Passage Reading and English Comprehension
(a) influence of mRNA concentrations on the development of red blood cells
(b) role of the synthesis and degradation of mRNA in cell functioning
(c) mechanism by which genes are transcribed into mRNA
(d) differences in mRNA concentrations in cell nuclei and in the cytoplasm
140. The passage suggests that a biologist who held the view described in the first sentence of the second paragraph would most probably also have believed which of the following?
(a) The rate of degradation of specific mRNA’s has little effect on protein concentrations.
(b) The rate of degradation of specific mRNA’s should be studied intensively.
(c) The rates of synthesis and degradation for any given mRNA are normally equal.
(d) Different mRNA’s undergo degradation at widely varying rates.
141. Which of the following best describes the relationship between the second and third paragraphs of the passage?
(a) The second paragraph presents arguments in support of a new theory and the third paragraph presents arguments against that same theory.
(b) The second paragraph describes a traditional view and the third paragraph describes the view that has replaced it on the basis of recent investigations.
(c) The third paragraph describes a specific case of a phenomenon that is described generally in the second paragraph
(d) The third paragraph describes an investigation that was undertaken to resolve problems raised by phenomena described in the second paragraph.
142. The accumulation of concentrations of hemoglobin in red blood cells is mentioned in the passage as an example of which of the following?
(a) The effectiveness of simultaneous variation of the rates of synthesis and degradation of mRNA
(b) The role of the ribosome in enabling a parent cell to develop properly into a more specialized form
(c) The importance of activating the genes for particular proteins at the correct moment
(d) The abnormal proliferation of a protein that threatens to make the cell cancerous
143. To begin to control a disease caused by a protein deficiency, the passage suggests that a promising experimental treatment would be to administer a drug that would reduce
(a) only the degradation rate for the mRNA of the protein involved
(b) only the synthesis rate for the mRNA of the protein involved
(c) both the synthesis and degradation rates for the mRNA of the protein involved
(d) the incidence of errors in the transcription of mRNA’s from genetic nucleotide sequences
144. According to the passage, which of the following best describes the current view on the relationship between the synthesis and the degradation of mRNA in regulating protein synthesis?
(a) Biologists have recently become convinced that the ribosome controls the rates of synthesis and degradation of mRNA.
(b) Degradation of mRNA is now considered to be as important as mRNA synthesis has been, and still is, believed to be.
(c) There is no consensus among biologists as to the significance of mRNA degradation in regulating protein synthesis.
(d) The concept of mRNA degradation is so new that most biologists still believe that the vital role in protein regulation belongs to mRNA synthesis.
145. According to the passage, which of the following can happen when protein synthesis is not appropriately regulated?
(a) Diabetes can result from errors that occur when the ribosomes translate mRNA into protein.
(b) Cancer can result from an excess of certain proteins and diabetes can result from an insulin deficiency.
(c) A deficiency of red blood cells can occur if bone marrow cells produce too much hemoglobin.
(d) Cancer can be caused by excessively rapid degradation of certain amino acids in the cytoplasm of cells.
146. The passage suggests that a biologist who detected high levels of two proteins in a certain type of cell would be likely to consider which of the following as a possible explanation?
(a) The rate of mRNA degradation for one of the proteins increases as this type of cell develops a more specialized function.
(b) The two proteins are most likely constituents of a complex substance supporting the cells’ specialized function.
(c) The cells are likely to proliferate abnormally and possibly become cancerous due to the levels of these proteins.
(d) The mRNA’s for both proteins are being degraded at a low rate in that type of cell.
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