Study with the several resources on Docsity
Earn points by helping other students or get them with a premium plan
Prepare for your exams
Study with the several resources on Docsity
Earn points to download
Earn points by helping other students or get them with a premium plan
Community
Ask the community for help and clear up your study doubts
Discover the best universities in your country according to Docsity users
Free resources
Download our free guides on studying techniques, anxiety management strategies, and thesis advice from Docsity tutors
A practice test for microbiology exam 1, covering key concepts in prokaryotic biology, genetics, and metabolism. It includes multiple-choice questions with verified answers, offering students a valuable resource for exam preparation. The questions address topics such as prokaryotic genome structure, dna replication, gene transfer, and microbial growth.
Typology: Exams
1 / 25
__________ of prokaryotic genomes are now available in public databases. - ANSThousands A change in the nucleotide sequence of DNA that is passed on to daughter cells is referred to as ___________. - ANSA mutation A chemoorganotroph and a photoautotroph in the same environment would NOT compete for ____________. - ANSCarbon and oxygen A glycoprotein is ______________. - ANSA type of peripheral protein above that can be used as a receptor or in enzymatic functions A halotolerant facultative anaerobe would grow BEST in which of the following environments? - ANSoxygenated non-saline A laboratory in which Ebola virus is studied would be classified as a BSL- ___________ laboratory. - ANS A medium containing known substances in precise amounts is known as a _________ media. - ANSDefined
A microbiology student in a research lab repeated an experiment described by others using the identical bacterial isolate, the same growth medium, and the same growth conditions. However, the student was unable to achieve the same O.D. at 600 nm. What is the LEAST likely cause for this descrepancy in measured turbidity? - ANSThe two experiments were carried out at vastly different elevations and did not consider the influence of pressure. A patient enters your office complaining of excessive stiffness and cramps after vigorous exercise. Tests reveal the patient has Brody disease, a muscle disorder characterized by impairment of skeletal muscle relaxation due to the inability of the muscle cells to regulate calcium levels in the cytoplasm. Which organelle is most likely affected in this patient? - ANSSmooth ER A plasmid differs from the bacterial chromosome in that it is _________________.
A student has a pure culture of bacteria growing in a flask and wants to know how many living cells are in the culture at a given time. Which method should she employ to get an estimate? - ANSPlate counts A triplet of bases on an mRNA molecule is known as a(n) - ANSCodon Accomplishments of Louis Pasteur: - ANSDeveloped the first rabies vaccine and treated thousands of individuals, developed heat sterilization techniques that involved the creation of a specialized swan-necked flask, determined that the alcohol-making process was mediated by microbial fermentation and thus refuted the theory of spontaneous generation All microorganisms require: - ANSPhosphorus, selenium, and sulfur An open reading frame (ORF) encodes for __________. - ANSA polypeptide An organism of the genus Staphylococcus is _________, while an organism of the genus Spirochaeta is __________________. - ANSSpherical/Coiled Archaea and Bacteria are unified as prokaryotes in lacking __________ which Eukarya contain, such as mitochondria. - ANSNuclei and membrane-enclosed organelles Archaea are: - ANSa group of diverse microorganisms that inhabit almost every environment on Earth, including the colon of humans and other mammals Aseptic technique refers to _______________________. - ANSA series of practices to avoid contamination
Axial filaments are found on - ANSSpirochetes Bacteria that are able to grow in humans and cause disease would be classified as __________. - ANSMesophiles Bacterial conjugation is often referred to as bacterial sex. Why is this term inaccurate? - ANSConjugation does not result in the formation of new offspring. Based on the animation, What is transferred during bacterial conjugation? - ANSA bacterial plasmid Competent cells are cells that - ANSCan take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination. Consider a mutation in which the change is from UAC to UAU. Both codons specify the amino acid tyrosine. Which type of point mutation is this? - ANSSilent mutation Deduce why viruses are excluded from the ribosomal RNAbased tree of life. - ANSThey lack ribosomal RNA (rRNA) Distinguish which list of structural properties and activities are true for ALL cells - ANSCytoplasmic membrane, ribosomes, metabolism, and evolution
DNA replication always proceeds in only one direction because the ________ of the incoming nucleotide is attached to the free ________ of the growing DNA strand. - ANS5-phosphate/ 3-hydroxyl During DNA replication Okazaki fragments are linked together by ________, an enzyme that creates phosphodiester bonds between nicked fragments of DNA. - ANSDNA ligase During DNA replication, which nucleotide will bind to an A nucleotide in the parental DNA? - ANST Each adenine-thymine base pair has ________ hydrogen bonds, while each guanine-cytosine base pair has ________ hydrogen bond(s). - ANSTwo/ three Electron microscopy has greater ______ than light microscopy, because the wavelength of visible light is much larger than the wavelength of visible light is much larger than the wavelength of electrons. - ANSresolution Explain why the presence of a capsule or slime layer would benefit a bacterial cell.
