MICR 271 Module 3 Proctored Exam Questions And Answers 2025 Approved.

How do bacteria replicate? what are the steps of this process? - correct answer binary fission (the process whereby a cell divides asexually to produce 2 daughter cells) 1. Replication of bacterial chromosome 2. Cell growth 3. Invagination of cell wall into 2 separate daughter cells Why must Peptidoglycan (PG) get restructured/remodelled? - correct answer since it is a rigid cellular component that maintains shape and integrity, it must be restructured in order for bacteria to grow and divide by binary fission why dont bacteria explode due to osmotic pressure? - correct answer they have cell walls How do bacteria grow if they have a strong cell wall used to combat osmotic pressure? - correct answer use pressure to slowly expand the cell wall (like inflating a baloon) osmotic pressure of bacterial cells. how can it be beneficial and how can it be harmful? - correct answer pressure is due to the higher concentration of solutes (or high osmolarity) inside the cell in some bacteria, osmotic pressure can be used to help make the rigid cell wall bigger during growth (like slowly inflating a baloon) Do bacteria age and die? - correct answer yes- they undergo senescence (a gradual deterioration of function) causes of bacterial aging - correct answer from binary fission inheriting... a. old cell wall material at the 'old pole' b. damaged DNA c. damaged proteins d. activation of damage defense systems (M) instead of growth systems (G) what is the difference b/w mother and daughter lineages in bactera? - correct answer the mother lineage (has the old pole) takes the damaged cellular components thus focuses on repair (rather than growth) and divides very slowly The daughter lineage (new pole) doesnt get damaged stuff, focuses on growth, and divides faster What is metabolism? anabolism? catabolism? - correct answer the chemical processes that occur within a living organism in order to maintain life. the building of components The breakdown of molecules to obtain energy facilitated diffusion - correct answer Movement of specific molecules across cell membranes through protein channels. no energy primary active transport - correct answer Active transport that relies directly on the hydrolysis of ATP. moved from area of high conc to low conc secondary active transport - correct answer Form of active transport which does not use ATP as an energy source; rather, transport is coupled to ion diffusion down a concentration gradient established by primary active transport. no energy used group translocation - correct answer chemical modification of the transported substance what factors affect microbial metabolism? - correct answer temp, pH, hydration, pressure (protein activity and structure) o2 levels (processes) obligate aerobes - correct answer undergo aerobic respiration-require oxygen facultative anaerobes - correct answer doesnt require O2 to grow. can live with or without oxygen- but does better with O2 aerotolerant anaerobes - correct answer do not utilize oxygen but can survive and grow in its presence strict anaerobes - correct answer oxygen is toxic. die in the least bit of oxygen. generate energy by fermentation or anaerobic respiration. microaerophiles - correct answer require oxygen concentration lower than air. damaged by atmospheric levels. What are Reactive Oxygen Species (ROS) and why are they bad? - correct answer O2 derivatives (bc theres 2 unpaired electrons on an O2 molecule making it unstable). If proteins transfer electrons to O2 then the radicals that result can cause damage to proteins, lipids, and nucleic acids. How to prokaryotes contribute to the carbon and nitrogen cycles? - correct answer Carbon: fix CO2, fixed carbon to CO2 Nitrogen: nitrifying bacteria produce their own energy by converting ammonia to nitrites and nitrates what are the major and minor components of microorganism nutrition? - correct answer major: carbon, nitrogen minor: hydrogen vitamins, trace elements why are there dif metabolic groupings for microorganisms? - correct answer bc they differ on how they obtain C, obtain energy, and how they obtain reducing equivalents (electrons) what are the different ways a microorganism can obtain energy? - correct answer Chemotrophic: energy from external chemical compounds Phototropic: energy from light what are the different ways a microorganism can obtain carbon? - correct answer Autotrophic: from CO2 Heterotrophic: from organic compounds Mixotrophs: both CO2 and organic compounds what are the different ways a microorganism can obtain reducing equivalents (electrons)? - correct answer Lithotrophic: from inorganic compounds Organotrophic: organic compounds What do you call a microorganism who collects its C from CO2 and makes energy from light? examples? - correct answer photoautotroph plants, algae, cyanobacteria use H2O as electron source What do you call a microorganims who collects C from CO2 and makes energy from chemical compounds? - correct answer chemoautotroph hydrogen, sulfur, and nitrifying bacteria, some archea What do you call a microorganism that obtains energy from light and uses organic compounds to obtain C? examples - correct answer photoheterotroph green or purple non sulfur bacteria, some archea What do you call a microorganism that obtains energy from chemicals and uses organic compounds to obtain C? examples - correct answer chemoheterotrophs aerobic respiration: fungi and many pathogenic bacteria anareobic respiration: protozoa, bacteria, and archaea fermentation: come bacteria, yeasts, and archea why are most bacterial pathogens chemoheterotrophs? - correct answer becuase the human hosts they invade are also chemoheterotrophs. They scavange. how to organisms make ATP in the presence of O2? without O2? - correct answer with: respiration without: fermentation persister cells - correct answer dormant variants of regular cells that o