Question

cell transport practice frq
table 1. changes in morning glory petal cells during flower opening
the petal color of the mexican morning glory (ipomoea tricolor) changes from red to blue, and the petal cells swell during flower opening. the pigment heavenly blue anthocyanin is found in the vacuole of petal cells. petal color is determined by the ph of the vacuole. a model of a morning glory petal cell before and after flower opening is shown in table 1.
(a) identify the cellular component in the model that is responsible for the increase in the ph of the vacuole during flower opening and describe the components role in changing the ph of the vacuole. (2pts)
(b) a researcher claims that the activation of the k+/h+ transport protein causes the vacuole to swell with water. provide reasoning to support the researchers claim. (1pt)

Explanation:

(a) The proton pump is responsible for the increase in pH of the vacuole during flower - opening. It actively transports protons ($H^+$) out of the vacuole. As $H^+$ are pumped out, the concentration of $H^+$ in the vacuole decreases, which leads to an increase in pH (since pH = -log[H+]).
(b) When the $K^+/H^+$ transport protein is activated, it transports $K^+$ into the vacuole and $H^+$ out of the vacuole. The influx of $K^+$ into the vacuole increases the solute concentration inside the vacuole. According to the principle of osmosis, water moves from an area of lower solute concentration (outside the vacuole) to an area of higher solute concentration (inside the vacuole), causing the vacuole to swell with water.

Answer:

(a) The cellular component is the proton pump. Its role is to actively transport protons ($H^+$) out of the vacuole, decreasing the $H^+$ concentration in the vacuole and increasing the pH.
(b) Activation of the $K^+/H^+$ transport protein increases the solute concentration (with the influx of $K^+$) inside the vacuole, and by osmosis, water moves into the vacuole, causing it to swell.