
• Where are soluble molecules absorbed in the digestive system?

  The small intestine
• What is the role of the stomach in digestion?

  Produces hydrochloric acid to kill bacteria and provide optimum pH for enzymes
• What does the liver produce that aids in digestion?

  Bile
• What is the function of the large intestine?

  Absorbs water from undigested food
• What is an enzyme?

  A biological catalyst that increases the rate of reaction without being used up
• Why is the shape of an enzyme important?

  Because each enzyme has a uniquely shaped active site for substrate binding
• What is the optimum temperature for most enzymes?

  Around 37 degrees Celsius
• What is the Lock and Key Hypothesis?

  The substrate shape is complementary to the active site shape, forming an enzyme-substrate complex
• What happens to enzymes at temperatures above their optimum?

  Their structure breaks down, changing the shape of the active site
• What is the optimum pH for most enzymes?

  7
• What is denaturation in enzymes?

  When the enzyme's active site changes shape and can no longer function
• What happens if the pH is too high or too low for an enzyme?

  The shape of the active site changes, leading to denaturation
• Why are enzymes vital in the digestive system?

  They break down molecules for absorption into the bloodstream
• What do carbohydrases convert carbohydrates into?

  Simple sugars
• What is an example of a carbohydrase?

  Amylase
• Where is amylase produced?

  In the salivary glands, pancreas, and small intestine
• What do proteases convert proteins into?

  Amino acids
• What is an example of a protease?

  Pepsin
• What do lipases convert lipids into?

  Fatty acids and glycerol
• Where are lipases produced?

  In the pancreas and small intestine
• What happens to soluble glucose, amino acids, fatty acids, and glycerol after digestion?

  They pass into the bloodstream to be carried to cells
• What is the purpose of the tests for carbohydrates, proteins, and lipids?

  To determine the composition of a solution
• What does Benedict's test indicate?

  The presence of sugars
• What color does iodine turn in the presence of starch?

  Blue-black
• What does the Biuret test indicate?

  The presence of proteins
• What is the emulsion test used for?

  To test for lipids
• What are the two roles of bile?

  Neutralises hydrochloric acid and emulsifies fats
• Why is bile alkaline?

  To neutralise the hydrochloric acid from the stomach
• What does emulsification do?

  Breaks down large drops of fat into smaller ones
• How can you investigate the effect of pH on an enzyme-controlled reaction?

  By carrying out a reaction at different pH levels and timing product formation