The phloem tissues in plants are responsible for the movement of sugars from the leaves to different areas of the plant. This allow all of the plant to have the necessary energy to carry out its cellular activities. Phloem is just one part of the plant's vascular system, which is a larger organ system that moves materials through out the plant. What animal organ system is most similar to the vascular system of a plant?

The content of manganese (mn) in steel was determined spectrophotometrically and with the use of the standard addition method. an unknown sample of mn from a digested steel sample gave an absorbance of 0.185 when analyzed spectrophotometrically. when 5.00 ml of solution containing 95.5 ppm mn was added to 50.0 ml of the unknown steel solution (digested sample), the absorbance was 0.248. calculate the concentration, in parts-per-million (ppm), of mn in the digested steel sample solution.