  For any reductive group G and a parabolic subgroup P with its Levi subgroup
L, the first author in [Ku2] introduced a ring homomorphism $ \xi^P_\lambda:
Rep^\mathbb{C}_{\lambda-poly}(L) \to H^*(G/P, \mathbb{C})$, where $
Rep^\mathbb{C}_{\lambda-poly}(L)$ is a certain subring of the complexified
representation ring of L (depending upon the choice of an irreducible
representation $V(\lambda)$ of G with highest weight $\lambda$). In this paper
we study this homomorphism for G=Sp(2n) and its maximal parabolic subgroups
$P_{n-k}$ for any $1\leq k\leq n$ (with the choice of $V(\lambda) $ to be the
defining representation $V(\omega_1) $ in $\mathbb{C}^{2n}$). Thus, we obtain a
$\mathbb{C}$-algebra homomorphism $ \xi_{n,k}:
Rep^\mathbb{C}_{\omega_1-poly}(Sp(2k)) \to H^*(IG(n-k, 2n), \mathbb{C})$. Our
main result asserts that $ \xi_{n,k}$ is injective when n tends to $\infty$
keeping k fixed. Similar results are obtained for the odd orthogonal groups.
