BS161 Biology Final Exam With Answers (272 Solved Questions)

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BS161 Biology Final Exam With Answers (272 Solved Questions) - Page 1 preview image

VERSION 2Compare and contrast the strength of each interaction in a solid versus an aqueous solution.- Solid has higher concentration of bonds than aqueous solution

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why water is able to form hydrogen bonds - they have polar covalent bonds and the partiallypositive hydrogen bonds to other partially negative oxygenswhy polar and charged species dissolve in water - molecules that have partially positive andpartially negative areas are polar and can be dissolved in waterwater can attract charged particles because it has partially positive and negative areas andif the attractions between the ions and water are stronger than attractions between ions itwill dissolve in waterbonds between solute compound are disrupted in order to increase bond length and allowaqueous solution to flow throughwhy oil will not dissolve in water - water is polar and oil is nonpolar so their molecules donot attract each otherList the common functions of proteins in cells - energy storage, structural support,transport, messengers, enzyme catalyst etc.Describe four levels of protein structure and identify common representations - Primary-amino acid chainSecondary- alpha helix beta pleated sheetsTertiary- proteins or polypeptidesQuaternary- multiple polypeptidesDefine a lipid. - Insoluble in water and soluble in organic substancesDraw the difference between saturated and unsaturated fats - Unsaturated has doublebonds, and saturated has a carbon bonded to at least 2 hydrogens

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Explain the difference between solid fats and liquid oils on a molecular level. - Solid fats havemore hydrogens, the more hydrogens there are the more concentrated it is therefore themore solid it isDefine a biological membrane. - Selectively permeable barrier between living thingsDescribe the fluid mosaic model of membrane structure. - Different transport proteins thatallow ions to be diffused through a bilayerDescribe difference between peripheral and integral membrane proteins. - Integral proteinsare on the inside and nonpolar regions of membranes of hydrophobic layer and peripheralproteins are on the surface and it is on mitochondria and chloroplastsList six major functions of membrane proteins. - Transporters enzymes- carry out chemicalreactionscell surface receptors- detect chemical messages and anchors to surfacecell surface id receptorscell to cell adhesion proteinscytoskeleton proteinsExplain why the lipid bilayer of a biological membrane forms spontaneously. - Doesn't needoutside source of energy to formExplain the meaning of the statement "Phospholipids and most other membrane constituents(e.g., proteins) are amphipathic molecules." - Phospholipids are both hydrophobic andhydrophilicExplain how membrane fluidity is influenced by temperature. - lower temperature higherfluidity- unsaturated fats

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Explain how cholesterol resists changes in membrane fluidity as temperatures change. - Atmoderate temperature, reduces fluidity bc reduces phospholipid movementAt lower temperature, stops solidificationExplain the role of membrane carbohydrates in cell-cell recognition. - Bond to lipids orproteins, function as markers to distinguish from one anotherExplain how the polarity of a molecule affects how it moves across a membrane. - Nonpolarcan move across membrane, polar can't without carrier proteinDescribe the difference between channel proteins and carrier proteins. - Both transportsubstances across cell membrane but carrier proteins change shape as they transportExplain how aquaporins facilitate the passage of water through membranes. - Channelproteins with water, water molecules travel through a pore in a single fileDefine diffusion. - Moving protein from higher to lower concentrationExplain why diffusion is a passive and spontaneous process. - Energy doesn't need to beinputtedExplain why a concentration gradient of a substance across a membrane representspotential energy. - Drives diffusionDescribe differences between solutions that are hypertonic, hypotonic, and isotonic to cellcontents. - Hypertonic- shrivels bc concentration on outside is higherHypotonic- swells bc concentration on inside is higherIsotonic- neutralDefine osmosis and predict the direction of water movement based on differences in soluteconcentrations. - Water particle diffusion of cell, higher to lower concentration

