Which is a multicellular filamentous green alga consisting of thin unbranched chains of cylindrical cells and found in floating masses near the surface of streams and ponds?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. Spirogyra.
Spirogyra is a multicellular, filamentous green alga composed of unbranched chains of cylindrical cells. It is commonly found floating near the surface of ponds, streams, and other freshwater bodies in the form of slimy green masses, especially during spring and summer. Spirogyra is named after its spirally arranged chloroplasts, which are clearly visible under a microscope. It reproduces both asexually (fragmentation) and sexually (conjugation). It belongs to the Chlorophyta group, and its ability to form dense floating mats plays an important role in the aquatic ecosystem, particularly in oxygen production and nutrient cycling.
Other Options:
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Ectocarpus – A brown alga, mostly found in marine environments, not freshwater.
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Laminaria – Another large brown alga (kelp), found in cold marine waters.
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Chlorella – A unicellular green alga, not filamentous or multicellular.