A seal is a mammal that spends most of its time in the sea. It breathes and respires in a very similar way to a human, but when it dives to hunt and catch fish, it is capable of staying under water for up to 20 minutes. The graph shows the percentage concentrations of oxygen and carbon dioxide, and the concentration of lactic acid in a seal's blood over a 40 minute period during which it dives to hunt and catch fish. [Figure 1.1]

1. (a)State the chemical process that is taking place in the seal's muscles before it dives.[2]
2. (b)(i)State how long after the start of the time period the seal begins its dive.[1]
3. (b)(ii)State the percentage of oxygen in the seal's blood 40 minutes after the start of the time period.[1]
4. (c)Name the chemical process which starts to take place in the seal's muscles during its dive and explain how the graph supports your answer. process explanation[3]
5. (d)Suggest and explain what would happen to the concentration of lactic acid in the seal's blood when it returns to the surface of the sea after its dive.[3]

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