Organisation

• What is the basic unit from which all living organisms are made?

  A cell
• What defines a tissue?

  A tissue is a group of cells with a similar structure and function.
• What is an organ?

  An organ is a group of tissues performing a specific function.
• What is an organ system?

  An organ system is a group of organs working together to carry out a function.
• What is an organism?

  An organism is a group of organ systems working together.
• What are the main components of the digestive system?

  • Mouth
  • Oesophagus
  • Stomach
  • Small intestine
  • Large intestine
  • Rectum
• How does food get broken down in the mouth?

  Food is broken into small pieces by the teeth and lubricated by saliva.
• What happens to food in the oesophagus?

  Food is squeezed down into the stomach.
• What role do enzymes play in the stomach?

  Enzymes break down food, and the food is churned in the stomach.
• What occurs in the small intestine?

  Enzymes continue to break down food, and nutrients are absorbed into the blood.
• What is the function of the large intestine?

  Water is absorbed from remaining food, and food waste is taken to the rectum.
• What happens in the rectum?

  Waste is stored here until it leaves the body.
• What is an enzyme?

  An enzyme is a biological catalyst that speeds up reactions without being changed or used up.
• What is the structure of enzymes?

  Enzymes are protein molecules made of a chain of amino acids folded into a unique shape.
• What is the active site of an enzyme?

  The active site is the part of the enzyme that has a specific shape that fits onto the substrate involved in a reaction.
• What does the lock and key model illustrate?

  The lock and key model illustrates how substrates fit into the active site of enzymes.
• What happens when an enzyme is denatured?

  If the shape of the active site changes, the enzyme can no longer bind to the substrate and cannot catalyse the reaction.
• What is the optimum temperature for enzyme activity?

  The optimum temperature is where the enzyme activity is highest.
• What happens to enzyme activity above the optimum temperature?

  The rate of reaction decreases because the enzyme denatures.
• How does temperature affect enzyme action?

  Initially, as temperature increases, the rate of reaction increases due to more energy in enzymes and substrates.
• What is the optimum pH for enzyme activity?

  The optimum pH is where enzymes are most active.
• What happens to enzymes on either side of the optimum pH?

  Enzymes denature, and the rate of reaction decreases.
• Why do we need digestive enzymes?

  • To break down large, complex molecules into small molecules
  • Only small molecules can pass through the walls of the small intestine
• What are the digestive enzymes and their functions?

  • Complex carbohydrates (e.g., starch) → Simple carbohydrates (e.g., sugars) by Carbohydrase (e.g., amylase)
  • Protein → Amino acids by Protease
  • Lipid → Glycerol and fatty acids by Lipase
• Where is bile produced and stored?

  Bile is produced in the liver and stored in the gallbladder.
• What are the two main functions of bile?

  Bile neutralizes stomach acid and emulsifies lipids.
• What is the procedure for testing for sugar using Benedict's Test?

  1. Mix powdered food with water in a test tube.
  2. Add an equal volume of Benedict's reagent.
  3. Heat in a water bath.
  4. Positive test: changes from blue to brick red.
• What is the procedure for testing for starch using the Iodine Test?

  1. Add a few drops of iodine solution to the food.
  2. Positive test: changes from brown to blue-black.
• What is the procedure for testing for protein using the Biuret Test?

  1. Mix powdered food with water in a test tube.
  2. Add an equal amount of Biuret reagent.
  3. Positive test: changes from blue to violet.
• What is the procedure for testing for fats using the Emulsion Test?

  1. Mix powdered food with ethanol in a test tube.
  2. Shake vigorously and allow to settle.
  3. Pour the liquid into another test tube half-filled with water.
  4. Positive test: changes from clear to white.
• What is gas exchange?

  Gas exchange is the exchange of oxygen and carbon dioxide in the alveoli.
• What is the equation for respiration?

  Glucose + Oxygen → Carbon dioxide + Water
• What happens during inhalation?

  The intercostal muscles contract, pushing the ribs up and out, and the diaphragm lowers, increasing chest volume and decreasing pressure.
• What happens during exhalation?

  The intercostal muscles relax, pushing the ribs down and in, and the diaphragm raises, decreasing chest volume and increasing pressure.
• How do inhalation and exhalation differ in terms of muscle action?

  Inhalation involves contraction of intercostal muscles and diaphragm, while exhalation involves their relaxation.
• What is the primary function of the heart?

  To pump blood throughout the body
• What type of blood does the right side of the heart carry?

  Deoxygenated blood
• What type of blood does the left side of the heart carry?

  Oxygenated blood
• What are the main components of the heart?

  • Made mostly of muscle
  • Contains two chambers: atrium (top) and ventricle (bottom)
• How does the heart pump blood?

  By contracting its muscles to squeeze blood out of the chambers