The upper forelimbs of humans and bats have fairly similar skeletal structures, whereas the corresponding bones in whales have very different shapes and proportions. However, genetic data suggest that all three kinds of organisms diverged from a common ancestor at about the same time. Which of the following is the most likely explanation for these data?

#Question id: 4949

#XL - T Zoology

What probably accounts for the switch to DNA-based genetic systems during the evolution of life on Earth?

#Question id: 4951

#XL - S Microbiology

The synthesis of new DNA requires the prior existence of oligonucleotides to serve as primers. On Earth, these primers are small RNA molecules. This latter observation is evidence in support of the hypothesized existence of

#Question id: 4951

#XL - T Zoology

The synthesis of new DNA requires the prior existence of oligonucleotides to serve as primers. On Earth, these primers are small RNA molecules. This latter observation is evidence in support of the hypothesized existence of

#Question id: 4952

#XL - S Microbiology

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: 4952

#XL - T Zoology

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: 4954

#XL - S Microbiology

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.