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Difficulty: HardCell Structure and Function

When a freshwater plant is exposed to drought or a hypertonic environment, water leaves the cytoplasm and causes the cell membrane to pull away from the rigid exterior boundary. Which cellular structure is primarily responsible for storing fluid and generating the internal turgor pressure needed to maintain structural rigidity in non-woody plant tissues?

  1. A
    Lysosome
  2. B
    Ribosome
  3. Central vacuoleAnswer
  4. D
    Nucleus

Answer

Central vacuole
The central vacuole is a large, membrane-bound organelle found in plant cells that sequesters water, nutrients, and waste products. By absorbing water via osmosis, it expands and pushes the plasma membrane against the rigid cell wall, establishing turgor pressure that maintains structural firmness and prevents wilting.

Step-by-Step Solution

1
Analyze the physiological process described in the scenario.
The scenario describes loss of internal hydrostatic pressure (plasmolysis/wilting) caused by fluid depletion within a plant cell.
Plant cells rely on internal water pressure pushing against the cell wall to support herbaceous tissue structures.
2
Identify the specific organelle that functions as the main fluid reservoir in plant cells.
The central vacuole occupies up to 90% of a mature plant cell's volume and regulates osmotic balance.
When filled with water and dissolved ions, the central vacuole exerts outward turgor pressure against the cellulose cell wall.
3
Evaluate and eliminate non-target organelles.
Lysosomes, ribosomes, and the nucleus carry out metabolic degradation, translation, and genetic storage respectively, rather than volumetric turgor maintenance.
Only the central vacuole provides the physical hydrostatic support described.

Key Concept

Plant Organelle Specialization and Turgor Pressure Regulation
Estimated Time:1m 15s
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Topics

Cell Structure and Function

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