PLEASE HELPP Compare Snow's experiments with HeLa experiments, Salk's experiments, and The Tuskegee study use reputable websites in at least four paragraphs

Explain the importance of producers, primary consumers, secondary consumers. and decomposers in an ecosystem

Explain why in any given geographical region, women tend to have lighter skins( by 3-4% on average) than men?

Imagine a self-reactive t cell that has not undergone clonal deletion in the thymus (that is to say, it has escaped central tolerance). if it encounters self antigen in the absence of an infection or inflammation, what will happen to this self-reactive t cell? (select two answers) (a) the t cell undergoes clonal expansion. (b) the t cell gains effector functions. (c) the t cell undergoes apoptosis. (d) the t cell becomes activated. (e) the t cell becomes anergic.