Unlike almost all ferns, seed plants

Unlike almost all ferns, seed plants  create two varieties of spores.

In biology, a spore is a part of sexual or asexual replication that may be accommodated for dispersal and for endurance, oftentimes for long duration of time, in adverse situations. Spores develop component of the life periods of various plants, algae, mildew and protozoa. Bacterial spores are not component of a reproductive cycle but are repellent compositions used for endurance following adverse situations. Myxozoan spores loose amoebulae into their hostesses for parasitic virus, but also generate within the hostesses by the pairing of two nuclei inside the plasmodium, which originates from specific amoebula.

enzyme speed up the reactions

substitution is the answer in this case