Frederick Griffith performed an experiment in which a live culture of avirulent "rough" strain of Streptococcus pneumoniae bacteria were mixed with dead cells of virulent "smooth" Streptococcus pneumoniae bacteria. Subsequently, the "rough" bacteria were "transformed" into "smooth" bacteria capable of killing mice. This experiment demonstrated that: - ANSMolecular genetic information can be transferred between bacterial cells Gene duplication is essential to organisms because _________________. - ANSDuplicate genes are more able to evolve into new genes Gene function is annotated based on homology between the ORFs of a genome and proteins whose function has been proven experimentally. What -omic approach could help us to determine the function and structure of proteins encoded by uncharacterized ORFs? - ANSProteomics Genes from different sources that are related in sequence due to shared evolutionary ancestry are called _________ genes and groups of such genes are known as _______________. - ANSHomologous/ gene families Given the following DNA sequence, what would be the DNA sequence on the complementary strand of a double-stranded helix molecule? DNA sequence: AGTCCGA - ANSTCAGGCT Highly alkaline environments, like those in which haloalkaliphiles are found, are best described by which of the following statements? - ANSThese environments contain relatively low concentrations of hydrogen ions. Horizontal gene flow is accomplished in prokaryotes by ____________. - ANSConjugation, transduction, and transformation
Horizontal gene transfer is: - ANScommon and may sometimes occur between unrelated organisms Horizontal gene transfer refers to the transfer of genes from one organism to another, as occurs during conjugation between bacteria. How does this differ from vertical gene transfer? - ANSIn horizontal gene transfer, genes are transferred from one mature adult organism to another. In vertical gene transfer, genes are transferred from adults to offspring. How are plasmids different than chromosomes? - ANSPlasmids contain genes that are NOT essential for cellular growth and replication. How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population? - ANSthe prophage takes an antibiotic resistance gene with it and is packages with the newly synthesized viral DNA How do stabilizing proteins work on the DNA? - ANSThey bind to the single stranded DNA How does specialized transduction differ from regular lysogeny? - ANSThe prophage in specialized transduction carries with it pieces of the host chromosomal DNA. How does water enter and exit a cell? - ANSBy simple diffusion or by use of an integral transport protein
How is fermentation of lactose detected? - ANSThe drop in pH turns the indicator dye yellow. How long does it take for the daughter cells from one round of replication to replicate themselves? - ANSNo time is required- they are read to divide immediately after DNA replication and separation of the daughter cells is complete if conditions are right. How m any answers are there to a question in a dichotomous key flowchart? - ANSTwo Identify which of the following is a major function of the cytoplasmic membrane - ANSEnergy conservation In a bacterial cell undergoing binary fisison and balanced growth, ____________. - ANSthe proportion of all cell constituents will remain the same over time In a batch culture, bacterial cultures typically exhibit four different phases of growth. In which phase are the cells rapidly synthesizing proteins, but cell numbers are not changing? - ANSLag phase In a typical brightfield microscope, at which point does magnification begin? - ANSThe objective lens In all cells, genes are composed of - ANSnucleic acids
In complementary base pairing of DNA, adenine pairs with ________ (or ________ in RNA) and cytosine always pairs with ________. - ANSThymine/ Uracil / Guanine In DNA replication there are leading and lagging strands, because - ANSDNA replication is semiconservative and each strand is copied simultaneously in opposite directions. In mesophiles, growth rates increase gradually as the temperature is increase, until the optimum growth temperature for the organism is reached. If the temperature is increased beyond the optimum, _______________. - ANSGrowth rates decline rapidly as the temperature increases In most salt lakes, which microbial group is the major oxygenic phototroph? - ANSDunaliella, a eukaryotic algae In what domains of life are microorganisms represented? - ANSArchaea, Bacteria, and Eukarya In which direction does the replication fork move? - ANSIt moves ahead of the newly synthesized DNA. Integral proteins are mostly involved in _______________. - ANSTransport function Koch's 4th postulate: - ANSThe suspected pathogen must be reisolated and show to be the same as the original.
