Question

wallway is a new general herbicide for aquatic plants. its main ingredient is a marine salt solution. it is effective against freshwater but not saltwater plants. it works by breaking down the cell walls of the plants. the freshwater plants die because their cells:

• swell and cease to function
• shrink
• remain the same size but malfunction
• are crushed by the weight of the plant

10.
a red blood cell has a salt concentration of 0.9%. what will happen if it is placed into a 1% salt solution?

• shrink if its membrane is permeable to both the salt and the water
• shrink if its membrane is impermeable to the salt and permeable to the water
• maintain its shape - nothing will happen
• swell and probably burst because its membrane is impermeable to salt and permeable to water
• swell and probably burst because its membrane is impermeable to water and permeable to salt

11.
flasks x, y, and z contain solutions with different concentrations of nacl:

• flask x: 0.5% nacl
• flask y: 0.9% nacl
• flask z: 1.5% nacl

red blood cells (0.9% nacl) are placed into each flask. predict what will happen to the blood cells in each flask:

• flask x: contract flask y: unchanged flask z: swell
• flask x: swell flask y: unchanged flask z: contract

Explanation:

Osmosis is the movement of water across a semi - permeable membrane from an area of lower solute concentration to an area of higher solute concentration. In question 10, when a red blood cell (0.9% salt) is placed in a 1% salt solution (hypertonic solution relative to the cell), if the membrane is impermeable to salt (solute) but permeable to water (solvent), water will move out of the cell. In question 11, for Flask X (0.5% NaCl, hypotonic to the cell), water will move into the cell (swell); Flask Y (0.9% NaCl, isotonic) - no net water movement (unchanged); Flask Z (1.5% NaCl, hypertonic) - water moves out (contract).

Answer:

For question 10: Shrink if its membrane is impermeable to the salt and permeable to the water.
For question 11: Flask X: Swell Flask Y: Unchanged Flask Z: Contract