BIO 1305 Final Baylor Questions & Answers

Which of the following is the smallest unit of organization that can perform all activities required for life? - ANSWERScell With evolution as the core theme of biology, we can explain traits shared by organisms as evidence of __________ and traits that differ among organisms as evidence of __________. - ANSWERSdescent from a common ancestor; adaptation through natural selection Which series of terms is in the correct sequence of biological organization, from the simplest to the most complex? - ANSWERScell, tissue, organ, population, community Regulation of molecules within an organism in response to a changing level of chemicals and the ability to self-regulate is called __________. - ANSWERSfeedback regulation Which of the following is an attribute of living things? - ANSWERSthey must be able to evolve and adapt The fundamental organizing principle of biology and core theme is __________. - ANSWERSevolution The process that directs the manufacture of a cell product from a gene is called __________. - ANSWERSgene expression the best method for determining whether bean plants require sodium is to _______ - ANSWERSgrow bean plants with and without sodium The energy used by most organisms for metabolism and growth ultimately comes from __________. - ANSWERSthe sun Natural selection tends to act at which of the following levels? - ANSWERSpopulation The units of inheritance are called __________. - ANSWERSgenes What is the appropriate term for an interacting group of individuals of a single type occupying a defined area? - ANSWERSpopulation How is the information encoded in DNA actually used by organisms? - ANSWERSthe information in DNA is transcribed to RNA and then translated into protein Using models that represented camouflaged and non-camouflaged mice, Hoekstra and her students tested the hypothesis that coloration of beach and inland mice provides camouflage that protects them from predation. Regardless of whether the models were placed in the beach or the inland habitat, the camouflaged model always acted as the __________ group. - ANSWERScontrol Which of the following statements best describes what is meant by "emergence"? - ANSWERSthe whole is greater than the sum of the parts A hypothesis must be testable and falsifiable to be scientifically valid. Being testable and falsifiable means that __________. - ANSWERSsome conceivable observation or experiment could reveal whether a given hypothesis is incorrect The information in a gene that directs the production of a cellular product is gene expression. The correct sequence for the transfer of information from a gene to a function protein is __________. - ANSWERStranscription, translation, and protein folding The two main forms of cells are __________ cells. - ANSWERSProkaryotic and Eukaryotic Which of the following statements is most clearly inductively derived? - ANSWERSIf the animals observed require organic molecules as nutrients, then it can be concluded that all animals require organic molecules as nutrients. Which of the following observations and inferences led Charles Darwin to his theory of natural selection as a mechanism for evolution? - ANSWERSDarwin synthesized his theory of natural selection from all of the listed observations and inferences. Feedback regulation includes __________. - ANSWERSboth negative feedback where the pathway shuts down and positive feedback where the pathway speeds up a scientific theory is - ANSWERSa well-supported concept that has broad explanatory power the genetic material within cells is called ________ and is organized into structures called _______ - ANSWERSDNA ; chromosomes A nonlinear, realistic model of the scientific process is called the process of science. The core activity of this process is __________. - ANSWERSforming and testing hypotheses What is the molecule that can account for both the unity and the diversity of life? - ANSWERSDNA In the theme of biological organization, the approach called reductionism __________. - ANSWERSallows us to reduce complex systems to simpler components that are more manageable to study Some properties and processes that are associated with life include all of the following except _____________. - ANSWERSreductionism The concept of "descent with modification" was proposed by __________. - ANSWERScharles darwin The use of energy and matter by living organisms __________. - ANSWERSinvolves chemical cycling from light energy from the sun for the production of chemical energy in food to the decomposition and the returning