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Question 4 (13 Marks) 4.1. Living organisms are open systems that continuously convert high-enthalpy. low-entropy nutrients to low-enthalpy, high-entropy waste products. Give three reasons why living systems should therefore maintain a non-equilibrium state. (3) 4.2. The co-enzymes NADH and NADPH are used in many biological redox reactions. Many enzymes catalyze such reactions by using NADH and NADPH interchangeably as co-factors. 4.2.1 What type of enzyme catalyzes the reactions alluded to above? 4.2.2 Give a specific example of the type of enzyme mentioned in 4.2.1 from the pentose phosphate pathway. (1) 4.2.3 Discuss why an enzyme might be capable of utilizing both NADH and NADPH as co-enzymes in biological redox reactions. Refer to the structures of the co- enzymes and the active site of the enzyme in your answer. (8)