#Question id: 4955
#Unit 9. Evolution & Diversity of Life Forms
If relatively small carbonaceous chondrites from space were a significant source of Earthʹs original amino acids, then which two of these would have been most important in permitting their organic materials to survive impact with Earth?
I. Carbonaceous chondrites must contain no D-amino acids.
II. Earthʹs early atmosphere must have had little free oxygen.
III. The chondrites must have arrived on Earth before 4.2 billion years ago.
IV. Earthʹs early atmosphere must have been dense enough to dramatically slow the chondrites before they impacted.
V. The chondrites must have impacted land, rather than a large body of water.
#Question id: 4956
#Unit 9. Evolution & Diversity of Life Forms
Which measurement would help determine absolute dates by radiometric means?
#Question id: 4957
#Unit 9. Evolution & Diversity of Life Forms
How many half-lives should have elapsed if 6.25% of the parent isotope remains in a fossil at the time of analysis?
#Question id: 4958
#Unit 9. Evolution & Diversity of Life Forms
What is true of the fossil record of mammalian origins?
#Question id: 4959
#Unit 9. Evolution & Diversity of Life Forms
If a fossil is encased in a stratum of sedimentary rock without any strata of igneous rock (e.g., lava, volcanic ash) nearby, then it should be
#Question id: 4960
#Unit 9. Evolution & Diversity of Life Forms
Letʹs say that a hypothetical submersible robot was used to collect samples of sedimentary rock from the sea floor along the section illustrated. The robot moved back and forth along the transect, collecting first from site A, then site III, then site B, then site II, and lastly site D. Assuming that sedimentation has occurred at a constant rate along the transect over the past million years, rearrange the sites mentioned above on the basis of the thickness of the sediments overlying the igneous rock, from thickest to thinnest.