There are algae that reproduce sexually and there are algae that reproduce asexually.
In unicellular algae reproduction is generally asexual by binary division.
In pluricellular algae asexual reproduction can occur by fragmentation or by sporulation.
In sexual reproduction of algae, uni or pluricellular, there is fusion of gametes (syngamy). There are algae in which all cells can become gametes and there are algae in which only some cells can play that role. Some species may present alternation of generations, forming gametophytes and sporophytes with different ploidies.
