microbiology exam 2: ch. 3, 8, 7 Mastering Pearson
Which type of media has ingredients that foster the growth of certain bacteria while suppressing the growth of others? defined synthetic differential selective complex
selective
In which growth phase do bacteria produce antibiotics and endospores? stationary phase lag phase acculturation phase death phase log phase
stationary phase
Gram-positive bacterial cell wall has:
thick layer of peptidoglycan teichoic acids single lipid bilayer membrane
Gram-negative bacterial cell wall has:
thin layer of peptidoglycan periplasmic space lipopolysaccharides dual lipid bilayer membranes
What is the purpose of the streak plate technique? to obtain a pure culture from a mixed or unknown source to identify the correct concentration of nutrients needed for optimal bacterial growth to identify the best temperature for growing a particular microbe to determine the concentration of a microbial sample to ascertain the age of a particular culture
to obtain a pure culture from a mixed or unknown source
Integral proteins are mostly involved in enzymatic function. transport function. recognition sites. receptors.
transport function.
Which of the following is an indirect cell-counting method? Coulter counter viable plate count turbidity measurement microscopic count flow cytometer
turbidity measurement
In the typical ATP-ADP cycle, which part of the ATP molecule is removed when energy is released and added back when energy is stored? ribose adenine the terminal two phosphate groups the terminal phosphate group all three phosphate groups
the terminal phosphate group
What is the primary difference between a disinfectant and an antiseptic? A disinfectant is used to decontaminate critical equipment, whereas an antiseptic is used to decontaminate semicritical equipment. A disinfectant is microbiocidal, whereas an antiseptic is microbiostatic. Disinfectants are low-level germicides, whereas antiseptics are high-level germicides. A disinfectant is used to decontaminate lifeless objects, whereas an antiseptic is applied to living tissue.
A disinfectant is used to decontaminate lifeless objects, whereas an antiseptic is applied to living tissue.
Urinary tract infections are commonly caused by Staphylococcus saprophyticus and Escherichia coli, less commonly caused by Proteus mirabilis. You have a mixed culture of these pathogens, which you inoculate onto both MacConkey agar and nutrient agar, and then you incubate the plates at optimal growth conditions. On the MacConkey agar, E. coli appears pink, P. mirabilis appears colorless, and S. saprophyticus does not grow. All three microorganisms appear cream on the nutrient agar plate. What is the best explanation for this data? Nutrient agar is both a selective and differential medium. MacConkey agar is a differential medium, whereas nutrient agar is a selective medium. MacConkey agar is a selective medium whereas nutrient agar is a differential medium. MacConkey is both a differential and a selective medium.
MacConkey is both a differential and a selective medium.
CIDEX is an activated glutaraldehyde solution used to kill microbial cells on medical instruments. Which of the following terms best describes CIDEX? Microbiostatic disinfectant Microbiocidal antiseptic Microbiostatic antiseptic Microbiocidal disinfectant
Microbiocidal disinfectant
Which of the following microbes is not correctly matched to an acceptable control method? Prions: chlorine treatment Enveloped virus: glutaraldehyde-based detergents Endospore: autoclaving Protozoan: boiling water Mycobacteria: hydrogen peroxide
Prions: chlorine treatment
Your patient has a suspected case of gas gangrene, which is caused by the obligate anaerobe Clostridium perfringens. Which of the following considerations should be made when culturing this organism? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. The clinical specimen should be placed inside a small anaerobic jar or chamber during incubation. The clinical specimen should be quickly deposited and capped in a vial with a reducing agent. The clinical specimen should be placed inside of a candle jar during incubation. The clinical specimen should be grown at a cooler temperature.
The clinical specimen should be placed inside a small anaerobic jar or chamber during incubation. The clinical specimen should be quickly deposited and capped in a vial with a reducing agent.
You need to collect a specimen from a patient who you suspect has strep throat. Which of the following considerations should be made when collecting this clinical specimen? To be marked correct, you'll need to select all applicable statements, as there may be more than one correct answer. The specimen should be quickly transported to the laboratory. The specimen should be collected from all areas of the mouth and throat, including the tongue. The specimen should transported to the laboratory at human body temperature. The specimen should be collected using aseptic techniques.
The specimen should be quickly transported to the laboratory.
Which of the following pH classifications would be able to grow in a pickle jar with vinegar? acidophiles neutralophiles alkaliphiles psychrophiles barophiles
acidophiles
Nutrients that a cell needs to build new cells and make up a bulk of a cell's dry weight are called micronutrients. essential nutrients. small nutrients. trace nutrients. tiny nutrients.
essential nutrients.
Which group of microbes prefers using oxygen but can survive without it? facultative anaerobe obligate aerobe obligate anaerobe microaerophile aerotolerant anaerobe
facultative anaerobe
The necessary substances that a cell can't make on its own are called nitrogenous bases. vitamins. growth factors. amino acids. carbohydrates.
growth factors.
