Question

a red blood cell placed in a beaker of solution immediately begins to swell and ultimately bursts. this occurs because the cytoplasm of the cell was _ to the solution in the beaker, which was _.
hypertonic, isotonic
hypotonic, hypertonic
hypotonic, isotonic
hypertonic, hypotonic
isotonic, hypotonic

Explanation:

To solve this, we recall osmosis concepts:

• A hypertonic solution has a higher solute concentration (lower water potential) than the cell.
• A hypotonic solution has a lower solute concentration (higher water potential) than the cell.
• An isotonic solution has the same solute concentration as the cell.

When a cell swells and bursts, water enters the cell. This happens when the cell’s cytoplasm (inside) is hypertonic (higher solute, lower water) relative to the beaker’s solution (outside), which is hypotonic (lower solute, higher water). Water moves from the hypotonic solution (beaker) into the hypertonic cytoplasm (cell), causing swelling/bursting.

Let’s analyze options:

• Option 1: Hypertonic (cell) and isotonic (beaker) → No net water movement, cell won’t swell. Eliminate.
• Option 2: Hypotonic (cell) and hypertonic (beaker) → Water would leave the cell (shrink), not swell. Eliminate.
• Option 3: Hypotonic (cell) and isotonic (beaker) → No net movement. Eliminate.
• Option 4: Hypertonic (cell) and hypotonic (beaker) → Water enters cell (swells/bursts). Correct.
• Option 5: Isotonic (cell) and hypotonic (beaker) → No net movement (isotonic) or slight, but not enough to burst. Eliminate.

Answer:

D. hypertonic; hypotonic (assuming the last option with "hypertonic; hypotonic" is labeled D, though labels in the image might vary—based on content, the correct pair is hypertonic (cytoplasm) and hypotonic (beaker solution)).