Plant central vacuole — identify what is not a function In plant cells, the large central vacuole serves many roles. Which listed item is not a normal function of the plant central vacuole?

Introduction / Context:
Plant cells contain a prominent central vacuole that can occupy most of the cell volume. Clarifying its functions helps differentiate plant physiology from protistan mechanisms such as contractile vacuoles.

Given Data / Assumptions:

• Plant central vacuoles are membrane bound compartments enclosed by the tonoplast.
• They store water, ions, metabolites, pigments, and wastes.
• They contribute to cell rigidity by maintaining turgor pressure.

Concept / Approach:

The contractile vacuole that actively pumps water out of the cell is characteristic of many freshwater protists, not higher plant cells. Plant central vacuoles are largely storage and homeostasis organelles; they do not perform rhythmic pumping to expel excess water. Instead, plant cells regulate water via osmotic balance and cell wall resistance to maintain turgor.

Step-by-Step Solution:

Verification / Alternative check:

Botany references attribute osmotic storage and turgor maintenance to plant vacuoles, while contractile activity is documented in amoebae and paramecia, confirming the distinction.

Why Other Options Are Wrong:

Storage of food reserves and metabolites, support via turgor, waste sequestration, and pigment storage are all recognized functions of plant central vacuoles.

Common Pitfalls:

Confusing plant vacuoles with contractile vacuoles due to shared terminology. The mechanisms and roles are very different across taxa.

Final Answer:

Contractile regulation of water content (pumping action)