Assessment 1: CH1-5

List examples of human influences on microbial ecosystems. Which of these is correct?

• Untreated or partially treated domestic sewage

• All

• Fertilizer runoff from agriculture fields, urban lawns, and golf courses

• Spilling large amounts of phosphates or nitrogen into lakes

All

Explain how chemotaxis direct flagellar motility. Which of these is incorrect?

• The flagellar rotate counter clock wise to move bacteria toward attractant. Oppositely, to move away from repellent, the flagellar rotate clock wise.

• None

• Bacterial cells perform random work when the food is used out.

• All but one

• The flagellar rotate counter clock wise to move bacteria toward attractant. Oppositely, to move away from repellent, the flagellar rotate clock wise.

• Chemotaxis allows the bacteria to migrate toward attractants or away from repellents.

The flagellar rotate counter clock wise to move bacteria toward attractant. Oppositely, to move away from repellent, the flagellar rotate clock wise.

Describe what constitutes a pure culture and how to obtain one:

A pure culture is grown from a single parental cell. It can be obtained via dilution/quadrant streaking.

True or False?

True

State the function of chemical imaging microscopy:

Chemical imaging microscopy uses mass spectrometry to visualize the distribution of chemicals within living cells.

True or False?

True

Name the chemical components within a bacterial cell.

• Macromolecules

• Essential ions

• All but one

• Water

• Proteins and DNA

• Small organic molecules

• All

All but one

Define barophiles, mesophiles, psychrophiles, and thermophiles.

[A] is an organism with optimal growth between 15 °C and 45 °C. [B] are microbes that can grow in extreme cold temperatures below 15 °C. [C] are species adapted to growth at high temperatures (50-80 °C). [D] are organisms that adapted to grow at overwhelmingly high pressures (up to 1000 atm).

[A] Mesophiles [B] Psychrophiles [C] Thermophiles [D] Barophiles

Analyze the relationship between solutes and water activity. Which of these is incorrect?

• All but one

• Interactions between water and solutes in solution will lower water activity.

• The less solutes there are in a solution, the less water available for microbes to use for growth.

• The more solutes there are in a solution, the less water available for microbes to use for growth.

• All but two

• The more solutes there are in a solution, the more water available for microbes to use for growth.

All but two

Recall the structures and functions of pili and flagella. Which of these is correct?

• All

• Pili is used for attaching bacterial cells to contact surfaces.

• Flagella is made of the protein flagellins. This threadlike structure is used to enable movement.

• Pili is constructed of straight filaments of protein monomers, pilin. They act as attachment and conjugation facilitators.

• Pili is used to carry out gene transfer.

All

Define aerotolerant anaerobe, facultative anaerobe, microaerophile, strict aerobe, and strict anaerobe and identify the metabolic strategies (i.e., respiration; fermentation; respiration or fermentation).

[A] is an organism that performs aerobic respiration and can grow only in the presence of oxygen (metabolic strategy: [b]). [C] is an organism that does not use oxygen for metabolism but can grow in the presence of oxygen (metabolic strategy: [D]). [E] is an organism that can grow in either the presence or absence of oxygen (metabolic strategy: [F]). [G] is an organism that cannot grow in the presence of oxygen (metabolic strategy: [H]). [I] is an organism that will grow only at low oxygen concentrations (metabolic strategy: [J]).

[A] Strict Aerobe [B] respiration [C] Aerotolerant anaerobe [D] fermentation [E] Facultative anaerobe [F] respiration or fermentation [G] Strict anaerobe [H] fermentation [I] Microaerophile [J] respiration

Explain the advantages of fixing and staining specimen. Which of these is incorrect?

• All but two

• All but one

• The cells are inactivated/killed

• It helps distinguish Gram negative and Gram positive cells.

• The cells are fixed

• The cells are living.

The cells are living.

• Describe the structure and functions of the bacterial cell wall.

• It is made up of single or multiple layer(s) of peptidoglycan.

• None of these is incorrect

• The cell wall is known as the sacculus and consists of a single interlinked molecule that envelops the cell.

• All but one

• It functions as structural support and additional protection.

