Q. The unicellular algae used to regulate the supply of oxygen in a space programme are

Explanation by: Mr. Dubey

Chlorella is a unicellular, green algae that has been used in space programs to regulate the supply of oxygen and remove carbon dioxide. It performs photosynthesis efficiently, making it ideal for creating a self-sustaining atmosphere in closed environments like space stations.
Why not the other options?
(A) Chlamydomonas → ❌
Although it is also a unicellular green algae, it is not widely used for oxygen supply in space programs.
(C) Codium → ❌
Codium is a multicellular green algae, not unicellular.
(D) Spirogyra → ❌
Spirogyra is filamentous, not unicellular, and is not used in space programs.
Thus, Chlorella is the correct answer as it is highly efficient in oxygen production and carbon dioxide absorption in closed systems.