What do all scientific investigations begin with? A: Forming a hypothesis

B: Conducting an experiment

C: Asking a question or observing a problem

D: Forming a conclusion

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.

Astudent measured the amount of carbon dioxide (co2) produced by yeast during an experiment. use the data in the table at the right to answer the questions below. which variable is the dependent variable?

Achange in which factor will affect the rate of reaction only when gases are involved? temperature pressure surface area concentration