Abuffer contains the weak acid ha and its conjugate base a-. the weak acid has a p ka of 4.82 and the buffer has a ph of 4.25. this is true of the relative concentration of the weak acid and its conjugate base in the buffer.
a) [ha} > [a-]
b) [ha} < [a-]
c) [ha]=[a-]

From the henderson-hasslebalch equation: pH=pKa+log[A−]/[HA]

it's apparent that when pKa=pH, c. [HA]=[A^-].
 

Pancreassalivary glandsliverlachrymal glandssweat glandoil glandsgoblet cells

By water evaporation from the leaves is created a negative pressure at the top of the tree that promotes the ascension  of the water through channels that are called xylem. there are also two molecule forces that are involved: the intra-water molecules cohesion (water molecules stick to each other) and the adhesion when the water molecules stick to the channels they are running in. this is what enables water to go from the roots to the top of a tall tree.