Practice Questions

TLS Online TPP Program

#Question id: 3818

DNA replication is studied in a newly discovered bacterium. It takes 30 min for the bacterium to complete a round of replication at 37oC. A Meselson-Stahl-type experiment was performed. The bacteria were grown for several generations in 14N-medium and then switched to 15N-medium. The DNA molecules were then analyzed.

If the mechanism of DNA replication in this bacterium were semi-conservative, what results would be found when the double-stranded DNA was analyzed in a CsCl density gradient after three generations in 15N-medium?

#Unit 3. Fundamental Processes

The DNA would form three bands: one with hybrid density, one with light density, and one with heavy density.
The DNA would form one band with hybrid density.
The DNA would form two bands: one with heavy density and one with hybrid density.
The DNA would form two bands: one with light density and one with hybrid density.

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TLS Online TPP Program

#Question id: 13018

#Unit 10. Ecological Principles

Generalized global air circulation and precipitation patterns are caused by

TLS Online TPP Program

#Question id: 13019

#Unit 10. Ecological Principles

Air masses formed over the Pacific Ocean are moved by prevailing westerlies where they encounter extensive north- south mountain ranges, such as the Sierra Nevada and the Cascades. Which statement best describes the changes that these air masses undergo?

TLS Online TPP Program

#Question id: 13020

#Unit 10. Ecological Principles

Experts in deer ecology generally agree that population sizes of deer that live in temperate climates are limited by winter snow. The deer congregate in ?yarding? areas under evergreen trees because venturing out to feed in winter is energetically too expensive when snowfall depths accumulate to above 40 cm. Deer often stay yarded until the spring thaw. Snow depth over 40 inches for more than 60 days results in high mortality due to starvation. This observation best illustrates which of the following principles about factors that limit distribution of organisms?

TLS Online TPP Program

#Question id: 13021

#Unit 10. Ecological Principles

Which marine zone would have the lowest rates of primary productivity (photosynthesis)?

TLS Online TPP Program

#Question id: 13022

#Unit 10. Ecological Principles

A certain species of pine tree survives only in scattered locations at elevations above 2,800 m in the western United States. To understand why this tree grows only in these specific places an ecologist should

TLS Online TPP Program

#Question id: 13023

#Unit 13. Methods in Biology

Which of the following enzymes are required for end labelling?