In which echinoderm is it most difficult to identify radial symmetry? A. sea stars B. Brittle stars C. Sea urchins D. sea cucumbers E crinoids

Ineed the answer asap. in order to be considered alive, an organism must simultaneously possess the characteristics of homeostasis, heredity, cells, reproduction, and

The earth's oceans are made up of chlorine, and trace elements. a) carbon, oxygen b) oxygen, silicon c) hydrogen, oxygen d) nitrogen, oxygen

If a cell is placed into a hypertonic environment, what will happen to it ? a)it will shrink or shrivel b)nothing c)it will burst d) it will expand or enlarge