Biology · BIOLOGICAL CLASSIFICATION

Red tides in oceans are caused by rapid multiplication of certain photosynthetic protists. Which organism is responsible for this phenomenon and what harmful effect can it cause?

1. A
   *Euglena*; forms an impenetrable surface mat blocking sunlight
2. B
   *Nostoc*; depletes oxygen concentrations resulting in algal blooms
3. C
   *Gonyaulax*; releases toxins that may kill other marine animals such as fishes
4. D
   *Trypanosoma*; causes fatal sleeping sickness in marine mammals