Koch's first postulate: - ANSThe suspected pathogen must be present in all cases of the disease and absent from healthy animals Koch's second postulate - ANSThe suspected pathogen must be grown in pure culture. Koch's third postulate: - ANSCells from a pure culture of the suspected pathogen must cause disease in a healthy animal. Laboratories that work with extremely low risk pathogens are classified as _______________________. - ANSBSL- Like all forms of life on Earth, all microbial cells perform three major types of activities: - ANSMetabolism, growth, and evolution List the steps of the central dogma of molecular biology in the correct order: - ANSDNA ---> RNA----> Protein LUCA is _________________. - ANSthe last universal common ancestor Match the bacterial genetic element with the correct characteristic: - ANSPlasmid---> nonessential genes Membrane-enclosed organelles, such as nuclei, lysosomes, endoplasmic reticulum, mitochondria, and chloroplasts - ANSIncrease structural complexity, help eukaryotes overcome diffusion limitation due to their size, and form specialized environments for specific functions to occur
Mice that are injected with only the R strain of Streptococcus pneumoniae - ANSstay healthy, because their immune systems can kill this strain easily. Microbial contamination is prevented by the _________________. - ANSUse of aseptic technique Microinsertions and microdeletions often result in ________ mutations. - ANSFrameshift Molecular sequencing suggests that mitochondria arose from a group of prokaryotic organisms within the ________________. - ANSAlphaproteobacteria Organic micronutrients are commonly called ____________. - ANSGrowth factors Organisms able to live in environments with high sugar concentrations are ________________. - ANSOsmophiles Part complete DNA replication is started with a(n) ________, which, in most cases, in vivo is a short stretch of ________. - ANSprimer/RNA Pasteur's experiments refuting the theory of spontaneous generation were crucial to the advancement of the field of microbiology because they led to the development of all EXCEPT which of the following? - ANS-Led to development of the germ theory of disease, sterile technique, food preservation -NOT OPTICAL ISOMERS
Photosynthetic organisms were present when Earth was primarily anoxic. Why was the appearance of cyanobacteria critical for the oxidation of the atmosphere?
Serial dilutions are generally made: - ANSBased on powers of 10, although other serial dilution factors are possible, when the appropriate viable count is unknown, to reach a suitable dilution while minimizing error. Some organisms seem to change names, for example VIbrio fischerii is now Aliivibrio fischerii. How can it be known which is the proper name. - ANSThe official source is the International Journal of Systematic and Evolutionary Microbiology. Staining increases the visible contrast of cells compared with the background. Because the Gram stain results in some types of bacteria staining purple and other types appearing pink, this is called __________ stain. - ANSa differential Starting with 3 cells, how many cells would result from three rounds of replication? - ANS Supercoiling is important for the DNA structure, because: - ANSit condenses the DNA so that it can fit inside the cell T/F A Bacterium whose optimal growth temperature is 35C would be classified as a thermophile. - ANSFalse T/F Direct microscopic counting of cells is an accurate method for estimating the number of viable cells in a sample. - ANSFalse T/F DNA replication is bidirectional in prokaryotes with circular chromosomes. - ANSTrue
T/F Horizontal gene transfer is one plausible explanation as to why organisms in Archaea, Bacteria, and Eukarya still share so many genes among such distinct domains. - ANSTrue T/F Knowledge of an organism's genome sequence yields important clues to how an organism functions and its evolutionary history. - ANSTrue T/F Most microorganisms are pathogenic. - ANSFalse T/F Most prokaryotic genomes are double-stranded circular DNA. - ANSTrue T/F Not only do some microorganisms tolerate extremely hot temperatures, some actually require high temperatures for optimal growth. - ANSTrue T/F Paralogs always have the same function - ANSFalse T/F the discipline of microbiology is intimately associated with biochemistry and genetics, because cells are both biochemical catalyst and genetic coding devices. - ANSTrue T/F The domain Archaea is divided into three phyla. - ANSFalse T/F The earliest nucleic acid was probably a simple DNA molecule. - ANSFalse T/F The rate of exponential growth varies greatly according to bacterial species and bioavailable nutrients. - ANSTrue
The ___________ produces plasma-membrane-associated proteins, which are then sent to the ___________ for sorting and processing - ANSrough ER; Golgi complex The cell wall of a Gram-positive bacterium is composed of a thick __________ layer. - ANSPeptidoglycan The codon on the ________ matches with the anticodon on the ________ to direct the addition of the correct amino acid to the growing polypeptide chain. - ANSmRNA/tRNA The cytoplasmic membrane could best be described as - ANSA highly selective permeability barrier The designations Phe-, Leu-, and Ser+ refer to an organisms - ANSPhenotype The earliest photosynthetic microbes, before the cyanobacterial lineage developed, oxidized substances other than water. What was produced by these microbes instead of oxygen? - ANSElemental sulfur The first catalytic and self-replication biological molecule was most likely ____________. - ANSRNA The first step of translation begins when ______________. - ANSthe ribosome binding site (RBS) on the mRNA binds to the 16S rRNA to begin the formation of the initiation complex.
