Question

Which organism was the first to develop in the absence of oxygen?


A.
prokaryotic


B.
eukaryotic


C.
cyanobacteria


D.
algae

Answer 1

i would have said bacteria but i guess the answer is more in depth then just that so...

Answer 2

A: prokaryotic

Answer 3

@Abhisar look at the question i sent you

Answer 4

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Answer 5

The first organism which evolved was indeed prokaryotic, after these cyanobacteria evolved which liberated oxygen by photosynthesis

Answer 6

it make sense to me now. thank you, both of you!:))

Answer 7

\(\color{red}{\huge\bigstar}\huge\text{You're Most Welcome! }\color{red}\bigstar\)
\(~~~~~~~~~~~~~~~~~~~~~~~~~~~\color{green}{\huge\ddot\smile}\color{blue}{\huge\ddot\smile}\color{pink}{\huge\ddot\smile}\color{red}{\huge\ddot\smile}\color{yellow}{\huge\ddot\smile}\)

Answer 8

no prob

Answer 9

@Abhisar @Tishockjo This is a horrible question; prokaryotes are eubacteria (Domain Bacteria) and the archaea (Domain Archaea). Both "A" and "C" are equally valid, after all cyanobacteria are prokaryotes.

I believe the question wants "C" as the answer. Cyanobacteria do not need oxygen, they need water. They split the water molecular into two protons (H+) and one oxygen and must do this twice, resulting in O2. The production of O2 by cyanobacteria is thought to be the cause of atmospheric O2 and a mass extinction of anaerobic bacteria.

Answer 10

@mrdoldum cyanobacteria are oxygenic photosynthetic bacteria which started producing oxygen during oxygen revolution. many other prokaryotes lived before cyanobacteria which were non-oxygenic photosynthetic.

Answer 11

@Abhisar Gaseous O2 has alway existed on a solidified Earth. The free O2 levels were so low that only non-aerobic respiration species could live. Cyanobacteria do not require O2. They can perform cyclic photosynthesis and avoid the O2 all together. So, I am not sure what the "correct" answer here is, but both A and C are valid.

Still, because it asks for "organism" I believe C is the best answer. "A" is not even a group of organisms actually. It is now an informal term used to refer to organisms with similar morphologies but are not closely related.

Answer 12

The first living being were prokaryotes like bacteria that were chemoheterotrophs.
@mrdoldum

Answer 13

@Abhisar It was chemoauthotrophs, not chemoheterotrophs. I really don't know what the question's answer should be because, as I have said, both A and C are correct. Cyanobacteria are in the informal group of prokaryotes and evolved pre-significant level of O2. In fact, they made the majority O2 on Earth via water molecules. So, we have C, which evolved before high levels of O2 AND are prokayotes. This means that if C is correct, A must be correct by default.

Check out the Archean eon:

http://en.wikipedia.org/wiki/Timeline_of_evolutionary_history_of_life#Detailed_timeline

I do have better citations but I do not want to dig out my Campbell's Biology right now.

Answer 14

No i can bet, it ws chemoheterotrophs !

Answer 15

They were anaerobic and synthesised organic material from inorganic materials !

Answer 16

due to continued withdrawl or organic molecules by chemoheterotrophs organic material decreased in oceans. Before all the material dissapeared, new modes of nutrition developed. One of them was chemoautotrophy

Answer 17

\(\color{blue}{\text{Originally Posted by}}\) @Abhisar
They were anaerobic and synthesised organic material from inorganic materials !
\(\color{blue}{\text{End of Quote}}\)
*chemoheterotrophs were anaerobic and directly absorbed organic molecule. They were unable to synthesise organic molecule from inorganic molecule

Answer 18

Martin W, Russell MJ. 2003. On the origins of cells: a hypothesis for the evolutionary transitions from abiotic geochemistry to chemoautotrophic prokaryotes, and from prokaryotes to nucleated cells. Phil. Trans. R. Soc. Lond. B 358:59–85.

Answer 19

@Abhisar Don't know where your quote is from, but the studies I have read do not support it.

Answer 20

Autotrophism evolved from heterotrophy !
\(\color{green}{\huge\ddot\smile}\)

Answer 21

I don't have much of source to refer !
But u r missreading ur source !
Its very general to say that "a hypothesis for the evolutionary transitions from abiotic geochemistry to chemoautotrophic prokaryotes, and from prokaryotes to nucleated cells."

Answer 22

It's obvs, abiogenesis states this only !
But ur source do not have a word about the correct sequence.

Answer 23

See this
http://science.opposingviews.com/did-heterotrophs-evolve-autotrophs-23027.html

Answer 24

Read the first paragraph !

Answer 25

@Abhisar I am not misreading it. I read the abstract and their conclusions. Sentence taken from their abstract:

The first free–living cells are suggested to have been eubacterial and archaebacterial chemoautotrophs that emerged more than 3.8 Gyr ago from their inorganic confines. We propose that the emergence of these prokaryotic lineages from inorganic confines occurred independently, facilitated by the independent origins of membrane–lipid biosynthesis: isoprenoid ether membranes in the archaebacterial and fatty acid ester membranes in the eubacterial lineage.

