BIOD 171 Module 4 Exam Questions and 100% Acculate Answers Graded A+ (LATEST UPDATE)

BIOD 171 Module 4 Exam Questions and 100% Acculate Answers Graded A+ (LATEST UPDATE) What is another name for a liquid growth media, and what are the basic components? - CORRECT ANSWERGrowth media in a liquid form is often referred to as nutrient broth. As the name implies its composition consists primarily of essential 'ingredients' such as a rich source of sugars, amino acids, and vitamins. Together, a nutrient broth provides the microbe with a source of carbon/energy, which, in turn, encourages its expansion. What is selective media? - CORRECT ANSWERSelective media allows for only the growth of certain microbes while restricting the growth of all others. What is differential media? - CORRECT ANSWERDifferential media is used to distinguish between two (or more) related microbes. What are the requirements of a fastidious microbe? - CORRECT ANSWER-A fastidious microbe is an organism with complex growth requirements such that if absent it will not grow. Enriched medias thus contain these specific and essential nutrients required for the growth of a particular subset of microorganisms. What is agar? - CORRECT ANSWER-In its simplest form agar is liquid growth media that has had a hardening agent added to it. Agar is created when a polysaccharide derived from seaweed (algae) extract is added to growth media. Agar is used to create a solid, smooth surface on which microbes can grow. LB agar is classified as a non-selective, differential media True False - CORRECT ANSWER-False LB agar is non-selective and non-differential What are the three forms of hemolysis found on blood agar plates? - CORRECT ANSWER-Alpha hemolysis, beta hemolysis, and gamma hemolysis Alpha hemolysis - CORRECT ANSWER-Presents with greenish-brown color on blood agar due to the partial lysis of red blood cells Beta hemolysis - CORRECT ANSWER-Clear zones on blood agar indicate beta hemolysis, which is the complete lysis of red blood cells Gamma hemolysis - CORRECT ANSWER-Presents a white/tan on blood agar due to the lack of hemolytic activity. What is the primary purpose of Columbia CNA agar? - CORRECT ANSWER-As it suppresses the growth of Gram-negative bacteria CNA agar is, therefore, used for isolation of Gram-positive microbes. Name the type of plate derived from BAP that contains lysed red blood cells - CORRECT ANSWER-Lysed red blood cells (RBCs) are a primary component in the formulation of Chocolate agar. Define the selective and differential abilities of a MacConkey agar plate - CORRECT ANSWERMacConkey agar is selective in that only Gram-negative microbes will grow on the agar -Gram-positive microbes simply do not grow. MacConkey agar is also considered a differential media as it distinguishes between microbes capable of fermenting lactose (red colonies) and those that are non-fermenters (white/tan colonies). What colors would you expect to see on an EMB plate containing E. coli? - CORRECT ANSWER-The EMB plate itself is red in color while in the presence of E. coli, the growing colonies will take on a distinctive metallic green sheen. What is the name of the process of spreading a bacterial culture onto a petri dish? - CORRECT ANSWER-Plating. Plating microbes can be done using a sterile loop, a sterile swab, or a sterilized wire loop. Each device is simply a means of spreading the bacteria, most commonly in a simple back-and-forth motion, across the plate. What is the primary advantage of plating a bacterial culture as opposed to having it grow in solution? - CORRECT ANSWER-The primary advantage of plating a bacterial sample onto agar is that cells are held in place. Unlike in a nutrient broth where bacterial cells can multiply but are free to move around in solution, bacteria plated onto agar are fixed in such a way as to support the formation and visualization of colonies. What is the purpose of the quadrant streak approach? - CORRECT ANSWER-The purpose of this method is to generate an individual colony so that a single (pure) bacterial sample can be picked from the plate. In a three-phase dilution gradient, which phase most likely contains individual colonies: phase 1 (P1) or phase 3 (P3)? - CORRECT ANSWER-Individual colonies are most likely going to appear within the phase 3 streaks. You being with P1 (highest concentration), dilute during P2 and then further dilute the sample in P3. However, it is possible to see individual colonies in P2 if only a small portion of P1 was carried over into P2. What growth requirements are necessary for growth and survival? - CORRECT ANSWER-Nutrients, temperature, and pH Photoautotrophs - CORRECT ANSWER--Organisms that use light as a source of energy and carbon dioxide as a source of carbon -Plants, algae, cyanobacteria Chemoautotrophs - CORRECT ANSWER--Organisms that use chemicals as a source of energy and carbon dioxide as a source of carbon -Hydrogen, sulfur, and nitrifying bacteria, some archaea Photoheterotrophs - CORRECT ANSWER--Organisms that use light as a source of energy and organic compounds as a source of carbon -Green nonsulfur bacteria and purple nonsulfur bacteria, archaea Chemoheterotrophs - CORRECT ANSWER--Organisms that use chemical compounds as a source of energy and organic compounds as a source of carbon -Most animals, fungi, and protozoa and many bacteria Toxic reactive oxygen species (ROS) - CORRECT ANSWER--1O2, O2-, O2 2-, OHObligate anaerobes - CORRECT ANSWER-Organisms that cannot live where molecular oxygen is present (so