gas exchange in fish

Question 1

describe ventillation in bony fish

Answer 1

mouth opens and floor of buccan cavity lowers
volume of buccal cavity increases and pressure is lowered inside buccal cavity
water flows in due to pressure difference

mouth closes and floor of buccal cavity raises
water is forced over the gills
pressure in gill cavity increases
this forces open the opperculum and water is forced out

Question 2

what type of fish does parallel flow occur in?

Answer 2

cartilaginous fish e.g sharks

Question 3

what is parallel flow?

Answer 3

blood and water flow in the same direction across the gill plates
blood with low oxygen coming from the body is in contact with water with high oxygen coming through the mouth
oxygen diffuses into the blood until equilibrium is reached
there is only 50% saturation of 02

Question 4

what type of fish does counter current flow occur in?

Answer 4

bony fish

Question 5

why is counter current flow more efficient than parallel flow?

Answer 5

in parallel flow equilibrium is reached across the gill plates so the concentration gradient is not maintained
whereas in counter current flow equilibrium is not reached so concentrationn gradient is maintained

in parallel flow there is a LOWER saturation of oxygen

Question 6

is counter current flow or parallel flow more efficient ?

Answer 6

counter current flow

Question 7

why would gill filaments not be an efficient gas exchange surface on land?

Answer 7

gills would dry out so it would prevent oxygen from dissolving on surface of gills

gills may stick together and not open as easily which would decrease the surface area

Question 8

how are gill filaments and adaptation to gas exchange?

Answer 8

they increase the surface area and diffusion takes place over the whole area