MICROBIO 4000 EXAM QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026

MICROBIO 4000 EXAM QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026 Out of the following, which are prokaryotes? Eukaryotes? Neither? Bacteria, archaea, protozoa, algae, fungi, helminths, viruses/viroids/prions - Answers Prokaryotes: bacteria and archaea Eukaryotes: protozoa, algae, fungi, helminths Neither: viruses/viroids/prions Out of the following, which ones are single celled? Multicellular? Both? Neither? Bacteria, archaea, protozoa, algae, fungi, helminths, viruses/viroids/prions - Answers Single: bacteria, archaea, protozoa Both: algae and fungi Multicellular: helminths Viruses: neither How does each group get nutrition? (organic, photosynthesis, inorganics) Bacteria, archaea, protozoa, algae, fungi, helminths - Answers Bacteria: organic, photosynthesis, inorganics Archaea: organics, inorganics Protozoa: organics, few are photosynthetic Algae: photosynthetic Fungi: organic Helminths: organic Which groups have cell walls? Bacteria, archaea, protozoa, algae, fungi, helminths - Answers Yes: bacteria, archaea, algae, fungi No: protozoa, helminths Which groups are pathogens? Bacteria, archaea, protozoa, algae, fungi, helminths, viruses/viroids/prions - Answers Yes: bacteria (some), protozoa (some), fungi (some), helminths, viruses/viroids/prions No: archaea, algae Which groups have single cell motility? Bacteria, archaea, protozoa, algae, fungi, helminths - Answers Yes: bacteria, archaea, protozoa, some algae, some fungi No: helminths Which groups are extremophiles? Bacteria, archaea, protozoa, algae, fungi, helminths - Answers Yes: bacteria (some), archaea (most), protozoa (few), algae (few), fungi (few), helminths (few) What groups use DNA vs RNA as genome? Bacteria, archaea, protozoa, algae, fungi, helminths, viruses/viroids/prions - Answers DNA: bacteria, archaea, protozoa, algae, fungi, helminths RNA: viruses/viroids/prions Common characteristics of prokaryotes - Answers No nucleus or membrane-bound organelles Unicellular Many have capsule and slime layer made of polysaccharide What were Hooke's contributions to microbiology? - Answers - coined the term cell after observing porous honeycomb like structures in cork - documented first known depiction of microorganism - compound microscope What were Van Leeuwenhoek's contributions to microbiology? - Answers - discovered existence of microbes (bacteria, protists, and microscopic organisms in rainwater, saliva, and plaque) - single lens microscope - red blood cells, sperm, nematodes - demonstrated that fleas and insects came from eggs, not nonliving matter (opposed theory of spontaneous generation) Germ theory of disease - Answers Microbes cause infectious disease by invading a host Importance of Koch's postulates - Answers Establishes causal link that a scientific microbe causes a specific disease. 1. Association - microbe must be present in all disease cases and absent from healthy organisms 2. Isolation - microbe must be isolated from diseased host and grown in pure culture 3. Inoculation - microbe must cause same disease when introduced into healthy susceptible host 4. Re-isolation - same microorganism must be re-isolated from experimentally infected host and be identical to the original agent What lab techniques allowed for postulates? - Answers Pure culture media Significance of Jenner's discovery - Answers Vaccination; using cowpox to prevent smallpox. Showed that weakened form of disease could protect against full blown illness What did Pasteur realize is important for successful vaccination? - Answers using attenuated (weakened) or inactivated microbes to induce immunity without causing the disease How are microorganisms named? What are strains? - Answers - Binomial nomenclature. Genus species (italicized when typing, underlined when handwritten) - Strain - subset of a microbial species that represents a certain variant derived from a single cell What are the three domains of life? Who is responsible for this organization? - Answers Bacteria, archaea, eukarya. Carl Woese What has the field of microbiology focused on more recently? - Answers combating antimicrobial resistance (AMR), exploring the human microbiome for personalized therapies, and leveraging AI for diagnostics and drug discovery. List ways in which microbes affect our lives (and the planet) -destructive and beneficial - Answers driving essential ecological processes, aiding human digestion, and producing food, while also causing disease, food spoilage, and material decay. They act as decomposers, nutrient recyclers, and oxygen producers. Why is our Microbiota so important? - Answers It aids digestion, extracts nutrients, synthesizes vitamins (like K and B), trains and supports your immune system to fight pathogens, maintains gut barrier integrity, influences metabolism, and even impacts brain health, with imbalances linked to chronic illnesses like IBD, diabetes, and obesity. Infectious diseases - Answers illnesses caused by harmful agents (pathogens) like bacteria, viruses, or parasites that enter the body, multiply, and cause symptoms Parasite - Answers specific type of organism that lives on or inside a host species, obtaining nutrients at the host's expense Pathogen - Answers any organism or agent, including bacteria, viruses, fungi, or parasites, that causes disease in a host Lancefield grouping - Answers Method to classify Streptococcus bacteria into groups based on differences in their cell wall carbohydrates Bacteria classes that don't Gram-stain well and why - Answers Mycoplasma, Mycobacterium, Chlamydia, Rickettsia, and Spirochetes. They fail to stain due to a lack of peptidoglycan (Mycoplasma), high waxy lipid content (Mycobacterium), or being too small/intracellular (Chlamydia/Rickettsia) to retain the dyes. Composition of archaea cell wall - Answers S-layer Pseudomurein (similar to peptidoglycan but different sugars and peptides) Other polysaccharides Composition of protozoa cell wall - Answers Don't really have cell wall. Flexible outer covering called pellicle, which is made of plasma