A Paramecium "knows" when it has encountered a noxious substance and backs off to veer away.As a one-celled organism,how does it "know" to do this?
A) The macronucleus has DNA coding that determines this reaction.
B) The micronucleus is dedicated to controlling just such responses.
C) This cell is essentially a small neuron, or nerve cell.
D) This is a rather simple stimulus that changes the electrical potential difference across the cell membrane and depolarization of the membrane results in cilia reversing their direction of beating.
E) None of the choices are correct.

Question

Quizplus · Accepted Answer

The Paramecium detects the noxious substance using its cilia, which are hair-like structures on the surface of the cell. The cilia detect the presence of the substance and cause a change in the electrical potential difference across the cell membrane. This change in potential results in the cilia reversing their direction of beating, which causes the Paramecium to back away from the noxious substance. The process does not involve the macronucleus, micronucleus, or neuron-like structures.

A Paramecium "Knows" When It Has Encountered a Noxious Substance