Some algae have chloroplasts and chlorophyll and obtain their energy through photosynthesis while some algae like euglena are both heterotrophic (decompose dead organic matter) and autotrophic (use photosynthesis) and can also obtain energy likewise.
Answer: 2500 i think don't count me on it though sorry if it is wrong.
Explanation:
1 reason is to kill disease in water
Due to the need to have completely controlled experiments to test a hypothesis, science can not prove everything. For example, the scientific method cannot alone say that global warming is bad or harmful to the world, as it can only study the objective causes and consequences.