Which of the following factors does not affect the efficiency of a germicide? the presence of excessive inorganic substances like minerals and salts in hard water the number of microbes to be killed what infectious agents are most likely present the presence of excessive organic substances like blood, soil, or fecal matter how the object is used
how the object is used
Which of the following pH classifications make up most of the pathogens we know today? psychrophiles acidophiles alkaliphiles neutralophiles barophiles
neutralophiles
When would a microbiologist want to use broth media? when growing large batches of microbes when performing the streak plate isolation technique when observing specific culture characteristics when isolating colonies when testing for motility
when growing large batches of microbes
When would a microbiologist use thioglycolate? when storing plates anaerobically when making complex media when storing selective plates when making defined media when storing differential plates
when storing plates anaerobically
Mycobacterium tuberculosis are grown for 80 hours. During that time, they go through four generations of growth. What is the generation time? 40 hours 60 minutes 20 hours 10 hours 20 minutes
20 hours
What are the products made during glycolysis? 4 ATP (net gain of 2) and 2 NADH and 2 pyruvic acid 4 ATP (net gain of 2) and 2 NADH 2 pyruvic acid 2 NADH 4 ATP (net gain of 2)
4 ATP (net gain of 2) and 2 NADH and 2 pyruvic acid
Which of the following best explains why the pressure cooker is so important in the canning process?
A pressure cooker utilizes steam to create a higher-pressure environment that allows the food to cook at higher temperatures than normal. The higher temperatures kill most contaminating microbes and endospores and therefore effectively sterilize the food.
Why is ATP required for glycolysis? ATP is used to convert DHAP into G3P. ATP is used to reduce NAD+ to NADH. ATP makes it easier to break apart glucose into two three-carbon molecules. ATP is used to convert PEP into pyruvic acid.
ATP makes it easier to break apart glucose into two three-carbon molecules.
What occurs at the bridge step? The formation of succinyl CoA Decarboxylation of pyruvic acid The production of GTP The formation of oxaloacetate
Decarboxylation of pyruvic acid
Which of the following microbial temperature classifications is improperly matched with its potential growth environment? Thermophile - compost pile Mesophile - human large intestine Extreme thermophile - hydrothermal vent Psychrotroph - arctic lake sediment
Psychrotroph - arctic lake sediment
What carbon molecules remain at the end of glycolysis? Glucose Pyruvic acid Dihydroxyacetone phosphate (DHAP) Glyceraldehyde 3-phosphate (G3P)
Pyruvic acid
What makes phospholipid membranes good at keeping some molecules out, and allowing others to freely pass? They are completely hydrophilic. They are positively charged. They are completely hydrophobic. They have both hydrophilic and hydrophobic regions.
They have both hydrophilic and hydrophobic regions.
How many net ATPs can be made from one molecule of glucose in glycolysis? Two One Four Six
Two
What results when a single bacterium reproduces? Two genetically unique daughter cells Two genetically identical daughter cells One parent cell and a genetically different cell One parent cell and a genetically identical daughter cell
Two genetically identical daughter cells
According to the animation, what does oxygen get reduced to at the end of the electron transport chain? Protons NADH Electrons Water ATP
Water
A reaction that involves the transfer of electrons from one molecule to another is referred to as a redox reaction. an oxidation reaction. a reduction reaction.
a redox reaction.
Which of the following factors may influence an enzyme's activity by altering its three-dimensional structure? temperature pH and temperature only pH, temperature, and competitive inhibitor pH competitive inhibitor
pH and temperature only
Enzymes can lower the activation energy of a chemical reaction by stabilizing the transition state. properly positioning reactants and raising the temperature so that reactants collide more forcefully. raising the temperature so that reactants collide more forcefully. properly positioning reactants and stabilizing the transition state. properly positioning reactants.
properly positioning reactants and stabilizing the transition state.
What enables competitive inhibitors to bind to a specific enzyme? Competitive inhibitors have structures that resemble the enzyme's substrate. Competitive inhibitors form unique covalent bonds with enzyme structures. Competitive inhibitors cover the entire surface of an enzyme. Competitive inhibitors have unique sugars that are attracted to the enzyme.
Competitive inhibitors have structures that resemble the enzyme's substrate.
Choose the true statement(s) about acid-fast bacteria. To be marked correct, you'll need to select all true statements, as there may be more than one correct answer. Genera Nocardia and Mycobacterium are acid-fast and stain blue during the acid-fast staining procedure. Acid-fast bacteria have a waxy lipid called mycolic acid in their cell walls. Genera Nocardia and Mycobacterium are acid-fast and stain pink during the acid-fast staining procedure. Acid-fast staining is important in the diagnosis of leprosy and tuberculosis.
Acid-fast bacteria have a waxy lipid called mycolic acid in their cell walls. Genera Nocardia and Mycobacterium are acid-fast and stain pink during the acid-fast staining procedure. Acid-fast staining is important in the diagnosis of leprosy and tuberculosis.