of chemicals to the cycle The three-domains of life ________ - ANSWERSare bacteria, archaea, and eukarya Weak chemical bonds such as hydrogen bonds __________. - ANSWERSform when a hydrogen atom that is covalently bonded to an electronegative atom like oxygen or nitrogen is attracted to another electronegative atom A covalent bond __________. - ANSWERSis the sharing of a pair of valence electrons by two atoms The reactivity of an atom arises from __________. - ANSWERSthe existence of unpaired electrons in the valence shell In a process called radiometric dating, scientists measure the __________ of an isotope to determine the age of the Earth. - ANSWERShalf-life Hydrogen bonds occur when __________. - ANSWERSpartial opposite charges on molecules come close enough to attract each other Which of the following has negligible mass? - ANSWERSelectron In chemical reactions, the __________ are the starting materials that are converted into the __________. - ANSWERSreactants; products When the proton number and electron number are unequal, the atom or molecule __________. - ANSWERSis an ion Which of the following statements is true about chemical reactions? - ANSWERSThey involve the making and breaking of chemical bonds. A covalent bond is likely to be polar if __________. - ANSWERSone of the atoms sharing electrons is much more electronegative Which statement is true of all atoms that are anions? - ANSWERSThe atom has more electrons than protons. The number of protons in an uncharged atom __________. - ANSWERSequals the number of electrons Trace elements _________ - ANSWERSare required by an organism in only minute quantities isotopes of an element will always differ in _______ - ANSWERSatomic mass radioactive tracers _________ - ANSWERSare important tools in biological research and medicine what are the four most abundant elements found in living systems - ANSWERShydrogen, oxygen, nitrogen, and carbon Nonpolar covalent bonds are always formed from atoms that are __________. - ANSWERSequal in their electronegativity The difference between a stable isotope and an unstable isotope of an element is that __________. - ANSWERSthe unstable isotope has a nucleus that decays spontaneously, is radioactive, and can be transformed into an atom of another element Which of the following four statements, if any, is true regarding essential elements and living organisms? - ANSWERSAlthough all forms of life require iron, other elements are required only by certain species. In ionic interactions, __________ - ANSWERSthe transfer of valence electrons results in a completed valence shell for each ion The fact that oxygen is an atom that is strongly electronegative means that __________. - ANSWERSit more strongly pulls shared electrons toward itself when forming a covalent bond with a less electronegative atom Molecular mimics _______ - ANSWERScan produce similar effects as the naturally occurring molecules When one or more pairs of valence electrons are shared by two neutral atoms, what type of bond is formed? - ANSWERSa covalent bond The molecular shape of a biological molecule is important because __________. - ANSWERSit determines how biological molecules recognize and respond to one another When a very electronegative atom strips a valence electron away from its partner, __________ form. - ANSWERSions Orbitals are best described as __________. - ANSWERSa three-dimensional space where an electron spends most of its time with no more than 1 other electron, forming a pair The behavior of an atom depends on the __________. - ANSWERSvalence electrons in the outermost electron shell The chemical characteristics or reactivity of an element depend mostly on the __________. - ANSWERSnumber of electrons in its outermost shell Ionic bonds form as a result of __________. - ANSWERSattraction between ions that have opposite charges Which of the following subatomic particles has appreciable mass and lacks a charge? - ANSWERSNeutron Adding a base tends to __________ of a solution. - ANSWERSlower the hydrogen ion concentration and increase the pH The phenomenon responsible for maintaining the upward movement of water through a vessel is __________. - ANSWERScohesion When the pH of a solution shifts from 3 to 7, the hydrogen ion concentration has changed, and __________. - ANSWERSit has decreased by 10,000 Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature? - ANSWERSthe absorption of heat by the breaking of hydrogen bonds Urine, at pH 6, contains __________ H+ as household bleach, at pH 13. - ANSWERS10,000,000 times as