The remnant of an organ that had a function in an early ancestor is known as a(n) a. vestigial structure
b. fossil structure
c. homologous structure
d. analogous structure

The gene that causes sickle-cell disease is present in a higher percentage of residents of sub-saharan africa than among those of african descent living in the united states. even though this gene causes sickle-cell disease, it also provides some protection from malaria, a serious disease that is widespread in sub-saharan africa but absent in the united states. discuss an evolutionary process that could account for the different percentages of the sickle-cell gene among residents of the two regions.

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.

Which statements best describe monsoons? check all that apply. they force cool, moist air from oceans to rise. they are winds that blow in the opposite direction of a normal wind. they bring rain in the summer and drought in the winter they increase rainfall in south asia, africa, and australia. they influence precipitation as wind moves near a mountain.