Is There a Way to Know Full Dependencies?

Hi, I'm just wondering, is there an easy way to know the full dependencies for installing a package? For instance, gnuplot depends on tetex, and tetex further depends on texinfo, then is it possible for me to know that gnuplot indirectly depends on texinfo before the actual downloading and compiling start? I ask this because I want to easily find out the full dependencies of installing a package before installing anything, so that if I don't like a particular dependency, I can edit the portfile to bypass it. Best Regards, Xin Liu