Question

if the number of photosynthesizing organisms on earth decreased drastically, which would happen as a result?
less water would be available on earths surface.
less solar energy would reach earths atmosphere.
more oxygen gas would be found in earths atmosphere.
more carbon - dioxide gas would be found in earths atmosphere.

Explanation:

Photosynthetic organisms convert carbon - dioxide and water into organic compounds and release oxygen through photosynthesis. If their number decreases drastically, less oxygen will be produced and more carbon - dioxide will remain in the atmosphere as there are fewer organisms to take it up for photosynthesis.

Answer:

More carbon dioxide gas would be found in Earth's atmosphere.