Explanation

Asexual reproduction is by flagellated zoospores produced in zoosporangia. The sexual reproduction shows considerable variation in the type and formation of sex cells and it may be isogamous, anisogamous or oogamous. In isogamy, gametes are morphologically and physiologically different but physiologically same and in oogamy, gametes are both morphologically and physiologically different, $e.g$., Ulothrix and Spirogyra members of Chlorophyceae