Biology Ch. 7

25 July 2022
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The double helix of DNA is composed of building blocks called
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nucleotides
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The rungs of the DNA ladder are formed by base pairs
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joined by hydrogen bonds
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In DNA molecules,
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adenine pairs with thymine
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The "Central Dogma" of molecular biology described by Watson and Crick describes
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the directional flow of genetic information in cells.
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RNA differs from DNA in many ways, including
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All answers are correct. -DNA contains deoxyribose and RNA contains ribose -DNA contains thymine and RNA contains uracil instead of thymine -DNA is double stranded and RNA is single stranded -RNA can catalyze some chemical reactions and DNA cannot.
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DNA differs from RNA because, unlike RNA,
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DNA contains thymine.
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What type of RNA carries the information that specifies a protein?
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messenger RNA
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What type of RNA carries amino acids to the ribosome?
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transfer RNA
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A DNA sequence that signals the start of a gene is
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a promoter
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In eurkaryotic cells, sequences of mRNA removed before translation are called
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introns
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What process converts the mRNA "message" into a sequence of amino acids?
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translation
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Initiation, elongation, and termination are the three main steps in
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transcription and translation
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A three-base sequence (loop) in tRNA that is complementary to a three-base sequence in mRNA is
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an anticodon
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A tRNA molecule is "bilingual" because it binds to
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codons of mRNA and amino acids
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The step of translation in which an mRNA, a small ribosomal subunit, and the initiator tRNA are aligned together is
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initiation
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The step of translation in which amino acids are added to the growing polypeptide is
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elongation
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The step of translation in which release factors bind to a stop codon is:
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termination
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Which of the following does NOT occur during termination of translation?
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A. The initiatior tRNA brings the amino acid methionine.
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A group of genes, a promoter, and an operator that control transcription are called a(n)
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E. operon
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In the lac operon, the protein that binds to the operator to prevent transcription is
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A. the repressor
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What are the proteins that initiate transcription in eukaryotes by recognizing sequences within the promoter region of a gene and attracting RNA polymerase?
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C. transcription factors
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A change in a cell's DNA sequence is
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a mutation
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In a "silent" mutation
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B. the codon that mutates does not cause a change in the amino acid specified
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In a "frameshift" mutation
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D. the mutation is caused by an addition or deletion of one or more nucleotides
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Which of the following is NOT a cause of mutation?
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All of the choices are causes of mutations. -Errors in DNA replication -errors during meiosis -exposure to radiation -exposure to tobacco
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If the DNA of a cell consists of 20% adenine, then it will also contain _____ guanine.
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30%
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If the DNA of a cell consists of 20% adenine, then it will also contain _____ thymine.
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20%
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The DNA sequence ATGCATGC will pair with which of the following DNA strands?
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TACGTACG
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Why would it take more energy to seperate DNA with the sequence GCGCGCGC and its complementary strand than the sequence ATATATAT and is complementary strand?
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C. G and C base pairs form more hydrogen bonds between DNA strands.
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The DNA sequence ATGCATGC will pair with which of the following RNA strands?
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UACGUACG
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Only one of the two strands of DNA is transcribed because
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A. RNA polymerase binds to the promoter, intiating transcription on only one strand of DNA.
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The length of a DNA sequence is _____ than the mature mRNA transcribed from it, because
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longer; it does not contain introns
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How many codons are in the mRNA sequence GGAAUGAAACAGGAACCC?
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6
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Using the genetic code, predict what type of mutation has occurred in the hemoglobin sickle cell anemia allele. Normal allele GGAAUGAAACAGGAACCC Mutant allele GGAAUGAAACAGGUACCC
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D. a point mutation, Val to Glu
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Cells have only two copies of most genes, but can make hundreds of copies of a protein from those genes per second, because
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during translation multiple ribosomes can bind to the same mRNA simultaneously.