• Its structure encloses maximal volume with minimal surface area.

None of these is incorrect

Describe and identify bacterial cell morphologies.

Bacilli/rods

Irregular shape colony

Spirochetes/tightly coiled spiral

Coccus/spheres

All but one

All but one

Explain the method and benefits of using cryo-techniques in cryo-electron microscopy (cryo-EM) and crystallography. Which of these is incorrect?

• In cryo-EM, the specimen does not require staining, because the high-intensity electron beams can detect smaller signals.

• Cryocrystallography uses frozen crystals with greatly decreased thermal vibrations and diffusions, enabling the determination of large macromolecular complexes’ structures.

• In cryo-EM, the specimen must be suspended in water and frozen rapidly in a refrigerant of high heat capacity.

• In cryo-EM, the freezing avoids ice crystallization, leaving the water solvent in a glass-like amorphous phase.

• None

• In cryo-EM, the specimen retains water content and thus closely resembles its living form.

None

Assess some of the practical obstacles in applying Koch’s postulates.

• Individual diseases and pathogens may not have one or more of the criteria: AIDS, HIV, and tuberculosis

• There are viable but non culturable microbes

• There are infectious agents that do not produce any symptoms

• None of these is incorrect

None of these is incorrect

List Winogradsky’s contributions to microbial culture technique. He discovered enrichment method for cultivation of environmental microorganisms.

• Microscope; spore-forming microbes

• Disproved spontaneous generation; canning preservation

• Winogradsky’s column; geochemical cycling

• Fermentation; antibiotics

Winogradsky’s column; geochemical cycling

Describe the relationship between growth rate and temperature. Which of these is incorrect?

• The growth rate roughly doubles for every 10 °C rise in temperature. The same relationship is observed for most chemical reactions.

• The typical temperature for the organism’s optimal growth usually ranges between 30–40 °C

• The growth rate roughly doubles for every 20 °C rise in temperature. The same relationship is observed for most chemical reactions.

The growth rate roughly doubles for every 20 °C rise in temperature. The same relationship is observed for most chemical reactions.

Compare and contrast light microscopy and electron microscopy. Which of these is incorrect?

• Light microscope has higher power of resolution than electron microscope.

• All

• Both light and electron microscopes are used to visualize viral particles.

• All but one

• Electron microscopy focuses beams of electrons to image cell membranes, chromosomes, and ribosomes with a resolution a thousand times that of light microscopy.

All but one

Explain why the microscope is an important tool in the field of microbiology.

• None of these is incorrect

• It enables the visibility of viral particles

• It enables the visibility of a microscopic object.

• The microscope allows us to see microbes, cells, and other living organisms that cannot be seen with the naked eye.

None of these is incorrect

List the negative impacts that microbes have had on human history.

• Syphilis

• Tuberculosis

• All but one

• Copper mining

All but one

Recall the contributions of various individuals to the discovery and implementation of vaccination: Edward Jenner; Lady Mary Montagu.

[A] practiced smallpox inoculation whereas the virus becomes “attenuated”. [B] infected patients with matter from cowpox lesions.

[A] Lady Mary Montagu [B] Edward Jenner

Describe the conditions under which dark-field microscopy is the best choice for viewing specimen. Which of these is correct?

• All but one

• All

• It produces darker background and uses the light to light up the specimen; hence, it improves the contrast of an microscopic image

• It makes the specimen stand out more than when using the other types of microscopy.

• Staining is not needed in this type of microscopy.

• It uses a light source from the side, light scattered by microbe, small proportion of light reaches objective lens.

All

Explain how membrane-permeant weak acids and bases cause pH stress. Which of these statements is correct?

• Membrane-permeant weak acids and bases cross the membrane in their uncharged form. Membrane-permeant acids conduct acid across the membrane causing acid stress, alkali stress for bases. If acidity on the outside is smaller than the inside, weak acids will be driven into the cell.

• These chemicals can be harmful when they come in contact with cells.

• Membrane-permeant weak acids and bases cross the membrane in their charged form. Membrane-permeant acids conduct acid across the membrane causing acid stress, alkali stress for bases. If acidity on the outside is greater than the inside, weak acids will be driven into the cell.

