Final answer:
The mature gymnosperm seed contains three generations: the seed coat, the female gametophyte, and the embryo. After fertilization, the ovule transforms into a seed with three distinct tissues. In gymnosperms, the gametophyte generation takes place in a cone on the sporophyte plant.
Step-by-step explanation:
The mature gymnosperm seed contains three generations of tissues: the seed coat that originates from the parent plant tissue, the female gametophyte that provides nutrients, and the embryo itself.
After fertilization, the ovule transforms into a seed, which involves the coordinated development of three distinct tissues.
In gymnosperms, the gametophyte generation takes place in a cone, which forms on the mature sporophyte plant.