Notes

• What is the reason for the need for specialized exchange surfaces in organisms?

  As the size of the organism and its surface area to volume ratio increases.
• Why can single-celled organisms easily exchange substances?

  Because the distance that needs to be crossed is short.
• What is a consequence of a higher surface area to volume ratio in multicellular organisms?

  They require specialized exchange surfaces for efficient gas exchange.
• What are two features of an efficient exchange surface?

  Large surface area and thin structure.
• Why is a good blood supply or ventilation important for exchange surfaces?

  To maintain a steep concentration gradient.
• What is the surface area to volume ratio like in fish?

  Fish have a small surface area to volume ratio for gas exchange.
• Why can't gases diffuse through the skin of fish?

  Because fish have an impermeable membrane.
• How many pairs of gills do bony fish have?

  Four pairs of gills.
• What are gill filaments and lamellae in fish?

  Gill filaments are projections along the gill arches, with lamellae participating in gas exchange.
• How does the counter current flow in fish gills benefit gas exchange?

  It maintains a steep diffusion gradient for oxygen to diffuse into the blood.
• What happens to the gill projections when fish are out of water?

  They stick together, making it difficult for fish to survive.
• What initiates the ventilation process in fish?

  The fish opens its mouth and lowers the floor of the buccal cavity.
• How does the operculum function in fish ventilation?

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

  Through spiracles and trachea or tracheoles.
• What role do spiracles play in insects?


  They are small openings that allow gases to enter and exit the insect's body.
• How do gases move in and out of the insect's body?

  Through diffusion and mass transport due to muscle contraction.
• What adaptations do plants have for efficient gas exchange?

  Leaves have stomata and air spaces for gas movement.
• What is the function of stomata in plant leaves?

  They allow gases to enter and exit the leaves.
• How do air spaces in leaves facilitate gas exchange?

  They allow gases to move around and contact mesophyll cells.
• What are the lungs and where are they located?

  The lungs are lobed structures located in the chest cavity.
• What role does the rib cage play in relation to the lungs?

  It 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 inflation and deflation.
• What muscles are involved in the ventilation process of mammals?


  External and internal intercostal muscles and the diaphragm.
• How does air enter the lungs?

  Through the nose, trachea, bronchi, and bronchioles.
• What is the primary site of gaseous exchange in mammals?

  The walls of the alveoli.
• What keeps the airways open in the trachea and bronchi?

  Rings of cartilage.
• 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?

  They are composed of cartilage, glandular and connective tissue, elastic fibres, smooth muscle, and blood vessels.
• What is the role of ciliated epithelium in the respiratory system?

  To move mucus along and prevent lung infection.
• What do goblet cells do in the respiratory system?

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

  It constricts the airway, controlling its diameter and airflow.
• What is the function of elastic fibres in the respiratory system?

  They stretch when we exhale and recoil when we inhale, controlling airflow.
• What is ventilation composed of?

  Inspiration and expiration.
• What happens during inspiration in terms of muscle contraction?

  The external intercostal muscles contract and the diaphragm flattens.
• How does the pressure change in the thorax during inspiration?

  The pressure decreases as the volume increases.
• What occurs during expiration in terms of muscle contraction?

  The internal intercostal muscles contract and the diaphragm relaxes.
• 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 each breath at rest.
• How is breathing rate calculated using a spirometer?

  By counting the number of peaks or troughs in a minute.