much Glucose has a molecular mass of 180 daltons. To make a 2-molar (2 M) solution of glucose, __________. - ANSWERSstir 360 g of glucose in water to dissolve the sugar, and then add enough water to bring the total volume of the solution up to 1 L A compound that donates hydrogen ions to a solution is __________. - ANSWERSan acid The amount of heat required to change the temperature of 1 g of any substance by one °C is defined as __________. - ANSWERSthe specific heat of that substance Nonpolar molecules that cluster away from water molecules are called __________ molecules. - ANSWERShydrophobic All of the following are hydrogen bonding properties except __________. - ANSWERSnonpolar covalent bonding The partial charges on a water molecule occur because of __________. - ANSWERSthe unequal sharing of electrons between the hydrogen and the oxygen atoms of a water molecule A solution at pH 10 contains __________ than the same amount of solution at pH 8. - ANSWERS100 times less H+ The amount of heat required to convert 1 g of any substance from the liquid to the gaseous state is defined as __________. - ANSWERSthe heat of vaporization of that substance Hydrophobic molecules __________ - ANSWERSare uncharged, nonionic substances that repel water Water molecules have __________ than molecules of similar size, such as ammonia and methane, reflecting its capacity to absorb large amounts of heat. - ANSWERSa higher boiling point an acid is __________ - ANSWERSa compound that donates hydrogen ions to a solution A substance that reduces the hydrogen ion concentration of a solution is __________. - ANSWERSa base When ice forms, the __________ are farther apart than in liquid water, allowing the ice to form an organized crystal structure and float. - ANSWERShydrogen bonds hydrophilic molecules _________ - ANSWERSare charged molecules that are attracted to the partial charge of the water molecule Water is a polar molecule. This means that __________. - ANSWERSthe opposite ends of the molecule have opposite electrical charges A mole of methanol (CH3OH) weighs 32 g. The number of grams of methanol that are needed to produce 1 L of a 1 millimolar solution is __________. - ANSWERS0.032 g The ability of water molecules to form hydrogen bonds with other water molecules and water's ability to dissolve substances that have charges or partial charges are __________. - ANSWERSboth caused by water's partial charges Adhesion is best described as __________. - ANSWERSthe clinging of one substance to another substance __________ is an emergent property of water that allows insects like the raft spider to walk on water. - ANSWERSsurface tension Sweating has a cooling effect because of water's high __________. - ANSWERSheat of vaporization The absorption of human-generated CO2 by the oceans __________. - ANSWERS-increases the oceanic concentration of carbonic acid -increases the oceans' acidity and lowers pH -reduced the carbonate ion concentration in the oceans and threatens calcifying organisms in marine ecosystems -increases the hydrogen ion concentration in the oceans but decreases the carbonate ion concentration and threatens the livability of the oceans for calcifying organisms Buffers are ___________ - ANSWERSsubstances that minimize changes in the concentration of H+ and OH- in a solution You can fill a glass of water to just slightly above the rim without it spilling over the glass. What property of water best explains this phenomenon? - ANSWERSsurface tension The specific heat of a substance is __________. - ANSWERSthe amount of heat that must be absorbed or lost for 1 g of that substance to change its temperature by 1°C Water moves up a plant because of hydrogen bonds by a process called __________. - ANSWERScohesion and adhesion Although the structures of the functional groups that are most important to life vary, they share one thing in common: They __________. - ANSWERSall help give each biological molecule its unique properties Structural isomers have __________. - ANSWERSthe same molecular formula but different covalent arrangements of their carbon skeletons Which of the following molecules is a weak base? - ANSWERSR-NH2 In the pharmaceutical industry, two enantiomers of a drug __________. - ANSWERSmay not be equally effective Carbon's atomic number is 6. This means that it has __________ electrons. After completing the first energy level, carbon has __________ valence electrons and can form __________ bonds. - ANSWERS6; 4; 4 What are the six most important chemical elements of