A visual exam in an 80-year-old man shows he has a reduced ability to see objects in the upper and lower quadrants of the left visual fields of both eyes but some vision remains in the central regions of the visual field. The diagnosis is

#Question id: 4952

#Unit 11. Evolution and Behavior

Several scientific laboratories across the globe are involved in research concerning the origin of life on Earth. 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?

#Question id: 4953

#Unit 11. Evolution and Behavior

Several scientific laboratories across the globe are involved in research concerning the origin of life on Earth. Which graph below, if the results were produced abiotically, would have the greatest promise for revealing important information about the origin or Earthʹs first genetic system?

#Question id: 4954

#Unit 11. Evolution and Behavior

If natural selection in a particular environment favored genetic systems that permitted the production of daughter ʺcellsʺ that were genetically dissimilar from the mother ʺcells,ʺ then one should expect selection for

I. polynucleotide polymerase with low mismatch error rates.

II. polynucleotide polymerases without proofreading capability.

III. batteries of efficient polynucleotide repair enzymes.

IV. polynucleotide polymerases with proofreading capability.

V. polynucleotide polymerases with high mismatch error rates.

#Question id: 4955

#Unit 11. Evolution and Behavior

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 11. Evolution and Behavior

Which measurement would help determine absolute dates by radiometric means?

#Question id: 4957

#Unit 11. Evolution and Behavior

How many half-lives should have elapsed if 6.25% of the parent isotope remains in a fossil at the time of analysis?