-Helicases are enzymes that bind and may even remodel nucleic acid or nucleic acid protein complexes. DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied.
-DNA is double stranded. Enzymes that are responsible for replication of DNA can only bind to a single strand of DNA. Helicase is the enzyme that unwinds the DNA by breaking hydrogen bonds between the two strands.It forms the so called replication fork. Other proteins assist helicase to keep the strands apart as long as required for the replication process.
The vessels of the xylem are more efficient than the tracheids in water conduction due to the presence of perforations in them. These perforations allow for the continuous flow of water into the xylem vessels.The xylem tracheids are long, narrow, tubelike cells. The walls of tracheids are thick and hard.