life? - ANSWERSCarbon, nitrogen, oxygen, hydrogen, phosphate, and sulfur Biologically important chemical groups include all of the following except __________. - ANSWERSwater (H2O) In Miller's 1953 laboratory experiment, __________. - ANSWERSabiotic compounds cycled through the apparatus and were sampled for organic compounds Molecules that contain only carbon and hydrogen are __________. - ANSWERScalled hydrocarbons The chemical group that helps stabilize protein structure is the __________. - ANSWERSsulfhydryl group (-SH) Which of the following are properties of hydrocarbons? - ANSWERSHydrophobic, nonpolar, and a good source of stored energy Chemical groups are significant because __________. - ANSWERSthey contribute to the molecular shape of a molecule and its unique properties Choose the pair of terms that completes this sentence about functional groups in organic chemistry: Carboxyl is to __________ as __________ is to base. - ANSWERSacid; amino Inorganic carbon such as CO2 differs from organic carbon because __________. - ANSWERSorganic carbon always has a hydrogen atom covalently attached to it Which element is always associated with organic chemistry? - ANSWERScarbon When a double bond joins two carbon atoms, __________ can form. - ANSWERScis-trans isomers Stanley Miller's experiments were significant because he demonstrated that __________. - ANSWERSa variety of simple organic compounds could be spontaneously synthesized from components in Earth's primitive atmosphere What is ATP's importance in the cell? - ANSWERSATP stores the potential to react with water, thereby removing a phosphate group and releasing energy for cellular processes. Which chemical group is most likely to be responsible for an organic molecule behaving as a base? - ANSWERSamino The chemical group that acts as an acid is the __________. - ANSWERScarboxyl group (-COOH) Enantiomers are __________. - ANSWERSmirror-image isomers of a molecule The carbon atom is tetravalent; this means that __________. - ANSWERSa carbon atom can complete its valence shell by forming four covalent bonds Which of the following molecules is a weak acid? - ANSWERSR-COOH The carbon skeleton can vary in all of the following except __________. - ANSWERSlacking hydrogen atoms When three phosphate groups are covalently attached to adenosine, __________ is formed. - ANSWERSATP Which of the following is found in all amino acids? - ANSWERSboth -COOH and -NH2 The chemical group that is involved in regulating DNA is the __________. - ANSWERSmethyl group (-CH3) Pharmaceutical companies are selling close to $200 billion worth of single-enantiomer drugs. Why might it be important to use only one form of an enantiomer? - ANSWERSOne enantiomer may provide an effective treatment whereas the other may be ineffective or even toxic. which of the following is a polymer - ANSWERScellulose, a plant cell wall component Which is the term for compounds that do not mix with water? - ANSWERShydrophobic Nitrogenous bases are classified as either purines or pyrimidines. Examples of purines are __________. - ANSWERSadenine and guanine The tertiary structure of a protein includes all of the following interactions except _________ bonds. - ANSWERSpeptide The type of bond that forms to join monomers (such as sugars and amino acids) into polymers (such as starch and proteins) is a(n) __________ bond. - ANSWERScovalent Macromolecules, the molecules of life, include all of the following except __________. - ANSWERStrace elements The sex hormones estrogen, progesterone, and testosterone belong to which class of molecules? - ANSWERSlipids Which type of protein shields a newly forming protein from cytoplasmic influences while it is folding into its functional form? - ANSWERSchaperonins A shortage of phosphorus in the soil would make it especially difficult for a plant to manufacture __________. - ANSWERSDNA Carbohydrates are used in our bodies mainly for __________. - ANSWERSenergy storage and release The molecule with four fused rings that is found in animal membranes and is the precursor of vertebrate sex hormones is __________. - ANSWERScholesterol A polysaccharide that is used for storing energy in human muscle and liver cells is __________. - ANSWERSgylcogen In living organisms, DNA exists as a __________ with the strand(s) __________. - ANSWERSdouble helix; running antiparallel Sugars are molecules that have __________ C:H:O and are called __________. - ANSWERSa 1:2:1 ratio of; carbohydrates The components of nucleic acids are __________. - ANSWERSa nitrogenous base, a pentose sugar, and a phosphate The