How does the immune system
produce memory cells for antigens?
This is the BEST research
question for students to ask if they are conducting research on antibodies
because t<span>he answer to this question must tell about
production of B-cells, recognition of antigen, T-helper cells, colony formation,
and phagocytosis of foreign antigen, T-killer cells, and all other details which
is possible.</span>
<span>vasoactive intestinal peptide</span>
Answer:
2.5 billion years ago.
Explanation:
Evolutionary tree is constructed to understand the phylogeny and evolution relationship of the organism. The evolutionary tree is constructed by looking at the molecular and physiology of the different organisms.
The eukaryotes are more closely related to the archaea. Depending on the biochamical and molecular evidence is has been found that they share the common ancestor almost 2.5 billion years ago. This can also be deduced by the fossil evidence as well.
Thus, the answer is 2.5 billion years ago.
