One significant difference between roots and stem is that ____________
A. branch root originate in the pericycle while branch stems do not B. stems are always below the ground while roots are always under the ground C. stems are positively geotropic while roots are negatively geotropic D. stems are sometimes used for storage while roots are never so used.
Correct Answer: A
Explanation
Tropism is the movement of a plant in response to, and directed by, an external stimulus. Tropic responses are described as positive or negative depending on whether growth is towards or away from the stimulus respectively. Geotropism is growth response to gravity. Shoots and colcoptiles are negatively geotropic, roots are positively geotropic. The pericycle (which occurs only in the root) retains the capacity for cell division and produces lateral roots