subunits (monomers) in cellulose are linked together by __________. - ANSWERSglycosidic linkages The sequence of amino acids in a protein is called the __________ structure of the protein. - ANSWERSprimary When comparing saturated and naturally occurring unsaturated fats, the unsaturated fats have __________ and are __________ at room temperature. - ANSWERScis double bonds; liquids One characteristic shared by sucrose, lactose, and maltose is that __________. - ANSWERSthey are all disaccharides Protein molecules are polymers (chains) of __________. - ANSWERSamino acids molecules The proper three-dimensional shape and folding of a protein is assisted by _________. - ANSWERSmolecules called chaperonins The peptide bond is __________. - ANSWERSa covalent bond joining amino acids together to form a polypeptide At a conference, the speaker's grand finale was sautéing mealworms (insect larvae) in butter and serving them to the audience. They were crunchy (like popcorn hulls) because their exoskeletons contain the polysaccharide __________. - ANSWERSchitin The secondary structure of a peptide backbone is stabilized by __________ forming either a(n) __________ or a(n) __________. - ANSWERShydrogen bonds; α helix; β pleated sheet In a dehydration synthesis reaction, __________ is always formed as a by-product of the reaction. - ANSWERSwater Generally, animals cannot digest (hydrolyze) the glycosidic linkages between the glucose molecules in cellulose. How then do cows get enough nutrients from eating grass? - ANSWERSMicroorganisms in their digestive tracts hydrolyze the cellulose to individual glucose units. Sickle-cell anemia is a disease that is caused by __________ in the __________ of the protein. - ANSWERSa single amino acid change; primary structure The lipids that form the main structural component of cell membranes are __________. - ANSWERSphospholipids Sugars have a(n) __________ group that interacts with a _________ group that forms ring structures when the dry molecule is placed in water. - ANSWERScarbonyl (-C=O); hydroxyl (-OH) __________ is always involved in hydrolysis reactions. - ANSWERSwater Cell junctions in plant cells are called __________, and communicating junctions in animal cells are called __________. - ANSWERSplasmodesmata; gap junctions Cell motility, which includes changes both in cell location and in the movement of cell parts, requires interactions of the cytoskeleton __________. - ANSWERSwith motor proteins Animal cells have unique organelles called __________ that are composed of structures called __________. - ANSWERScentrosomes; centrioles Which of the following is false in respect to cells' chromosomes? - ANSWERSchromosomes are only visible as a cell is about to divide Observing a fluorescent micrograph cell with intermediate filaments would help you identify the cell as a __________. - ANSWERShuman skin cell Microfilaments function in cell motility including __________. - ANSWERSmuscle contraction, amoeboid movement, and cytoplasmic streaming in plants The network of fibers that organizes structures and activities in a cell __________. - ANSWERSin the cytoskeleton Evidence that supports the prokaryotic origins of mitochondria and chloroplasts are all of the following except __________. - ANSWERSthat mitochondria and chloroplasts have multiple copies of linear DNA molecules associated with their inner membranes The organelle that is a plant cell's compartment for the storage of inorganic ions such as potassium and chloride is the __________. - ANSWERScentral vacuole Cilia and flagella move due to the interaction of the cytoskeleton with which of the following? - ANSWERSmotor proteins Which of the following is present in a prokaryotic cell? - ANSWERSribosomes Your intestine is lined with individual cells. No fluids leak between these cells from the gut into your body. Why? - ANSWERSthe intestinal cells are bound together by tight junctions In terms of cellular function, what is the most important difference between prokaryotic and eukaryotic cells? - ANSWERSEukaryotic cells are compartmentalized, which allows for specialization. The extracellular matrix of the animal cell has all of the following molecular components except __________. - ANSWERSa middle lamella Bacterial cells are prokaryotic. Unlike a typical eukaryotic cell they __________. - ANSWERShave no membrane-bounded organelles in their cytoplasm You would expect a cell with an extensive Golgi apparatus to __________. - ANSWERSsecrete a lot of protein Which statement about the cytoskeleton is true? - ANSWERSComponents