  SU(3) symmetry relations between the octet baryons are introduced in order to
connect both the unpolarized and polarized quark distributions of the octet
baryons with those of the nucleon. Two different parametrizations of the
nucleon quark distributions are used. A new scenario of quark flavor and spin
structure of the $\Lambda$ is found and compared with two other models: a
perturbative QCD based analysis and a quark diquark model. The $u$ and $d$
quarks inside the $\Lambda$ are predicted to be positively polarized at large
Bjorken variable $x$ in the new scenario. By using an approximate relation
connecting the quark fragmentation functions with the quark distributions, the
hadron polarizations of the octet baryons in $e^+e^-$-annihilation, polarized
charged lepton deep inelastic scattering (DIS) processes, and neutrino
(antineutrino) DIS processes are predicted. The predictions for $\Lambda$
polarizations in several processes are compatible with the available data at
large fragmentation momentum fraction $z$, and support the prediction of
positively polarized $u$ and $d$ quarks inside the $\Lambda$ at large $x$.
Predictions for Drell-Yan processes from $\Sigma^{\pm}$ and $\Xi^-$ beams on an
isoscalar target are also given and discussed.
