MIC 205 EXAM 1 QUESTIONS WITH VERIFIED SOLUTIONS LATEST UPDATE 2026

MIC 205 EXAM 1 QUESTIONS WITH VERIFIED SOLUTIONS LATEST UPDATE 2026 Microbe - Answers A microscopic organism or agent; includes bacteria, archaea, protozoa, fungi, microscopic algae, and viruses. How do microbes benefit humans? - Answers They help digest food, produce vitamins, protect against pathogens, produce foods and medicines, recycle nutrients, and perform other essential biological processes. How do microbes benefit the environment? - Answers They decompose dead organisms and wastes, recycle nutrients, fix nitrogen, produce oxygen, and participate in important ecological cycles. What are the 3 Domains of life? - Answers Bacteria, Archaea, and Eukarya. Domain Bacteria - Answers Prokaryotic organisms whose cells lack a nucleus and membrane-bound organelles; most have cell walls containing peptidoglycan. Domain Archaea - Answers Prokaryotic organisms that lack a nucleus and membrane-bound organelles but differ chemically and genetically from bacteria; their cell walls do not contain peptidoglycan. Domain Eukarya - Answers Organisms whose cells contain a true nucleus and membrane-bound organelles; includes protists, fungi, plants, and animals. Bacteria vs. Archaea - Answers Both are prokaryotic, but bacteria typically contain peptidoglycan in their cell walls while archaea do not. Archaea also have distinctive membrane lipids and genetic characteristics. Bacteria vs. Eukarya - Answers Bacteria are prokaryotic and lack a nucleus and membrane-bound organelles; eukaryotic cells contain a nucleus and membrane-bound organelles. Kingdom Fungi - Answers Eukaryotic organisms that absorb nutrients from their environment; includes yeasts and molds. Fungal cell walls contain chitin. Kingdom Protista - Answers A diverse group of mostly unicellular eukaryotes that includes protozoa and algae. Kingdom Plantae - Answers Multicellular, photosynthetic eukaryotes with cellulose-containing cell walls and chloroplasts. Kingdom Animalia - Answers Multicellular eukaryotes that obtain nutrients by ingestion and lack cell walls. Robert Koch - Answers Established the relationship between specific microbes and specific diseases and developed Koch's postulates. Koch's postulates - Answers A set of criteria used to establish that a particular microorganism causes a particular disease. Louis Pasteur - Answers Disproved spontaneous generation, demonstrated that microbes cause fermentation and spoilage, contributed to germ theory, and developed pasteurization and vaccines. Edward Jenner - Answers Developed the first successful vaccine by using cowpox to protect people against smallpox. Alexander Fleming - Answers Discovered penicillin after observing that Penicillium mold inhibited the growth of bacteria. Robert Hooke - Answers Used an early microscope to observe and describe microscopic fungi and coined the term "cell" from his observations of cork. Anton van Leeuwenhoek - Answers First to observe and describe living microorganisms using simple microscopes; called them "animalcules." Paul Ehrlich - Answers Helped establish chemotherapy and developed the concept of using chemicals that selectively kill microbes without seriously harming the host. Spontaneous generation - Answers The historical belief that living organisms could arise spontaneously from nonliving matter. How was spontaneous generation disproven? - Answers Experiments, especially Pasteur's swan-neck flask experiment, showed that microorganisms arise from existing microorganisms rather than spontaneously from nonliving matter. Biogenesis - Answers The principle that living organisms arise from other living organisms. Scientific name - Answers A two-part name consisting of an organism's genus and species; the genus is capitalized and the species is lowercase, and both are italicized when typed. Example of a scientific name - Answers Escherichia coli; Escherichia is the genus and coli is the species. Taxonomic hierarchy - Answers Domain → Kingdom → Phylum → Class → Order → Family → Genus → Species. Taxonomy - Answers The science of classifying and naming organisms. Phylogeny - Answers The evolutionary history and relationships among organisms. Taxonomy vs. phylogeny - Answers Taxonomy organizes and names organisms, while phylogeny describes their evolutionary relationships. Virus - Answers An acellular infectious agent consisting primarily of genetic material (DNA or RNA) surrounded by a protein coat; some also have an envelope. General characteristics of viruses - Answers Viruses are acellular, contain DNA or RNA, lack independent metabolism and ribosomes, and reproduce only inside living host cells. Acellular - Answers Not composed of cells. Types of eukaryotic microbes - Answers Protozoa, fungi, algae, and microscopic stages/forms of helminths. Major microbial groups from generally largest to smallest - Answers Helminths → fungi/protozoa/algae → bacteria and archaea → viruses. Four major biological macromolecules - Answers Carbohydrates, lipids, proteins, and nucleic acids. Carbohydrates - Answers Macromolecules composed primarily of carbon, hydrogen, and oxygen; important for energy and structural support. Examples include glucose, glycogen, and cellulose. Lipids - Answers Hydrophobic molecules used for energy storage and as components of cell membranes; examples include fats, phospholipids, and steroids. Proteins - Answers Polymers of amino acids that function as enzymes, structural components, receptors, transporters, antibodies, and many other cellular components. Nucleic acids - Answers DNA and RNA; molecules composed of nucleotides that store, transmit, and help express genetic information. Structures found in all cells - Answers A cell membrane, cytoplasm, ribosomes, and genetic material (DNA). Normal (resident) microbiota - Answers Microorganisms that normally live on or in the body without causing disease under typical conditions and often provide benefits. Pathogen - Answers A microorganism or infectious agent capable of causing disease. Decomposer - Answers An organism that breaks down dead organisms and organic waste, returning nutrients to the environment. Ubiquitous - Answers Present or found nearly everywhere. Methanogen - Answers An archaeon that produces methane as a metabolic product, usually under anaerobic conditions. Thermophile - Answers A microorganism adapted to grow at relatively high temperatures. Halophile - Answers A microorganism adapted to environments with high salt concentrations. Mycology - Answers The study of fungi. Protozoa - Answers Mostly unicellular eukaryotic organisms that generally lack a rigid cell wall; many are motile and obtain nutrients from organic matter. Helminth - Answers A parasitic worm; adults are usually macroscopic, but their eggs and larvae may be microscopic and are studied in microbiology. Chemotherapy - Answers The use of chemical substances to treat disease; in microbiology, it commonly refers to antimicrobial chemicals used to destroy or inhibit pathogens. Nucleoid - Answers The region of a prokaryotic cell where its main chromosome is located; it is not surrounded by a membrane. Major bacterial shapes - Answers Coccus (spherical), bacillus (rod-shaped), vibrio (curved rod), spirillum (rigid spiral), and spirochete (flexible spiral). Coccus - Answers A spherical or roughly round bacterial cell. Bacillus - Answers A rod-shaped bacterial cell. Vibrio - Answers A curved or comma-shaped bacterial cell. Spirillum - Answers A relatively rigid spiral-shaped bacterial cell. Spirochete - Answers A thin, flexible, corkscrew-shaped bacterial cell. Diplococci - Answers Cocci arranged in pairs. Streptococci - Answers Cocci arranged in chains. Staphylococci - Answers Cocci arranged in irregular, grape-like clusters. Tetrads - Answers Groups of four cocci. Sarcinae - Answers Cubical packets of cocci, commonly containing eight or more cells. Streptobacilli - Answers Rod-shaped bacterial cells arranged in chains. Pleiomorphic - Answers Capable of varying in shape and size rather than maintaining one consistent cellular shape. Biofilm - Answers A community of microorganisms attached to a surface and embedded within a self-produced extracellular matrix. Where can biofilms form? - Answers On living tissues and nonliving surfaces, including teeth, medical devices, pipes, catheters, and other moist surfaces. Why are biofilms important in infectious disease? - Answers Biofilms help microorganisms attach to surfaces and can protect them from antibiotics, disinfectants, immune defenses, and environmental stresses, making infections difficult to eliminate. Organism responsible for anthrax - Answers Bacillus anthracis. Three types of anthrax - Answers Cutaneous anthrax, inhalation anthrax, and gastrointestinal anthrax. Cutaneous anthrax - Answers Anthrax acquired through the skin, usually when spores enter a cut or abrasion. Inhalation anthrax - Answers Anthrax caused by inhaling B. anthracis spores; it can progress to severe systemic disease. Gastrointestinal anthrax - Answers Anthrax acquired by consuming food contaminated with B. anthracis spores. Typical bacterial cell components - Answers Cell membrane, cytoplasm, nucleoid/chromosome, ribosomes, cell wall, and often structures such as a glycocalyx, flagella, pili, plasmids, and inclusions. Bacterial appendages for motility and attachment - Answers Flagella primarily provide motility; fimbriae and pili primarily assist with attachment or DNA transfer. Flagellum - Answers A long cellular appendage that rotates to propel a bacterial cell. Fimbriae - Answers Short, numerous protein appendages that allow bacteria to attach to surfaces or host cells. Pilus - Answers A longer protein appendage; certain pili attach bacterial cells to one another and allow DNA transfer during conjugation. Purpose of a sex pilus - Answers Connects a donor bacterial cell to a recipient so DNA, often a plasmid, can be transferred during conjugation. Monotrichous flagella - Answers A single flagellum located at one pole of a bacterial cell. Lophotrichous flagella - Answers A tuft of flagella located at one pole of a bacterial cell. Amphitrichous flagella - Answers Flagella located at both poles of a bacterial cell. Peritrichous flagella - Answers Flagella distributed over the entire surface of a bacterial cell. Chemotaxis - Answers Directed movement of a cell toward a beneficial chemical stimulus or away from a harmful one. Glycocalyx - Answers A sticky outer