membrane, microtubules, and sometimes alveoli Composition of algae cell wall - Answers Primarily made of polysaccharides like cellulose that provide structure and protection, with some complex proteins Composition of fungal cell wall - Answers Dynamic structures that provide protection, mainly composed of polysaccharides like chitin, mannans, and glucans, and glycoproteins. Robust inner layer made of chitin and glucan scaffolding What is bacterial secretion and what is it used for? - Answers Protein complexes on cell membrane secrete substances called virulence factors to invade host cells. Eukaryotic secretion is multistep complex process, which often relies on membrane-bound organelles and vesicles. Whereas prokaryotic secretion often happens in one step Axial filament - Answers Structure located in the periplasmic space between inner and outer membrane. Wraps around cell body, enabling corkscrew-like twisting motility essential for navigating viscous environments Where are ribosomes found in prokaryotes? How do they differ from eukaryotes? - Answers Freely suspended throughout cytosol. Eukaroytes have some ribosomes bound to rough ER and some floating around, prokaryotes do not have rough ER Evidence of endosymbiotic theory - Answers Mitochondria and chloroplasts have their own DNA and ribosomes, double membrane structure, and independent replication through binary fission Flagella - Answers whiplike tails found in one-celled organisms to aid in movement Pili - Answers Appendages that allow bacteria move, attach to each other, and to transfer DNA Fimbriae - Answers Appendages that allow bacteria to stick to a surface Sex pili - Answers Appendages that allow for DNA exchange in bacteria Capsule - Answers Sticky outermost layer that surrounds cell walls of prokaryotes and helps cell from drying out Peptidoglycan - Answers Polymer of linked sugar and polypeptides that make up the cell wall of bacteria What are archaeal cell walls made of? - Answers Pseudopeptidoglycan, a similar molecule to peptidoglycan. Some are also composed of proteins or other types of polymers Nucleoid - Answers Part of the cytoplasm in prokaryotes that contains the chromosome Plasmids - Answers Small ring of double-stranded extrachromosomal DNA that carry non-essential genes. Copied independently of the chromosome and can be transferred between prokaryotes, sometimes spreading genes essential for survival R gene - Answers Gene in a plasmid that makes bacteria resistant to antibiotics Siderophore - Answers Molecules in bacteria that bind to iron in the extracellular environment so that iron can be transported into the cell What is a disadvantage of not having a flagella? - Answers Not being able to move around, often causes organisms to compete for nutrients and puts stress on the population Which characteristics apply to the cell membrane, and which characteristics apply to the cell wall of a Gram positive cell? Will be ruptured by osmotic shock Protects the cell from osmotic shock Impermeable to ions Ions pass freely Thin and flexible Ridged and holds its shape Components not covalently linked Components are covalently linked together Mainly made of lipids and proteins Mainly made of polysaccharide - Answers Cell membrane: - Will rupture from osmotic shock - Impermeable to ions - Thin and flexible - Components not covalently linked - Mainly made of lipids and proteins Cell wall: - Protects cell from osmotic shock - Ions pass freely - Ridged and holds its shape - Components covalently linked together - Mainly made of polysaccharide What properties would you look for in the cell envelope of Gram negative bacteria that is not present in Gram positive bacteria? - Answers Lipopolysaccharide and periplasm Periplasm - Answers Concentrated, gel-like aqueous compartment located between the inner cytoplasmic membrane and outer membrane in Gram negative bacteria Endotoxins - Answers Toxic compounds, such as lipolysaccharides, that get released when Gram negative bacteria die Are Gram positive or Gram negative bacteria more resistant to antibiotics? - Answers Gram negative; outer membrane acts as an impermeable barrier. Contains lipopolysaccharides and efflux pumps, which actively expels toxins and limits drug penetration Why is gram negative bacteria deadlier than gram positive bacteria? - Answers Lysis releases lipopolysaccharides, which are extremely toxic Why must a cell use energy to bring nutrients into the cell? - Answers Nutrient molecules are too big to be moved through the membrane and must be brought into the cell by endocytosis, which always requires energy Endocytosis - Answers Eukaryotic cells engulf nutrients by budding off a section of their plasma membrane, which forms a vesicle. Requires energy Exocytosis - Answers Contents of a cell vacuole are released to the exterior through fusion of vacuole membrane with cell membrane Efflux - Answers Energy dependent process in bacteria that uses pumps to expel toxic substances to the external environment Symport - Answers Energy coupling process. One molecule is being transported against its concentration gradient, and another is transported with its concentration gradient. But they are moving in the same direction Antiport - Answers Energy coupling process. One molecule is being transported against its concentration gradient, and another is transported with its concentration gradient. But they are moving in different directions Briefly explain the steps bacteria use to obtain iron from their environment. - Answers 1. Secretes siderophore to environment 2. Siderophore binds iron 3. Siderophore-iron complex binds to surface receptors. 4. Hydrolysis of ATP by ABC transporter allows transport of siderophore-iron complex into cytoplasm 5. Ferric iron is released by siderophore for use by the cell. What two classes of organic molecules are used to form peptidoglycan? - Answers Sugar molecules and amino acids. Contrast Gram positive and Gram negative bacteria cell walls - Answers Gram positive - Thick layer of peptidoglycan outside of plasma membrane, contains teichoic and lipotechoic acids