Fish Gas Exchange 2

In a fish counter-current flow system?

• The water and blood flow in the same direction.
• The water and blood flow in the opposite direction.

Blood flowing next to water in the opposite direction means the water?

• Has given up less of its oxygen and the blood is able to absorb more oxygen.
• Has given up most of its oxygen and the blood is able to absorb less oxygen.

Blood flow at the very end of the lamellae is reaching water flow at the beginning of the lamellae that is?

• High in dissolved oxygen
• Low in dissolved oxygen
• In an equilibrium of dissolved oxygen

The counter-current flow of water and blood ensures that?

• There is an equilibrium of oxygen between the blood and the water.
• There is a weak concentration gradient between the blood and the oxygen in the water.
• There is a strong concentration gradient between the blood and the oxygen in the water.

Ventilation of the gills combined with counter-current flow allows maximum extraction of oxygen from the water. This extraction value is?

• 10%
• 20%
• 50%
• 80%

A parallel current flow would not achieve the same oxygen extraction rates because?

• The concentrations across the gill would increase.
• The concentrations across the gill would decrease.
• The concentrations across the gill would equalise quickly.

The blood flow in the capillaries of the gills encounters water that is?

• Low in dissolved oxygen
• High in dissolved oxygen
• An equilibrium of dissolved oxygen
• Lacking in dissolved oxygen

The main challenges of the environment for fish gas exchange are?

• 1% dissolved oxygen in the water

• Detritus in the water clogging up gill filaments

• High energy demand for gas exchange

• Drink water to counter osmosis across the gill surface

• All the above

The main limitations of the fish gas exchange system are?

• Gills are permeable to water as well as gases

• Gill filaments need water to keep them separate and buoyant

• Both of the above