cellquestion - •Nonpolar region of phospholipid. Answer:...

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Unformatted text preview: •Nonpolar region of phospholipid. Answer: C •Glycocalyx. Answer: A •Polar region of phospholipid. Answer: B •Peripheral protein. Answer: E •Integral protein. Answer: D •Identification "tags" for the cell. Answer: A • •Receptors for signal transducers. Answer: D •Hydrophilic portion. Answer: B 17) Forms part of the protein synthesis cite in the cytoplasm. Answer: 18) Act as "interpreter" molecules that recognize specific amino acids and nucleotide base sequences. Answer: 19) Attaches the correct amino acid to its transfer RNA. Answer: 20) Provides the energy needed for synthesis reactions. Answer: 21) Found in the cytoplasm, this structure specifies the exact sequence of amino acids of the protein to be made. Answer: 22) May be attached to the ER or scattered in the cytoplasm. Answer: A) Synthetase enzymes B) Messager RNA C) Transfer RNA D) Ribosomal RNA E) ATP 17) Forms part of the protein synthesis cite in the cytoplasm. Answer: D 18) Act as "interpreter" molecules that recognize specific amino acids and nucleotide base sequences. Answer: C 19) Attaches the correct amino acid to its transfer RNA. Answer: A 20) Provides the energy needed for synthesis reactions. Answer: E 21) Found in the cytoplasm, this structure specifies the exact sequence of amino acids of the protein to be made. Answer: B 22) May be attached to the ER or scattered in the cytoplasm. Answer: D A) Synthetase enzymes B) Messager RNA C) Transfer RNA D) Ribosomal RNA E) ATP 23) Chromosomes decoil to form chromatin. Answer: 24) Chromosomal centromeres split and chromosomes migrate to opposite ends of the cell. Answer: A) Early prophase B) Metaphase C) Late prophase D) Telophase E) Anaphase 25) Nuclear membrane and nucleolus disintegrate. Answer: 26) Chromosomes align on the spindle equator. Answer: 27) Centrioles move to opposite ends of the cell. Answer: 23) Chromosomes decoil to form chromatin. Answer: D 24) Chromosomal centromeres split and chromosomes migrate to opposite ends of the cell. Answer: E A) Early prophase B) Metaphase C) Late prophase D) Telophase E) Anaphase 25) Nuclear membrane and nucleolus disintegrate. Answer: C 26) Chromosomes align on the spindle equator. Answer: B 27) Centrioles move to opposite ends of the cell. Answer: A 28) Plays a role in synthesis of steroid­based hormones and proteins. Answer: 29) The actual site of protein synthesis. Answer: A) Ribosomes B) Microtubules C) Nucleoli D) Nucleus E) Endoplasmic reticulum 30) Hollow cytoskeletal elements that act as organizers for the cytoskeleton. Answer: 31) Dense spherical bodies in the nucleus that are synthesis site for ribosomal RNA. Answer: 32) Houses DNA and RNA. Answer: 28) Plays a role in synthesis of steroid­based hormones and proteins. Answer: E 29) The actual site of protein synthesis. Answer: A A) Ribosomes B) Microtubules C) Nucleoli D) Nucleus E) Endoplasmic reticulum 30) Hollow cytoskeletal elements that act as organizers for the cytoskeleton. Answer: B 31) Dense spherical bodies in the nucleus that are synthesis site for ribosomal RNA. Answer: C 32) Houses DNA and RNA. Answer: D True/False Questions 1) Each daughter cell resulting from mitotic cell division has exactly as many chromosomes as the parent cell. Answer: 2) Apoptosis is programmed cell suicide, but cancer cells fail to undergo apoptosis. Answer: 3) The spindle is formed by the migration of the chromatin. Answer: 4) Final preparation for cell division is made during the cell life cycle subphase called G2. Answer: 5) Chromatin consists of DNA and RNA. Answer: 6) In osmosis, movement of water occurs toward the solution with the lower solute concentration. Answer: 1) Each daughter cell resulting from mitotic cell division has exactly as many chromosomes as the parent cell. Answer: TRUE 2) Apoptosis is programmed cell suicide, but cancer cells fail to undergo apoptosis. Answer: TRUE 3) The spindle is formed by the migration of the chromatin. Answer: FALSE 4) Final preparation for cell division is made during the cell life cycle subphase called G2. Answer: TRUE 5) Chromatin consists of DNA and RNA. Answer: FALSE 6) In osmosis, movement