Alevel biology - Module 3 - exchange surfaces

• Why do multicellular organisms require specialized exchange surfaces?

  Because their surface area to volume ratio decreases as size increases.
• How do single-celled organisms exchange substances?

  They can easily absorb substances due to a short distance to cross.
• What is a key feature of efficient exchange surfaces?

  A large surface area is essential for efficient exchange.
• What is an example of a structure with a large surface area?

  Root hair cells.
• Why should an exchange surface be thin?

  To ensure that the distance substances need to cross is short.
• What role does a good blood supply or ventilation play in exchange surfaces?

  It maintains a steep concentration gradient for efficient exchange.
• What are the lungs primarily responsible for?

  Gas exchange in mammals.
• What protects the lungs in the chest cavity?

  The rib cage protects the lungs.
• What is the function of the lubricating substance secreted around the lungs?

  To prevent friction between the rib cage and lungs during breathing.
• What is the role of the diaphragm in respiration?

  It separates the lungs from the abdominal area and aids in breathing.
• How does air enter the lungs?

  Air enters through the nose, trachea, bronchi, and bronchioles.
• Where does gaseous exchange occur in the lungs?

  In the walls of the alveoli.
• What keeps the airways open?

  Rings of cartilage help keep the airways open.
• How do the trachea and bronchi differ?

  Bronchi are narrower than the trachea.
• What is the composition of the wall of the trachea and bronchi?

  The wall is mostly composed of cartilage and several layers of tissue.
• What type of epithelium lines the inner surface of the trachea and bronchi?

  Ciliated epithelium.
• What is the function of goblet cells in the respiratory system?

  They secrete mucus to trap bacteria and dust.
• How do smooth muscles contribute to the respiratory system?

  They control the diameter of the airways, regulating airflow.
• What is the role of elastic fibers in the respiratory system?

  They stretch during inhalation and recoil during exhalation.
• What are the two stages of ventilation in mammals?

  • Inspiration: Air enters the lungs.
  • Expiration: Air is expelled from the lungs.
• What happens during inspiration in terms of muscle contraction?

  The external intercostal muscles contract while the internal ones relax.
• What is the effect of diaphragm contraction during inspiration?

  It causes the diaphragm to flatten, increasing thoracic volume.
• What occurs during expiration in terms of muscle activity?

  The internal intercostal muscles contract while the external ones relax.
• What is a spirometer used for?

  To measure lung volume.
• What is vital capacity?

  The maximum volume of air that can be inhaled or exhaled in a single breath.
• What is tidal volume?

  The volume of air breathed in and out at rest.
• How is breathing rate calculated using a spirometer?

  By counting the number of peaks or troughs in a minute.
• What is residual volume?

  The volume of air always present in the lungs.
• What is inspiratory reserve volume?

  The additional volume of air that can be inhaled beyond tidal volume.
• What is expiratory reserve volume?

  The additional volume of air that can be exhaled beyond tidal volume.
• Why do fish need specialized exchange surfaces?

  Because they have a small surface area to volume ratio and an impermeable membrane.
• How many pairs of gills do bony fish have?

  Four pairs of gills.
• What is the function of gill filaments in fish?

  They participate in gas exchange.
• How does blood and water flow across the lamellae in fish gills?

  They flow in a counter current direction.
• What happens to gill filaments when fish are out of water?

  They stick together, preventing gas exchange.
• What initiates ventilation in fish?

  Opening the mouth and lowering the floor of the buccal cavity.
• What role does the operculum play in fish ventilation?

  It acts as a valve and pump to let water in and out.
• How do insects transport oxygen to their tissues?

  Through spiracles and tracheal tubes.
• What is the function of tracheal fluid in insects?

  It allows gases to dissolve and diffuse into cells.
• How do spiracles help insects manage water loss?

  They can be opened and closed to avoid excessive water loss.