of the cytoskeleton often mediate the movement of organelles within the cytoplasm. The walls of plant cells are largely composed of polysaccharides and proteins that are synthesized __________. - ANSWERSin the rough endoplasmic reticulum and in the Golgi apparatus __________ are membrane-bound metabolic compartments that specialize in the production of hydrogen peroxide (H2O2) and its conversion to water. - ANSWERSperoxisomes Which of the following groups is primarily involved in synthesizing molecules needed by the cell? - ANSWERSRibosomes, rough endoplasmic reticulum, and smooth endoplasmic reticulum Dye injected into a plant cell might be able to enter an adjacent cell through __________. - ANSWERSplasmodesmata What is the functional connection between the nucleolus, nuclear pores, and the nuclear membrane? - ANSWERSSubunits of ribosomes are assembled in the nucleolus and pass through the nuclear membrane via the nuclear pores. A substance moving from outside the cell into the cytoplasm must pass through __________. - ANSWERSthe plasma membrane The endosymbiont theory explains the origins of __________. - ANSWERSmitochondria and chloroplasts The endoplasmic reticulum is part of the endomembrane system, which also includes the __________. - ANSWERSnuclear envelope, the Golgi apparatus, lysosomes, and vesicles The function of the rough endoplasmic reticulum (RER) is __________. - ANSWERSto synthesize proteins that are secreted as glycoproteins The region of a bacterial cell that contains the genetic material is called the __________. - ANSWERSnucleoid Cells are small because __________. - ANSWERSof the geometric relationships between surface and volume Basal bodies are most closely associated with which of the following cell components? - ANSWERScilia A protein that ultimately functions in the plasma membrane of a cell is most likely to have been synthesized __________. - ANSWERSin the rough endoplasmic reticulum A cell is placed into a solution and the cell shrinks. Which of the following is true regarding the solution? - ANSWERSthe solution is hypertonic How does the "fluid mosaic model" describe the structure of the plasma membrane? - ANSWERSProteins in the membrane contribute to the mosaic quality of the membrane while the lateral and rotational movements of phospholipids contribute to its fluidity. Which of the following cell structures exhibits selective permeability between a cell and its external environment? - ANSWERSplasma membrane What function do carbohydrates fulfill in the plasma membrane? - ANSWERScell-to-cell recognition Which of the following statements concerning carbohydrates associated with the plasma membrane is correct? - ANSWERSMembrane carbohydrates function primarily in cell-cell recognition. Cells A and B are the same size, shape, and temperature, but cell A is metabolically less active than cell B; cell B is actively converting oxygen to water in cellular respiration. Oxygen will diffuse more rapidly into cell __________ because __________. - ANSWERSB; the diffusion gradient in cell B is steeper Which of the following statements about diffusion is true? - ANSWERSit is a passive process Which of the following is correct regarding integral proteins? - ANSWERSThese proteins exhibit both hydrophilic and hydrophobic properties. Which of the following is correct regarding peripheral proteins? - ANSWERSThese proteins are found only on the surface of the plasma membrane. Which of the following is a correct difference between active transport and facilitated diffusion? - ANSWERSActive transport requires energy from ATP, and facilitated diffusion does not. All cells have voltages across their membranes. This voltage is called a(n) __________ and is often maintained by __________. - ANSWERSmembrane potential; electrogenic pumps A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via which process? - ANSWERSendocytosis Which of the following substances would be most likely to pass through the plasma membrane without the help of a transport protein? - ANSWERSa nonpolar molecule, such as a hydrocarbon Why is energy required for active transport? - ANSWERSBecause it moves solutes against their concentration gradient In facilitated diffusion, __________ proteins provide openings in the plasma membrane for substances to flow through without changing structure, and __________ proteins allow passage of substances through the plasma membrane after undergoing a subtle change in shape. - ANSWERSchannel; carrier If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells? - ANSWERSBoth