What was the "oxygen revolution," which took place 2.3 billion years ago?

A)The "oxygen revolution" was the rapid increase in atmospheric oxygen that took place 2.3 billion years ago, immediately preceding the origin of animals.
B)The "oxygen revolution" was the rapid increase in atmospheric oxygen that took place 2.3 billion years ago, with the origin of plants.
C)The "oxygen revolution" was the rapid increase in atmospheric oxygen that took place 2.3 billion years ago, dooming many prokaryotic groups..

Option-C

Explanation:

The oxygen revolution refers to the increasing concentration of oxygen in the atmosphere around 2.3-2.4 billion years ago.

The studies have suggested that before the oxygen revolution the Earth's atmosphere was full of the hydrogen sulfide and methane gas in which the anoxygenic prokaryotes were evolving.  

The cyanobacteria and other photosynthetic bacteria evolved the photosynthetic pigments which performed the experiment and oxygen gas was produced as a by-product.

With time this oxygen got accumulated in the atmosphere and the oceans and became one of the factors of anaerobic prokaryotic, the condition which they cannot escape. Later the oxygen producing prokaryotes evolved and formed the first eukaryotes.

Thus, the selected option is the correct answer.

b.

hoped i

explanation:

hydroxyl -oh

alcohols, always polar, can form hydrogen bonds with h2o molecules

carboxyl -cooh  

cargoxylic acids, has acidic properties which is a source of hydrogen ions, found in cells in ionized for with a charge of oh-1

carbonyl > co

ketone if within skeleton, aldehyde if group is at the end of skeleton, k & a may be structural isomers, it determines 2 sugars (ketose & aldose)

amino -nh2

amines, acts as a base, it can pick up h+ ions from surrounding solution, ionized with charge of 1+

methyl ch2

addition to rna/dna affects and gene expression

phosphate -opo3 ²⁻

organic phosphates, contributes to negative charge to, molecule that it is a part of, and potential to react with h20

sulfhydryl -sh

thiols, cross-linking stabilize the protein, and it is structure