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TLS Online TPP Program

#Question id: 4640

During drought years on the Galapagos, small, easily eaten seeds become rare, leaving mostly large, hard-cased seeds that only birds with large beaks can eat. If a drought persists for several years, what should one expect to result from natural selection?

#Unit 11. Evolution and Behavior

  1. Small birds gaining larger beaks by exercising their mouth parts.

  2. Small birds mutating their beak genes with the result that later-generation offspring have larger beaks.

  3. Small birds anticipating the long drought and eating more to gain weight and, consequently, growing larger beaks.

  4. More small-beaked birds dying than larger-beaked birds. The offspring produced in subsequent generations have a higher percentage of birds with large beaks.

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TLS Online TPP Program

#Question id: 18855

#Unit 13. Methods in Biology

to elute target proteins from an affinity chromatography matrix, which of the following conditions would be the most appropriate?
TLS Online TPP Program

#Question id: 31258

#Unit 5. Developmental Biology

In salamanders, regeneration blastema formed from:
TLS Online TPP Program

#Question id: 32140

#Unit 1. Molecules and their Interaction Relevant to Biology

Successive base pairs in B-DNA show a mean rotation of 
TLS Online TPP Program

#Question id: 28576

#Unit 5. Developmental Biology

Sry gene resides on the___
TLS Online TPP Program

#Question id: 3820

#Unit 3. Fundamental Processes

Meselson and Stahlʹs experiments involved growing E. coli on a medium containing 15N (heavy nitrogen) which increased the density of the bacterial DNA. Cells were then grown on a medium containing only 14N. DNA samples were obtained for analysis after one, two and three rounds of replication (generations) and centrifuged on a density gradient. The double-helical DNA forms bands in the gradient depending on its density. How many bands did Meselson and Stahl see after two generation of cells were grown on the 14N medium?