More than 2 billion years ago _________ began producing oxygen?

Question

Hi this was a question on my science homework! Can someone help me fill in the blank?

Answer 1

cyanobacteria.

Answer 2

Ancient Global Pollution

The first "pollution crisis" hit the Earth about 2.2 billion years ago. Several pieces of evidence -- the presence of iron oxides in paleosols (fossil soils), the appearance of "red beds" containing metal oxides, and others -- point to a fairly rapid increase in levels of oxygen in the atmosphere at about this time. Oxygen levels in the Archaean had been less that 1% of present levels in the atmosphere, but by about 1.8 billion years ago, oxygen levels were greater than 15% of present levels and rising. (Holland, 1994) It may seem strange to call this a "pollution crisis," since most of the organisms that we are familiar with not only tolerate but require oxygen to live. However, oxygen is a powerful degrader of organic compounds. Even today, many bacteria and protists are killed by oxygen. Organisms had to evolve biochemical methods for rendering oxygen harmless; one of these methods, oxidative respiration, had the advantage of producing large amounts of energy for the cell, and is now found in most eukaryotes.

Where was this oxygen coming from?

Cyanobacteria, photosynthetic organisms that produce oxygen as a byproduct, had first appeared 3.5 billion years ago, but became common and widespread in the Proterozoic. Their photosynthetic activity was primarily responsible for the rise in atmospheric oxygen.

Answer 3

The above answer is a good one. The unfortunate implication is the oxygen appearing in the atmosphere well before the point of DNA's random assembly, as postulated by Darwinian evolution. This is a problem because oxygen in the atmosphere would have stopped that "random assembly" before it even got started.

Answer 4

Chlorophyll

Answer 5

cyanobacteria