Practice Questions

TLS Online TPP Program

#Question id: 3981

The diagram below represents a hypothetical operon in the bacterium E. coli. The operon consists of two structural genes (A and B), which code for the enzymes A-ase and B-ase, respectively, and also includes P (promoter) and O (operator) regions as shown.

When a certain compound (X) is added to the growth medium of E. coli, the separate enzymes A-ase and B-ase are both synthesized at a 50-fold higher rate than in the absence of X. (X has a molecular weight of about 200.) Which of the following statements is true of the operon decribed above?

#Unit 3. Fundamental Processes

All four genes (A, B, O, and P) will be transcribed into an mRNA that will then be translated into four different proteins.
The 3' end of the mRNA from the operon will correspond to the left end of the operon as drawn.
The 5' end of the messenger from this operon will correspond to the right end of the operon as drawn.
When RNA polymerase makes mRNA from this operon, it begins RNA synthesis just to the left of gene A.

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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?