Which one of the following shows isogamy with flagellated gametes?
Sexual reproduction takes place through fusion of two gametes. These gametes can be flagellated and similar in size (as in Ulothrix) or non-flagellated (non-motile) but similar in size (as in Spirogyra). Such reproduction is called isogamous. Fusion between one large, non-motile (static) female gamete and a smaller, motile male gamete is termed oogamy. e.g., Volvox, Fucus.