(a) All organisms respire. The ATP produced as a result of respiration is used as the energy currency of the cell. (b) Fur seals are mammals that are adapted to live in cold temperatures. Fur seals have large quantities of a type of fat tissue known as brown adipose tissue. Brown adipose cells contain many mitochondria. These mitochondria contain a transport protein called thermogenin. Fig. 2.1 shows the role of thermogenin in a mitochondrion of a brown adipose cell when external temperatures are cold. [Figure 2.1]

1. (a)(i)Outline two examples of movement in cells that use ATP.[2]
2. (a)(ii)ATP cannot be stored in cells so it has to be continually re-synthesised to meet the demands of an organism. A person with a total quantity of 0.2 moles of ATP needs to hydrolyse 150 moles of ATP per day. Calculate how many times the total quantity of 0.2 moles of ATP has to be re-synthesised per hour to meet the demand of 150 moles per day. Show your working and give your answer to the nearest whole number. answer =[2]
3. (a)(iii)Name the stages in which chemiosmosis occurs in respiration and in photosynthesis. respiration photosynthesis[2]
4. (b)(i)With reference to Fig. 2.1, describe and explain the effect of thermogenin on ATP synthesis.[3]
5. (b)(ii)When the external temperature is warm, thermogenin cannot function. When the external temperature becomes cold, thermogenin is able to function as a result of cell signalling: • adrenaline is released • adrenaline acts on brown adipose cells • a sequence of events is triggered that results in the activation of the enzyme lipase • lipase hydrolyses triglycerides in the cells into fatty acids • fatty acids enter the mitochondrion • thermogenin starts to function. Outline the stages of cell signalling that trigger the functioning of thermogenin.[3]

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