of water occurs toward the solution with the lower solute concentration. Answer: FALSE 7) The genetic information is coded in DNA by the regular alternation of sugar and phosphate molecules. Answer: 8) A process by which large particles may be taken into the cell for protection of the body or for disposing of old or dead cells is called phagocytosis. Answer: 9) The orderly sequence of the phases of mitosis is prophase, metaphase, anaphase, and telophase. Answer: 10) Diffusion is always from areas of greater to areas of lesser concentration. Answer: 11) Facilitated diffusion always requires a carrier protein. Answer: 12) Pressure caused by gravity is necessary for any filtration pressure to occur in the body. Answer: 7) The genetic information is coded in DNA by the regular alternation of sugar and phosphate molecules. Answer: FALSE 8) A process by which large particles may be taken into the cell for protection of the body or for disposing of old or dead cells is called phagocytosis. Answer: TRUE 9) The orderly sequence of the phases of mitosis is prophase, metaphase, anaphase, and telophase. Answer: TRUE 10) Diffusion is always from areas of greater to areas of lesser concentration. Answer: TRUE 11) Facilitated diffusion always requires a carrier protein. Answer: FALSE 12) Pressure caused by gravity is necessary for any filtration pressure to occur in the body. Answer: FALSE 13) DNA transcription is another word for DNA replication. Answer: 14) The glycocalyx is often referred to as the "cell coat," which is somewhat fuzzy and sticky with numerous cholesterol chains sticking out from the surface of the cell membrane. Answer: 15) In their resting state, all body cells exhibit a resting membrane potential ranging from ­50 to about +50 millivolts. Answer: 16) Microfilaments are thin strands of the contractile protein myosin. Answer: 17) Interstitial fluid represents one type of extracellular material. Answer: 13) DNA transcription is another word for DNA replication. Answer: FALSE 14) The glycocalyx is often referred to as the "cell coat," which is somewhat fuzzy and sticky with numerous cholesterol chains sticking out from the surface of the cell membrane. Answer: FALSE 15) In their resting state, all body cells exhibit a resting membrane potential ranging from ­50 to about +50 millivolts. Answer: FALSE 16) Microfilaments are thin strands of the contractile protein myosin. Answer: FALSE 17) Interstitial fluid represents one type of extracellular material. Answer: TRUE 18) Hyperplasia generally means that an organ will increase in size due to the excessive formation of extracellular fluids. Answer: 19) A chemical that inhibits DNA synthesis has yet to be found in aging cells. Answer: 20) The cell (plasma) membrane normally contains substantial amounts of cholesterol. Answer: 21) Aquaporins are believed to be present in red blood cells, kidney tubules, and very few other cells in the body. Answer: 22) Most organelles are bounded by a membrane that is quite different in structure from the lipid bilayer of the plasma membrane. Answer: 18) Hyperplasia generally means that an organ will increase in size due to the excessive formation of extracellular fluids. Answer: FALSE 19) A chemical that inhibits DNA synthesis has yet to be found in aging cells. Answer: FALSE 20) The cell (plasma) membrane normally contains substantial amounts of cholesterol. Answer: TRUE 21) Aquaporins are believed to be present in red blood cells, kidney tubules, and very few other cells in the body. Answer: FALSE 22) Most organelles are bounded by a membrane that is quite different in structure from the lipid bilayer of the plasma membrane. Answer: FALSE Aquaporins: Water Channels Water crosses cell membranes by two routes: by diffusion through the lipid bilayer and through water channels called aquaporins. Major Sites of Expression Aquaporin­0 Comments Eye: lens fiber cells Red blood cells Kidney: proximal tubule Fluid balance within the lens Osmotic protection Concentration of urine Production of aqueous humor Production of cerebrospinal fluid Alveolar hydration state Mediates antidiuretic hormone activity Reabsorbtion of water into blood Secretion of water into trachea Reabsorbtion of water CSF fluid balance