Which life cycle components appear only in mosses and ferns?

Flagellated sperm

Explanation:

Mosses are generally in the class of non-vascular plants and ferns are vascular plants that are non-seed bearing. They both produces gametophyte that come in the form of spores, rather than seeds.

Flagellated sperm: These type of sperm will come together with egg cells in the presence of water to produce spores, instead of seeds.

Most of the times in the cases of mosses, the spores are produced on stalks which are above the low-growing vegetative portion of the plant. While in the instances of the ferns, the spores are basically produced in tiny spore cases along the back side of the leaves.