Answer:
Speciation is the evolutionary process by which reproductively isolated biological populations evolve to become distinct species. The biologist Orator F. Cook was the first to coin the term 'speciation' for the splitting of lineages or "cladogenesis," as opposed to "anagenesis" or "phyletic evolution" occurring within lineages.
Explanation:
Helper T cells become activated by interacting with antigen presenting cells. and the second blank space is either cytotoxic t cells or B cells
By having a unicellular form, a protist will gain two major advantage:
1. It would be able to reproduce on its own, asexually without having to look for sexual partners. It will be able to reproduce by binary fission, multiple fission or budding.
2. It will benefit from a simple body system that does not need system specialization. Having specialized systems with many parts can results in some of the system having problems at times.