cells would lose water; the red blood cell would shrivel, and the plant plasma membrane would pull away from the cell wall. Which of the following molecules is most likely to passively diffuse across the plasma membrane? - ANSWERScarbon dioxide Which of these statements describes some aspect of facilitated diffusion? - ANSWERSFacilitated diffusion of solutes may occur through channel or transport proteins in the membrane. The sodium-potassium pump __________. - ANSWERStransports sodium ions out of the cell and transports potassium ions into the cell Which of the following statements about passive transport is correct? - ANSWERSPassive transport permits the solute to move in either direction, but the net movement of the population of solute molecules occurs down the concentration gradient of the molecule. Which of the following structural arrangements of the components in biological membranes facilitates the cell membrane's property of selective permeability? - ANSWERSproteins embedded in two layers of phospholipids The internal solute concentration of a plant cell is about 0.8M. To demonstrate plasmolysis, it would be necessary to suspend the cell in what solution? - ANSWERS1.0 M The plasma membrane exhibits selective permeability. This means that __________. - ANSWERSthe plasma membrane allows some substances to flow through it more easily than others Which of the following processes and organelle(s) accounts for the replacement of lipids and proteins lost from the plasma membrane? - ANSWERSexocytosis and smooth and rough ER Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct? - ANSWERSPhospholipids form a selectively permeable structure. Red blood cells contain approximately a 2% concentration of solutes. A red blood cell is placed into a solution that contains a 4% concentration of solutes to which the cell is not permeable. What will happen to the red blood cell? - ANSWERSThe cell will decrease in size as water flows out of it. Which of the following would be least likely to diffuse through a plasma membrane without the help of a transport protein? - ANSWERSa large polar molecule How does cholesterol affect membrane fluidity? - ANSWERSAt body temperature, it makes the membrane less fluid. Which of the following plant cells would exhibit the most turgor pressure? - ANSWERSa cell placed in a hypotonic solution Which of the following molecules are most abundant in the plasma membrane? - ANSWERSphospholipids Which of these statements about enzyme inhibitors is true? - ANSWERSthe action of inhibitors may be reversible or irreverible Which of the following statements about the active site of an enzyme is correct? - ANSWERSThe active site may resemble a groove or pocket in the surface of a protein into which the substrate fits. An exergonic reaction __________ free energy, and an endergonic reaction __________ free energy. - ANSWERSreleases; absorbs At low temperatures, a particular enzyme catalyzes a reaction, but at a slow rate. At high temperatures, the enzyme is completely inactive. What statement best explains the difference in how temperature affects the function of this enzyme? - ANSWERSAt low temperatures, there is not enough free energy for the enzyme to function at a high rate, and at high temperatures, the enzyme is denatured, leaving it nonfunctional. Enzyme activity is affected by pH because __________. - ANSWERShigh or low pH may disrupt hydrogen bonding or ionic interactions and thus change the shape of the active site Which of the following statements about enzymes is true? - ANSWERSEnzymes speed up the rate of the reaction without changing the ΔG for the reaction. Which of the following reactions would be endergonic? - ANSWERSGlucose + fructose → sucrose How does ATP drive transport work inside a cell? - ANSWERSBy phosphorylating a transport protein Which of the following statements about enzyme function is correct? - ANSWERSEnzymes can lower the activation energy of reactions, but they cannot change the equilibrium point because they cannot change the net energy output. Which of the following states the relevance of the first law of thermodynamics to biology? - ANSWERSEnergy can be freely transformed among different forms as long as the total energy is conserved. As ATP begins to build up in a cell, metabolism slows down. How does this happen? - ANSWERSATP acts as an allosteric inhibitor to many of the enzymes involved in metabolism, thus slowing their function. If the entropy of a living organism is decreasing, which of the following is most likely to be occurring