The liver acts to keep blood glucose at a relatively constant level. it takes up glucose from the blood when levels are too high, and adds glucose to the blood when levels are too low. are these actions of the liver an example of homeostasis? a. yes, because homeostasis involves the maintenance of constant internal conditions. b.yes, because homeostasis is the interaction between two separate organs or tissues, such as the liver and blood. c.no, because homeostasis involves only positive feedback, not feedback inhibition. d.no, because homeostasis involves only tissues and organs from the same organ system.

Ans.

Liver helps to keep the blood sugar in a constant level by different means. When blood sugar level increases, liver cells increase glucose uptake due to influence of insulin hormone and thus, decrease sugar level in blood. When sugar level decreases, liver cells show gluconeogenesis and add sugar into the blood due to the action of glucagon hormone, and thus, increase blood sugar level.

As homeostasis is a mechanism that involves maintenance of constant internal conditions, and liver shows maintenance of constant sugar level in body, the correct answer is 'option a).'

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!