Which of the following is/are true about glucose transport across the membrane?
ID: 212961 • Letter: W
Question
Which of the following is/are true about glucose transport across the membrane? (Select ALL that are TRUE.)
a)
The role of the Na+ - K+ ATPase is to keep the levels of Na+ high in the cell by pumping Na+ into the cell from the extracellular environment.
b)
Glucose from your digested food within the lumen of your intestine is absorbed at the basalsurface of the cells in your intestinal epithelium through passive diffusion.
c)
Movement of glucose out of the basal surface of the intestinal cell occurs via passive transport to an area of lower glucose concentration.
d)
The concentration of glucose in the cytoplasm of the intestinal epithelial cell is higher than the concentration of glucose in the intestinal lumen or in the extracellular fluid outside the basaldomain.
e)
Any movement of molecules that occurs through proteins present in the bilayer is a form ofactive transport.
a)
The role of the Na+ - K+ ATPase is to keep the levels of Na+ high in the cell by pumping Na+ into the cell from the extracellular environment.
b)
Glucose from your digested food within the lumen of your intestine is absorbed at the basalsurface of the cells in your intestinal epithelium through passive diffusion.
c)
Movement of glucose out of the basal surface of the intestinal cell occurs via passive transport to an area of lower glucose concentration.
d)
The concentration of glucose in the cytoplasm of the intestinal epithelial cell is higher than the concentration of glucose in the intestinal lumen or in the extracellular fluid outside the basaldomain.
e)
Any movement of molecules that occurs through proteins present in the bilayer is a form ofactive transport.
Explanation / Answer
A) False.
3 Sodium ions are forced to move outside the cell and 2 Potassium ions are forced to move inside the cell through a single pump. Level of sodium ion is higher in the extracellular medium not inside the cell. It is done against the concentration gradient. So, ATP is required to suppy required energy.
B) Glucose absroption is done in two steps.
The first step is movement of glucose from intestinal lumen to inside of epithelial cell. The second one is, movement of glucose from epithelial cell to the blood stream.
For first step, glucose cannot direct enter into the cell. Firstly, sodium ions are transferred outside the epithelial cell. So there is deficiency of sodium ion inside. Now, when cell tries to get back that sodium ion from out side the cell, glucose moves along with sodim inside the cell. So it is done by cotransport of glucose and sodium. It occurs at the apical part of the cell.
Now second step, here glucose is now inside of the cell. And now, it moves to the blood stream from the cell at the basal region via facilitated (passive ) diffusion. So, at basal region, it is done by passive diffusion amd it is true statement.
C) According to the principle of diffusion, molecules move from higher concentration to lower concentration and it tends to make the concentration equal. So this statement is true. As passive diffusion takes place during the absorption of glucose.
D) F.
The concentration of glucose in lumen is less than the conc. of epithelial cell. For this reason, sodium cotransporter is needed to move the glucose inside the cell. Because, no passive diffusion can occur at the apical region as passive diffusion works down the gradient and without the help of ATP.
E) True. All carrier proteins are driven by energy ATP. As it requires energy, is it known as active transport. Where as, molecules which move along with the down conc. gradient via diffusion doesnot require ATP. So it is passive transport.
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