Which is the key difference between aerobic and anaerobic respiratory chains? Aerobic respiratory chains are found in prokaryotic cells only while anaerobic chains are found in eukaryotic cells only. Aerobic respiratory chains accept electrons from both NADH and FADH2 while anaerobic chains only accept electrons from FADH2. Aerobic respiratory chains are organized so that electrons are passing from a higher to lower energy state while anaerobic chains are organized so that electrons are passing from a lower to a higher energy state. Aerobic respiratory chains always use oxygen as the final electron acceptor while anaerobic respiratory chains may use a variety of inorganic substances other than oxygen as the final electron acceptor. Aerobic respiratory chains that accept electrons depend on membrane-associated electron carrier molecules that carry out redox reactions while anaerobic chains use cytoplasm-associated molecules that carry out redox reactions.
Aerobic respiratory chains always use oxygen as the final electron acceptor while anaerobic respiratory chains may use a variety of inorganic substances other than oxygen as the final electron acceptor.
Choose the true statement(s) about prokaryotic cells. To be marked correct, you'll need to select all true statements, as there may be more than one correct answer. Prokaryotes do not change shape or arrangement to enhance their survival. All prokaryotes lack a membrane-bound nucleus and organelles. All prokaryotes are unicellular organisms. Most of a prokaryote's nutrients are obtained through diffusion.
All prokaryotes lack a membrane-bound nucleus and organelles. All prokaryotes are unicellular organisms. Most of a prokaryote's nutrients are obtained through diffusion.
Where would you expect to find electron transport chains in a prokaryote? Along the inner mitochondrial membrane Along the cell wall Free-floating in the cytoplasm Along the outer mitochondrial membrane Along the plasma membrane
Along the plasma membrane
What is the function of GTP? A scaffolding for carbon atoms An electron carrier An oxidizer to produce CO2 An energy carrier
An energy carrier
Why aren't Archaea discussed as much as bacteria? Archaea only live in extreme environments. Archaea are only found in a few limited environments. Archaea infections are easy to treat. Archaea haven't been linked to human diseases. Archaea are not part of the human microbiome.
Archaea haven't been linked to human diseases
You decide that the introduction should also discuss the extremophiles that are referred to as the archaea. These single-cell organisms are considered "extremophiles" due to their ability to survive and reproduce in environmental conditions that would be hostile for most living organisms. Archaea species have been isolated from highly acidic sulfur springs, ocean floor thermal vents with temperatures that exceed boiling, and subarctic ice well below freezing. While still considered to be prokaryotic, the archaea have numerous differences that place them apart from the bacteria. Choose the characteristics that separate the archaea from other prokaryotic cells. The morphology of the cell is rigid and is geometric in shape, similar to a sphere or cylinder. All currently identified and characterized archaea have been linked as the causative agent to an animal or human disease. Archaea lack true peptidoglycan in their cell walls. The cytoplasmic membrane lipids of archaea have branched or ringform hydrocarbon chains.
Archaea lack true peptidoglycan in their cell walls. The cytoplasmic membrane lipids of archaea have branched or ringform hydrocarbon chains.
Which of the following is a key distinguishing characteristic between budding and binary fission? Binary fission results in daughter cells of equal size, whereas budding is an uneven division Budding is a much more common mechanism of bacterial reproduction than binary fission is. While binary fission results in the creation of genetically identical daughter cells, budding results in daughter cells that are genetically diverse. You will recall that budding is an example of sexual reproduction, whereas binary fission is an example of asexual reproduction.
Binary fission results in daughter cells of equal size, whereas budding is an uneven division
Choose the true statement(s) about binary fission in prokaryotic cells. To be marked correct, you'll need to select all true statements, as there may be more than one correct answer. Binary fission results in offspring, which are genetically identical to the parent cell. Binary fission is a type of sexual reproduction which introduces genetic variation from parent to offspring. Binary fission frequency differs between species and is affected by environmental conditions. Binary fission is a type of asexual reproduction that is simpler than mitosis.
Binary fission results in offspring, which are genetically identical to the parent cell. Binary fission frequency differs between species and is affected by environmental conditions. Binary fission is a type of asexual reproduction that is simpler than mitosis.
How does water enter and exit a cell? By use of a peripheral transport protein By use of an integral transport protein By simple diffusion or by use of an integral transport protein By simple diffusion across the membrane
By simple diffusion or by use of an integral transport protein
When we say that catabolic and anabolic reactions are coupled, what does that really mean? Anabolic reactions provide the reducing equivalents that catabolic reactions require to reduce intermediates. Catabolic reactions provide energy and smaller molecules required by anabolic reactions. Catabolic reactions provide the activation energy required for anabolic reactions to proceed. Catabolic reactions regenerate the ADP that anabolic reactions require to power reactions.
Catabolic reactions provide energy and smaller molecules required by anabolic reactions
Catabolic and anabolic reactions depend upon each other, as evidenced by which of the following statements? Catabolic reactions split bigger molecules into smaller components which are used by anabolic reactions to build more complex molecules. Catabolic reactions release energy which is used by anabolic reactions. Catabolic reactions split bigger molecules into smaller components which are used by anabolic reactions to build more complex molecules AND catabolic reactions release energy which is used by anabolic reactions. Anabolic reactions split bigger molecules into smaller components, which are in turn used by catabolic reactions to build more complex molecules. Anabolic reactions split bigger molecules into smaller components, which are in turn used by catabolic reactions to build more complex molecules AND catabolic reactions release energy which is used by anabolic reactions.
