We consider rotating strings and D2-branes on type IIA background, which
arises as dimensional reduction of M-theory on manifold of G2 holonomy, dual to
N=1 gauge theory in four dimensions. We obtain exact solutions and explicit
expressions for the conserved charges. By taking the semiclassical limit, we
show that the rotating strings can reproduce only one type of semiclassical
behavior, exhibited by rotating M2-branes on G2 manifolds. Our further
investigation leads to the conclusion that the rotating D2-branes reproduce two
types of the semiclassical energy-charge relations known for membranes in
eleven dimensions.Comment: LaTeX, 29 pages, no figures; V2:comments added; V3:no changes, to
appear in JHE