Barnacles belong to phylum Crustacea.
In a water molecule, the oxygen atom and hydrogen atoms share electrons in covalent bonds, but the sharing is not equal. In the covalent bond between oxygen and hydrogen, the oxygen atom attracts electrons a bit more strongly than the hydrogen atoms.
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Answer:
D. A hormonal signaling pathway between endocrine glands and tissues
Explanation:
Our body is formed by a complex organization of various tissue, organs and organ-systems. It has specific mechanisms to regulate the functions of all its cell, tissue and organs. Besides neural system, the endocrine system also plays a crucial role in the regulation of body functions. This system consists of many pathways that originate from the hormone secreting glands called endocrine glands and reaches to the target cell or tissue or organ. These pathways are collectively named as the endocrine axis.