Which property of muscle tissue gives it the ability to contract and relax?

Its is dependent upon calcium. The calcium-dependent channels. The proetis involved in the same are sarcoplasmic reticulum and voltage gated L-type channels. The excitation-contraction coupling leads to muscular action potential, and thus, myofibrils contract by the process.

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.

They became more resistant.