Osmosensing function? Bronchial fluid secretion Production of saliva Production of tears Very low water permeability; function? Transports glycerol out of adipocytes Aquaporin­1 Eye: ciliary epithelium Brain: choriod plexus Lung: alveolar epithelial cells Aquaporin­2 Aquaporin­3 * Kidney: collecting ducts Kidney: collecting ducts Trachea: epithelial cells Kidney: collecting ducts Brain: ependymal cells Brain: hypothalamus Lung: bronchial epithelium Salivary glands Lacrimal glands Kidney Fat cells Aquaporin­4 Aquaporin­5 Aquaporin­6 Aquaporin­7 * Testis and sperm Testis, pancreas, liver, others Leukocytes Aquaporin­8 Aquaporin­9 * 23) Only one cell type in the human body has a flagellum. Answer: 24) Microtubules are hollow tubes made of subunits of the protein tubulin. Answer: 25) Telomeres are the regions of chromosomes that code for the protein ubiquitin. Answer: 23) Only one cell type in the human body has a flagellum. Answer: TRUE 24) Microtubules are hollow tubes made of subunits of the protein tubulin. Answer: TRUE 25) Telomeres are the regions of chromosomes that code for the protein ubiquitin. Answer: FALSE Multiple­Choice Questions 1) W hich of the following is true regarding the generation of a membrane potential? A) Both potassium and sodium ions can "leak" through the cell membrane due to diffusion. B) In the polarized state, sodium and potassium ion concentrations are in static equilibrium. C) The maintenance of the potential is based exclusively on diffusion processes. D) W hen the sodium­potassium pump is activated, potassium is pumped into the cell twice as fast as the sodium is pumped out, thus causing the membrane potential. 2) Transcytosis is ________. A) combining an endosome with a lysosome and degrading or releasing the contents B) transporting an endosome from one side of a cell to the other and releasing the contents by exocytosis C) recycling the contents of the endosome back to the surface of the cell D) storing the contents of the endosome 1) W hich of the following is true regarding the generation of a membrane potential? A) Both potassium and sodium ions can "leak" through the cell membrane due to diffusion. B) In the polarized state, sodium and potassium ion concentrations are in static equilibrium. C) The maintenance of the potential is based exclusively on diffusion processes. D) W hen the sodium­potassium pump is activated, potassium is pumped into the cell twice as fast as the sodium is pumped out, thus causing the membrane potential. Answer: A 2) Transcytosis is ________. A) combining an endosome with a lysosome and degrading or releasing the contents B) transporting an endosome from one side of a cell to the other and releasing the contents by exocytosis C) recycling the contents of the endosome back to the surface of the cell D) storing the contents of the endosome Answer: B 3) Calcium ions are stored (in the cell) ________. A) in the smooth ER B) in the rough ER C) in both smooth and rough ER D) in the cytoplasm 3) Calcium ions are stored (in the cell) ________. A) in the smooth ER B) in the rough ER C) in both smooth and rough ER D) in the cytoplasm Answer: A 4) The RNA responsible for bringing the amino acids to the "factory" site for protein formation is the ________. A) rRNA B) mRNA C) tRNA D) ssRNA 5) A red blood cell placed in pure water would ________. A) shrink B) swell initially, then shrink as equilibrium is reached C) neither shrink nor swell D) swell and burst 4) The RNA responsible for bringing the amino acids to the "factory" site for protein formation is the ________. A) rRNA B) mRNA C) tRNA D) ssRNA Answer: C 5) A red blood cell placed in pure water would ________. A) shrink B) swell initially, then shrink as equilibrium is reached C) neither shrink nor swell D) swell and burst Answer: D 6) The plasma membrane (cell membrane) is ________. A) a single­layered membrane that surrounds the nucleus of the cell B) a double layer of protein enclosing the plasma C) the phospholipid bilayer surrounding the cell D) a membrane composed of tiny shelves or cristae 7) W hich of these is not a function of the plasma membrane? A)It is selectively permeable. B) It prevents potassium ions from leaking out and sodium ions from crossing into the cell. C) It acts as a site of cell­to­cell interaction and recognition. D) It encloses the cell contents. 