Q.48 The shape of chloroplast in Spirogyra is
1. Cup-shaped
2. Spiral
3. Girdle shaped
4. Discoid
Spirogyra, a filamentous green alga, features distinctive chloroplasts key to NEET cell biology questions. Question 48 tests chloroplast morphology across algae, with the correct shape being spiral. This identifies Spirogyra’s helical chloroplast band wrapped around its vacuole.
Correct Answer
The shape of the chloroplast in Spirogyra is 2. Spiral. These chloroplasts form a ribbon-like, spirally coiled structure around the central vacuole, often with pyrenoids for starch storage, aiding photosynthesis in freshwater habitats.
Option Explanations
Each option represents chloroplast shapes in different algae, helping distinguish genera in exams.
| Option | Shape | Example Alga | Description |
|---|---|---|---|
| 1. Cup-shaped | Cup-shaped | Chlamydomonas | Single chloroplast resembling a bowl or cup, common in unicellular flagellates. |
| 2. Spiral | Spiral | Spirogyra | Helical band coiled around vacuole; signature of Spirogyra filaments. |
| 3. Girdle-shaped | Girdle-shaped | Ulothrix | Band-like chloroplast encircling the cell like a belt. |
| 4. Discoid | Discoid | Chlorella, higher plants | Flat, lens-shaped plates stacked in cells. |
Option 2 fits Spirogyra perfectly, as its name derives from the Greek “spira” for spiral, reflecting this coiled chloroplast visible under microscopy.
Chloroplast Diversity in Algae
Chloroplast shapes vary by alga type, optimizing light capture.
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Spirogyra specifics: 1-20 spiral chloroplasts per cell, flat and twisted for maximum surface area.
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Comparison note: Unlike discoid in mesophyll cells or girdle in Ulothrix, Spirogyra’s spiral enables efficient photosynthesis in low-light ponds.
This question reinforces algal classification for molecular biology and botany exams.