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Amanatin is a toxin found in the death cap mushroom, Amanita phalloides. It inhibits RNA polymerase, thus blocking
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A. transcription
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If E. coli bacterium are grown in the presence of lactose
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C. the repressor will NOT bind the operator, thus allowing transcription of the lac operon genes
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If E. coli bacterium are grown in the absence of lactose
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D. the repressor will bind the operator, thus preventing transcription of the lac operon genes
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What type of mutation occurred in the following? Normal allele GGAAUGAAACAGGAACCC Mutant allele GGAAUGAAACAGGUACCC
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A. substitution
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What type of mutation occurred in the following? Normal allele GGAAUGAAACAGGAACCC Mutant allele GGAAUGAAAUCAGGaACCC
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A. insertion
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In the section "Investigating Life: Clues to the Origin of Language", what did scientists discover was the primary cause for language disorder in the affected family?
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A. The cause was one mutation in a single gene on one chromosome.
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In the section "Investigating Life: Clues to the Origin of Language", FOXP2 sequences differed the most between mice and ____.
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D. humans
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Which DNA mutation leads to the change of a single amino acid in a protein?
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substitution
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In the section "Investigating Life: Clues to the Origin of Language", how did the researchers estimate that the original mutation occurred 300,000-400,000 years ago? A. They estimated by examining the fossil record. B. The estimate by using a molecular clock C. They found the mutation in chimpanzee DNA. D. They found the mutation in Neandertal DNA. E. They found the mutation in 300,000 year old mice remains.
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----
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The process by which cells use the information of RNA to make proteins is called transcription.
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FALSE
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There are only two main types of RNA needed to make proteins, tRNA and rRNA.
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FALSE
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The type of RNA that delivers amino acids to the ribosome during protein synthesis is tRNA.
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TRUE
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A gene is an RNA sequence that is transcribed to mRNA only.
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FALSE
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In eukaryotes, transcription copies only one gene from one DNA strand of the chromosome.
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TRUE
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A gene is any DNA sequence that is transcribed to any type of RNA.
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TRUE
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A poly A tail is added to the mature mRNA after transcription.
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TRUE
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Cystic fibrosis may be caused by a protein that does not fold correctly.
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TRUE
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Little energy is needed for protein production because cells are efficient in transcription and translation.
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FALSE
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In eukaryotes, a mRNA molecule can only be translated by one ribosome at a time.
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False
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In the bacterium E. coli, a repressor protein binds to the operator region of the DNA in the absence of lactose, thus preventing the transcription of the genes of the lactose operon.
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TRUE
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In prokaryotic cells, gene expression is regulated by preventing mRNA from exiting the nucleus.
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FALSE
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What role do hydrogen bonds play in the DNA molecule?
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A. Hydrogen bonds link complementary nitrogenous bases, thus keeping the two strands of DNA parallel to each other.
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If one strand of DNA has a nitrogenous base sequence ATTCGACGCTA, then the complementary strand has the nitrogenous base sequence
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A. TAAGCTGCGAT
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Using the genetic code, what is the sequence of amino acids represented by the codons AUGUCAACGUGA?
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A. Met, Ser, Thr, (Stop)
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Using the genetic code, how many amino acids are encoded by the following sequence from the start codon and up to the stop codon? AUGCUUGACUAAGUCCCC
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D. 3
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All prokaryotic DNA is transcribed, but not all eukaryotic DNA is transcribed.
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TRUE
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Which of the following is conducted by both prokaryotes and eukaryotes during protein synthesis?
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A. Transcription starts at a promoter on the DNA.
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Mutations create new alleles that
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All of the choices are correct. Are beneficial to the organism's fitness, have no effect on the fitness of the organism, decrease the fitness of the organism.
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Mutations cause incorrect sequencing of nucleic acids. Incorrect sequencing of DNA will result in new alleles, and it may lead to evolution. Incorrect sequencing of mRNA will result in a faulty protein, but will not lead to evolution.
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TRUE
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Most viruses
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A. infect only a few closely-related species.
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Which of the following diseases is NOT caused by viruses?