6) The plasma membrane (cell membrane) is ________. A) a single­layered membrane that surrounds the nucleus of the cell B) a double layer of protein enclosing the plasma C) the phospholipid bilayer surrounding the cell D) a membrane composed of tiny shelves or cristae Answer: C 7) W hich of these is not a function of the plasma membrane? A)It is selectively permeable. B) It prevents potassium ions from leaking out and sodium ions from crossing into the cell. C) It acts as a site of cell­to­cell interaction and recognition. D) It encloses the cell contents. Answer: B 8) W hich structures are fingerlike projections that greatly increase the absorbing surface of cells? A) stereocilia B) microvilli C) cilia D) flagella 9) W hich of the following statements is correct regarding diffusion? A) The rate of diffusion is independent of temperature. B) The greater the concentration of gradient, the faster the rate of diffusion. C) Molecular weight of a substance does not affect the rate of diffusion. D) The lower the temperature, the faster the diffusion rate. 8) W hich structures are fingerlike projections that greatly increase the absorbing surface of cells? A) stereocilia B) microvilli C) cilia D) flagella Answer: B 9) W hich of the following statements is correct regarding diffusion? A) The rate of diffusion is independent of temperature. B) The greater the concentration of gradient, the faster the rate of diffusion. C) Molecular weight of a substance does not affect the rate of diffusion. D) The lower the temperature, the faster the diffusion rate. Answer: B 10) Cell junctions that promote the coordinated activity of cells by physically binding them together into a cell community include all of the following except ________. A) gap junctions B) desmosomes C) peroxisomes D) tight junctions 11) If cells are placed in a hypertonic solution containing a solute to which the membrane is impermeable, what could happen? A) The cells will swell and ultimately burst. B) The cells will lose water and shrink. C) The cells will shrink at first, but will later reach equilibrium with the surrounding solution and return to their original condition. D) The cells will show no change due to diffusion of both solute and solvent. 10) Cell junctions that promote the coordinated activity of cells by physically binding them together into a cell community include all of the following except ________. A) gap junctions B) desmosomes C) peroxisomes D) tight junctions Answer: C 11) If cells are placed in a hypertonic solution containing a solute to which the membrane is impermeable, what could happen? A) The cells will swell and ultimately burst. B) The cells will lose water and shrink. C) The cells will shrink at first, but will later reach equilibrium with the surrounding solution and return to their original condition. D) The cells will show no change due to diffusion of both solute and solvent. Answer: B 12) W hich of the following is not a subcellular structure? A) intercellular material B) membranes C) cytoplasm D) organelles 13) Once solid material is phagocytized and taken into a vacuole, which of the following statements best describes what happens? A) A ribosome enters the vacuole and uses the amino acids in the "invader" to form new protein. B) A lysosome combines with the vacuole and digests the enclosed solid material. C) The vacuole remains separated from the cytoplasm and the solid material persists unchanged. D) Oxygen enters the vacuole and "burns" the enclosed solid material. 12) W hich of the following is not a subcellular structure? A) intercellular material B) membranes C) cytoplasm D) organelles Answer: A 13) Once solid material is phagocytized and taken into a vacuole, which of the following statements best describes what happens? A) A ribosome enters the vacuole and uses the amino acids in the "invader" to form new protein. B) A lysosome combines with the vacuole and digests the enclosed solid material. C) The vacuole remains separated from the cytoplasm and the solid material persists unchanged. D) Oxygen enters the vacuole and "burns" the enclosed solid material. Answer: B 14) Riboswitches are folded