Miss Estruch Summary

• Why is surface area to volume ratio important for organisms?

  It affects efficiency of substance transport
• How does the size of an organism relate to its surface area to volume ratio?

  Larger organisms have a smaller ratio
• What is the surface area of a cube with side length 1 cm?

  6 cm squared
• What is the volume of a cube with side length 1 cm?

  1 cm cubed
• How do you calculate the surface area to volume ratio of a cube?

  Divide surface area by volume
• What is the surface area to volume ratio of a cube with a surface area of 6 cm squared and volume of 1 cm cubed?

  6:1 ratio
• What happens to the surface area to volume ratio as an organism increases in size?

  It decreases
• Why do small organisms like amoebas not need specialized exchange systems?

  They can exchange substances directly across their surface
• How do smaller mammals maintain body temperature in cold environments?

  By having a high metabolic rate
• What adaptations do larger organisms have for gas exchange?

  Increased surface area at exchange surfaces
• What is the definition of breathing?

  Movement of air into and out of lungs
• What is the scientific term for breathing?

  Ventilation
• How does respiration differ from breathing?

  Respiration is a chemical reaction
• What is gas exchange?

  Diffusion of gases across a surface
• What are the three features of gas exchange surfaces?

  Large surface area, short diffusion distance, concentration gradient
• What are the five structures of the human gas exchange system?

  Alveoli, bronchioles, bronchi, trachea, lungs
• What happens to the diaphragm during inhalation?

  It contracts and moves down
• What is the role of the external intercostal muscles during inhalation?

  They contract to pull rib cage up
• What happens to air pressure in the lungs during inhalation?

  It decreases
• What is the tidal volume?

  Volume of air inhaled or exhaled in one breath
• What is the equation for pulmonary ventilation?

  Tidal volume times ventilation rate
• What is the adaptation of alveoli for gas exchange?

  Large surface area due to many alveoli
• How is a short diffusion distance achieved in alveoli?

  Single layer of epithelial cells
• How is the concentration gradient maintained in alveoli?

  Surrounded by a network of capillaries
• What is the challenge fish face regarding oxygen in water?

  Less oxygen dissolved in water than air
• What are gills made up of?

  Stacks of gill filaments
• What is the function of lamelli in fish gills?

  Site of gas exchange
• How does water flow over fish gills?

  Water rushes in through the mouth
• What is the countercurrent flow mechanism in fish?

  Blood and water flow in opposite directions
• Why is the countercurrent flow mechanism advantageous?

  It maintains a diffusion gradient
• What is the role of spiracles in terrestrial insects?

  They allow gases to enter and leave
• What structures make up the tracheal system in insects?

  Trachea, tracheoles, spiracles
• How do spiracles function in gas exchange?

  They can open and close like stomata
• What is the advantage of the exoskeleton in terrestrial insects?

  Protection and prevention of water loss
• What is the disadvantage of the exoskeleton for gas exchange?

  Reduces space for gas exchange
• What is the role of tracheoles in the tracheal system?

  Transport gases directly to tissues
• How do insects achieve gas exchange without lungs?

  Through the tracheal system
• What is the significance of having a high surface area to volume ratio in small organisms?

  It allows efficient gas exchange
• Why do larger animals have a lower metabolic rate compared to smaller mammals?

  They have a smaller surface area to volume ratio
• What adaptations do fish have to maximize gas exchange?

  Gills with lamelli and countercurrent flow