  The quark exchange model (QEM) is reformulated for the $A=12$ and $14$
systems to obtain the constituent quark distributions of $^{12}C$ and $^{14}N$
nuclei, respectively. Afterwards, the different types of the point-like parton
distribution functions (PDFs), i.e., the valence quarks, the sea quarks and the
gluons, are extracted from the constituent quark model (CQM), at the hadronic
scale $Q_0^2=0.34$ $GeV^2$ to generate the constituent quark exchange model
(CQEM = QEM $\oplus$ CQM) PDFs. From the resulted PDFs, the structure functions
and the European Muon Collaboration (EMC) ratios of the above-mentioned nuclei
at the appropriate hadronic scale are calculated. To make our results more
comparable with the available experimental data, we evolve the PDFs, by using
the standard DGALP evolution equations, to the higher hard scales.
Subsequently, the EMC ratios of $^{12}C$ and $^{14}N$ nuclei at the some higher
energy scales, corresponding to the scales of available data, are calculated,
at the leading (LO) and the next-to-leading (NLO) orders of pQCD. By doing so,
it is observed that the EMC ratios do not significantly depend on the hard
scale $Q^2$, and the outcomes are consistent with the various experimental data
such as HERMES, BCDMS, JLab, SLAC, NMC, and EMC. Especially, in the mid-range
of Bjorken $x$ values, the results are so desirable. Like our previous works
for the $^4He$ and $^6Li$ nuclei, we again observe that at a fixed scale $Q^2$,
the LO and the NLO EMC ratios with high precision are approximately the same.
Therefore, one can conclude that at a given hard scale, the LO approximation is
good enough for calculating the EMC ratios of light nuclei.