RNAs that act as switches to turn protein synthesis on or off in response to _________. A) changes in the environment B) specific tRNAs C) specific codes from the DNA D) presence or absence of ubiquitins 15) W hich of the following is a function of a plasma membrane protein? A) circulating antibody B) molecular transport through the membrane C) forms a lipid bilayer D) oxygen transport 14) Riboswitches are folded RNAs that act as switches to turn protein synthesis on or off in response to _________. A) changes in the environment B) specific tRNAs C) specific codes from the DNA D) presence or absence of ubiquitins Answer: A 15) W hich of the following is a function of a plasma membrane protein? A) circulating antibody B) molecular transport through the membrane C) forms a lipid bilayer D) oxygen transport Answer: B 16) W hich of the following statements is correct regarding RNA? A) Messenger RNA, transfer RNA, and ribosomal RNA play a role in protein synthesis. B) If the base sequence of DNA is ATTGCA, the messenger RNA template will be UCCAGU. C) There is a specific type of mRNA for each amino acid. D) rRNA is always attached to the rough ER. 17) W hich of the following would not be a constituent of a plasma membrane? A)glycolipids B) messenger RNA C) glycoproteins D) phospholipids 16) W hich of the following statements is correct regarding RNA? A) Messenger RNA, transfer RNA, and ribosomal RNA play a role in protein synthesis. B) If the base sequence of DNA is ATTGCA, the messenger RNA template will be UCCAGU. C) There is a specific type of mRNA for each amino acid. D) rRNA is always attached to the rough ER. Answer: A 17) W hich of the following would not be a constituent of a plasma membrane? A)glycolipids B) messenger RNA C) glycoproteins D) phospholipids Answer: B 18) Mitosis is ________. A) formation of sex cells B) nucleus replication C) to create diversity in genetic potential D) division of a cell 19) The electron microscope has revealed that one of the components within the cell consists of microtubules arranged to form a hollow tube. This structure is ________. A) centrosome B) centriole C) chromosome D) ribosome 18) Mitosis is ________. A) formation of sex cells B) nucleus replication C) to create diversity in genetic potential D) division of a cell Answer: B 19) The electron microscope has revealed that one of the components within the cell consists of microtubules arranged to form a hollow tube. This structure is ________. A) centrosome B) centriole C) chromosome D) ribosome Answer: B 20) W hich of these is an inclusion, not an organelle? A) melanin B) lysosome C) microtubule D) cilia 21) Hyperplasia means __________. A) programmed cell death B) abnormalities in cell structure C) a condition where the cell overproduces "cell glue" D) accelerated growth 20) W hich of these is an inclusion, not an organelle? A) melanin B) lysosome C) microtubule D) cilia Answer: A 21) Hyperplasia means __________. A) programmed cell death B) abnormalities in cell structure C) a condition where the cell overproduces "cell glue" D) accelerated growth Answer: D 22) If the nucleotide or base sequence of the DNA strand used as a template for messenger RNA synthesis is ACGTT, then the sequence of bases in the corresponding mRNA would be ________. A) TGCAA B) ACGTT C) UGCAA D) GUACC 23) W hich of the following is true regarding cells in humans? A) Organelles are independent life forms. B)Maximum cell diameter is limited to 2 micrometers. C) Cells can be as long as 1 meter. D) Most cells of an adult have a very short life span. 22) If the nucleotide or base sequence of the DNA strand used as a template for messenger RNA synthesis is ACGTT, then the sequence of bases in the corresponding mRNA would be ________. A) TGCAA B) ACGTT C) UGCAA D) GUACC Answer: C 23) W hich of the following is true regarding cells in humans? A) Organelles are independent life forms. B)Maximum cell diameter is limited to 2 micrometers. C) Cells can be as long as 1 meter. D) Most cells of an adult have a very short life span. Answer: C 24) Phospholipids ________. A) are exclusively hydrophilic molecules B) contain polar tails and nonpolar head groups C) are both hydrophilic and hydrophobic in nature D) form the lipid