• Membrane-permeant weak acids and bases cross the membrane in their uncharged form. Membrane-permeant acids conduct acid across the membrane causing acid stress, alkali stress for bases. If acidity on the outside is greater than the inside, weak acids will be driven into the cell.

Membrane-permeant weak acids and bases cross the membrane in their uncharged form. Membrane-permeant acids conduct acid across the membrane causing acid stress, alkali stress for bases. If acidity on the outside is greater than the inside, weak acids will be driven into the cell.

Define extremophile.

An extremophile is an organism that thrives in extreme environments.

True

Describe the components of the bacterial cell envelope.

• Cell wall

• Inner membrane

• All

• Proteins and DNA

• Outer membrane

• All but one

All but one

Compare the cell envelope of firmicutes, mycobacteria, and proteobacteria.

[A] have a thick cell wall with 3-20 layers of peptidoglycan, interpenetrated by teichoic acids. It consists of Gram-positive species. [B] have a thin cell wall with one or two layers of peptidoglycan, enclosed by an outer membrane. It includes Gram-negative species. [C] have a complex, multilayered envelope that includes defensive structures.

[A] firmicutes [B] Proteobacteria [C] Mycobacteria

List and describe the four stages of bacterial growth in batch culture. Which of the following is listed in the correct sequence?

1. Lag Phase-cells transferred from an old culture to fresh growth media typically experience a lag period; the bacterial cells are preparing their cell machinery for growth.

2. Log or exponential phase-cells have retooled their physiology to accommodate the new environment, they begin to grow exponentially.

3. Stationary phase-cell numbers stop rising owing to the lack of a key nutrient or the build-up of waste products.

4. Death phase-the number of cells that die in a given time period is proportional to the number that existed at the beginning of the time period.

Explain how some microbes resist germicidal agents. Which of these is correct?

• Bacterium can survive exposure to disinfectants through biofilm formation.

• All but one

• Disinfectants that have multiple targets at a high concentration may have only a single target at lower concentrations.

• All

• Bacteria can achieve low-level resistance to disinfectants through membrane-spanning proteins.

All

State what kind of information is obtained from x-ray crystallography analysis. Which of these is correct?

• It gives us a molecular model of certain molecules for study.

• All but one

• It determines the Gram property of a bacterial specimen.

• It also provides the functions of many biological molecules.

• X-ray crystallography analysis determines the arrangement of atoms within a crystal.

• All but two

All but one

Describe examples of biological control of microbes. Which of these is correct?

• All

• Antibiotic treatment

• Probiotics

• All but one

• Phage therapy

All but one

Compare the roles of antibiotics, antiseptics, and immunization in human disease treatment and prevention.

[A] is the stimulation of an immune response by inoculation with an attenuated pathogen. [B] are chemicals that kills off microbes. [C] stop infections caused by bacteria, killing only bacteria.

[A] Immunization [B] Antiseptics [C] Antibiotics

Describe the mechanisms employed by microbes to protect against osmotic stress. Which of these is incorrect?

• When stranded in a hypertonic medium, bacteria try to protect their internal water from leaving the cell by synthesizing or importing compatible solutes that increase intracellular osmolarity.

• None

• Cells also contain pressure-sensitive channels that can be used to leak solutes out of the cell.

• The mechanosensitive channels allow small solutes to escape, lowering internal osmolarity and preventing too much water from entering the cell.

• Increasing intracellular level of compatible solutes elevates cytoplasmic osmolarity without any detrimental effects, making it unnecessary for water to leave the cell.

None

Explain what determines a microbe’s survival and growth in a particular environment. Which of these is incorrect?

• Temperature

• pH

• None

• Salinity

• Pressure

None

Explain the disadvantages of fixing and staining specimen. Which of these is correct?

• All but one

• None of these is correct

• It denatures the cells' proteins

• The cells are non-motile

• All

• The cells are dead

All

Compare and contrast different types of direct and indirect microbial counts. Which of these is correct?

• Direct: Microorganisms can be counted directly by microscopy.

• All

• Direct counting without microscopy can be achieved using an electronic technique called flow cytometry.

