Exchange Surface

Question 1

Why do multicellular organisms need to gave specialised exchange surface?

Answer 1

Meet cellular needs as have high metabolic demands and SA:V gets smaller as organism gets bigger

Question 2

What makes a good exchange surface?

Answer 2

Short diffusion pathway

Good blood supply

Large SA

Ventilation

Question 3

Why can single celled organisms survive without specialised exchange system?

Answer 3

Have larger SA : V ratio so have short diffusion pathway directly to cells
Low metabollic activity

Question 4

How to work SA:V?

Answer 4

4piR2

divided by

4/3piR3

Question 5

How is naval cavity adapted?

Answer 5

Large SA and good blood supply = warm up blood

Hairy lining which secrete mucus to trap dust

Moist surface which increase humidity of air which reduce water loss

Question 6

Describe structure of trachea?

Answer 6

Incomplete rings of cartilage

Ciliated epithelium - cilia beat to move mucus

Goblet cells - produce mucus and secrete on to epithelium

Question 7

Which has incomplete rings of cartilage Bronchus or bronchioles?

Answer 7

Bronchus

Question 8

How do bronchioles control amount of air that reach lungs?

Answer 8

Have smooth muscle which can contract and dilate

Question 9

How are alveoli adapted?

Answer 9

Large SA

Squamous epithelial cells are only one cell thick = short diffusion pathway

Elastin which allows elastic recoil to they can return to original which squeezes air out

Good blood supply as surrounded by millions of capillaries

Good ventilation from lungs

Inner surface covered with surfactant allowing water to dissolve and then move into blood which keeps alveoli inflated