Question

Trees need water so they can make their own food. Trees take in water using their roots. If a drought occurred—reducing the amount of available water—some trees, such as those with deep roots that can reach the water table, would be naturally selected over other trees. If the drought continued for an extended period of time, the trees would likely evolve until most of the trees possessed drought-resistant characteristics.

Which of the following allows natural selection and evolution to occur?
A.
using other plant parts instead of roots to absorb water
B.
differences in the characteristics of individual trees
C.
increasing the height of the water table
D.
having an identical genetic make-up

Answer 1

B. differences in the characteristics of individual trees

Natural selection requires heritable variation among individuals; the drought would favor trees with drought-resistant traits (e.g., deep roots), allowing those traits to become more common over generations. Identical genetics would prevent evolution.