  As an alternative explanation of the entropy excess and the steepening of the
X-ray luminosity-temperature relation in groups and clusters, the galaxy
formation-regulated gas evolution (GG) model proposed recently by Bryan makes
an attempt to incorporate the formation of galaxies into the evolution of gas
without additional heating by nongravitational processes. This seems to provide
a unified scheme for our understanding of the structures and evolution of both
galaxies and gas in groups and clusters. In this paper, we present an extensive
comparison of the X-ray properties of groups and clusters predicted by the GG
model and those revealed by current X-ray observations, using various large
data sources in the literature and also taking the observational selection
effects into account. These include an independent check of the fundamental
working hypothesis of the GG model, i.e., galaxy formation was less efficient
in rich clusters than in groups, a new test of the radial gas distributions
revealed by both the gas mass fraction and the X-ray surface brightness
profiles, and an reexamination of the X-ray luminosity-temperature and
entropy-temperature relations. In particular, it shows that the overall X-ray
surface brightness profiles predicted by the GG model are very similar in
shape, insensitive to the X-ray temperature, and the shallower X-ray surface
brightness profiles seen at low-temperature systems may arise from the current
observational selection effect. This can be used as the simplest approach to
distinguishing between the GG model and the preheating scenario. The latter
yields an intrinsically shallower gas distribution in groups than in rich
clusters.
