Throughout the spring and summer, trees take nutrients from the soil. These nutrients are spread throughout the
tree. In the autumn, some of these nutrients are lost
when the tree drops its leaves.
In a young, rapidly growing forest, scientists calculated
that 23 kilograms of a nutrient are taken up from the soil
by the trees in one year. In the autumn, the leaves that
fall contain 21 kilograms of the nutrient.
18 The trees can be considered a subsystem of the
larger ecosystem. If there are no other inputs or outputs from the trees, how much of the nutrient
is added to the tree subsystem (stored in the trees) in this year?
A. 2 kg
B. 21 kg
C. 23 kg
D. Not enough information is available to determine.
(help) science