TLS Online TPP Program

#Question id: 4959


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

#Unit 11. Evolution and Behavior
  1. easy to determine the absolute age of the fossil, because the radioisotopes in the sediments will not have been ʺresetʺ by the heat of the igneous rocks.

  2. easy to determine the absolute age of the fossil, because the igneous rocks will not have physically obstructed the deposition of sediment of a single age next to the fossil.

  3. difficult to determine the absolute age of the fossil, because the ʺmarker fossilsʺ common to igneous rock will be absent.

  4. difficult to determine the absolute age of the fossil, because radiometric dating of sedimentary rock is less accurate than that of igneous rock.

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TLS Online TPP Program

#Question id: 15655

#Unit 13. Methods in Biology

You are studying a new strain of E. coli that can utilize the disaccharide melibiose very efficiently. You find that utilization depends on the enzyme melibiase, which is encoded by the gene Mel1. Mel1 is not expressed unless melibiose is present in the growth medium. Next you isolate a mutation, designated MelB–, which gives uninducible melibiase activity. Mapping experiments show that MelB– is linked to Mel1. Using an F' factor that carries the chromosomal region surrounding Mel1, you perform the following genetic tests:

 
Describe the proposal for the type of regulatory functions affected by the MelB– mutation.

TLS Online TPP Program

#Question id: 7037

#Unit 5. Developmental Biology

How does E-cadherin influence blastocyst cell fates?

TLS Online TPP Program

#Question id: 7059

#Unit 5. Developmental Biology

A Drosophila gene active in both males and females, but whose RNA transcript is spliced in a sex-specific manner to produce sex-specific transcription factors-

TLS Online TPP Program

#Question id: 4907

#Unit 8. Inheritance Biology

Two corn plants are studied. One is resistant (R) and the other is susceptible (S) to a certain pathogenic fungus. The following crosses are made, with the results shown

R male X S female = all S progeny

R female X S male = all R progeny

Which of the following are correct about inheritance?

TLS Online TPP Program

#Question id: 23853

#Unit 13. Methods in Biology

The segment of DNA shown in Figure, has restriction sites I and II, which create restriction fragments A, B, and C. Which of the gels produced by electrophoresis shown below best represents the separation and identity of these fragments?