1.4 - Exchanging materials - the lungs

Question 1

What is the purpose of exchange surfaces?

Answer 1

Large, complex organisms have exchange surfaces to obtain all the food and oxygen they need

Question 2

What exchange surface in the human body is used to absorb food?

Answer 2

The intestine absorbs soluble food molecules (solutes)

Question 3

What is the purpose of the lungs as an exchange surface?

Answer 3

To absorb oxygen and remove carbon dioxide

Question 4

What are three features of an efficient exchange surface?

Answer 4

• a large surface area
• thin walls or a short diffusion path
• an efficient transport system

Question 5

What is the transport system for exchange surfaces in animals?

Answer 5

The blood supply

Question 6

What type of exchange surface do the lungs contain?

Answer 6

A gaseous exchange surface

Question 7

How do the lungs effectively exchange materials? (3)

Answer 7

• The surface area is increased by alveoli (air sacs)
• The alveoli have thin walls, a large surface area and a good blood supply
• The lungs are well-ventilated to maintain a steep concentration gradient

Question 8

What happens to oxygen and carbon dioxide in the lungs?

Answer 8

• Oxygen diffuses into the many capillaries surrounding the alveoli
• Carbon dioxide diffuses back out into the lungs to be breathed out