[Campbell Biology P.182] Referring to the 'VISUAL SKILLS' question and considering the princ... | Practice Question

Referring to the 'VISUAL SKILLS' question and considering the principles from Figure 7.11 and 7.12, if an orange dye permeable to the membrane was added to the left side of the U-tube initially containing sugar solutions , what would be the final distribution of the dye and the effect on the solution levels?

  • A: The orange dye would remain concentrated on the left side, and the final solution levels would be unaffected by its presence.
  • B: The orange dye would be evenly distributed throughout the tube, and the final solution levels would be affected similarly to the original osmosis experiment, with the left side level decreasing and the right side increasing.
  • C: The orange dye would be evenly distributed, and its presence would cause the final solution levels to become equal on both sides, overriding the osmotic effect of sugar.
  • D: The orange dye would only diffuse to the right side if the sugar concentration was lower there, and this would reverse the original osmotic water movement.

Explanation

According to Figure 7.11b, each substance diffuses down its own concentration gradient independently. Therefore, the orange dye, being permeable, would spread evenly throughout the tube left to right until equilibrium is reached. Simultaneously, as shown in Figure 7.12, the sugar concentration gradient would still drive osmosis: water would move from the left lower sugar, higher free water to the right higher sugar, lower free water , causing the left side's solution level to decrease and the right side's to increase.