bilayer, with tails directed to the outside 25) Passive membrane transport processes include ________. A) movement of a substance down its concentration gradient B) movement of water from an area of low concentration to an area of high concentration C) consumption of ATP D) the use of transport proteins when moving substances from areas of low to high concentration 26) Enzymes called _________ destroy the cell's DNA and cytoskeleton, producing a quick death to the cell. A) ubiquitins B) cyclins C) capsases D) DNA polymerase III 24) Phospholipids ________. A) are exclusively hydrophilic molecules B) contain polar tails and nonpolar head groups C) are both hydrophilic and hydrophobic in nature D) form the lipid bilayer, with tails directed to the outside Answer: C 25) Passive membrane transport processes include ________. A) movement of a substance down its concentration gradient B) movement of water from an area of low concentration to an area of high concentration C) consumption of ATP D) the use of transport proteins when moving substances from areas of low to high concentration Answer: A 26) Enzymes called _________ destroy the cell's DNA and cytoskeleton, producing a quick death to the cell. A) ubiquitins B) cyclins C) capsases D) DNA polymerase III Answer: C 27) Mitochondria ________. A) are always the same shape B) are single­membrane structures involved in the breakdown of ATP C) contain some of the code necessary for their own duplication D) synthesize proteins for use outside the cell 28) Ribosomes, endoplasmic reticulum, and the Golgi apparatus functionally act in sequence to synthesize and modify proteins for secretory use (export) only, never for use by the cell. This statement is ________. A) false; proteins thus manufactured are for use inside the cell only B) false; integral cell membrane proteins are also synthesized this way C) false; lipids, not proteins, are synthesized this way D) true 27) Mitochondria ________. A) are always the same shape B) are single­membrane structures involved in the breakdown of ATP C) contain some of the code necessary for their own duplication D) synthesize proteins for use outside the cell Answer: C 28) Ribosomes, endoplasmic reticulum, and the Golgi apparatus functionally act in sequence to synthesize and modify proteins for secretory use (export) only, never for use by the cell. This statement is ________. A) false; proteins thus manufactured are for use inside the cell only B) false; integral cell membrane proteins are also synthesized this way C) false; lipids, not proteins, are synthesized this way D) true Answer: B 29) Peroxisomes ________. A) also called microbodies, contain acid hydrolases B) are able to detoxify substances by enzymatic action C) function to digest particles ingested by endocytosis D) sometimes function as secretory vesicles 30) DNA replication ________. A) can also be called mitosis B)is spontaneous, not requiring enzyme action C)takes place during interphase of the cell cycle D) occurs only in translationally active areas 29) Peroxisomes ________. A) also called microbodies, contain acid hydrolases B) are able to detoxify substances by enzymatic action C) function to digest particles ingested by endocytosis D) sometimes function as secretory vesicles Answer: B 30) DNA replication ________. A) can also be called mitosis B)is spontaneous, not requiring enzyme action C)takes place during interphase of the cell cycle D) occurs only in translationally active areas Answer: C 31) W hich statement is the most correct regarding transcription/translation? A) The nucleotide sequence in a mRNA codon is an exact copy of the DNA triplet that coded for it. B) The nucleotide sequence in a mRNA codon is an exact copy of the DNA triplet that coded for it except that uracil is substituted for thymine. C) The nucleotide sequence in a tRNA anticodon is an exact copy of the DNA triplet that coded for it. D) The nucleotide sequence in a tRNA anticodon is an exact copy of the DNA triplet that coded for it except that uracil is substituted for thymine. 