Most of metabolic processes are extremely complicated but occur spontaneously and steadily, the essential reason of which may be either a thermodynamic problem or related to some quantum properties. Here, collapse selection is interpreted with an analytical model of energy transfer, from which the concept of quantum cloud is defined as that during undetectable changes of a group of particles between its effective changes, particles are in the superposition of various energy states and the group is named as a cloud. It is deduced from the interpretation of collapse selection and the notion of matter proportions that cloud collapses have different expectations: active cloud collapses have least-time expectation while passive collapses have matter-proportion expectation.
