B3

• What is the primary function of gas exchange in organisms?

  To bring gases in and out of the organism
• Why do aquatic organisms also need gas exchange?

  Because they still bring gases in and out while living underwater
• What is a type 1 pneumocyte?

  A cell that makes up part of the alveoli in the lungs
• What are the common characteristics of gas exchange surfaces?

  • Very thin to decrease diffusion distance
  • Permeable to gases
  • Large surface area to volume ratio
  • Moist covering to facilitate gas diffusion
• How does moisture affect gas exchange?

  It allows gases to diffuse more easily when dissolved in solution
• What is diffusion in the context of gas exchange?

  The passive movement of molecules from high to low concentration
• What drives the diffusion process in gas exchange?

  The concentration gradient between areas of high and low concentration
• How do unicellular organisms maintain a concentration gradient for gas exchange?

  By consuming oxygen, which keeps its concentration low
• What are the components of the mammalian respiratory system?

  1. Mouth
  2. Trachea
  3. Bronchi (singular: bronchus)
  4. Bronchioles
  5. Alveoli
  6. Lungs
  7. Diaphragm
• What is the function of the diaphragm in respiration?

  To contract and expand the chest cavity for breathing
• What happens to the diaphragm during inhalation?

  It contracts and flattens
• What is the role of type 2 pneumocytes?

  To produce surfactant that reduces surface tension in alveoli
• What is surfactant and its function in the alveoli?

  A substance that reduces surface tension and prevents alveoli from collapsing
• How does ventilation maintain a high concentration of oxygen in the alveoli?

  By inhaling fresh air to replace used air
• What occurs during exhalation?

  The diaphragm relaxes and the chest cavity volume decreases
• What are the key lung volumes in respiration?

  • Tidal Volume (TV): Volume of air inhaled/exhaled in each breath
  • Inspiratory Reserve Volume (IRV): Additional air that can be inhaled after a normal breath
  • Expiratory Reserve Volume (ERV): Additional air that can be exhaled after a normal breath
  • Vital Capacity (VC): Total maximum amount of air the lungs can hold
• What is a spirometer used for?

  To measure lung volumes and ventilation rate
• How can lung volumes be measured without a spirometer?

  By using a bell jar filled with water to measure air displacement
• What happens to the water level in a bell jar when air is exhaled into it?

  The water level decreases as air bubbles are produced