More Oxygen = ?

[Arachn'auQuébec]

Also though as you mentioned, Plants work both ways, using both CO2 and O2, but what about when there was no O2. If plants created all the O2 from CO2, then how did they evolve to a point were they could switch the process?

Most of the oxygen came from cyaneobacterias, wich basically were almost the only organisms from 3 billion to 1.4 billions years ago. Plants appeared in an atmosphere already rich in O2.

 

[Radamanthys]

Most of the oxygen came from cyaneobacterias, wich basically were almost the only organisms from 3 billion to 1.4 billions years ago. Plants appeared in an atmosphere already rich in O2.

People tend to think that only plants do photosynthesis. Microalgae, cyaneobacterias and lots of other organisms get their food from light. But the plants gave the boost when they appeared on land and were the only organisms out of water.

 

[wedge07]

It is my understanding that the first life on earth were unicellular organisms capable of photosynthesis.

 

[skips]

It is my understanding that the first life on earth were unicellular organisms capable of photosynthesis.

Since we're already off topic and I love where this discussion is going, the first "life" on earth to me were, very arguably, self replication RNA's. There's some credible evidence that more viral type organisms were the first "living" things on earth. it really depends what your concept of life is. But yeah, if you mean the first really complex cell then yeah, autotrophic (photosynthetic) bacteria would have to be the first I think. I'm too lazy at this point to look up if that's correct.

 

[wedge07]

Since we're already off topic and I love where this discussion is going, the first "life" on earth to me were, very arguably, self replication RNA's. There's some credible evidence that more viral type organisms were the first "living" things on earth. it really depends what your concept of life is. But yeah, if you mean the first really complex cell then yeah, autotrophic (photosynthetic) bacteria would have to be the first I think. I'm too lazy at this point to look up if that's correct.

That's pretty interesting skips I'll have to look into that.

 

[skips]

That's pretty interesting skips I'll have to look into that.

Definately do. RNA is the perfect candidate for a substance that can go from a pure chemical to a complex structure. They don't need any kind of enzyme to change them up. Look up the "RNA world" hypothesis. And if you're interested Mimivirus and newly discovered virophages. virophages are rediculous. They're viruses (considered not to be alive) that infect bigger virusses like mimivirus (which is a very large virus that functions alot like a bacteria).

There was just an article in scientific american about a guy that ran a bunch of tests with different types of RNA's, which were allowed to replicate for a given amount of time. He found that they did in fact change up their sequence and structure, and the ones that were most stable were dominant. Evolution in a 20 minute bottle.

 

[ZergFront]

Something about the "oxygen" idea being associated with large size isn't agreeing with me. It was mentioned before, if the theory is true the genetic code that was formed because of the environment back then isn't there anymore because, up to the present, they have evolved with less oxygen and their genetic code has conformed to that. They don't have the "grow" gene to deal with more oxygen is what I'm thinking. I feel more oxygen wouldn't do much as far as "growth" goes with present day inverts. High levels of O2 can easily be toxic to life today. Haha, fun see all the info and opinions .

I agree. Wasn't there a tarantula kept in the Tarantula Keepers Guide that got so big she couldn't right herself once she was turned up-side-down? She was big for her species, but not big like the few of the largest species of spider. I will try to find that section again later. If anyone has the latest edition, you can probably find it.

I would think the combination of the arachnid's body weight and the hydrolic pressure used for their locomotion would play a part on their max size as well. Bigger spiders couldn't move as well; couldn't escape predators and didn't pass on their genes.

I don't know. What do you guys think? Physics hasn't been my best. I'm more with biology.