The circulatory system - hemoglobin in the blood transports oxygen :)
The answer is wavelength. It is the distance between corresponding points of two consecutive waves (corresponding points are particles or points in the same phase, meaning the points have completed identical fractions of their periodic motion. In a transverse wave it is the distance between two successful crests or troughs while in a longitudinal wave is the distance between two successful compressions or rarefactions.
The answer is semiconservative replication. Semiconservative meaning that half of the original molecule (one of the two strands in the double helix) is conserved in the new molecule. Replication is the process by which double stranded DNA molecule is copied to produce two identical DNA molecules. It is one of the most basic process that occurs within a cell. Each time a cell divides, the two resulting daughter cells must contain exactly the same genetic information, or DNA, as the parent cell. To accomplish this, each stand of existing DNA acts as a template for replication.