C and D, but it can be B, since it occurs during cytokinesis and it begins before mitosis ends.
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.
Proteins are formed from monomers called amino acids. These are naturally found substances that polymerize in order to form proteins. These are compounds which has amine and carboxyl groups and are characterized by an R-group. In proteins, there are about 20 amino acids that can be found.
Answer:
The correct answer is option B. pheromones.
Explanation:
Pheromones are chemical substances that are released and produced by a different type of animals, into the environment, for marking their territory or affecting behaving of its species.
Wolves communicate by the chemical messages using their sense of smell. Such chemical messages are called pheromones, between different members of the same species.
Thus, the correct answer is option B. pheromones.
