Scientific understanding can always be challenged and even changed, with new ways of observing and with different interpretations. For example, new tools and techniques have resulted in new observations and the discovery of additional information. This has resulted in revised ways of understanding how molecules are moves across the plasma membrane of cells. Hence, there is no certainty in science, only degrees of probability (likelihood) and potential for change. In light of this understanding, which of the following statements is most meaningful?

Scientific knowledge is absolute knowledge
Scientific knowledge is rigid collection of invariable facts
Scientific knowledge is based on current knowledge
Scientific knowledge is a static and unchanging collection of facts

Scientific knowledge is based on current knowledge