Catabolic reactions split bigger molecules into smaller components which are used by anabolic reactions to build more complex molecules AND catabolic reactions release energy which is used by anabolic reactions.
In a section that will be a brief survey of the prokaryotic bacteria, you want to give an overview of the multiple groups of bacteria and representative bacteria within each group. The groupings have been developed based on many characteristics of the bacterial cells and attempt to group together different species with similar cellular characteristics. Cellular morphology, cell wall composition, and metabolism have historically been used as means to roughly group bacteria together into different classes and genera. Current technologies have been expanding and reorganizing these groupings based on lipid content and genomic characterizations. Which of the following characteristics would NOT be used to aid in classifying a newly discovered bacterial species? DNA composition cell wall composition cellular size cellular appendages nutrients required
Cellular size
The process of generating ATP using a proton gradient is referred to as water damming. chemiosmosis. the electron transport chain.
Chemiosmosis
Which of the following statements regarding competitive inhibitors is true? The inhibitor will degrade the substrate. The inhibitor will destroy the substrate. Competitive inhibitors decrease the rate of enzyme activity. The inhibitor will destroy the enzyme.
Competitive inhibitors decrease the rate of enzyme activity.
Choose the false statement about cellular transport mechanisms. Facilitated diffusion does not require energy and uses membrane proteins to move substances down their concentration gradient. Osmosis is the passive movement of water from a low-solute concentration to a high-solute concentration. Diffusion is the passive movement of substances from areas of low concentration to areas of high concentration. Active transport requires energy and uses carrier proteins to move substances against their concentration gradient.
Diffusion is the passive movement of substances from areas of low concentration to areas of high concentration.
Which of the following is NOT a step in bacterial cell division? Replication of the genetic material Splitting apart of two new daughter cells Cell elongation Disappearance of nuclear envelope
Disappearance of nuclear envelope
Escherichia coli is characterized as a facultative anaerobe. You set up an experiment to examine the growth of Escherichia coli in three environments: a GasPak jar (0% oxygen), a candle jar (10% oxygen), and the benchtop (22% oxygen). Aside from differing oxygen levels, all other culture conditions (such as temperature and media used) were kept constant. Which of the following represents the most likely outcome of the experiment? E. coli should grow equally in all three growth environments. E. coli will have heavy growth in the GasPak jar and moderate growth in the candle jar and the benchtop. E. coli will have heavy growth on the benchtop, moderate growth in the candle jar, and no growth in the GasPak jar. E. coli will have heavy growth on the benchtop but moderate growth in the candle jar and the GasPak jar.
E. coli will have heavy growth on the benchtop but moderate growth in the candle jar and the GasPak jar.
Another characteristic that you want to include in the introduction is bacterial reproduction. Prokaryotic cells have only one chromosome and lack any organelles such as a nucleus, which limits the requirement for numerous cellular processes when a cell divides to form two daughter cells. In both major forms of bacterial reproduction, binary fission and snapping, the single chromosome must replicate so that each daughter cell will carry a complete chromosome. During binary fission, the cell replicates its DNA and each DNA molecule is attached to the cytoplasmic membrane. The growing cell elongates the cytoplasmic membrane, which separates the daughter DNA chromosomes. The formation of a cross wall allows for invagination of the cytoplasmic membrane. The cross wall completely divides daughter cells, which may or may not separate. Snapping division, seen in some Gram-positive bacilli, occurs when only the inner portion of a cell wall is deposited across the dividing cell. This new cross wall puts tension on the outer layer of the old cell wall. Eventually, the outer wall breaks at its weakest point with a snapping movement that tears it most of the way around. The daughter cells can then remain hanging together almost side by side being held by a small remnant of the original outer wall. Choose from the following statements the ones that correctly discuss reproduction using binary fission in a bacterial cell. Select all that apply. Each daughter cell is an exact copy of the other, both genetically and morphologically. Due to the stretching of the cytoplasmic membrane, both cells will contain a complete genome. The daughter cell will be a permanently smaller copy of the mother cell but will contain a complete genome. Each daughter cell will contain an equal number of organelles.
Each daughter cell is an exact copy of the other, both genetically and morphologically. Due to the stretching of the cytoplasmic membrane, both cells will contain a complete genome.
Why do all enzymatic reactions need activation energy? Energy is required by an enzyme so that it can be reused. Energy is needed for the enzyme to find its substrate. Energy is required to disrupt a substrate's stable electron configuration. Energy allows only the substrate to bind.
Energy is required to disrupt a substrate's stable electron configuration.
