Answer:
The correct option is d) head.
Explanation:
Bicoid protein works as a transcription factor. It enters the nuclei of the embryos in early segmentation, where it activates the hunchback gene. In Drosophila, embryonic development begins at the time of fertilization. The sperm enters the mature oocyte through the micropile, a structure located in what will be the anterior region of the egg. Bicoid and hunchback mRNAs, protein products are critical for the formation of the head and thorax. Already in the early stages of oocyte development, certain mRNAs are located in specific regions of the oocyte: mRNA molecules encoding the Bicoid protein are preferentially located in the anterior region of the oocyte. Moderate levels of the bicoid protein are necessary to activate the formation of the thorax (i.e., the expression of the hunchback gene) but the formation of the head requires high concentrations of Bicoid, the promoters of a specific gap gene of the head must have sites of low affinity binding for Bicoid, so that this gene can be activated only in extremely high concentrations of Bicoid.
The lack of Bicoid protein affects the formation of the head and other structures in the anterior region of the oocyte.