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E. diabetes
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Viruses
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are smaller than cells
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The genetic information in viruses
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is either DNA or RNA
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A layer of membrane attached to a virus is called
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an envelope
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HIV is a
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single-stranded RNA virus
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Viruses that infect bacteria are:
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bacteriophages
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The shape of a virus is determined by
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its coat protein organization
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The correct sequence of stages of viral replication is
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attachment penetration synthesis assembly release
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The stage of viral replication in which the viral nucleic acid is released inside the cell is
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penetration
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The stage of viral replication in which the host cell produces viral nucleic acids and proteins is
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synthesis
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The stage of viral replication in which the virus binds to a cell surface receptor is
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attachment
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The stage of viral replication in which the new viruses leave the host cell is
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release
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The stage of viral replication in which the viral components are put together to form new viruses is
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assembly
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The type of viral infection is which a virus enters a host cell, immediately replicates, and causes the host cell to burst is
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a lytic infection
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The type of viral infection is which a virus enters a host cell and remains dormant in the host cell's chromosomes is
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a lysogenic infection
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Treatment of a viral infection by inoculating the host with a bacterial virus
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is phage therapy
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HIV
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is a retrovirus
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The enzyme that HIV uses to convert its RNA into DNA is
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reverse transcriptase
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Our most potent weapon in the fight against viruses is
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vaccinations
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A highly-wound circle of RNA without a protein coat is a
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viroid
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An infectious protein is a
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prion
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One key reason why viruses are not considered living organisms is
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viruses do not reproduce on their own
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Most antibiotics are not effective against viruses because they ___ and this does not affect the activity of viruses.
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inhibit synthesis of cell walls
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Viruses are not considered to be alive, yet they share this ability with living cells:
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they can evolve.
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Since viruses have no active methods of entering plant cells, they must rely upon mechanically-caused wounds, vegetative propagation of plants, grafting, seeds, pollen, and being carried on the mouth parts of chewing insects. Tobacco mosaic virus is most commonly introduced into plants through small wounds caused by handling and by insects chewing on plant parts. What would prevent viruses from easily entering plant cells?
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the cell wall on the plant
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Oral infections with herpes simplex virus 1 can lie dormant in nerve cells for years, and when a patient becomes stressed, the virus is released, forming cold sores on the lips. While lying dormant, the virus is in which of the following states?
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latent
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Oral infections with herpes simplex virus 1 can lie dormant in nerve cells for years, and when a patient becomes stressed, the virus is released, forming cold sores on the lips. In a cold sore, the virus is in which of the following states?
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lytic
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Oral infections with herpes simplex virus 1 can lie dormant in nerve cells for years, and when a patient becomes stressed, the virus is released, forming cold sores on the lips. Why would the virus form a cold sore?
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to spread to a new host
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Oral infections with herpes simplex virus 1 can lie dormant in nerve cells for years, and when a patient becomes stressed, the virus is released, forming cold sores on the lips. Where is the virus located while dormant in the nerve cell?
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integrated in the nerve cell chromosomes
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The Human Immunodeficiency Virus (HIV) only affects a specific class of cells in the immune system called helper T cells, and not other types of T cells. What is the best explanation for this observation?
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Only helper T cells have the correct receptor on their cell surface.
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The influenza virus contains an RNA genome. Why do scientists typically have to make a new vaccine for the flu every year?
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because the virus can mutate into new strains
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Viruses always lack which of the following?
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organelles
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What is the genetic material found in HIV?
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RNA
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It has been difficult to generate drugs to treat AIDS for which reason?
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HIV mutates rapidly.
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Viruses can infect all higher life forms such as plants and animals, but cannot infect bacteria.
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FALSE
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Many viruses are inhabited by antibiotics.
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FALSE
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How does the spread of viruses differ between plants and animals?
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Viruses must penetrate through cell walls of plant cells and not animal cells.
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Although antibiotics do not kill viruses, they offer promise for destroying viroids and prions because of their actions on cell ribosomes and enzymes.
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TRUE
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Where is the majority of DNA located in a human cell?
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nucleus
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What is the role of DNA in living things?
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DNA stores the information required to make proteins.
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Which of the following best describes the relationship between DNA, proteins, and RNA?
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DNA is transcribed into RNA, then RNA is translated into proteins.
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A cell can recieve new genes from a virus and then produce a new set of proteins.
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TRUE
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RNA is made up of many
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nucleotides
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DNA is made up of many
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nucleotides
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Proteins are made up of many
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amino acids