What is the relationship between the ATP-ADP cycle and catabolic and anabolic reactions? Catabolic reactions require energy, which is provided by anabolic reactions. ADP is recharged to ATP by energy from anabolic reactions. Energy released from catabolic reactions is used to recharge ADP back to ATP. Then the energy needed for anabolic reactions is released by breaking ATP down to ADP. Energy released from anabolic reactions is used to recharge ADP back to ATP. Then the energy needed for catabolic reactions is released by breaking ATP down to ADP. Energy released from catabolic reactions is used to break ATP down to ADP. Then the energy needed for anabolic reactions is released by to recharging ADP back to ATP. There is no relationship between the ATP-ADP cycle and catabolic and anabolic reactions.
Energy released from catabolic reactions is used to recharge ADP back to ATP. Then the energy needed for anabolic reactions is released by breaking ATP down to ADP.
Why are enzymes important to biological systems? Enzymes decrease the amount of activation energy required for chemical reactions to occur. Enzymes increase the energy barrier required of chemical reactions. Enzymes prevent unwanted chemical by-products from forming. Enzymes are reuseable.
Enzymes decrease the amount of activation energy required for chemical reactions to occur.
What is meant by the statement "Enzymes are biological catalysts"? Enzymes produce biological organisms. Enzymes speed up the chemical reactions in living cells. Enzymes are products of biological systems. Enzymes produce products useful for biology.
Enzymes speed up the chemical reactions in living cells.
According to the animation, which compounds provide electrons to the system? NADH NADH and FADH2 Oxygen Water FADH2
NADH and FADH2
Which of the following is one way that enzymes decrease activation energy? Enzymes permanently change from an inactive form to an active configuration. Enzymes stabilize the reaction's transition state. Enzymes denature, allowing more physical space for reactants to bind. Enzymes decrease the rate of collisions between reactants.
Enzymes stabilize the reaction's transition state.
A cell wall is a requirement for all living bacteria.
False
At this point in writing your tutorial, you have to find a way to get across to the students the importance of a cell wall to a bacterium. How do you convey that the bacterial cell will be at the mercy of its environment? The cell wall will need to act as a support mechanism to neutralize the inflow or outflow of water that would alter the shape of the cell. The cell cannot search out for a better place in the environment that has more available water; or if there is water that it has a high enough solute concentration that the cell will not gain water. Because that's the problem for a bacterial cell, it cannot control the tonicity due to solute concentrations in the surrounding water. Water will flow in or out depending on solute concentrations and the only thing a bacterial cell can do to keep from collapsing due to water loss or rupturing due to too much water coming in is to have a strong cell wall that will hold its shape regardless of the osmotic pressures. The rigidity of the cell wall will maintain a set shape regardless of water flow. The proteins and lipids that anchor the cytoplasmic membrane to the cell wall will tether the membrane to the peptidoglycan layer so that when environmental conditions result in the loss of water from the cell, the membrane will not collapse in on itself. Similarly, changes in environmental conditions that would result in the inflow of water would expand the volume of the cell to the limits of the cell wall and no more. The composition of the cell wall allows for the expansion and contraction of the cell wall in response to the gain or loss of water from the cell.
False
With the description of the different cell walls, membranes, and associated proteins set in the students' minds, you now need to introduce them to the idea that the cell wall can also act as a foundation to build things upon. Bacterial appendages require a strong foundation that will offer the support needed to move and function in a dynamic world. For example, flagella are long, whiplike protein structures that are used by many Gram-positive and Gram-negative bacteria for locomotion. In order to function effectively, a flagellum must be firmly anchored to the cell wall. How will you be able to get across the idea that the peptidoglycan cell wall is strong enough to support such a mechanism? With a protein rod that passes through the cell wall and protein rings used to anchor it in the membranes, these basal bodies are the rudimentary biological motors that use ATP power to spin the hook and the flagella attached to it.Bacterial flagella have a biological motor that spins within the cell wall and is powered by ATP. This allows the flagella to spin in a whiplike motion to propel the bacterium.
False
Use of moist heat can control microbial growth in many circumstances, but heat-sensitive items and those susceptible to moisture cannot be sterilized in this manner. Which of the following correctly describes a method of physical control used to control microbial growth on or in such items?
Filtration is the passage of a liquid or a gas through a screenlike material with pores small enough to retain microorganisms. A vacuum is typically used to force the liquid through the mesh, and then the sterile liquid or gas is collected in a sterile container on the other side. Nonionizing radiation, such as UV light, has a wavelength longer than that of ionizing radiation. The wavelengths of UV light are absorbed by cellular DNA in organisms directly exposed to the light. Desiccation is a process that removes water from microorganisms, leaving them unable to grow or reproduce, but still viable. Osmotic pressure is a process that uses high concentrations of salts and sugars to preserve food.
If you begin with six cells, how many cells would you have after three rounds of division? Twelve cells Nine cells Eighteen cells Twenty-four cells Forty-eight cells It is impossible to determine.
Forty-eight cells
Based on the animation, how many electron carriers are reduced in the Krebs cycle only? Three Four Five Six
Four
Which of the following statements about glycolysis is true? Glycolysis produces glucose. Glycolysis is the main source of NADH in the cell. Glycolysis is also called the Embden-Meyerhof pathway. All cells perform glycolysis
Glycolysis is also called the Embden-Meyerhof pathway.
