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Question #46297

Difficulty: 8/10 | 🟢 Free

The Question

In a terrestrial ecosystem, a sudden and rapid increase in the rate of detritus mineralization significantly elevates the concentration of inorganic ions in the rhizosphere. Which of the following sequences accurately describes how this specific shift in soil chemistry directly alters the ecosystem's evapotranspiration budget?

Options

A.
Decreased soil water potential ( $\Psi_w$ ) → ABA synthesis in roots → Xylem translocation → $K^+$ efflux from guard cells → Decreased stomatal conductance
B.
Increased soil solute potential ( $\Psi_s$ ) → Cytokinin synthesis in roots → Phloem translocation → $K^+$ influx into guard cells → Increased stomatal conductance
C.
Decreased soil water potential ( $\Psi_w$ ) → ABA synthesis in roots → Phloem translocation → Malate accumulation in guard cells → Decreased stomatal conductance
D.
Increased soil water potential ( $\Psi_w$ ) → Ethylene synthesis in roots → Xylem translocation → $Ca^{2+}$ influx into guard cells → Increased stomatal conductance

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Comparative_Analysis

Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.

Concepts Behind This Question

Stomatal Apparatus Anatomy|Ecosystem|Root System Architecture

Why This Question Is Tricky

Common Mistakes

Conceptual Pivot: Integrating Ecosystem ecology (mineralization) with Plant Physiology (water potential, ABA signaling, and stomatal mechanics).

The trap relies on multiple common misconceptions: confusing the effect of solutes on water potential (solutes always lower $\Psi_w$ ), misidentifying the transport tissue for root-derived stress signals (xylem vs. phloem), and reversing the ionic mechanism of stomatal closure ( $K^+$ efflux vs. influx).

Quick Facts About This Question

Question Information

Subject	Biology
Chapter	Anatomy of Flowering Plants - Class 11
Concept	Stomatal Apparatus Anatomy
Difficulty	8
Cognitive Load	5
Target Solve Time	120 sec
Access	Free