Additionally see, page 295 left column first full paragraph:

Novoselov AA, Serrano P, Pacheco MLAF, Chaffin MS, O’Malley-James JT, Moreno SC, Ribeiro FB. 2013. From cytoplasm to environment: The inorganic ingredients for the origin of life. Astrobiology 13:294–302.

Answer 26

@Abhisar I have seen more evidence for the autotroph hypothesis than the heterotroph hypothesis as this time. I think I will go find my molecular evolution books and get back to you.

Answer 27

May be, but there will always remain a discrepancy !
btw i believe in heterotrophic hypothesis more. And in any case the answer will not be cyanobacteria.
:)

Answer 28

@mrdoldum

Answer 29

@Abhisar It is too vague, as A includes C, it shouldn't then be A.

Answer 30

U r just seeing ur perspective !
Question wants u to see its perspective :)

Answer 31

Read this
http://faculty.fmcc.suny.edu/mcdarby/Animals&PlantsBook/History/07-Explaining-Life-on-Earth.htm

Answer 32

@Abhisar That is the issue though. Questions should not have "perspective." They should be clear and concise so that it is fair to the student. Believe me, questions like this are a HUGE issue when students take tests from a certain professor, and we, the TAs, have to try to work it out with the students and help them along. All because the professor writes poorly worded questions what are unclear or technically incorrect.

Example, one questions asked the ATP production by glycolysis and fermentation and proceeded to give all the answers with 2 ATP for glycolysis. Do you see the problem?

Answer 33

2ATP (SLP), rest 8 from ETS. Net 8 since 2 is used up in the process. I agree the question is incomplete.

Answer 34

but u know what, in our country we have to go through a very tough competitive pre test for getting admission into medical colleges. (2000 from 100000 appearing students get selected) When i was preparing for it i used to encounter many of such questions. Then i figured it out that sometime the questions like the original one (prokaryote/cyanobacteria) is purposely asked to see the judgement level of the student.

Answer 35

*I am confused wthr its 6 atp or 8 atp from ets

Answer 36

@Abhisar It is not 8, it is 4. Glycolysis splits a glucose molecule into two groups, each of which go through the full process. However, 2 ATP are used during Glycolysis giving us a net 2 ATP production from one round of glycolysis. Well, she did not as for net or gross, so there is actually no answer.

Answer 37

yes it's 4 atp via slp and 6 atp from ets, only 2 is counted since 2 are used up

Answer 38

So net gain should be 8 ATP (SLP+ETS)

Answer 39

@Abhisar, no it is 4 ATP per glucose (gross) with 2 ATP used up so there is only 2 net ATP.

Answer 40

Glycolysis produces 2 NADH+H\(^+\) also, whch produces 6 atp's in ELECTRON TRANSPORT CHAIN. 4 ATP"S are via Substrate level production. Only 2 is counted since 2

Answer 41

are used up

Answer 42

@Abhisar I didn't ask about the ETC, only glycolysis.

Answer 43

That's why i said the question is incomplete.

Answer 44

ETS ATP is also due to glycolysis

Answer 45

if talking about aerobic respiration then it's obvious

Answer 46

to include ETS

Answer 47

@Abhisar The question, as I gave it to you, was not incomplete for my point. She explicitly separated out glycolysis from other metabolic pathways, did not specify net or gross, and only listed 2 ATP as an option, so everything was technically wrong.

Answer 48

It's all about point of view !

Answer 49

Just like chemoautotrophic hypothesis and Chemoheterotrophic hypothesis !

Answer 50

both have their plus and minus points !

Answer 51

@Abhisar From everything I can find, the most recent research does not support the chemoheterotrophs. That website you sent is from 2005 or so, and majority of literature within the last 5 years or so that I could find, does not support that hypothesis. I'll keep digging though, because most bio books still report things like eye color, cleft chin, tongue folding, hitchhiker's thumb, etc as simple mendelian dom/rec traits, but they are not.

Answer 52

\(\color{green}{\huge\ddot\smile}\)

Answer 53

Well if we go by the oparin Haldane soup hypothesis, then chemoheterotrophs sounds the best

Answer 54

@Abhisar In case you want to read about it as well, the big change in the hypothesis, or at least the most commonly reported reason for the change, is the discovery of chemosynthetic prokaryotes in/at deep sea vents. Deep sea vents are thought to be highly similar to the primordial earth.

Answer 55

May be, it's possible. After all both are hypotheses. I am not much aware about the extreme current affairs since we don't debate this in medical colleges !
:D

Answer 56

I just remember what i studied back in A level and i believe same is still taught in those grades :)

Answer 57

@Abhisar My most up-to-date books are at the department, so I'll have to wait to get them. I'll do some more research, but as I said, the most recent stuff does not support the heterotroph theory. If you want I can send you a message about what I find after I conclude my search. It is a question that I am indirectly interested in (similar to what were the first fungi), so I will spend quite a bit of effort to find out if it is most likely hetero or auto.

Answer 58

Appreciate it !
@mrdoldum