simultaneously? - ANSWERSEnergy input into the organism must be occurring to drive the decrease in entropy. Which of the following is changed by the presence of an enzyme in a reaction? - ANSWERSthe activation energy In general, the hydrolysis of ATP drives cellular work by __________. - ANSWERSreleasing free energy that can be coupled to other reactions Which of the following statements is correct regarding ATP? - ANSWERSThe energy in an ATP molecule is released through hydrolysis of one of the phosphate groups. Which of the following statements is correct regarding kinetic and potential energy? - ANSWERSKinetic energy is associated with the relative motion of objects, and potential energy is the energy that matter possesses because of its location or structure. How does ATP drive mechanical work inside a cell? - ANSWERSBy binding to motor proteins The primary manner in which cells manage their energy resources in order to do work is called energy coupling. Which of the following statements accurately defines energy coupling? - ANSWERSexergonic reactions drive endergonic reactions Which of the following statements is correct regarding competitive and noncompetitive enzyme inhibitors? - ANSWERSCompetitive inhibitors bind to the active site of an enzyme while noncompetitive inhibitors bind to an enzyme away from the active site. Cells use ATP constantly, but ATP is considered a renewable resource. What process makes this possible? - ANSWERSATP can be regenerated by the addition of a phosphate group to ADP. Which of the following statements correctly describes cofactors and coenzymes? - ANSWERSBoth are nonprotein enzyme helpers; but most cofactors are metal ions, and coenzymes are organic molecules that are a specific type of cofactor. What best characterizes the role of ATP in cellular metabolism? - ANSWERSThe free energy released by ATP hydrolysis that may be coupled to an endergonic process via the formation of a phosphorylated intermediate. At low pH, a particular enzyme catalyzes a reaction at a high rate. At neutral pH, the enzyme is completely inactive. What statement best explains the difference in how pH affects the function of this enzyme? - ANSWERSThe enzyme is adapted for low pH but is denatured at neutral pH, leaving it nonfunctional. An exergonic (spontaneous) reaction is a chemical reaction that __________. - ANSWERSreleases energy when proceeding in the forward direction What would the value of ΔS be for a chemical reaction in which a molecule is broken down into smaller components? - ANSWERSpositive Which of the following is an example of the second law of thermodynamics as it applies to biological reactions? - ANSWERSThe aerobic respiration of one molecule of glucose produces six molecules each of carbon dioxide and water. The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule is an example of __________. - ANSWERSallosteric regulation ATP allosterically inhibits enzymes in ATP-producing pathways. The result of this is called __________. - ANSWERSfeedback inhibition Which of the following correctly states the relationship between anabolic and catabolic pathways? - ANSWERSAnabolic pathways synthesize more complex organic molecules using the energy derived from catabolic pathways. Which of the following is true regarding metabolic pathways? - ANSWERSMetabolic pathways consist of a series of reactions, each catalyzed by a different enzyme. Which of the following metabolic pathways produce(s) the most ATP, per glucose molecule metabolized, during cellular respiration? - ANSWERSThe electron transport chain and oxidative phosphorylation The energy from the electrons in NADH and FADH2 fuel what process in the electron transport chain? - ANSWERSThe pumping of H+ across the cristae of the mitochondrion After completion of the citric acid cycle, most of the usable energy from the original glucose molecule is in the form of __________. - ANSWERSNADH Cells must regulate their metabolic pathways so that they do not waste resources. What is the most common mechanism that regulates cellular respiration in most cells? - ANSWERSfeedback inhibition of glycolysis Which of the following is a correct description of the events of cellular respiration and the sequence of events in cellular respiration? - ANSWERSOxidation of glucose to pyruvate; oxidation of pyruvate; oxidation of acetyl-coA; oxidative phosphorylation A small amount of ATP is made in glycolysis by which of the following processes? - ANSWERSTransfer of a phosphate group from a fragment of glucose to ADP by substrate-level phosphorylation