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Q33 - Biphasic Kinetics of Potassium Uptake by Trichomes

Theoretical 2 Real exam question - full text reproduced under IBO's CC BY-NC-SA 4.0 license
Mineral Nutrition & Nutrient Uptake

Physiological studies have been accomplished on the adaptations of bromeliad plants to nutrient acquisition and plant utilization of potassium. The Figure shows biphasic kinetics of potassium uptake by foliar trichomes of a tank bromeliad plant in the presence of 0.01-90 mM substrate. Uptake rates were calculated during the first 1-2 h of the experiment. The obtained results suggested that there were two transporter systems, and their Michaelis-Menten constants (Km) were calculated to be 41.3+/-8.7 uM and 56.5+/-13.7 mM.

Figure 1. Figure 1.

Using the information and data, determine which of the statements are true or which are false.

A. The low affinity system accumulated K+ slower than the high affinity system
B. Km of 56.5 mM belongs to B transporter system
C. Applying ATPase inhibitor compounds inhibits B transporters
D. B transporters are blocked more by potassium channel blockers, as compared to A transporters
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Question reproduced from IBO 2018, Theoretical Paper 2, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)