• Indirect measurement can be achieved using optical density. This method generates relative cell numbers.

• Indirect: Microorganisms can be counted indirectly via biochemical assays of protein content, or metabolic rate.

All

Define antisepsis, disinfection, sanitation, and sterilization.

[A] is when all living cells, spores, and viruses are destroyed on an object. [B] is the killing or removal of disease producing organisms from inanimate surfaces. [C] removes pathogens from the surface of living tissues. [D] reduces the microbial population to safe levels and cleaning and disinfecting an object.

[A] Sterilization [B] Disinfection [C] Antisepsis [D] Sanitation

Describe the advantages of a wet mount. Which of these is incorrect.

• It does not use chemical treatment

• All but one

• The cells are dead

• Organism is viewed in as natural state as possible

• All but two

• live behavior can be observed

All but two?

Describe the advantages of super-resolution imaging.

Super-resolution imaging can define the position of a fluorescent protein better than the resolution limit of light magnification.

True

Explain the implications of microbial genome sequencing. Which of these statements is incorrect?

• It helps differentiate microorganisms at genus and species level.

• It helps determine variants/strains among microorganisms of the same genus and species

• It allows the comparison of genomes and reveals a set of core genes shared by all organisms.

• It is used to sequence thousands of genomes of microbes sampled from a natural environment.

• All but two

• All but one

• It uses metagenomics.

• All but three

It allows the comparison of genomes and reveals a set of core genes shared by all organisms.

Recall the definition of a microbe.

A microbe is defined as a living organism that requires a microscope to be seen.

True

Explain how studies on microbes fostered our knowledge of DNA functions and enhanced DNA technology.

The mechanisms of bacterial recombination led to the construction of artificially recombinant of DNA and the making of life essential products (i.e., insulin, lactase, antibiotics, fermented products, food bio-preservatives, etc).

True

List the positive impacts that microbes have had on human history.

• All but three

• Polio; smallpox

• Copper mining

• Food & drink fermentation and preservation uses

• All but two

• Syphilis; tuberculosis

• Leprosy

• All but one

All but three

Which of these correctly describe some problems with the definition of a microbe?

• Many microbes form complex multicellular clusters.

• All

• All but two

• They may be seenable without a microscope.

• Viruses are noncellular microscopic, biological particle but contain some genetic material that takes over a cell’s metabolism to make more virus particles.

• They require a microscope to be seen.

• All but one

All but one

Describe microbial responses to starvation. Which of these is incorrect?

• When severely stressed by starvation, some members of a bacterial population appear to sacrifice themselves to save others; they do so by undergoing what is termed programmed cell death.

• Enzymes are produced to increase the efficiency of nutrient gathering and to protect cell macromolecules from damage.

• The resulting metabolic slow down generates increased concentration of critically important and signaling molecules.

• Some organisms growing on nutrient-limited agar can form colonies with intricate/complex geometrical shapes that help the population cope, in some unknown way, with food stress.

• None

None

Explain how the structure of the bacterial cell wall relates to its Gram-stain status. Which of these is incorrect?

• Gram-negative cell wall contains 1-3 layers of peptidoglycan

• Most Gram-negative species of bacteria possess a thinner cell wall and more porous than that of a Gram-Positive species

• Gram-positive has five or more layers of peptidoglycan

• Gram negative cells stain purple

Gram negative cells stain purple

Differentiate among absorption, reflection, refraction, and scattering.

[A] means that the absorbing object gains the photon’s energy. [B] is when the wavefront redirects from an object’s surface at an angle equal to its incidents angle. [C] is the bending of light as it enters one substance to another that slows its speed. [D] means that a portion of the wavefront is converted to a spherical wave originating from the object.

[A] Absorption [B] Reflection [C] Refraction [D] Scattering

Identify the conditions required by halophiles for growth. Which of these is incorrect?

• They make compatible solutes.

• They need to achieve a low internal Na+ concentration

• Halophilic microbes use special ion pumps to excrete sodium and replace it with other cations.

Halophilic microbes use special ion pumps to excrete sodium and replace it with other cations?

List Koch’s postulates.

