Which of the following statements best describes negative feedback loops? A. They respond to changes with changes in the same direction, to move a value toward an endpoint.
B. They produce negative outcomes for the organism.
C. They aren't used often in maintaining homeostasis.
D. They respond to changes with changes in the opposite direction, to keep a value in the optimal range.

According to the big bang theory, after the "bang," the universe remained dark until about  300,000 yearsone billion yearsthree minutesthree billion years  later, when neutral atoms began to form.

Hey me with this one❤☺❤ how do you say that a cell also has a life span and death like an organism? give one example.

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.