Some birds follow moving swarms of army ants in the tropics. As the ants march along the forest floor hunting insects and small vertebrates birds follow and pick off any vertebrates that fly or jump out of the way of the ants. This situation is an example of what kind of species interaction between the birds and the ants? a. resource partitioning
b. competitive
c. exclusion
d. mutualism
e. parasitism

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.

It depends on the surface of the levels. the rougher the surface, the greater is the frictional force. for rougher surfaces, you would need to exert greater force to move the object. the concept is that, you must overcome the frictional force in order to bring the object into motion. this is the reason why we add lubricants to the joints so they could easily move. this answer was on