32) In the maintenance of the cell resting membrane potential ________. A) extracellular sodium levels are high B) cells are more permeable to Na+ than K+ C) the steady state involves only passive processes D) the inside of the cell is positive relative to its outside 31) W hich statement is the most correct regarding transcription/translation? A) The nucleotide sequence in a mRNA codon is an exact copy of the DNA triplet that coded for it. B) The nucleotide sequence in a mRNA codon is an exact copy of the DNA triplet that coded for it except that uracil is substituted for thymine. C) The nucleotide sequence in a tRNA anticodon is an exact copy of the DNA triplet that coded for it. D) The nucleotide sequence in a tRNA anticodon is an exact copy of the DNA triplet that coded for it except that uracil is substituted for thymine. Answer: D 32) In the maintenance of the cell resting membrane potential ________. A) extracellular sodium levels are high B) cells are more permeable to Na+ than K+ C) the steady state involves only passive processes D) the inside of the cell is positive relative to its outside Answer: A 33) W hich of the following is a concept of the cell theory? A) Simple cells can arise spontaneously from rotting vegetation. B) A cell is the basic structural and functional unit of living organisms. C) The subcellular organelle is the basic unit of life. D) Only higher organisms are composed of cells. 34) Cells are composed mainly of ________. A) carbon, potassium, sodium, nitrogen B) carbon, sodium, nitrogen, calcium C) calcium, oxygen, sodium, potassium D) carbon, hydrogen, nitrogen, oxygen 33) W hich of the following is a concept of the cell theory? A) Simple cells can arise spontaneously from rotting vegetation. B) A cell is the basic structural and functional unit of living organisms. C) The subcellular organelle is the basic unit of life. D) Only higher organisms are composed of cells. Answer: B 34) Cells are composed mainly of ________. A) carbon, potassium, sodium, nitrogen B) carbon, sodium, nitrogen, calcium C) calcium, oxygen, sodium, potassium D) carbon, hydrogen, nitrogen, oxygen Answer: D 35) W hich of the following is a principle of the fluid mosaic model of cell membrane structure? A) Phospholipids form a bilayer that is largely impermeable to water­soluble molecules. B) Phospholipids consist of a polar head and a nonpolar tail made of three fatty acid chains. C)The lipid bilayer is a solid at body temperature, thus protecting the cell. D) All proteins associated with the cell membrane are contained in a fluid layer on the outside of the cell. 36) W hich of the following statements is most correct regarding the intracellular chemical signals known as "second messengers"? A) Second messengers act through receptors called K­proteins. B) Second messengers usually inactivate protein kinase enzymes. C) Cyclic AMP and calcium are second messengers. D) Second messengers usually act to remove nitric oxide (NO) from the cell. 35) W hich of the following is a principle of the fluid mosaic model of cell membrane structure? A) Phospholipids form a bilayer that is largely impermeable to water­soluble molecules. B) Phospholipids consist of a polar head and a nonpolar tail made of three fatty acid chains. C)The lipid bilayer is a solid at body temperature, thus protecting the cell. D) All proteins associated with the cell membrane are contained in a fluid layer on the outside of the cell. Answer: A 36) W hich of the following statements is most correct regarding the intracellular chemical signals known as "second messengers"? A) Second messengers act through receptors called K­proteins. B) Second messengers usually inactivate protein kinase enzymes. C) Cyclic AMP and calcium are second messengers. D) Second messengers usually act to remove nitric oxide (NO) from the cell. Answer: C 37) The main component of the cytosol is ________. A) proteins B) sugars C) salts D) water 38) Lysosomes ________. A)are used mainly for the cell to "commit suicide" B)contain acid hydrolases that are potentially dangerous to the cell C)maintain a highly alkaline internal environment D) are the major site of protein synthesis 37) The main component of the cytosol is ________. A) proteins B) sugars C) salts D) water Answer: D 38) Lysosomes ________. A)are used mainly for the cell to "commit suicide" B)contain acid hydrolases that are potentially dangerous to the cell C)maintain a highly