Sap by the fact that phloem sap is physiologically extreme in terms of animal digestion, and it is hypothesized that few animals take direct advantage of this because they lack two adaptations that are necessary to enable direct use by animals. These include the existence of a very high ratio of non-essential/essential amino acids in phloem sap for which these adapted Hemiptera insects contain symbiotic microorganisms which can then provide them with essential amino acids; and also insect "tolerance of the very high sugar content and osmotic pressure of phloem sap is promoted by their possession in the gut of sucrase-transglucosidase
Ascent of sap Ascent of sap The ascent of sap in the xylem tissue of plants is the upward movement of water and minerals from the root to the crown. Xylem is a complex tissue consisting of living and non-living cells. The conducting cells in xylem are typically non-living and include, in various groups of plants, vessels members and tracheids. Both of these cell types have thick, lignified secondary cell walls and are dead at maturity. Although several mechanisms have been proposed to explain the phenomenon, the cohesion-tension mechanism has the most evidence and support. Although cohesion-tension has received criticism, for example due