Organisms need a source of energy for many cellular processes. Respiration involves the release of energy from energy-rich molecules for the synthesis of ATP molecules. ATP is described as the energy currency of cells.

1. (a)Name two energy-rich molecules that enter the respiration pathway to synthesise ATP.[2]
2. (b)Fig. 1.1 shows a molecule of ATP. [Figure 1.1] Explain the features of ATP that make it suitable to be the universal energy currency of cells.[4]
3. (c)Identify the type of phosphorylation reaction to synthesise ATP that occurs during glycolysis and the Krebs cycle.[1]
4. (d)(i)Pyruvate moves into the matrix of the mitochondrion only when a particular inorganic molecule is present. Name the inorganic molecule that must be present in the cell for pyruvate to enter the matrix of the mitochondrion.[1]
5. (d)(ii)Explain how the presence of the inorganic molecule named in (d)(i) affects the ATP yield from respiration.[3]

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