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.
The evolution of the peppered moth is an evolutionary instance of directional colour change in the moth population as a consequence of air pollution during the Industrial Revolution. ... Later, when pollution was reduced, the light-coloured form again predominated.
As the trees darkened with soot, the light-colored moths were easier to see. They were eaten by birds more and more, while the rare dark colored moths blended in better on the darker trees. This made the dark colored moths have a higher survival rate.