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Describe how living cells with and without cell walls regulate water balance. - Vacuolesregulate water levels in plant cellsOsmosis for cells without cell wallsDescribe differences between osmosis, facilitated diffusion, and active transport. - Osmosisis diffusion in waterfacilitated goes with concentration gradient and doesn't need energyactive transport goes against and needs energyExplain how transport proteins facilitate diffusion. - Go from higher concentration to lowerconcentrationDescribe how solutes can move against their concentration gradient. - Go through activetransportDescribe the process of co-transport - Active transport is indirectly driven by ATP poweredpumpExplain how large molecules are transported across a cell membrane. - Exocytosis-secretes large molecules by the fusion of vesiclesIdentify the common structural components of prokaryotic and eukaryotic cells anddescribe their functions and interactions. - Eukaryotic has membrane bound organelles,mitochondria, nucleus, animal cellsProkaryotic has nucleoid, and chloroplast, has DNA in cytoplasm, plant cellsExplain why there are both upper and lower limits to cell size. - If structure is not big enoughto produce what it needs it won't effectively survive

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Explain the advantages of compartmentalization in eukaryotic cells - Cell is more organized,each organelle has its own structure to maintainDescribe the structure and function of the nuclear envelope. - Double layer membraneallows passage of materials into and outside the nucleusExplain how the nucleus controls protein synthesis in the cytoplasm. - Translates dna intomrna and mrna leaves nucleus through envelopes and once in the cytoplasmthe mrna binds to the ribosomes and initiates protein synthesisExplain the role of the nucleolus in protein synthesis. - Breaks nucleotide link between dnaand rnaDescribe the differences between free and bound ribosomes in terms of location andfunction - Bound ribosomes are attached to the rough er and free ribosomes are in thecytoplasm and they are used for protein synthesisDescribe the structure and function of each component of the endomembrane system. -nuclear envelope: a double membrane perforated by pores that regulate the movement ofmaterials between the nucleus and the cytoplasmendoplasmic reticulum: continuous with the nuclear envelope and encloses a network ofinterconnected tubules or compartments called cisternaeGolgi apparatus: consists of a stack of flattened sacsLysosome: membrane-enclosed sacs of hydrolytic enzymes used by animal cells to digestmacromoleculesVacuoles: formed as a result of phagocytosisPlasma membrane: surrounding every cell must provide sufficient surface area forexchange of oxygen, nutrients, and wastes relative to the volume of the cell

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Compare the structure and functions of smooth and rough ER. - The smooth ER servesdiverse functions in different cells: its enzymes are involved in phosopholipids and steroids(including sex hormone) synthesis, carbohydrate metabolism, and detoxification of drugsand poisons. The smooth ER is also in st- The rough ER manufactures membranes from thecell. Enzymes built into the membrane assemble phospholipids, and membrane proteinsformed by bound ribosomes are inserted into the ER membraneExplain the significance of the cis and trans sides of the Golgi apparatus. - Cis and trans helpdirect the vesicles to the plasma membrane or to other organellesExplain how a protein travels through the endomembrane system - Protein carriersDescribe three examples of intracellular digestion by lysosomes. - Phagocytosis- engulfingof debrisPinocytosis- engulfing of liquidMacrophages - are also in intracellular digestion by lysosomes that is a type of white bloodcells that is made to destroy ingested bacteriaExplain why pH is important for lysosomal function. - pH has to be acidic for lysosomes to beable to digest cellular debrislysosomes are sacs containing digestive enzymesDescribe the structure of a mitochondrion - Two membranes, each a phospholipid bilayerwith unique embedded proteins, encloses the mitochondrion. A narrow intermembranespace exists between the smooth outer membrane and the convoluted inner membrane,called cristae, create a large surface area and encloses the mitochondrial matrix. Manyrespiratory enzymes, mitochondrial DNA, and ribosomes are housed in this matrix. Otherrespiratory enzymes and proteins are built into the inner membraneIdentify the three functional compartments of a chloroplast. - The stroma is in the innermembrane that is a fluid surrounding a membranous system of flattened sacs called

