Adog gives birth to three puppies one year. three years later, she gives birth to six puppies. which type of life history pattern is characteristic of this organism?

The answer is iteroparity.

There are two reproductive strategies among living organisms: semelparity and iteroparity. Semelparity is characterised by only one reproductive episode before death. It is characteristic for some insects, molluscs, and fish. Iteroparity is characterised by multiple reproductive episodes before death. It can be found among most insects, molluscs, fish, and reptiles, as well as among all birds and mammals. Thus, a dog, as a mammal, and, in this example with two reproductive episodes, belongs to iteroparous organisms.

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.