_____________ bacteria lack an outer membrane, have a thick layer of peptidoglycan, contain teichoic acid, and lack mycolic acid. View Available Hint(s) Gram-variable Gram-positive Gram-negative Acid-fast
Gram-positive
Choose the false statement regarding prokaryotic plasma membranes Gases, water, and small non-charged substances can diffuse through the selectively permeable plasma membrane. The plasma membrane's phospholipid bilayer contains hydrophilic phosphates and hydrophobic fatty acids. The plasma membrane is a phospholipid bilayer that serves as barrier for a cell. Ions and large polar substances can diffuse through the plasma membrane without assistance.
Ions and large polar substances can diffuse through the plasma membrane without assistance.
How is nevirapine used to treat HIV infections? It binds to the active site of HIV reverse transcriptase, decreasing that enzyme's activity. It increases the immune system's ability to detect the virus. It decreases the virus's ability to find host cells. It alters the active site of reverse transcriptase, decreasing that enzyme's activity.
It alters the active site of reverse transcriptase, decreasing that enzyme's activity.
Lactate dehydrogenase converts lactate to pyruvic acid. In this reaction the enzyme also converts NAD+ to NADH. Choose the statement that best describes lactate dehydrogenase's actions. Lactate dehydrogenase reduces NAD+ to NADH and oxidizes lactate to pyruvic acid. Lactate dehydrogenase oxidizes NAD+ to NADH and reduces lactate to pyruvic acid. Lactate dehydrogenase oxidizes both NAD+ and lactate in order to form the reduced products pyruvic acid and NADH. Lactate dehydrogenase reduces both NAD+ and lactate in order to form the oxidized products pyruvic acid and NADH.
Lactate dehydrogenase reduces NAD+ to NADH and oxidizes lactate to pyruvic acid.
The bactericidal antibiotic penicillin kills bacterial cells by preventing peptidoglycan (cell wall) biosynthesis. Which of the following phases of the bacterial growth curve would you expect penicillin to be most active against? Lag phase Stationary phase Logarithmic phase Death phase
Logarithmic phase
Helicobacter pylori is a bacterial pathogen known to cause duodenal and gastric ulcers in humans. One of the cornerstones for treatment of H. pylori is a proton pump inhibitor. Which of the following terms best describes H. pylori? Mesophilic acidophile Extreme thermophilic neutralophile Thermophilic alkaliphile Psychrophilic barophile
Mesophilic acidophile
Select the best definition of metabolism Metabolism refers to the cellular reactions that combine energy and molecules to build new substances. Metabolism refers to all of the chemical reactions in a cell that impact energy use and release. Metabolism refers to the collection of amphibolic pathways in a cell. Metabolism refers to the collection of cellular reactions that break down substances to release energy.
Metabolism refers to all of the chemical reactions in a cell that impact energy use and release.
How do electrons get from glycolysis, the intermediate step, and the Krebs cycle to the electron transport chain? Oxygen recruits electrons to the electron transport chain. Acetyl-CoA carries electrons to the electron transport chain using redox reactions. NADH and FADH2 transport electrons to the electron transport chain. Pyruvic acid transports the electrons using decarboxylation reactions.
NADH and FADH2 transport electrons to the electron transport chain.
What would be the likely outcome if you increased the concentration of substrate for an enzyme in the presence of a noncompetitive inhibitor? You would begin to see an increase in the enzyme's rate of activity. A decrease in the amount of inhibitor would be observed. A decrease in the concentration of enzyme would be observed. No change in enzyme activity would be observed.
No change in enzyme activity would be observed.
What is the final electron acceptor in aerobic cellular respiration? Sulfate Oxygen Water Nitrate
Oxygen
If high amounts of sulfanilamide are in the presence of an enzyme whose substrate is PABA, what outcome is expected? PABA products will increase in concentration. PABA will not be catalyzed. The substrate will destroy the inhibitor. Sulfanilamide products will be in higher concentration.
PABA will not be catalyzed.
Choose the true statement(s) about prokaryotic external appendages. To be marked correct, you'll need to select all true statements, as there may be more than one correct answer. Pili allow for adhesion, movement, and aid in gene transfer through conjugation. Flagella allow for motility. Fimbriae aid in gene transfer through conjugation. The glycocalyx promotes adhesion and interferes with phagocytosis.
Pili allow for adhesion, movement, and aid in gene transfer through conjugation. Flagella allow for motility. The glycocalyx promotes adhesion and interferes with phagocytosis.
Which of the following statements regarding redox reactions is true? No metabolic reactions are redox reactions. Redox reactions must either be oxidizing reactions or reducing reactions. Redox reactions are only seen in the electron transport chain. Redox reactions involve an oxidation reaction coupled with a reduction reaction.
Redox reactions involve an oxidation reaction coupled with a reduction reaction.