1. The microbe is found in all cases of the disease but is absent from health individuals.

2. The microbe is isolated from the diseased host and grown in pure culture.

3. When the microbe is introduced into a healthy, susceptible host, the host shows the same disease.

4. The same strain of microbe is obtained from the newly diseased host. When cultured, the strain shows the same characteristics as before.

Propose applications for scanning probe microscopy.

The scanning probe microscopy is used to observe cell surfaces.

True

Compare and contrast eukaryotes and prokaryotes with respect to DNA structures

[A] have no nucleus or organelles with small amount of DNA. [B] have a nucleus, multiple organelles, and more DNA. They both help organize the complementary base of nucleotides.

[A] Prokaryotes [B] Eukaryotes

Compare and contrast batch culture and continuous culture.

[A] culture is when nutrient consumption and toxic by-products eventually slow the growth rate until it halts together. In [B] culture all the cells in a population achieve a steady state that analyzes different growth rates of microbial physiology; used nutrients and microbial waste are constantly replaced.

[A] batch culture [B] Continuous culture

Differentiate among complex, synthetic, selective, and defined media.

[A] or [B] media contain known lists of chemical components. Minimally [C] media contain only the specified nutrients essential for the growth of a given organism. [D] or rich media contain many, undefined nutrients. [E] media contain antimicrobial agent that limits the growth of certain group of microbes.

[A] Defined [B] Synthetic [C] defined [D] Complex [E] Selective

Classify stains as differential or simple.

A [A] stain adds dark color specifically to cells, but not to the external medium or surrounding tissue. [B] stains colors one kind of cell but not another.

[A] simple [B] Differential

List the functions of membrane proteins. Which of these is correct?

• Structural support

• Detection of environmental signals

• All but one

• Ion transport and energy storage

• All

• Make proteins and DNA

• Secretion of virulence factors and communication signals

All but one

Describe the disadvantages of a wet mount. Which of these is incorrect?

• All but one

• Most living cells are transparent and therefore show little contrast with the external medium.

• It uses chemical treatment

• All but two

• The cells are living

• The sample rapidly converts absorbed light to heat, thus tending to overheat and dry out.

• None of these is incorrect

It uses chemical treatment

Compare and contrast Lazzaro Spallanzani’s, Louis Pasteur’s, and John Tyndall’s experiments that tested spontaneous generation.

[A] showed that sterilization prevent the growth of microbes and that microbes are replicated (Cell fission). He used sealed flask in his experiment. [B] proved that oxygen is required for the growth of microbial species. He used swan-necked flask in his experiment. [C] showed that heat can eliminate spores formed by microbes. These scientist were attempting to disprove the theory of spontaneous generation.

[A] Lazzaro Spallanzani [B] Louis Pasteur [C] John Tyndall

Differentiate between detection and resolution.

[A] is the smallest distance between two objects that allows us to see them as separate objects. [B] is the ability to determine the presence of an object.

[A] Resolution [B] Detection

Differentiate among Active transport, passive diffusion, and passive transport.

[A] is the movement of substances in the direction of the concentration gradient. [B] does not require energy to move substances across the cell membrane. [C] is the movement of molecules across the cell membrane to a level of higher concentration requiring cellular energy

[A] Passive diffusion [B] Passive transport [C] Active transport

Recall the forms in which cells store energy.

• All but one

• Cell membrane potential

• Elemental phosphorus

• Adenosine triphosphate (ATP)

All but one

Define essential nutrients, macronutrients, and micronutrients.

[A] are compounds that microbes must have but cannot make. [B] are nutrients that are needed in large quantities. [C] are very small amounts of certain trace elements.

[A] Essential nutrients [B] Macronutrients [C] Micronutrients

Describe the different methods of obtaining single bacterial colonies. Which of these is incorrect?

• Solid media are useful for separating mixtures of different organisms as they are found in the natural environment or clinical specimens.

• This can be done by 1/10 serial dilution

• None

• This can be done by quadrant streaking or spread plate.

• This can be done by dilution streaking or spread plate.

This can be done by 1/10 serial dilution

Define acidophiles, alkaliphiles, and neutralophiles.

