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#Question id: 1744


Which of the following events occurs earliest in T-cell signaling?

#SCPH05 I Biotechnology
  1. Activation of phospholipase C

  2. Activation of protein kinase C

  3. Production of inositol triphosphate

  4. Activation of protein tyrosine kinase

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TLS Online TPP Program

#Question id: 4954

#SCPH28 | Zoology

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.

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#Question id: 4955

#SCPH06 I Botany

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.

TLS Online TPP Program

#Question id: 4955

#SCPH28 | Zoology

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.

TLS Online TPP Program

#Question id: 4956

#SCPH06 I Botany

Which measurement would help determine absolute dates by radiometric means?

TLS Online TPP Program

#Question id: 4956

#SCPH28 | Zoology

Which measurement would help determine absolute dates by radiometric means?

TLS Online TPP Program

#Question id: 4957

#SCPH06 I Botany

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