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#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

  1. All four genes (A, B, O, and P) will be transcribed into an mRNA that will then be translated into four different proteins.

  2. The 3' end of the mRNA from the operon will correspond to the left end of the operon as drawn.

  3. The 5' end of the messenger from this operon will correspond to the right end of the operon as drawn.

  4. 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: 20283

#Unit 7. System Physiology – Animal

The following statements regarding to the pancreas and its function.
a. The pancreas is composed of two major types of tissues, (1) the acini, which secrete digestive juices into the duodenum, and (2) the islets of Langerhans, which secrete insulin and glucagon directly into the blood.
b. The islets contain three major types of cells, alpha, beta, and delta cells
c. The beta cells, constituting about 25 percent of all the cells of the islets, lie mainly in the middle of each islet and secrete insulin and amylin.
d. The alpha cells, about 60 percent of the total, secrete glucagon and the delta cells, about 10 percent of the total, secrete somatostatin.
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#Question id: 534

#Unit 1. Molecules and their Interaction Relevant to Biology

If glucose labeled with 14C in C-3 is metabolized to lactate via fermentation, the lactate will contain 14C in:
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#Question id: 5029

#Unit 11. Evolution and Behavior

Which of the following was the least likely factor causing the Cambrian explosion?
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#Question id: 18229

#Unit 8. Inheritance Biology

You are conducting genetic linkage studies of an autosomal dominant disease. You are focused on two SSR markers that may be linked to each other and to the disease. Here is a family in which some individuals are affected:
 
Calculate LOD scores for linkage at θ = 0.1 between SSR62 and SSR93
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#Question id: 15762

#Unit 5. Developmental Biology

Which of the following is not a property of the stem cells?