Which step of binary fission is the reason for genetically identical daughter cells? Splitting of the two daughter cells Replication of the bacterial chromosome Elongation of the cell There are four new daughter cells that result from one parental cell
Replication of the bacterial chromosome
How are ribozymes different from enzymes? Ribozymes are made of ribonucleic acid, whereas enzymes are made of protein. Ribozymes act on a wider variety of substrates (including RNA, sugars, and proteins) than do enzymes. Ribozymes are only man-made molecules, whereas enzymes are found in nature. Ribozymes raise the activation energy of a reaction, whereas enzymes lower it.
Ribozymes are made of ribonucleic acid, whereas enzymes are made of protein.
Which phosphorylation mechanism for recharging ADP to ATP is incorrectly matched with its description? Photophosphorylation: Passes electrons energized by solar energy through an electron transport chain Oxidative Phosphorylation: Passes electrons stripped from nutrients through an electron transport chain Substrate-level phosphorylation: A phosphate is transferred to ADP from a high-energy substrate after passing through an electron transport chain. The descriptions for oxidative phosphorylation and photophosphorylation are incorrectly matched. The descriptions for oxidative phosphorylation, photophosphorylation, and substrate-level phosphorylation are incorrectly matched.
Substrate-level phosphorylation: A phosphate is transferred to ADP from a high-energy substrate after passing through an electron transport chain.
Which of the following is an example of microbial control? Sue washes off the vegetables before serving them in a meal. Mary warms food up in a microwave before putting it on the table. Sue uses bleach to clean the kitchen counters. Mary places leftovers in the refrigerator after the meal.
Sue washes off the vegetables before serving them in a meal. Sue uses bleach to clean the kitchen counters. Mary places leftovers in the refrigerator after the meal.
Choose the true statement about the Domain Bacteria. The Domains Bacteria and Archaea are genetically identical. Bacteria inhabit extreme environments and are not linked to human diseases. The Domain Bacteria is made up of prokaryotes and likely originated 3.8 billion years ago. The Domain Eukarya is more closely related to the Domain Bacteria than to the Domain Archaea.
The Domain Bacteria is made up of prokaryotes and likely originated 3.8 billion years ago.
Considering the process of osmosis, what will occur if a bacterial cell is put into a hypotonic solution? There will be no net movement of water into or out of the cell. The cell will take on water and may lyse if its cell wall is damaged. The cell will absorb salt from its environment. The cell will lose water and undergo plasmolysis.
The cell will take on water and may lyse if its cell wall is damaged.
According to the animation, what does the electron transport chain do to the concentration of hydrogen ions (protons)? The concentration of protons is higher outside the membrane than inside. The concentration of protons is lower outside the membrane than inside. The concentration of protons inside the membrane is equal to the concentration outside of the membrane.
The concentration of protons is higher outside the membrane than inside
Why is reduction the term used to describe the gain of an electron? The electron acceptor's net charge decreases. The amount of energy in the molecule decreases. The electron acceptor gets smaller. The number of molecules in the reaction decreases.
The electron acceptor's net charge decreases.
How does a competitive inhibitor slow enzyme catalysis? They compete with the substrate for the enzyme's active site. They bind to the substrate. They produce products toxic to the enzymes. They degrade the substrate.
They compete with the substrate for the enzyme's active site.
Which of the following statements correctly describes what happens during chemiosmosis? Protons flow through the ATP synthase enzyme from the side of the membrane where they are lower in concentration to the side where they are higher in concentration. Only electrons from the reduced carrier NADH are deliver to the electron transport chain; the reduce carrier FADH2 takes its electrons elsewhere. The purpose is to generate water from oxygen. The energy of protons flowing through the ATP synthase enzyme powers the recharge of ADP to ATP. Protons are added directly to ADP to recharge it to ATP.
The energy of protons flowing through the ATP synthase enzyme powers the recharge of ADP to ATP.
What was the MOST likely source of the family's botulism food poisoning?
The family consumed botulism toxin in the canned green beans.
The generation time for Escherichia coli inside of the human intestinal tract has been estimated at 12 hours. However, when grown in Luria Bertani medium as a pure culture under standard laboratory conditions, the generation time for E. coli is 20 minutes. Which of the following accounts for this discrepancy in generation time? The human intestinal tract contains other microbes, which compete for limited nutrients. The human intestinal tract does not contain the growth factors necessary to sustain E. coli. The human intestinal tract is not at an optimal temperature for E. coli. The human intestinal tract has more oxygen than standard lab conditions.
The human intestinal tract contains other microbes, which compete for limited nutrients.
How does a noncompetitive inhibitor reduce an enzyme's activity? The inhibitor degrades the enzyme. The inhibitor inactivates the enzyme. The inhibitor binds to the enzyme in a location other than the active site, changing the shape of the active site. The inhibitor degrades the enzyme's normal substrate.
The inhibitor binds to the enzyme in a location other than the active site, changing the shape of the active site.
What is the fate of metabolites during respiration? They are oxidized completely to form pyruvic acid. They are rearranged to form GTP. They are oxidized completely to carbon dioxide and water. They are reduced to from NADH and FADH2.
They are oxidized completely to carbon dioxide and water.
