Sub-atomic particles, Atoms, small molecules, Macro-molecules, molecular assembles, organelle, cell, tissue, organ, organ system, organism, populations of species, species, Community ad Abiotic components, Ecosystem, Biosphere
T cell receptor, Cytotoxic T Cell, CD4, Antigen, Bacterium,
B – cell, Cell mediated response, Class II MHC, Cytokines, and Humoral Response
are the components for the activation of a helper t cell by a dendritic cell.
it gives off protons because it's in a basic solution (pH>7)
As long as you are referring to the green plants aka producers of the food chain/web.
At least 12 million years ago?