Which amino acid does not occur in proteins stucture ?

To maintain asepsis when administering an injection, all parts of the syringe can be handled except the:

Which of the follow describes a disadvantage secondary sources have compared to primary sources?

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?