The flow of biological information begins with - ANSDNA replication The functional unit of genetic information is the ________. - ANSGene The genes for 16S rRNA are used to determine genetic relatedness amongst microbes because __________. - ANSthese highly conserved genes are of adequate length to show deep relationships The genome sequence of an organism can provide information about the organisms _________________. - ANSGenes, function, and evolutionary history The lipopolysaccharide (LPS) layer is found ONLY in the cell walls of _________. - ANSgram-negative Bacteria The membrane-enclosed compartments that contain digestive enzymes in eukaryotic cells are called: - ANSLysosomes The molecule that seals the gaps between the pieces of DNA in the lagging strand is - ANSDNA ligase The number of colonies obtained in a plate count does NOT depend on the _______________. - ANSSize of the colonies The number of organisms in a broth culture was determined using the standard plate count method (SPC) and spectrophotometry (SPEC). Which of the results below would you expect to see from each method? - ANSSPC= 12 x 10^6 cfu/ml; SPEC= 11 z 10^7 cfu/ml
The oxic atmosphere created conditions that led to the evolution of various new metabolic pathways such as ____________________________________. - ANSSulfide oxidation, nitrification, and iron oxidation the person who describe the "wee animalcules" was _____________. - ANSAntoni van Leeuwenhoek The process of synthesizing proteins involves translating one "language" nucleic acid sequences, into another "language" amino acid sequences. The cellular component that does the actual translating from codons to amino acids is the _________. - ANStRNA The site of translation is - ANSribosomes in the cell cytoplasm The structure and function of a protein are determined by its ________ sequence.
The uptake of free DNA from the environment ________________, while transfer of DNA from cell-to-cell contact would most likely result in _____________. - ANSTransformation, conjugation The use of the Gram stain in microbiology is important because it differentiates - ANSbacterial cells with different types of cell walls Traditional classification of fungi by sexual spore type has been _____________ - ANSUpheld by phylogenetic analysis Two eukaryotic organelles that are hypothesized to be the result of endosymbiosis are the ________ and the ________. - ANSMitochondrion/ chloroplast What are the products of semiconservative replication for a double-stranded DNA molecule? - ANSTwo double-stranded DNA molecules, each consisting of one parental strand and one daughter strand. What characteristic of the S strain allows it to evade the immune system of the mice? - ANSThe cells have a capsule. What enables the copied chromosomes to separate during binary fission? - ANSThe chromosomes are attached to different parts of cell membrane, which elongates and thus separates the chromosomes. What ensures that the single strands of DNA do not come back together? - ANSStabilizing proteins
What happens to the light rays when they hit the specimen? - ANSThey are reflected, refracted, or absorbed by the specimen What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell? - ANSThe host DNA integrates, with the prophage, into the new recipient chromosome. What is meant by light rays being divergent? - ANSIt is spreading out. What is one feature of fungi that distinguishes them from plants? - ANSSome fungi can be dikaryotic at a specific stage of their life cycle. What is the biological function of endospores? - ANSThey enable organisms to endure extremes of temperature, drying and nutrient depletion What is the function of the parental DNA in replication? - ANSIt serves as the template for DNA replication. What is the hallmark of all horizontal gene transfers? - ANSTransfer of DNA between organisms of the same generation What is the role of lenses in microscopy? - ANSLenses focus either light or electrons to create a magnified image of a specimen. What is the role of the ocular lens? - ANSTo recreate the image in the viewers eye
What makes phospholipid membranes good at keeping some molecules out, and allowing others to freely pass. - ANSThey have both hydrophilic and hydrophobic regions What most likely explains the recovery of live S strain cells from a mouse injected with heat-killed S strain mixed with live R strain cells? - ANSThe R strain picked up the S strain DNA, enabling it to produce a capsule. What must occur for bacterial conjugation to take place? - ANSThe cells must come into contact with each other. What test result indicates that the unknown can utilize citrate as its sole carbon source? - ANSThe medium turns blue What was the LUCA? - ANSthe last organism prior to the divergence of bacteria and archaea When counting colonies on an agar plate. - ANSIt is assumed that each colony arose from division of one or a few cells Which enzyme breaks the hydrogen bonds during replication? - ANSDNA helicase Which finding is most surprising from Griffith's experiments? - ANSS strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains. Which is a valid cell morphology? - ANSSpirochete
Which is an example of a micronutrient? - ANSIron Which list contains the correct components of a bacterial flagellum? - ANSFilament, hook, basal body Which of the following best states the germ theory of disease? - ANSSome microorganisms can cause disease. Which of the following build(s) new strands of DNA? - ANSDNA polymerases Which of the following does not occur during RNA processing? - ANSmRNA attaches to the small subunit of a ribosome. DOES OCCUR: -Segments of RNA that do code for the protein are reconnected. -A modified nucleotide is added to the beginning of the RNA strand as a cap. -Adenine nucleotides are added to the end of the RNA strand, forming a tail. -Segments of the RNA strand that do not actually code for the protein are removed. Which of the following events occurs during transcription? - ANSA molecule of RNA is formed based on the sequence of nucleotides in DNA. Which of the following forms of oxygen is/are generally toxic to living organisms? - ANSSuperoxide, hydrogen peroxide and hydroxyle radicals are all toxic.
