Phylum´s textbook definition reads - a principal taxonomic category that ranks above class and below kingdom. Phylogeny is the study of Phylogenesis, which to a broad degree, is the classification of organisms.
P.S. Phylogenesis also discusses the evolutionary process of said organisms.
<u>A</u>. Lymph nodes produce antibodies and aid the the removal of pathogens. Without functional lymph nodes, the individual would be significantly more vulnerable to being harmed by common viruses.