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BS161 Biology Final Exam With Answers (272 Solved Questions)

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    VERSION 2 Compare 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 partially positive hydrogen bonds to other partially negative oxygens why polar and charged species dissolve in water - molecules that have partially positive and partially negative areas are polar and can be dissolved in water water can attract charged particles because it has partially positive and negative areas and if the attractions between the ions and water are stronger than attractions between ions it will dissolve in water bonds between solute compound are disrupted in order to increase bond length and allow aqueous solution to flow through why oil will not dissolve in water - water is polar and oil is nonpolar so their molecules do not attract each other List 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 chain Secondary- alpha helix beta pleated sheets Tertiary- proteins or polypeptides Quaternary- multiple polypeptides Define a lipid. - Insoluble in water and soluble in organic substances Draw the difference between saturated and unsaturated fats - Unsaturated has double bonds, 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 have more hydrogens, the more hydrogens there are the more concentrated it is therefore the more solid it is Define a biological membrane. - Selectively permeable barrier between living things Describe the fluid mosaic model of membrane structure. - Different transport proteins that allow ions to be diffused through a bilayer Describe difference between peripheral and integral membrane proteins. - Integral proteins are on the inside and nonpolar regions of membranes of hydrophobic layer and peripheral proteins are on the surface and it is on mitochondria and chloroplasts List six major functions of membrane proteins. - Transporters enzymes- carry out chemical reactions cell surface receptors- detect chemical messages and anchors to surface cell surface id receptors cell to cell adhesion proteins cytoskeleton proteins Explain why the lipid bilayer of a biological membrane forms spontaneously. - Doesn't need outside source of energy to form Explain the meaning of the statement "Phospholipids and most other membrane constituents (e.g., proteins) are amphipathic molecules." - Phospholipids are both hydrophobic and hydrophilic Explain how membrane fluidity is influenced by temperature. - lower temperature higher fluidity- unsaturated fats

