  The net-baryon number fluctuations for three-flavor quark matter are computed
within the Polyakov extended Nambu$-$Jona-Lasinio model. Two models with
vanishing and nonvanishing vector interactions are considered. While the former
predicts a critical end point (CEP) in the phase diagram, the latter predicts
no CEP. We show that the nonmonotonic behavior of the susceptibilities in the
phase diagram is still present even in the absence of a CEP. Therefore, from
the nonmonotonic behavior of the susceptibilities solely, one cannot assume the
existence of a CEP. We analyze other possible properties that may distinguish
the two scenarios, and determine the behavior of the net-baryon number
fluctuations and the velocity of sound along several isentropes, with moderate
and small values. It is shown that the value of the susceptibilities ratios and
the velocity of sound at two or three isentropic lines could possibly allow to
distinguish both scenarios, a phase diagram with or without CEP. Smoother
behaviors of these quantities may indicate the nonexistence of a CEP. We also
discuss the critical behavior of the strange sector.
