TEST BANK FOR PORTH’S PATHOPHYSIOLOGY 10TH EDITION BY NORRISCHAPTER 4: Genetic Control of Cell Function and Inheritance

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1. How could a health care professional most accurately explain an aspect of the underlying structure of DNA to a colleague who is unfamiliar with genetics? A) “DNA consists of nucleotides plus one... of the four nitrogenous bases.” B) “In the base pairs, adenine combines with thymine and guanine with cytosine.” C) “Thymine and cytosine are considered the purine bases.” D) “The backbone of a DNA molecule consists of either deoxyribose or phosphoric acid.” Ans: B Feedback: The base pairings of DNA are such that adenine combines with thymine and guanine with cytosine. DNA also includes the sugar deoxyribose, while thymine and cytosine are considered the pyrimidine bases. The backbone of DNA includes both deoxyribose and phosphoric acid. 2. A student is trying to understand the possible reasons that a genetic abnormality might exist in an individual. Which of the following reasons is most plausible? A) DNA has combined with several types of protein and a small amount of RNA. B) Histones have exerted control on the folding of DNA strands. C) DNA has blocked genetic transcription by preventing access of nucleotides to the DNA surface. D) Chromatin has maintained its stable structure during the DNA replication process. Ans: D Feedback: To facilitate DNA replication and gene expression, chromatin must change its structure through the process of chromatin remodeling. Answers A, B, and C all denote normal genetic processes. 3. A 45-year-old client who experienced exposure to radiation during an industrial accident several years prior is being assessed. Which of the following phenomena may underlie the genetic changes that have been noted in the client? A) Base pairs may have been rearranged by the radiation in the accident. B) Endonucleases may have influenced the DNA structure following exposure. C) Two paired bases may have exchanged helical position after the accident. D) The radiation may have produced a redundant or degenerate genetic code. Ans: A Feedback: Radiation exposure can cause the rearrangement of base pairs and resultant mutation. Endonucleases facilitate gene repair, and base pairs are not noted to swap positions from their respective sides of the helical strand. Redundant or degenerate genetic code is a normal trait. 4. A researcher is involved in the investigation of an individual's genetic abnormality. Which of the following situations could the researcher most likely rule out as the genetic cause of a mutation? A) Loss of a cytosine–guanine base pair B) Formation of an adenine–uracil base pair C) Substitution of an adenine–thymine base pair for a cytosine–guanine base pair D) Insertion of an extra adenine–thymine base pair Ans: B Feedback: RNA contains uracil instead of thymine. Formation of an adenine–uracil base pair is a normal event during assembly of messenger RNA. [Show More]

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