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?

Which element provides strength to the exoskeleton of clams and oysters

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.

Gregor mendel is best known for his work with pea plants and for uncover many of the mysteries of genetics. one of his major findings stated that there were specific, physical units of inheritance that are transmitted during reproduction. what is the the name given to these units of inheritance which can be found on chromosomes? a) centromeres b) cytoplasm c) genes d) nucleotides