Oxidation of nutrients by cells results in a release of energy, which is released by converting ATP to ADP. a release of energy, which can be used to recharge ADP to ATP. a requirement of energy which can be obtained by converting ATP to ADP. a requirement for energy which can be used to recharge ADP to ATP. either a release or a requirement for energy depending on what type of nutrient is available.
a release of energy, which can be used to recharge ADP to ATP.
Anabolic reactions are endergonic. are endergonic and involve dehydration synthesis. involve breaking down larger molecules into smaller molecules. involve dehydration synthesis. are endergonic and involve breaking down larger molecules into smaller molecules.
are endergonic and involve dehydration synthesis.
Catabolic reactions are endergonic and are hydrolytic. involve breaking down larger molecules into smaller molecules. are hydrolytic and involve breaking down larger molecules into smaller molecules. are hydrolytic. are endergonic.
are hydrolytic and involve breaking down larger molecules into smaller molecules.
Which structural and functional feature(s) listed are key to an enzyme's activity? consumed each time a reaction takes place consumed each time a reaction takes place and consists of a three-dimensional protein structure that interacts with a substrate in a fixed "lock-and-key" model consists of a three-dimensional protein structure that interacts with a substrate in a fixed "lock-and-key" model contains an active site where the enzyme can interact with a specific substrate consumed each time a reaction takes place and contains an active site where the enzyme can interact with a specific substrate
contains an active site where the enzyme can interact with a specific substrate
When electrons are removed from nutrients via an oxidation reaction, the coupled reduction reaction may be NAD → NADH. NADH → NAD+. FAD → FADH2. either FAD → FADH2 or NAD+ → NADH. either NAD+ → NADH or NADH → NAD+.
either FAD → FADH2 or NAD+ → NADH.
All of the following are examples of inclusion bodies in prokaryotic cells except __________. carboxysomes magnetosomes glycogen granules endospores
endospores
Enzymes are necessary for cells because enzymes slow down chemical reactions that would otherwise occur too quickly to facilitate life. enzymes allow chemical reactions to take place that would otherwise be impossible. enzymes allow chemical reactions to occur quickly enough to facilitate life. enzymes allow chemical reactions to occur under physiological conditions. enzymes allow chemical reactions to occur under physiological conditions and within a time frame conducive to life.
enzymes allow chemical reactions to occur under physiological conditions and within a time frame conducive to life.
Which of the following is not an environmental factor that would affect the growth of E. coli? antibiotics produced from other bacterial species temperature concentration of other bacteria availability of nutrients generation time of E. coli
generation time of E. coli
The immediate result of electron movement through the electron transport chain is the pumping of protons across the bacterial cell membrane, creating a _____ outside the cell than inside the cell. higher concentration of electrons higher concentration of protons lower concentration of electrons lower concentration of protons
higher concentration of protons
A glycoprotein can be used in enzymatic functions. can be used as a receptor. is a type of peripheral protein. is a type of peripheral protein above that can be used as a receptor or in enzymatic functions.
is a type of peripheral protein above that can be used as a receptor or in enzymatic functions.
In which growth phase do bacteria adjust to their environment and grow little, if any? stationary phase lag phase acculturation phase habituation phase log phase
lag phase
In which growth phase do bacteria grow exponentially? log phase lag phase acculturation phase habituation phase stationary phase
log phase
The main function of the Krebs cycle during cellular respiration is to ______. create acetyl-CoA make NADH and FADH2 through redox reactions produce a large amount of ATP break glucose in half
make NADH and FADH2 through redox reactions
Which temperature group are most pathogens associated with? extreme thermophiles thermophiles mesophiles psychrotrophs psychrophiles
mesophiles
Prokaryotic cells house a single circular chromosome in their __________. ribosomes periplasmic space nucleus nucleoid region
nucleoid region
Peptidoglycan is a polymer of millions of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) sugars based on glucose molecules linked together in long chains cross-braced with four amino acids that link individual polymer chains together in a chain-link fence pattern. Layers of cross-braced NAG and NAM sheets are stacked vertically and held together by proteins with lipid anchors attached to the cell's cytoplasmic membrane to form a scaffold of sugars and proteins that is able to hold the bacterial cell's shape, even in response to extreme osmotic pressures. How would you expect a microbiology student to be able to describe the composition of peptidoglycan? What is the composition of the peptidoglycan layers found in the cell wall of bacteria? Pick the answer that lists the composition of the bacterial cell wall. NAG and NAM proteins and sugars amino acids, NAG, and NAM short amino acid chains, NAG, NAM, and some lipid proteins
short amino acid chains, NAG, NAM, and some lipid proteins
Glycolysis makes ATP using ______. substrate-level phosphorylation chemiosmosis oxidative phosphorylation photophosphorylation
substrate-level phosphorylation
Glycolysis literally means energy producing. sugar splitting. sugar producing. Embden-Meyerhof.
sugar splitting.
During an oxidation reaction, the acceptor molecule loses an electron and becomes oxidized. the donor molecule gains an electron and becomes oxidized. the acceptor molecule gains an electron and becomes oxidized. the donor molecule loses an electron and becomes oxidized.
the donor molecule loses an electron and becomes oxidized.
