A student investigates respiration in germinating seeds using a simple respirometer. The student measures the volume of oxygen consumed and carbon dioxide produced over a period of 30 minutes for three different types of seeds. The respiratory quotient (RQ) values obtained are shown in the table.
| Type of seed | RQ |
|---|---|
| Pea | 1.0 |
| Sunflower | 0.7 |
| Castor bean | 0.3 |
The student then tests an unknown seed and records an oxygen uptake of 20 cm³ and carbon dioxide output of 15 cm³.
(a) Outline the features of ATP that make it a suitable universal energy currency. Include in your answer two examples of cellular processes that require ATP.
(b) Outline how a simple respirometer can be used to determine the volume of oxygen consumed and carbon dioxide produced by the germinating seeds.
(c) Explain how the RQ for the unknown seed would be found and, using the table, identify the most likely respiratory substrate being used. Explain your reasoning.