Q.Draw a neat labelled diagram: Spirogyra.

Spirogyra is described in this chapter as a multicellular, unbranched, filamentous green alga (Chlorophyceae). To draw and label it:

Step 1. Overall shape. Draw one rectangular/cylindrical cell as a representative segment of the long, unbranched filament (the full filament is simply a chain of such cells joined end to end).

Step 2. Outer layers. Label the outermost boundary as the cell wall (cellulose), with a thin mucilage sheath just outside it.

Step 3. Distinctive chloroplast. Draw one or more ribbon-like bands spiralling around the inside of the cell wall, and label this the chloroplast — its spiral, ribbon shape is Spirogyra's most recognisable feature. Along the chloroplast, mark small round bodies as pyrenoids (starch-storage sites). …

Draw one representative cell of the unbranched filament and label, from outside in: cell wall, mucilage, spiral chloroplast …

• Drawing the chloroplast as a simple round shape instead of the diagnostic spiral ribbon. …