If you want to reabsorb sodium ions, but you do not want to increase the volume of the blood by reabsorbing large amounts of water from the filtrate, how would you adjust the amounts of ADH and aldosterone to accomplish this job?

a. Increase the amount of aldosterone and decrease the amount of ADH.
b. Decrease the amount of aldosterone and increase the amount of ADH.
c. Decrease the amount of both aldosterone and ADH.
d. Increase the amount of both aldosterone and ADH.

a. Increase the amount of aldosterone and decrease the amount of ADH.

Explanation:

Aldosterone is a hormone which is responsible for the absorption of salts and water that is filtered in the kidneys according to the requirement of the body while ADH is also a hormone which helps in the regulation of water in your blood and also maintain volume of the blood in your body. If you want to reabsorb sodium ions, but do not want to increase the volume of the blood by reabsorbing large amounts of water from the kidneys, so increase the concentration of aldosterone but decrease ADH in the body.

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!