Britannica Sources used in this answer

How do algae produce oxygen through photosynthesis?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

“mermaid's wine glass” algae — Algae The macroscopic genus of algae known as *Acetabularia* is commonly called “mermaid's wine glass” because of the distinctive umbrella-like shape of the tips of its stalks.

Algae produce oxygen through a process called photosynthesis, which occurs primarily within specialized structures called chloroplasts.12

The production of oxygen is a key component of the "light reactions" of photosynthesis. During these reactions, pigments such as chlorophyll absorb sunlight, which excites electrons and initiates an electron transport chain. To replace these excited electrons, the organism performs photolysis, a process that splits water molecules. This splitting of water releases oxygen as a by-product, along with hydrogen ions and electrons.345

These light-driven reactions are essential for the subsequent "dark reactions" (or Calvin cycle), where the energy generated is used to convert carbon dioxide into organic molecules like carbohydrates. Because algae are responsible for replacing a significant portion of the oxygen in the biosphere, they are considered vital primary producers in aquatic ecosystems.6572