topic 2 - organisation

• What is the main function of enzymes?

  Enzymes speed up chemical reactions
• What is the active site of an enzyme?

  The active site is a groove on the enzyme's surface where the substrate fits
• What is the substrate in an enzyme-catalyzed reaction?

  The substrate is the molecule that the enzyme reacts with
• What does the lock and key theory describe?

  It describes how the substrate must fit perfectly into the active site of the enzyme
• What happens to enzyme activity as temperature increases?

  Enzyme activity increases as temperature increases until it reaches the optimum temperature
• What is the optimum temperature for most human enzymes?

  37 degrees Celsius
• What occurs when the temperature exceeds the optimum for an enzyme?

  The enzyme activity rapidly decreases to zero and the enzyme becomes denatured
• What does it mean when an enzyme's active site is denatured?

  It means the shape of the active site has changed, preventing the substrate from fitting
• How does pH affect enzyme activity?

  Each enzyme has an optimum pH where activity is maximum, and extreme pH levels can denature the enzyme
• What is an example of an enzyme that works best at an acidic pH?

  A protease enzyme in the stomach
• What is an example of an enzyme that works best at an alkaline pH?

  A lipase enzyme released from the pancreas into the small intestine
• What are the effects of temperature on enzyme activity?

  • Enzyme activity increases with temperature until optimum
  • Optimum temperature for most human enzymes is 37
  • Beyond optimum, enzyme activity decreases and can lead to denaturation
• What are the effects of pH on enzyme activity?

  • Each enzyme has a specific optimum pH
  • Extreme pH levels can denature the enzyme
  • Example: Protease works best in acidic pH, Lipase works best in alkaline pH
• What is the circulatory system in fish like?

  • Single circulatory system
  • Deoxygenated blood is pumped to the gills
  • Blood collects oxygen and becomes oxygenated
  • Oxygenated blood goes to the organs
  • Blood returns to the heart
• What is a disadvantage of a single circulatory system in fish?

  Blood loses pressure as it passes through the gills, traveling slowly to the organs
• How does the double circulatory system in humans work?

  • Deoxygenated blood is pumped to the lungs
  • Blood collects oxygen in the lungs
  • Oxygenated blood returns to the heart
  • Heart pumps oxygenated blood to the organs
  • Blood transfers oxygen to body cells
• What is the benefit of the double circulatory system in humans?

  It allows blood to travel rapidly to body cells, delivering oxygen efficiently
• What are the four chambers of the human heart?

  • Left atrium
  • Right atrium
  • Left ventricle
  • Right ventricle
• What separates the atria from the ventricles in the heart?

  Valves
• Why does the heart appear back to front in diagrams?

  Diagrams show the heart as if viewed from a person’s perspective
• What are the four main blood vessels associated with the heart?

  • Vena cava
  • Pulmonary artery
  • Pulmonary vein
  • Aorta
• What does the vena cava do?

  It brings deoxygenated blood from the body to the heart
• What is the function of the pulmonary artery?

  It carries deoxygenated blood from the heart to the lungs
• What happens to blood in the lungs?

  It collects oxygen and becomes oxygenated
• What is the role of the pulmonary vein?

  It carries oxygenated blood from the lungs to the heart
• What does the aorta do?

  It pumps oxygenated blood from the heart to the body
• What is the pattern of blood flow through the heart?

  1. Blood enters the left and right atria
  2. Atria contract, forcing blood into the ventricles
  3. Ventricles contract, forcing blood out of the heart
  4. Valves prevent backflow into the atria
• Why does the left side of the heart have a thicker muscular wall than the right side?

  Because the left ventricle pumps blood around the entire body, requiring greater force
• What are coronary arteries and their function?

  Coronary arteries branch from the aorta and supply oxygen to the heart muscle cells
• What is the purpose of oxygen in the heart muscle cells?

  It is used in respiration to provide energy for contraction
• What controls the natural resting heart rate?

  A group of cells found in the right atrium called the pacemaker
• What happens if the pacemaker stops working correctly?

  Doctors can implant an artificial pacemaker to correct irregularities in heart rate
• What is an artificial pacemaker?

  • A small electrical device
  • Corrects irregularities in heart rate
• What are cardiovascular diseases?

  Diseases of the heart and blood vessels
• What is a key feature of cardiovascular diseases?

  They are non-communicable and cannot be passed from person to person
• What is an example of a cardiovascular disease?

  Coronary heart disease
• What is the function of the coronary arteries?

  To provide oxygen to the muscle cells of the heart
• How is oxygen used in the heart muscle?

  It is used in respiration to provide energy for contraction
• What happens in coronary heart disease?

  Layers of fatty material build up inside the coronary arteries, narrowing them
• What is the effect of narrowed coronary arteries?

  It reduces the flow of blood and causes a lack of oxygen for the heart muscle