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    Explain how cholesterol resists changes in membrane fluidity as temperatures change. - At moderate temperature, reduces fluidity bc reduces phospholipid movement At lower temperature, stops solidification Explain the role of membrane carbohydrates in cell-cell recognition. - Bond to lipids or proteins, function as markers to distinguish from one another Explain how the polarity of a molecule affects how it moves across a membrane. - Nonpolar can move across membrane, polar can't without carrier protein Describe the difference between channel proteins and carrier proteins. - Both transport substances across cell membrane but carrier proteins change shape as they transport Explain how aquaporins facilitate the passage of water through membranes. - Channel proteins with water, water molecules travel through a pore in a single file Define diffusion. - Moving protein from higher to lower concentration Explain why diffusion is a passive and spontaneous process. - Energy doesn't need to be inputted Explain why a concentration gradient of a substance across a membrane represents potential energy. - Drives diffusion Describe differences between solutions that are hypertonic, hypotonic, and isotonic to cell contents. - Hypertonic- shrivels bc concentration on outside is higher Hypotonic- swells bc concentration on inside is higher Isotonic- neutral Define osmosis and predict the direction of water movement based on differences in solute concentrations. - 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. - Vacuoles regulate water levels in plant cells Osmosis for cells without cell walls Describe differences between osmosis, facilitated diffusion, and active transport. - Osmosis is diffusion in water facilitated goes with concentration gradient and doesn't need energy active transport goes against and needs energy Explain how transport proteins facilitate diffusion. - Go from higher concentration to lower concentration Describe how solutes can move against their concentration gradient. - Go through active transport Describe the process of co-transport - Active transport is indirectly driven by ATP powered pump Explain how large molecules are transported across a cell membrane. - Exocytosis- secretes large molecules by the fusion of vesicles Identify the common structural components of prokaryotic and eukaryotic cells and describe their functions and interactions. - Eukaryotic has membrane bound organelles, mitochondria, nucleus, animal cells Prokaryotic has nucleoid, and chloroplast, has DNA in cytoplasm, plant cells Explain why there are both upper and lower limits to cell size. - If structure is not big enough to 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 maintain Describe the structure and function of the nuclear envelope. - Double layer membrane allows passage of materials into and outside the nucleus Explain how the nucleus controls protein synthesis in the cytoplasm. - Translates dna into mrna and mrna leaves nucleus through envelopes and once in the cytoplasm the mrna binds to the ribosomes and initiates protein synthesis Explain the role of the nucleolus in protein synthesis. - Breaks nucleotide link between dna and rna Describe the differences between free and bound ribosomes in terms of location and function - Bound ribosomes are attached to the rough er and free ribosomes are in the cytoplasm and they are used for protein synthesis Describe the structure and function of each component of the endomembrane system. - nuclear envelope: a double membrane perforated by pores that regulate the movement of materials between the nucleus and the cytoplasm endoplasmic reticulum: continuous with the nuclear envelope and encloses a network of interconnected tubules or compartments called cisternae Golgi apparatus: consists of a stack of flattened sacs Lysosome: membrane-enclosed sacs of hydrolytic enzymes used by animal cells to digest macromolecules Vacuoles: formed as a result of phagocytosis Plasma membrane: surrounding every cell must provide sufficient surface area for exchange 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 serves diverse functions in different cells: its enzymes are involved in phosopholipids and steroids (including sex hormone) synthesis, carbohydrate metabolism, and detoxification of drugs and poisons. The smooth ER is also in st- The rough ER manufactures membranes from the cell. Enzymes built into the membrane assemble phospholipids, and membrane proteins formed by bound ribosomes are inserted into the ER membrane Explain the significance of the cis and trans sides of the Golgi apparatus. - Cis and trans help direct the vesicles to the plasma membrane or to other organelles Explain how a protein travels through the endomembrane system - Protein carriers Describe three examples of intracellular digestion by lysosomes. - Phagocytosis- engulfing of debris Pinocytosis- engulfing of liquid Macrophages - are also in intracellular digestion by lysosomes that is a type of white blood cells that is made to destroy ingested bacteria Explain why pH is important for lysosomal function. - pH has to be acidic for lysosomes to be able to digest cellular debris lysosomes are sacs containing digestive enzymes Describe the structure of a mitochondrion - Two membranes, each a phospholipid bilayer with unique embedded proteins, encloses the mitochondrion. A narrow intermembrane space exists between the smooth outer membrane and the convoluted inner membrane, called cristae, create a large surface area and encloses the mitochondrial matrix. Many respiratory enzymes, mitochondrial DNA, and ribosomes are housed in this matrix. Other respiratory enzymes and proteins are built into the inner membrane Identify the three functional compartments of a chloroplast. - The stroma is in the inner membrane 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 in the thylakoids, which may be stacked together to form structures called grana Describe the evidence that mitochondria and chloroplasts are semiautonomous organelles. - Both have 2 membranes, releases energy Explain the roles of peroxisomes in eukaryotic cells. - Peroxisomes are oxidative organelles filled with enzymes that function in a variety of metabolic pathways, such as breaking down fatty acids for energy or detoxifying alcohol and other poisons Describe the functions of the cytoskeleton - The cytoskeleton is a network of protein fibers that give mechanical support, function in cell motility (of both internal structures and the cell as a whole), and transmit mechanical signals from the cell's surface to its interior. It also interacts with special proteins called motor proteins to produce cellular movements Compare the structures and functions of microtubules, microfilaments, and intermediate filaments of the cytoskeleton - Microtubules -have hollow rods constructed of columns of globular proteins called tubulins. Microtubules change length through the addition or subtraction 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 the globular protein actin. Actin filaments are microfilaments function in support forming a network just inside the plasma membrane and the core of small cytoplasmic extensions called microvilli Intermediate filaments- Intermediate filaments are intermediate in size between microtubules and microfilaments are more diverse in their composition. Intermediate fibers appear to be important in maintaining cell shape. The nucleus is securely help in a web of intermediate filaments, and the nuclear lamina lining the inside of the nuclear envelope is composed 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 of cellulose embedded in a matrix of polysaccharides and protein Describe the structure and roles of the extracellular matrix in animal cells. - Animal cells lack cell walls but are covered by an elaborate extracellular matrix (ECM). The ECM is made up of glycoproteins such as collagen, proteoglycans, and fibronectin. ECM proteins bind to receptor proteins in the plasma membrane called integrins Describe the function of each type of intercellular junction in plants and animals. - Plasmodesmata: channels in plant cell walls through which the plasma membranes of bordering cells connect, thus linking most cells of a plant into a living continuum. Three intercellular junctions between animal cells are: Tight junction: where proteins hold adjacent cell membranes tightly together, creating an impermeable seal across a layer of epithelial cells Desmosomes (anchoring junctions): reinforced by intermediate filaments and rivet cells into strong sheets Gap junctions (communicating junctions): are cytoplasmic connections that allow for the exchange of ions and small molecules between cells through protein-lined pores Explain how the extracellular matrix integrates changes inside and outside the cell. - The main ingredients of the ECM are glycoproteins. The most abundant of these glycoproteins is collagen, which forms strong fibers outside of cells. The collagen fibers are woven in a network of proteoglycans. Communicating with a cell through integrins, the ECM can regulate a cell's behavior. The ECM around a cell can also influence the activity of genes in the nucleus. The extracellular matrix of a particular tissue could help coordinate the behavior of all the cells within that tissue Explain how proteins are targeted to various locations inside and outside of the cell. - These proteins 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's available and kinetic energy is whats being used Explain the first and second laws of thermodynamics in your own word - First- energy cant be created or destroyed Second- entropy is always increasing Describe differences between exergonic and endergonic reactions in terms of free energy change. - Exergonic is - delta G endergonic is + delta G Describe the structure of ATP and identify the major class of macromolecules to which ATP belongs. - Triphosphate, adenine, ribosomes, belongs to monosaccharides Explain how ATP performs cellular work. - Coupling exergonic reaction of atp hydrolysis with an endergonic reaction Describe the function of enzymes in biological systems. - Catalyze a reaction Explain why an investment of activation energy is necessary to initiate a spontaneous reaction. - To speed up the rate of an exergonic reaction Describe the induced-fit model of enzyme function. - Activation site corresponds to an enzyme shape Describe some mechanisms by which enzymes lower activation energy. - By speeding up a reaction, stressing/destabilizing the bonds Explain how substrate concentration affects the rate of an enzyme-catalyzed reaction and, based on this, a metabolic advantage of multienzyme complexes - More substrates mean more reactions can occur Describe how allosteric regulators may inhibit or stimulate the activity of an enzyme. - Alters the enzyme shape which alters the function

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