gas exchange in bony fish

Question 1

explain gas exchange in fish

Answer 1

• the blood passes through capillaries in the gill plates
• oxygen passes through the gill plates into the capillaries
• blood vessels carry the oxygen away

Question 2

how do fish take in water

Answer 2

• the mouth opens
• the operculum closes the opening at the back of the pharynx
• the floor of the mouth cavity is lowered
• the volume of the mouth cavity increases
• the pressure of the mouth cavity decreases
• water moves into the mouth

Question 3

how do fish force water over their gills

Answer 3

• the mouth closes
• the floor of the mouth cavity is raised
• the volume of the mouth cavity decreases
• the pressure of the mouth cavity increases
• water falls out over the gills
• the operculum is forced open

Question 4

explain the counter current system

Answer 4

• the blood in the capillaries flow in the opposite direction to the water
• the blood will always encounter water with more oxygen in it
• leads to a small concentration gradient maintained across the whole surface