Which important development in the evolution of life was found during the Protoz

Question

Which important development in the evolution of life was found during the Protozoic era at the end of the Precambrian?

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Question 21 pts

All of the following provide evidence that RNA most likely originated before both DNA and proteins, except:

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Question 31 pts

Which of the following are synapomorphies for the apes?

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Question 41 pts

What is incorrect with the above diagram representing human evolution?

Explanation / Answer

Answer 1: Diversification of all major animal phyla (As explained below)

The end of the Precambrian era is marked by the Cambrian Explosion, when many life forms started appearing within a short period of time. It took place around 541 million years ago and is vastly known as the prior during which major animal phyla started showing up. So first option is correct. RNA based life forms existed 3.8 billion years ago. So, third option is incorrect. Around 630 million years ago, some animals with bilateral symmetry evolved. So, fourth option is incorrect. 440 million years ago, reptiles and mammals evolved. So, second option is incorrect.

Answer 2: RNA is very unstable (As explained above)

The inclusion of the hydroxyl group in the pentose ring in the 2' position of RNA makes it more unstable than DNA. But despite that, the prevalent conditions prior to the evolution of DNA were suitable for the organisms who could change rapidly. These were the organisms which tended to use RNA as their genetic material.

Answer 3: Increased hip, ankle, and wrist flexibility, Relatively large brains, More erect posture, "Absence" of a tail. (As explained below)

No tail, erect posture, flexible hips/ankles, flexible thumb/wrist, structure arm/shoulder and DNA analyses are all synapomorphies for the apes.

Answer 4: All of the above. (As explained below)

The human race has been proven to evolve not from one form of hominid. There were several species of hominids distributed on various landforms that were separated then and some went extinct, some evolved. So, there cannot be a single lineage of hominids. So, last option is correct. Also, the representation considers the more organized group to finally evolve. This is redoubtable. Hence third option is also correct. Also, the representation does not take into account the extinct sister lineages, like hominids or hominid-like species that went extinct on some of the landmasses. So, the first option is also correct.

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