coating outside the bacterial cell wall that may occur as a capsule or slime layer. Capsule - Answers An organized, firmly attached glycocalyx that can aid attachment and protect bacteria from drying and host defenses such as phagocytosis. Slime layer - Answers A loose, unorganized glycocalyx that aids attachment and biofilm formation and can help prevent dehydration. Capsule vs. slime layer - Answers A capsule is organized and firmly attached to the cell; a slime layer is diffuse, unorganized, and loosely attached. Cell membrane - Answers A selectively permeable phospholipid bilayer surrounding the cytoplasm that regulates movement of substances into and out of the cell. Bacterial cell envelope - Answers The layers surrounding the bacterial cytoplasm, including the cell membrane and cell wall and, in Gram-negative bacteria, an outer membrane. Gram-positive bacteria - Answers Bacteria with a thick peptidoglycan cell wall containing teichoic acids and no outer membrane; they stain purple in a Gram stain. Gram-negative bacteria - Answers Bacteria with a thin peptidoglycan layer located between the cell membrane and an outer membrane containing lipopolysaccharide (LPS); they stain pink/red in a Gram stain. Gram-positive cell envelope - Answers Cell membrane + thick peptidoglycan cell wall containing teichoic and lipoteichoic acids. Gram-negative cell envelope - Answers Inner/cytoplasmic membrane + thin peptidoglycan layer in the periplasm + outer membrane containing LPS. Peptidoglycan - Answers A strong mesh-like polymer of sugars and peptides that gives bacterial cell walls shape and strength. Teichoic acids - Answers Polymers associated with the cell walls of Gram-positive bacteria that contribute to cell wall structure and surface properties. Lipopolysaccharide (LPS) - Answers A component of the outer membrane of Gram-negative bacteria; its lipid A portion acts as an endotoxin. Periplasm - Answers The region between the inner and outer membranes of Gram-negative bacteria containing the thin peptidoglycan layer and various proteins and enzymes. Acid-fast bacterial cell wall - Answers A cell wall containing peptidoglycan plus a waxy layer rich in mycolic acids, making it resistant to many stains and chemicals. Mycolic acid - Answers A waxy lipid found in large amounts in acid-fast bacterial cell walls. Mycoplasmas - Answers Bacteria that naturally lack a cell wall and therefore have flexible, pleomorphic cells; their cell membranes contain sterols for stability. Inclusion - Answers A storage body or deposit in a bacterial cell that may contain nutrients or other substances. Substances stored in bacterial inclusions - Answers May include glycogen, lipids, polyphosphate, sulfur, and other reserve materials. Bacterial endospore - Answers A dormant, highly resistant structure produced inside certain bacterial cells that allows survival during unfavorable conditions. Why are bacterial endospores dangerous? - Answers They can survive heat, drying, chemicals, and other harsh conditions for long periods and later germinate into active vegetative cells. Sporulation - Answers The process by which a vegetative bacterial cell produces an endospore in response to unfavorable conditions. Germination - Answers The process by which an endospore returns to an active vegetative cell when environmental conditions become favorable. Prokaryotic cell - Answers A cell lacking a membrane-bound nucleus and other membrane-bound organelles; bacteria and archaea are prokaryotic. Eukaryotic cell - Answers A cell containing a membrane-bound nucleus and membrane-bound organelles. Prokaryotic vs. eukaryotic DNA - Answers Prokaryotes usually have a single main circular chromosome located in the nucleoid and may contain plasmids; eukaryotes have multiple linear chromosomes enclosed within a nucleus. Prokaryotic vs. eukaryotic ribosomes - Answers Prokaryotic cytoplasmic ribosomes are 70S; eukaryotic cytoplasmic ribosomes are 80S. 70S ribosome - Answers Prokaryotic ribosome composed of a 50S large subunit and a 30S small subunit. 80S ribosome - Answers Eukaryotic cytoplasmic ribosome composed of a 60S large subunit and a 40S small subunit. Cellular respiration - Answers A series of metabolic reactions that harvest energy from nutrients and use it to generate ATP. Where does cellular respiration occur in bacteria? - Answers Because bacteria lack mitochondria, major respiratory processes occur in the cytoplasm and at the cytoplasmic membrane. Where does cellular respiration occur in eukaryotes? - Answers Glycolysis occurs in the cytoplasm, while most aerobic respiration occurs in mitochondria. Photosynthesis - Answers A process that captures light energy and converts it into chemical energy used to synthesize organic compounds. Where does photosynthesis occur in photosynthetic bacteria? - Answers On specialized internal membrane systems associated with the cytoplasmic membrane, such as chromatophores in some photosynthetic bacteria. Where does photosynthesis occur in eukaryotes? - Answers In the chloroplasts of photosynthetic eukaryotes. Chromatophores - Answers Photosynthetic membrane structures found in certain photosynthetic bacteria that contain pigments and components needed to capture light energy.