Human and animal exchange surfaces B3

Question 1

How is the effectiveness of an exchange surface increased?

Answer 1

Large surface area

Thin walls –> Short diffusion path

(animals), efficient blood supply

(in animals, for gaseous exchange) being ventilated

Question 2

What increases the difficulty of exchanging materials?

Answer 2

Size + complexity of an organism

Question 3

Describe gaseous exchange in the lungs

Answer 3

Oxygen absorbed

Carbon dioxide removed

Question 4

What is the role of alveoli (air sacs)?

Answer 4

Increasing the surface area of the lungs

Question 5

How is a steep diffusion gradient maintained in the lungs?

Answer 5

Ventilated

Steep diffusion gradient

Question 6

Describe gaseous exchange in the alveoli

Answer 6

Oxygen diffuses into capillaries around alveoli. Air > Lung > Bloodstream

Carbon dioxide diffuses into lungs to be breathed out. Bloodstream > Lung > Air

Question 7

What are solutes?

Answer 7

Soluble food matrials

Question 8

What is the role of villi?

Answer 8

Increasing surface area of small intestine

Exchange surface for food molecules

Question 9

What are solutes?

Answer 9

Soluble food materials

Question 10

What happens in the small intestine?

Answer 10

Solute are absorbed into blood

Question 11

Why is the villi a good exchange surface?

Answer 11

Large surface area

Extensive network of capillaries –> absorb products of digestion by diffusion and active transport.