Question

Please explain in your own words at least five sentences.  

1 pressure flow mechanism in phloem.

2 cohesion-tension mechanism of water transport and how transpiration generates tension to pull xylem sap.

Answer 1

Answer 1-

Pressure flow mechanism in phloem is due to the transport nutrients between from source and sink. This mechanism of pressure flow is due to the concentration difference between the low potential of sugar in the sink and the high concentration of sugar at the source. This builds a high-pressure potential which leads to the transport of water and sugar.
Answer 2-

Cohesion- tension theory which explains the ascent of sap in the xylem, it s occur when the water is evaporated through the stomata which produces a tension that leads to pull the water through the column. The theory elaborates the attraction between molecules of water which is pulled from the roots and reaches to the leaf where the transpiration occurs.