Answer:
In trees, most savanna adaptations are to drought--long tap roots to reach the deep water table, thick bark for resistance to annual fires (thus palms are prominent in many areas), deciduousness to avoid moisture loss during the dry season, and use of the trunk as a water-storage organ (as in baobab).
200,000 is the population density.
In the DNA, that is why they are called the building blocks of life.
