Q.Draw and label the parts of ultra-structure of plant cell.

A labelled diagram of the plant cell ultrastructure shows the cell wall and plasma membrane at the boundary, the nucleus, and a cytoplasm packed with organelles - ER, Golgi bodies, mitochondria, plastids, ribosomes - plus a large central vacuole.

A typical plant cell, as revealed by the electron microscope, shows the following labelled parts, arranged from the outside in:

1. Cell wall: The outermost, rigid, non-living layer made of cellulose, lying external to the plasma membrane; gives shape and protection, and is a feature unique to plant cells (absent in animal cells).

2. Plasma membrane (cell membrane): A thin, living, selectively permeable membrane just inside the cell wall, enclosing the cytoplasm.

3. Nucleus: The prominent, usually centrally or peripherally located control centre, bounded by a double-membraned nuclear envelope (with nuclear pores), containing the nucleolus and chromatin (DNA-protein complex).

4. Cytoplasm (cytosol): The semi-fluid matrix filling the cell, in which all the organelles are suspended.

5. Endoplasmic reticulum (ER): A network of interconnected membranous tubules and sacs; rough ER (studded with ribosomes, involved in protein synthesis) and smooth ER (lacking ribosomes, involved in lipid synthesis).

6. Golgi apparatus (dictyosomes): Stacks of flattened, membrane-bound sacs (cisternae) involved in processing, packaging, and secretion of materials, including cell wall components.

7. Mitochondria: Double-membraned organelles with inner membrane folded into cristae; the site of aerobic respiration and ATP production.

8. Plastids: Especially chloroplasts, double-membraned organelles containing internal membrane stacks (grana, made of thylakoids) embedded in a matrix (stroma); the site of photosynthesis.

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