Which of the following is a correct statement about mRNA? - ANSmRNA moves from the nucleus to the cytoplasm following RNA processing. Which of the following is an example of horizontal gene transfer in bacteria? - ANSTransduction, conjugation, and transformation Which of the following is formed on the lagging strand during DNA synthesis? - ANSOkazaki fragments Which of the following is NOT correct regarding DNA and RNA synthesis? - ANSBoth processes require an RNA primer to begin. True: The template strand is antiparallel to the newly synthesized strand. -The overall direction of chain growth is from the 5 to 3 end. -DNA is the template for both DNA and RNA synthesis. Which of the following is TRUE of natural competence? - ANSIt requires special proteins such as a cell wall autolysin. Which of the following represents the digestion center of the cell responsible for breakdown macromolecules and worn-out organelles? - ANSLysosome Which of the following scenarios is an example of bacterial motility? - ANSa bacterium moving towards a food source Which of the following types of microscopy could be used to visualize the layers of the cell membrane and the cell wall? - ANSTransmission electron microscopy
Which of the following types of microscopy is especially effective for viewing details of internal structures within live cells? - ANSPhase-contrast microscopy Which of the following would be used by a chemoorganotrophy for energy? - ANSC2H3O2- Which one of the following does not play a role in translation? - ANSDNA Which response best explains why promoters for the same sigma subunit do not have identical sequences? - ANSThe sequences within the promoter region at -10 and -35 are the most important for recognition by the sigma subunit. Which statement about conjugation is false? - ANSTrue statements: After conjugation, each cell involved has a copy of the shared DNA and E.Coli is the model for bacterial conjugation. False: Conjugation is a process of bacterial reproduction Which statement about DNA replication is CORRECT? - ANSThe leading strand is built continuously, and the lagging strand is built in pieces. Which statement about DNA replication is FALSE? - ANSDNA ligase adds nucleotides to the lagging strand. True statements: -The two strands of parental DNA are separated during DNA replication.
-The lagging strand is made of a series of pieces that must be joined together to make a continuous strand. -Because the two strands of parental DNA run in opposite directions, the new strands must be made in different ways. -DNA polymerase builds a new strand by adding DNA nucleotides one at a time. Which statement best describes an operon? - ANSSeveral genes, next to each other in prokaryotic DNA, that are transcribed as a single piece of mRNA Which statement illustrates how prokaryotes determine where to begin translation so the correct protein is synthesized? - ANSThe rRNA recognizes the correct start codon with the aid of an upstream Shine-Dalgarno sequence. Which statement illustrates why DNA polymerase cannot initiate a new DNA strand? - ANSDNA polymerase requires a preexisting 3' hydroxyl group in order to add nucleotides Which statement is the correct definition of polycistronic mRNA? - ANSa single piece of mRNA that contains the transcript for multiple genes Which statements describe the evidence that supports the endosymbiotic theory?
why are flowcharts useful for dichotomous keys? - ANSThey allow the researcher to visualize relationships between different bacteria Why is a specimen smaller than 200 nm not visible with a light microscope? - ANSAnything smaller than 200 nm cannot interact with visible light. Why is DNA replication essential for a cell? - ANSAn organism must copy its DNA to pass genetic information to its offspring. Why is ribosomal RNA especially useful for the study of phylogenetic relationships? - ANSIt is highly conserved. You are studying 12 new isolates from the human skin. Their average nucleotide identity for shared orthologous genes is 97%.The isolates would most likely be - ANSclassified as individual strains of the same species