Which of the following was a major event in the history of cell biology? a. cloning animals
c. discovery of cell parts
b. growing bone tissue for transplant d. All of the above

Ivan is looking at a cross section of a stem taken from a vascular plant. he sees two different types of vascular tissue: the xylem, which is closer to the center of the stem, and the phloem, located around the xylem, closer to the outside of the stem. how do these two structures work together in a living plant?

14. which of the following codons code for threonine? a. ucg b. ugu c. cga d. aca

Which of the following do all living things have in common