[Campbell Biology P.436] Researchers injected bicoid mRNA into the anterior end of an egg fr... | Practice Question

Researchers injected bicoid mRNA into the anterior end of an egg from a female with a mutation disabling the bicoid gene. Given that the hypothesis about Bicoid's role was supported by their wild-type experiments, what would be the most likely result for this injected egg?

  • A: The embryo would develop normally with a head at the anterior end.
  • B: The embryo would develop two heads, one at the anterior and one at the posterior.
  • C: The embryo would lack a head structure.
  • D: The embryo would develop legs instead of a head at the anterior end.

Explanation

The 'WHAT IF?' section describes this exact scenario. Since the bicoid gene in the female was disabled, the egg would normally lack Bicoid protein, resulting in no head. However, injecting bicoid mRNA into the anterior end would restore the necessary morphogen gradient, leading to the normal development of a head at that end, consistent with Bicoid's role as a head-specifying morphogen.