gaseous exchange DEFINITELY IN EXAM

Question 1

how are the lungs adapted for gaseous exchange

Answer 1

• large numbers of alveoli (sites of gaseous exchange) gives the lungs a large surface area

adaptations of the alveoli

• thin walls (short diffusion pathway)
• good blood supply from capillaries (maintains a concentration gradient)
• Good ventilation with air so that diffusion gradients can be maintained
• Alveoli are folded to increase their surface area to volume ratio

Question 2

adaption of the trachea

Answer 2

contain rings of cartilage to prevent the trachea from collapsing during inhalation

Question 3

how does breathing increase the rate of diffusion

Answer 3

breathing increases the rate of diffusion as breathing brings fresh oxygen into the alveoli and takes away the carbon dioxide