Fish

Question 1

Why do sharks die if they stop swimming?

Answer 1

Water must flow constantly to maintain a concentration gradient for the exchange of oxygen and carbon dioxide

Question 2

How do fish get their oxygen?

Answer 2

From the water via gill filaments

Question 3

What helps increase the SA of gill filaments?

Answer 3

They’re stacked to increase SA and have thin walls to reduce the diffusion pathway. Lamellae help to increase SA.

Question 4

What is countercurrent flow?

Answer 4

Water is taken in through the mouth and forced over the gills and out an opening at the side of the body, but the flow of water and flow of blood are in opposite directions.

Question 5

Name the gas exchange surface of fish

Answer 5

Lamallae and gills

Question 6

How is a large surface area achieved in fish?

Answer 6

Many flattened lamallae

Question 7

Where does the required gas come from in fish?

Answer 7

Water

Question 8

How is the water/air moved across the gas exchange surface in fish?

Answer 8

Countercurrent

Question 9

What are gill filaments attached to?

Answer 9

Gill arches

Question 10

What are gill filaments made up of? What does this mean?

Answer 10

Lamellae so surface area increases

Question 11

What does water constantly flow through?

Answer 11

The lamallae

Question 12

What surrounds the lamallae?

Answer 12

Capillaries

Question 13

Why does the oxygen diffuse into the capillaries of the fish?

Answer 13

Because the water has a higher concentration of oxygen, it diffuses into the blood from a high to low concentration.

Question 14

Why does co2 diffuse from the fish into the water?

Answer 14

Because there’s a higher concentration of carbon dioxide in the capillaries than in the water so it diffuses from a high to low concentration

Question 15

What adaptions do fish have that ensure efficient gas exchange?

Answer 15

• Water and blood flowin opposite directions across the lamallae (countercurrent flow) this enables the fish to maintain a steep concentration gradient of oxygen and carbon dioxide
• they have a number of gills, gill filaments, lamellae and capillaries that increase the surface area for the diffusion of oxygen and carbon dioxide

Question 16

explain how the countercurrent flow system maximises efficiency of gas exchange

Answer 16

Blood and water flow in opposite directions to maintain an oxygen concentration gradient along the whole length of the gill. Thus maximises gas exchange and achieves a higher level of oxygen concentration in the blood