Question

In plants, the tubular extensions of plasma-membrane that connect the cytoplasm of adjacent cells are called

• A. Apoplast
• B. Symplast
• C. Plasmodesmata
• D. Root hairs

Hint:

"Plasmodesmata" are the physical, membrane-lined molecular bridges between adjacent plant cells. The continuous cytoplasmic network they form is called the "Symplast," while the non-living cell wall space is the "Apoplast."

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Unlike animal cells, adjacent plant cells are separated by a rigid cellulose cell wall.
To allow direct intercellular communication and transport of water, nutrients, and signal molecules, plants utilize specialized membrane-lined microscopic channels.

Step 2: Detailed Explanation:
Let us define the structural components of plant cell transport:
Plasmodesmata (C): These are microscopic, membrane-lined tubular channels that cross the cell wall to connect the cytoplasm of adjacent cells.
A plasmodesma contains a central tubule of modified endoplasmic reticulum called a desmotubule.
The space between the desmotubule and the channel's outer plasma membrane forms a cytoplasmic sleeve through which water, ions, hormones, transcription factors, and small RNAs can pass directly from cell to cell.
Symplast (B): This is the collective, continuous network of living cytoplasm connected by plasmodesmata throughout the plant body.
The plasmodesmata are the physical structures that make up the symplast.
Apoplast (A): This is the continuous non-living space outside the plasma membrane, consisting of cell walls and intercellular spaces.
Root Hairs (D): These are tubular outgrowths of root epidermal cells that absorb water and minerals from the soil.

Step 3: Final Answer:
The tubular plasma-membrane extensions connecting adjacent cells are called Plasmodesmata, corresponding to option (C).