What modern organisms are thought to be most like the first life-forms on Earth?
Probably either cyanobacteria or archaea, both of which flourish today in all kinds of wet environments.
The question makes the assumption that the first life forms on Earth were what we would now refer to as organisms. Various authorities define "life-form" differently; pre-cellular arrangements of molecules may or may not be considered life.
Cyanobacteria and Archaea are the oldest known unicellular organisms still in existence. There is some debate regarding the proper taxonomy of archaea, at least when it comes to its grouping into phyla.
The "RNA world" hypothesis suggests that, before cellular life-forms, there might have been even more primitive self-replicating molecules. This is similar to the idea that life evolved from a primitive form based on self-replicating RNA strands.
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Simple prokaryotic organisms, like some bacteria and archaea, are thought to be the closest modern organisms to the first life forms on Earth.
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When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.
When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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