Question

the concentration of solutes in a red blood cell is about 2%. sucrose cannot pass through the membrane, but water and urea can. osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions?

• a hypertonic sucrose solution
• a hypotonic sucrose solution
• a hypertonic urea solution
• a hypotonic urea solution
• pure water

5.
sea water is dangerous to drink because:

• one cup of sea water contains enough sodium to poison you.
• sea water is hypertonic to your body tissues and drinking it will cause you to lose water.
• sea water is isotonic to your body fluids and you will absorb too much water.
• the salt causes hypertension and you will promptly die of a stroke.
• it contains toxic levels of iodine.

6.
if the volume of a cell increases when it is pl🔗ed in a solution, that solution is said to be ______ to the cell.

• hypertonic
• subatomic

Explanation:

• For the first question: Osmosis is the movement of water across a semi - permeable membrane from an area of low solute concentration to an area of high solute concentration. Sucrose cannot pass through the membrane. A hypertonic sucrose solution has a higher solute concentration outside the cell (compared to the 2% solute concentration in the red blood cell). Water will move out of the cell, causing it to shrink. Urea can pass through the membrane, so in a hypertonic urea solution, urea will also move into the cell (along its concentration gradient) which will reduce the net movement of water out due to the change in internal solute concentration. Hypotonic solutions (sucrose or urea) and pure water will cause water to move into the cell (cell swells).
• For the second question: Sea water is hypertonic to body tissues. When drunk, water will move out of body cells (due to osmosis, from an area of lower solute concentration in cells to an area of higher solute concentration in sea water) causing dehydration (loss of water). One cup of sea water does not contain enough sodium to poison in the sense of acute sodium poisoning. Sea water is not isotonic. While salt can contribute to hypertension over time, the immediate danger is dehydration. It does not contain toxic levels of iodine in terms of acute poisoning from a small amount drunk.
• For the third question: When a cell is placed in a hypotonic solution, the solute concentration outside the cell is lower than inside. Water moves into the cell (by osmosis) causing an increase in cell volume. A hypertonic solution would cause water to move out (cell shrink). "Subatomic" is not a term related to tonicity of solutions with respect to cells.

Answer:

• First question: A hypertonic sucrose solution
• Second question: Sea water is hypertonic to your body tissues and drinking it will cause you to lose water.
• Third question: Hypotonic