both the number of species and population density decreases as altitude above sea level increases
question 2:
increase in birth rate => greater number of young organisms
Explanation:
As altitude above sea level increases, O2 density decreases, the amount of UV rays increases and the difference between daytime and nighttime temperature increases
An undifferentiated cell of a multicellular organism which is capable of giving rise to indefinitely more cells of the same type, and from which certain other kinds of cell arise by differentiation.