uncertainty about which gases comprised early Earth’s atmosphere A) 1 only B) 2 only C) 1 and 2 D) 1 and 3 E) 2 and 32) How were conditions on the early Earth of more than 3 billion years ago different from those on today’s Earth?A) Only early Earth was intensely bombarded by large space debris. C) Less ultraviolet radiation penetrated early Earth’s atmosphere.
C) Laboratory experiments have produced liposomes abiotically. E) The oldest fossilized cells resemble prokaryotes.17) What is true of the Cambrian explosion? E) all fossils with feathers are actually some kind of bird. At the arrow labeled “I” (the rift valley), the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating. The figure represents a cross section of the sea floor through a mid-ocean rift valley, with alternating patches of black and white indicating sea floor with reversed magnetic polarities.
Which of these questions is currently the most problematic and would have the greatest impact on our understanding if we were able to answer it?
A) How can amino acids, simple sugars, and nucleotides be synthesized abiotically? C) How did RNA sequences come to carry the code for amino acid sequences?
9) If natural selection in a particular environment favored genetic systems that permitted the production of daughter “cells” that were genetically dissimilar from the mother “cells,” then one should expect selection for which of the following? polynucleotide polymerase with low mismatch error rates II.
polynucleotide polymerases without proofreading capability III. batteries of efficient polynucleotide repair enzymes IV.