In XY cells, the early promoter is not active and there is no early Sxl protein because-

#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?

#Question id: 4958

#Unit 11. Evolution and Behavior

What is true of the fossil record of mammalian origins?

#Question id: 4959

#Unit 11. Evolution and Behavior

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