ROS is toxic) Obligate aerobes - CORRECT ANSWER-Organisms that contain enzymes and antioxidants that protect from ROS Facultative anaerobes - CORRECT ANSWER-- Organisms that live in environments w/ or w/o oxygen -An example is E. coli What makes up 14% of the dry weight of bacterial cells? - CORRECT ANSWER-Nitrogen What is the growth-limiting nutrient? - CORRECT ANSWER-Nitrogen Trace elements - CORRECT ANSWER-Required by an organism in only minute quantities Growth factors - CORRECT ANSWER-Organic chemicals needed in small quantities to support metabolism Extreme thermophiles - CORRECT ANSWER-- Archaebacteria that live in extremely hot environments, such as hydrothermal vents under the ocean -65-120C Thermophiles - CORRECT ANSWER--Archaea that thrive in very hot environments, such as volcanic springs. -40-75C Mesophiles - CORRECT ANSWER--Bacteria that grow in moderate environments -Human pathogens are mesophiles -20-40C Psychrotrophs - CORRECT ANSWER--Bacteria that grow in cold temperatures -Can cause food to spoil -0-30C Psychrophiles - CORRECT ANSWER--Bacteria that grow in very cold temperatures - -20-10C Acidophiles - CORRECT ANSWER--Bacteria that grow in acidic environments -Beer, vinegar, black coffee, wine, tomatoes Neutrophiles - CORRECT ANSWER-Bacteria that grow at or near neutral pH Alkalinophiles - CORRECT ANSWER--Bacteria that grow in alkaline environments -Milk of magnesia, bleach, sodium hydroxide Inoculum - CORRECT ANSWER-A sample of a microbe that is introduced into a medium Medium - CORRECT ANSWER-Broth (liquid) or solid media Culture - CORRECT ANSWER-The microbes grown in the media Colonies - CORRECT ANSWER-Clusters of cells arising from one parent cell Growth media - CORRECT ANSWER--Nutrient rich broth for general purpose growth -Most common is lysogeny broth (LB) Undefined growth medium - CORRECT ANSWERGrowth medium that contains mixtures of unknown ratios Defined growth medium - CORRECT ANSWER-Growth medium that contains exact quantities of all ingredients Selective media - CORRECT ANSWER--Grows specific bacteria while restricting others -Can limit nutrients, vary pH or temperature or growth factors, and add antibiotics Differential media - CORRECT ANSWER--Distinguishes between two or more microbes by changes in the media or the colonies -Blood agar is an example of a differential media Enriched media - CORRECT ANSWER--Complex media meant to grow fastidious organisms -Can be a combination of selective, differential, and enriched medias Agar - CORRECT ANSWER-A gel-like polysaccharide compound used for culturing microbes; extracted from certain red algae (seaweed) Characteristics of agar - CORRECT ANSWER--Cannot be digested by microbes -Dissolves at 100C -Solidifies below 40C -Temperature must be >100C to melt Lysogeny Broth (LB) Agar - CORRECT ANSWER-- Multipurpose, grows a wide array of microbes -Non-selective and non-differential Trypticase Soy Agar (TSA or TSAYE) - CORRECT ANSWER--Multipurpose medium -Non-selective and non-differential Blood Agar Plate (BAP) - CORRECT ANSWER-- Enriched, differential, non-selective -Grows fastidious microbes -Can differentiate between streptococcus strains (alpha, beta, and gamma hemolysis) Columbia CNS Agar - CORRECT ANSWER--Enriched, selective, and differential media -Used to culture gram-positive microbes because it suppresses the growth of gram-negative microbes -Antimicrobial agents: Colistin and Nalidixic acid Chocolate Agar - CORRECT ANSWER--Enriched, nonselective, non-differential derivative of blood agar -Used for fastidious and pathogenic microbes -Made of lysed blood cells -Doesn't allow you to observe hemolysis MacConkey Agar - CORRECT ANSWER--Selective and differential -Grows gram-negative microbes -Selective components are crystal violet and bile salts -Differential components are lactose and a pH indicator (neutral red) Lactose fermentation of MacConkey Agar - CORRECT ANSWER-If a microbe is a lactose fermenter (lac+), the colony will appear red. If a microbe is not a lactose fermenter (lac-), the colony will appear white/tan pH indicator of MacConkey Agar - CORRECT ANSWER-- Neutral red -Base plate of the agar changes color according to the nutrients consumed by the microbes within the agar -Area surrounding a growing non-fermenting microbe will turn yellowish (pH > 8.0) -Area surrounding a growing fermenting microbe will turn pink or darker red (pH < 6.8) Pure culture - CORRECT ANSWER-A culture containing only one species of cells Plating - CORRECT ANSWER-The process of spreading a bacterial culture onto a petri dish to isolate colonies What is a very important aspect of plating? - CORRECT ANSWER-Everything must be sterilized What temperature must an incubator be for plating? - CORRECT ANSWER-37C Advantages of plating - CORRECT ANSWER--Growth -Each colony should be genetically identical -Immobile colonies allow for observation of size, shape, gram status, biochemical properties, etc 4 phase dilution streaking - CORRECT ANSWER--The goal of this method is to isolate a colony or clone from one culture -Most common method -Only deals with one culture -Sample is plated in four different streaks or phases, each phase more dilute than the last Quadrant growth plate - CORRECT ANSWER--Goal is to test whether multiple cultures will grow on a plate or w/ specified conditions -Uses 4 cultures Spread plate method - CORRECT ANSWER-A diluted sample is spread on the surface of a solid medium Pour plate serial dilution - CORRECT ANSWER-Uses colonies on the surface of and within the medium