In the 1700s, organisms were broken into only two kingdoms - animalia and vegetabilia. throughout the next few hundred years, the name plantae replaced vegetabilia, and other kingdoms began to emerge. finally, in the 1900s, the currently accepted six kingdom system was adopted. currently, the kingdoms include: plantae, animalia, fungi, protista, archaebacteria, and eubacteria. the development of the current classification system is probably due to

Hormones are chemical molecules produced by endocrine glands. one such endocrine gland is the thyroid gland, which synthesizes the thyroid hormone, which in turn affects the heart muscles. which two statements describe the probable reason for the function of the hormone? the cells in the heart have specific receptors that allow for the intake of hormones. the heart and the endocrine glands have the exact same types of cells. all cells make the same types of hormones. thyroid hormones show their effect on the heart by means of specialized cells. thyroid cells and cardiac cells have different dna.