We develop a high level action description language to express knowledge about cellular processes and mechanisms. This involves representation and reasoning about both discrete properties and continuous processes. Both of them may be changed by exogenous actions or triggers. We use differential equations to represent continuous processes. We give syntax and semantics of the language and also present an approximate characterization. We present a temporal query language for such domains. We then illustrate the use of our language with respect to biological examples and discuss an implementation of the approximate characterization.