Final answer:
An identifiable benchmark that triggers the activation of another process in biology is known as a Signaling Pathway, which begins with a ligand binding to a cell-surface receptor and initiates various biological events.
Step-by-step explanation:
The term for an identifiable benchmark that signals the activation of another process in biological systems is often referred to as a Signaling Pathway or a signaling cascade. This process begins when a ligand binds to a cell-surface receptor. This binding activates the receptor's intracellular components, initiating a chain of events involving second messengers, enzymes, and activated proteins. Each of these elements interacts in sequence, leading to a certain outcome, such as an increase in metabolism or changes to specific gene expression. In this context, the ligand can be seen as the identifiable benchmark that triggers these downstream events in the biological process.
For example, when a hormone (as a ligand) binds to its receptor on the surface of a cell, this binding is the event that activates the signaling pathway. The interactions and activations within the signaling pathway are organized in a linear sequence, analogously to how a river flows. Terms such as upstream and downstream events are used to describe interactions occurring before or after a certain point in the signaling cascade, respectively.