4. Nitrogen gas is more abundant in our atmosphere than oxygen! However, nitrogen needs to be
converted into different forms to be used by many
organisms. Bacteria are highly involved in this!
Describe the role of (A) bacteria fixing nitrogen as
they live symbiotically with some plant species, (B)
nitrifying bacteria, and (C) denitrifying bacteria in
the nitrogen cycle.

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.

Describe the relationship between isotonic solutions, equilibrium, and water movement into and out of a cell.

Facilitated diffusion move large molecules and/or polar molecules across the cell membrane. what does facilitated diffusion use to do this?