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thylakoids, inside of which is the thylakoid space. Photosynthetic enzymes are embedded inthe thylakoids, which may be stacked together to form structures called granaDescribe the evidence that mitochondria and chloroplasts are semiautonomous organelles. -Both have 2 membranes, releases energyExplain the roles of peroxisomes in eukaryotic cells. - Peroxisomes are oxidative organellesfilled with enzymes that function in a variety of metabolic pathways, such as breaking downfatty acids for energy or detoxifying alcohol and other poisonsDescribe the functions of the cytoskeleton - The cytoskeleton is a network of protein fibersthat give mechanical support, function in cell motility (of both internal structures and thecell as a whole), and transmit mechanical signals from the cell's surface to its interior. Italso interacts with special proteins called motor proteins to produce cellular movementsCompare the structures and functions of microtubules, microfilaments, and intermediatefilaments of the cytoskeleton - Microtubules -have hollow rods constructed of columns ofglobular proteins called tubulins. Microtubules change length through the addition orsubtraction of tubulin dimers. They also provide the supporting framework of the cell,microtubules serve as tracks along which organelles move with the aid or motor molecules.Microfilaments (actin)- solid rods consisting of a twisted double chain of molecules of theglobular protein actin. Actin filaments are microfilaments function in support forming anetwork just inside the plasma membrane and the core of small cytoplasmic extensionscalled microvilliIntermediate filaments- Intermediate filaments are intermediate in size betweenmicrotubules and microfilaments are more diverse in their composition. Intermediate fibersappear to be important in maintaining cell shape. The nucleus is securely help in a web ofintermediate filaments, and the nuclear lamina lining the inside of the nuclear envelope iscomposed of intermediate filaments

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Describe the basic structure of a plant cell wall. Distinguish between the primary cell wall,middle lamella, and secondary cell wall. - Plant cell walls are composed of microfibrils ofcellulose embedded in a matrix of polysaccharides and proteinDescribe the structure and roles of the extracellular matrix in animal cells. - Animal cellslack cell walls but are covered by an elaborate extracellular matrix (ECM). The ECM is madeup of glycoproteins such as collagen, proteoglycans, and fibronectin. ECM proteins bind toreceptor proteins in the plasma membrane called integrinsDescribe the function of each type of intercellular junction in plants and animals. -Plasmodesmata: channels in plant cell walls through which the plasma membranes ofbordering cells connect, thus linking most cells of a plant into a living continuum. Threeintercellular junctions between animal cells are:Tight junction: where proteins hold adjacent cell membranes tightly together, creating animpermeable seal across a layer of epithelial cellsDesmosomes (anchoring junctions): reinforced by intermediate filaments and rivet cells intostrong sheetsGap junctions (communicating junctions): are cytoplasmic connections that allow for theexchange of ions and small molecules between cells through protein-lined poresExplain how the extracellular matrix integrates changes inside and outside the cell. - Themain ingredients of the ECM are glycoproteins. The most abundant of these glycoproteins iscollagen, which forms strong fibers outside of cells. The collagen fibers are woven in anetwork of proteoglycans. Communicating with a cell through integrins, the ECM canregulate a cell's behavior. The ECM around a cell can also influence the activity of genes inthe nucleus. The extracellular matrix of a particular tissue could help coordinate thebehavior of all the cells within that tissueExplain how proteins are targeted to various locations inside and outside of the cell. - Theseproteins have amino acid tags that ensure they are shipped back to the ER if they "escape"into the Golgi

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Describe differences between kinetic and potential energy. - Potential energy is what'savailable and kinetic energy is whats being usedExplain the first and second laws of thermodynamics in your own word - First- energy cantbe created or destroyedSecond- entropy is always increasingDescribe differences between exergonic and endergonic reactions in terms of free energychange. - Exergonic is - delta G endergonic is + delta GDescribe the structure of ATP and identify the major class of macromolecules to which ATPbelongs. - Triphosphate, adenine, ribosomes, belongs to monosaccharidesExplain how ATP performs cellular work. - Coupling exergonic reaction of atp hydrolysis withan endergonic reactionDescribe the function of enzymes in biological systems. - Catalyze a reactionExplain why an investment of activation energy is necessary to initiate a spontaneousreaction. - To speed up the rate of an exergonic reactionDescribe the induced-fit model of enzyme function. - Activation site corresponds to anenzyme shapeDescribe some mechanisms by which enzymes lower activation energy. - By speeding up areaction, stressing/destabilizing the bondsExplain how substrate concentration affects the rate of an enzyme-catalyzed reaction and,based on this, a metabolic advantage of multienzyme complexes - More substrates meanmore reactions can occurDescribe how allosteric regulators may inhibit or stimulate the activity of an enzyme. -Alters the enzyme shape which alters the function

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