B1: Exchanging Substances

Question 1

gas exchange in the lungs

Answer 1

the job of the lungs is to transfer oxygen to the blood and to remove waste carbon dioxide ( to do this lungs contain little air sacs called alveoli)

Question 2

adaptations of alveoli to maximise diffusion

Answer 2

• enormous surface area
• moist lining for dissolving gases
• thin walls so diffusion path is short

Question 3

adaptations of the small intestine

Answer 3

• covered in small villi (so that digested food is absorbed much more quickly into the blood)
• large surface area
• one cell thick wall layer for quick absorption
• good blood supply to assist with absorption