Why do very few trees exist in a grassland ecosystem?
a. not enough heat
b. not enough topsoil
c. not enough sunlight
d. not enough precipitation?

Awave has a wavelength of 15 mm and a frequency of 6 hertz. what is its speed?

The wind speed in the region between cities a and b was probably the greatest at noon on which day?

Which statements explains what the fossil records indicates? check all that apply. a) earth is 4.5 billion years old b) many organisms have become extinct c) mammals have always existed on earth d) mass extinctions have occurred several times on earth e) the amount of water on earth has decreased over time?