The diagram shows the circulatory system of a fish. The lungs of a human and the gills of a fish both have a large surface area for gas exchange. [Figure 2.0]

1. (a)(i)State two differences between the structure of the heart of a fish and the structure of the heart of a human. 1 2[2]
2. (a)(ii)Draw a ring around the correct words to complete the sentence below. higher than the same as lower than The pressure of blood in the aorta of a fish will be ..................................................... the pressure of blood in the aorta of a human.[1]
3. (b)(i)The photograph shows an Antarctic icefish. The blood of Antarctic icefish is colourless. State which component of human blood is not present in the blood of an Antarctic icefish.[1]
4. (b)(ii)Antarctic icefish live in the Antarctic Ocean where the water temperature is very cold. Aerobic respiration is an enzyme-controlled reaction. More oxygen is able to dissolve in water at a lower temperature. Antarctic icefish have a larger heart, wider blood vessels and a greater volume of blood than fish of the same size that live in warmer water. Suggest how Antarctic icefish with colourless blood are able to survive in the low temperatures of the Antarctic Ocean.[5]

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