When a single, genetically marked neoblast is injected into a healthy adult planarian, it joins the existing population of neoblast cells,
which constitute about 20% of the total cell population. Thus, a neoblast injected into a normal adult planarian constitutes a tiny
fraction of the organism's total cell population.
However, if the host animal recieves a high dose of x-rays before the marked neoblast is injected, the frequency of genetically marked
cells in a surviving adult increases. Ultimately, what percentage of a surviving planarian's total cell population would you expect to carry
the genetic mark of the injected cell? Why?
Choose one:
A. About 20%, because the host myoblasts would be transformed into new tissues.
B. 100%, because the irradiated cells in the host cannot divide and, thus, would die.
C. Only a tiny fraction, because the injected genetically marked neoblast can't divide.
D. About 50%, because the newly derived neoblasts would mix with host neoblasts.