[A] are bacteria that grow between pH 5 and pH 8. [B] are bacteria and archaea that live in extremly acidic environments (pH 0-5). [C] occupy the opposite end of the pH spectrum, growing best at values ranging from pH 9 to pH 11.

[A] Neutralophiles [B] Acidophiles [C] Alkaliphiles

Identify the contributions of the following individuals: Robert Hooke; John Tyndall; Florence Nightingale; Louis Pasteur; Antonie van Leeuwenhoek.

[A] used methods to demonstrate high mortality rate due to disease among British soldiers during the Crimean War. [B] built a compound microscope and observed distinct units of living material which he called “cells”. [C] observed bacteria with a single lens. He was the first to observe single-celled microbes. [D] discovered pasteurization and fermentation. [E] found that some broths give rise to microbes because hay infusion is contaminated with heat resistant endospores.

[A] Florence Nightingale [B] Robert Hooke [C] Antonie van Leeuwenhoek [D] Louis Pasteur [E] John Tyndall

Describe how viruses were discovered.

• Robert Koch and Louis Pasteur discovered viruses as filterable infective particles by observing the tobacco mosaic leaves.

• Robert Hooke and Antonie van Leeuwenhoek discovered viruses as filterable infective particles by observing the tobacco mosaic leaves.

• Edward Jenner and Lady Mary Montagu discovered viruses as filterable infective particles by observing the tobacco mosaic leaves.

• Dmitri Ivanovsky and Martinus Beijerinck discovered viruses as filterable infective particles by observing the tobacco mosaic leaves.

Dmitri Ivanovsky and Martinus Beijerinck discovered viruses as filterable infective particles by observing the tobacco mosaic leaves.

Describe the mechanisms used by microbes to maintain pH homeostasis. Which of these is incorrect?

• Microbes can prevent pH stress using an emergency global response system referred to as acid tolerance or acid resistance.

• Microbes can make compatible solutes.

• Microbes can change the pH of the medium by using various amino acid deaminases.

• None

• Microbes can change the pH of the medium by using various amino acid decarboxylases.

• Microbes can prevent the unwanted influx of protons by exchanging extracellular K+ for intracellular H+ when the internal pH becomes too low.

Microbes can make compatible solutes.

List the various kinds of differentiated cells that bacteria can produce for cyanobacteria, Gram-positive bacteria, Myxococcus santhus, and Streptomyces.

[A] form endospores.

[B], soil bacterium, form fruiting bodies.

[C] form aerial hyphae and arthrospores.

[D] form heterocysts (thick-walled cell).

[A] Gram-positive bacteria [B] Myxococcus santhus [C] Streptomyces [D] cyanobacteria

List some functions of biofilms. Which of these is correct?

• Protect bacterial cells from harsh conditions

• All

• Serves as direct sources of infection

• Help filter groundwater through the soil

All

Recall the structure of the bacterial nucleoid. Which of these is correct?

• It is found in a nucleus

• It is enclosed in a nuclear membrane

• It is found in all organisms

• The nucleoid organizes the DNA in loops called domains which extends through the cytoplasm.

The nucleoid organizes the DNA in loops called domains which extends through the cytoplasm.

Recall the role of quorum sensing in biofilm development.

The role of quorum sensing is to send and receive chemical signals that achieve a specific concentration that the cells can sense; it enables communication within cell population.

True

Explain why some microbes require growth factors for culture and why some cannot be grown in pure culture. Which of these is incorrect?

• Some microbes cannot be grown in pure culture because they have adapted to their natural habitats (i.e., they co-exist with its mutualistic partner).

• Microbes can evolve to become un-culturable or to require specific growth factors depending on the nutrient richness of their natural ecological niche.

• To grow a microorganism, you must add special nutrients, or growth factors (as needed).

• None

To grow a microorganism, you must add special nutrients, or growth factors (as needed).

Define osmolarity and osmotic stress.

[A] is a measure of the concentration of solute molecules in a solution. [B] is a change in the solute concentration around a cell, causing a change in water movement across the cell membrane; it can cause hypertonic or hypotonic stress to bacterial cells.

