Question

multiple choice question when photosynthetic bacteria began to use —— as an electron donor in photosynthesis, —— began to be released and to accumulate in earths atmosphere, evidenced by iron - rich sediments in oceans. options: water; oxygen, water; sulfur, methane; carbon dioxide, methane; oxygen

Explanation:

In photosynthesis by certain bacteria, when water is used as an electron - donor, oxygen is produced as a by - product and accumulates in the atmosphere. This is a key concept in understanding the oxygenation of Earth's atmosphere. Iron - rich sediments are related to the early Earth environment where such photosynthetic processes occurred.

Answer:

water; oxygen