If algae lives under water, using which part of the organism does it absorb oxygen from water?

Question

If algae lives under water, using which part of the organism does it absorb oxygen from water?

Answer 1

Algae are photosynthetic, so they are more like to produce oxygen from water during photosynthesis.  In order to do this, they need PLASTIDS, which are specialized organelles, with large amounts of chlorophylll and other antenna pigments.  Plastids with chlorophyll are usually called CHLOROPLASTS.

Answer 2

Algae generate the O2 they need for cellular respiration during photosynthesis. They absorb dissolved inorganic CO2 from the sea water they need as a substrate during the chemical reactions of photosynthesis.  Most algae actively concentrate their CO2 to increase the efficiency of photosynthesis. Algae use this to avoid CO2 limiting their rate of photosynthesis while sunlight is available.

Algae expend energy to move CO2 across membranes at the cell wall, the plasma membrane and the chloroplast membrane. They move bicarbonate ions as well as CO2.

http://www.plantphysiol.org/cgi/content/...

http://arjournals.annualreviews.org/doi/...

http://www.pubmedcentral.nih.gov/article...

http://books.google.com/books?id=gDz5jGs...

Water contains two types of dissolved carbon. First is the organic carbon from decomposing algae and animals, second is the dissolved inorganic carbon in several forms: carbon dioxide (CO2), bicarbonate (HCO3), and carbonate (CO3).

The inorganic forms vary in their relative concentration by pH. Higher pH results in less free dissolved CO2 and more carbonate forms.

http://www.chem.usu.edu/~sbialkow/Classe...