[A] Osmolarity [B] Osmotic stress

Describe how microbes obtain iron. Which of these is correct?

• They can convert ferric ions into ferrous ions

• All

• Microbes obtain iron through their synthesized and secreted siderophores

• They can uptake ferric ions available in the environment

All

Explain how limiting nutrient supplies limits bacterial growth. Which of these is incorrect?

• All but one

• It limits the availability of essential elements.

• It limits the availability of micronutrients, eg., nitrogen

• It limites the availability of macronutrients, eg., phosphorus

It limits the availability of micronutrients, eg., nitrogen

Explain the principles behind phase-contrast microscopy.

The phase contrast of microscope is based on the principle that small phase changes in the light rays induced by differences in the thickness and refractive index of the different parts of an object can be transformed into difference in brightness or light intensity.

True

Define biofilms. Which of these is incorrect?

• Biofilms are a community of microbes growing on a solid surface.

• Biofilms are composed of micro colonies of bacterial cells.

• They are made of multi-layers of cells.

• Biofilms are formed when food is scarce.

• Biofilms are composed of planktonic (freely moving) cells.

Biofilms are composed of planktonic (freely moving) cells.

Explain how temperature affects microbial physiology.

A species grows most quickly at temperatures where all of the cell’s proteins work most efficiently as a group to produce energy and synthesize cell components.

True

Recall the factors that determine the cell specificity of a fluorophore.

• Labeled antibodies

• Gene fusion reporter

• The cell shape

• Chemical affinity

• DNA hybridization

• All

• All but one

All but one

Recall the properties of spores. Which of these is incorrect?

• Spores are non-viable cells.

• All but two

• Spores are resistant to heat.

• Spores are non-vegetative cells.

• Spores are resistant to extreme pH.

Spores are non-viable cells.

Describe the cell membrane structure.

The cell membrane consists of a phospholipid monolayer containing lipid-soluble proteins. It behaves as a two-dimensional fluid, within which proteins and lipids can diffuse.

False

Compare and contrast autotrophs, chemotrophs, heterotrophs, and phototrophs.

[A] build biomass by fixing CO2 into complex organic molecules. [B] break down organic compounds from other organisms to gain energy and harvest carbon to build their own biomass. [C] obtain energy by the oxidation of reduced compounds. [D] use visible light as a primary energy source for metabolism (Photosynthesis).

[A] Autotrophs [B] Heterotrophs [C] Chemotrophs [D] Phototrophs

List example of microbes.

• Bacteria and fungi only

• Archaea and fungi only

• Escherichia coli and Saccharomyces cerevisiae

• Archaea and bacteria only

• Archaea; bacteria; eukaryotes

Archaea; bacteria; eukaryotes

Describe the nitrogen cycle including the roles of microbial denitrifiers, nitrogen fixers, and nitrifiers.

Various groups of organisms collaborate to recycle ammonium ions and nitrate ions into nitrogen gas (N2 )in what is called nitrogen cycle. The [A] acquire nitrogen by reducing atmospheric nitrogen gas. The [B] gain energy by converting or oxidizing ammonia in two steps to form nitrate (nitrification). Other microbes, [C] can reduce nitrate to N2 via denitrification. They use nitrate and related inorganic forms of nitrogen as terminal electron acceptors for certain electron transport chains. These bacteria send an amount of nitrogen into the atmosphere that roughly balances the amount of N2 removed by nitrogen fixation.

[A] Nitrogen fixers [B] nitrifiers [C] denitrifiers

Identify the type(s) of microscopy needed to view a particular specimen. Which of these is used to view the shape of bacterial cells?

• X-ray crystallography

• Electron microscopy

• Chemical imaging microscopy

• None of these

• Light microscopy

• Scanning probe microscopy

Light microscopy

Describe the stages of biofilm development. Arranges the stages in the correct order.

1. The specific environmental signal (food) induces a genetic program in planktonic cells.

2. They start to attach to contact surfaces and form micro colonies.

3. They begin to coat that surface with an organic monolayer of polysaccharides or glycoproteins so more planktonic cells can attach.

4. They begin to disperse in planktonic cells when the food is depleted.