Let F ⊆P4 be a 3-fold with
one ordinary double point p, and let F′ be the proper transform of F under the
blowing up of P4 at p. If H ⊆ F′ is the preimage of p on F′, we prove that for F
general the algebraic 1-cycle given by the difference of the two generators of the
smooth quadric surface H, is not algebraically equivalent to zero on F′. Griffiths has
shown this cycle to be homologically equivalent to zero. Also, we show that on a
general quintic 3-fold X there are no non-trivial algebraic equivalence relations
between the lines of X.