Exchange Surface

Question 1

Name an unicellular organism?Where it is it found?

Answer 1

An Amoeba, its found in ponds and marshes and such

Question 2

How does unicellular organism gain oxygen?

Answer 2

Diffusion

Question 3

Surface Area:Volume Ratio for unicellular and multicellular organisms?

Answer 3

unicellular = large surface area:low volume multicellular = small surface area : high volume

Question 4

common features of multicellular organisms for exchange surface? Examples?

Answer 4

incresed surface area-villi,roots hairs thin layers-Alveoli Good blood supply-Alveoli , gills, villi venilation-lungs

Question 5

Reason for thin layers?

Answer 5

shorter distance for substances to move

Question 6

Reason for good blood supply?

Answer 6

substances delivered and taken away quickly.

Question 7

Reason for ventilation?

Answer 7

maintain a concentration gradient

Question 8

How does control of breathing occur?

Answer 8

Chemoreceptors in the medulla sensitive to concentration of co2 in blood. If concentration is high, nerve impulses sent to the diaphragm to increase breathing rate. Lungs Expand, stretch receptors , send impulses to the expiratory centre. Inspiratiry centre switched off. Stretch receptors not stimulated, becomes inactive.