B2 - Organisation

• What do we call similar cells that are connected?

  Tissue
• What do tissues form in the body?

  Organs
• What is an example of an organ?

  Your heart
• What do organs work together to form?

  Organ systems
• What does the digestive system do?

  Breaks down food into nutrients
• What breaks down food in the stomach?

  Acid
• What works together in the small intestine to break down food?

  Bile and enzymes
• Where is bile made?

  Liver
• What is the function of bile?

  Neutralizes stomach acid and emulsifies fats
• What do enzymes do?

  Act as biological catalysts
• What is amylase?

  An enzyme that breaks down starch
• Where is amylase found?

  Small intestine and saliva
• What is the specificity of enzymes?

  They only break down certain molecules
• What do carbohydrases break down?

  Carbohydrates into simple sugars
• What do proteases break down?

  Proteins into amino acids
• What do lipases break down?

  Fats into glycerol and fatty acids
• What principle do enzymes operate on?

  Lock and key principle
• What happens when the substrate binds to the enzyme's active site?

  A complex is formed
• What is required for the substrate to fit the active site?

  The right shape
• What happens to enzyme activity as temperature increases?

  It increases until denaturation occurs
• What is denaturation?

  Change in enzyme shape preventing binding
• What is the optimum temperature for enzyme activity?

  The temperature at which activity is highest
• How does pH affect enzyme activity?

  It can denature enzymes at extremes
• What is the practical method to test enzyme activity with starch?

  1. Mix amylase with starch at different temperatures or pH.
  2. Start timing and remove drops every 10 seconds.
  3. Use iodine to test for starch presence.
  4. Record the time until iodine stays orange.
  5. Plot times against pH or temperature.
  6. Identify optimum conditions from the graph.
• What color does iodine turn in the presence of starch?

  Black
• What color does Benedict's solution turn in the presence of sugars?

  Orange
• What color does Biuret's reagent turn in the presence of proteins?

  Purple
• What happens to cold ethanol in the presence of lipids?

  It turns cloudy
• What is the role of the respiratory system?

  Facilitates breathing and gas exchange
• What is the difference between breathing and respiration?

  Breathing provides oxygen for respiration
• What is the pathway of air during breathing?

  Trachea, bronchi, bronchioles, alveoli
• What happens in the alveoli?

  Gas exchange occurs with blood vessels
• What binds to hemoglobin in red blood cells?

  Oxygen
• What happens to carbon dioxide produced from respiration?

  It diffuses into the lungs and is exhaled
• What is the heart's role in the circulatory system?

  It pumps blood throughout the body
• What type of circulatory system do humans have?

  Double circulatory system
• How many times does blood enter the heart in a double circulatory system?

  Twice
• What vein carries deoxygenated blood into the heart?

  Vena cava
• What prevents backflow of blood in the heart?

  Valves
• Where does deoxygenated blood go after the right atrium?

  Right ventricle