Un electrón se mueve al Este con una velocidad de 2X106 m/s y experimenta una fuerza de 5X10-12 N hacia arriba debido al Campo Magnético de la tierra. Encontrar la magnitud del Campo Magnético en ese punto.​

Icant be totally sure but i would say with confidence that it is example #1 about 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.