What makes a planet earth-like
a. rocks
b. craters
c. people
d. liqued water

Several billion years ago which gas was the least prevailant in the atmosphere

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.

Adistinctive characteristic of mammals that is not observed in other vertebrates is