alkaline internal environment D) are the major site of protein synthesis Answer: B 39) The endomembrane system is ________. A) a system by which cells are riveted together by desmosomes B) an interactive system of organelles whose membranes are physically or functionally connected C) the process by which bacteria took up residence in ancient cells D) a system of hydrophilic lipid monolayers that surround cell organelles 40) The functions of centrioles include ________. A) organizing the mitotic spindle in cell division B) providing a whiplike beating motion to move substances along cell surfaces C) serving as the site for ribosomal RNA synthesis D) producing ATP 39) The endomembrane system is ________. A) a system by which cells are riveted together by desmosomes B) an interactive system of organelles whose membranes are physically or functionally connected C) the process by which bacteria took up residence in ancient cells D) a system of hydrophilic lipid monolayers that surround cell organelles Answer: B 40) The functions of centrioles include ________. A) organizing the mitotic spindle in cell division B) providing a whiplike beating motion to move substances along cell surfaces C) serving as the site for ribosomal RNA synthesis D) producing ATP Answer: A 41) A gene can best be defined as ________. A) a three­base triplet that specifies a particular amino acid B) noncoding segments of DNA up to 100,000 nucleotides long C) a segment of DNA that carries the instructions for one polypeptide chain D) an RNA messenger that codes for a particular polypeptide 41) A gene can best be defined as ________. A) a three­base triplet that specifies a particular amino acid B) noncoding segments of DNA up to 100,000 nucleotides long C) a segment of DNA that carries the instructions for one polypeptide chain D) an RNA messenger that codes for a particular polypeptide Answer: C 42) Extracellular matrix is ________. A) composed of strands of actin protein B) the most abundant extracellular material C) a type of impermeable cell junction found in epithelia D) not present in connective tissue 43) Crenation is an example of ________. A) blood cells in an isotonic solution B) blood cells in a hypotonic solution C)blood cells in a hypertonic solution D) blood cells in blood plasma 42) Extracellular matrix is ________. A) composed of strands of actin protein B) the most abundant extracellular material C) a type of impermeable cell junction found in epithelia D) not present in connective tissue Answer: B 43) Crenation is an example of ________. A) blood cells in an isotonic solution B) blood cells in a hypotonic solution C)blood cells in a hypertonic solution D) blood cells in blood plasma Answer: C 44) Some hormones enter cells via ________. A) exocytosis B) endocytosis C) pinocytosis D) receptor­mediated endocytosis 45) If a tRNA had an AGC anticodon, it could attach to a(n) ________ mRNA codon. A) AUG B) UCG C) TCG D) UGA 44) Some hormones enter cells via ________. A) exocytosis B) endocytosis C) pinocytosis D) receptor­mediated endocytosis Answer: D 45) If a tRNA had an AGC anticodon, it could attach to a(n) ________ mRNA codon. A) AUG B) UCG C) TCG D) UGA Answer: B Fill­in­the­Blank/Short Answer Questions 1) The RNA that has an anticodon and attaches to a specific amino acid is ________ RNA. Answer: 2) W ater may move through membrane pores constructed by transmembrane proteins called ________. Answer: 3) ________ is the division of the cytoplasm. Answer: 4) The metabolic or growth phase of a cell life cycle is called ________. Answer: 5) In order for the DNA molecule to get "short and fat" to become a chromosome, it must first wrap around small molecules called ________. Answer: 1) The RNA that has an anticodon and attaches to a specific amino acid is ________ RNA. Answer: transfer 2) W ater may move through membrane pores constructed by transmembrane proteins called ________. Answer: aquaporins 3) ________ is the division of the cytoplasm. Answer: Cytokinesis 4) The metabolic or growth phase of a cell life cycle is called ________. Answer: interphase 5) In order for the DNA molecule to get "short and fat" to become a chromosome, it must first wrap around small molecules called ________. Answer: histones 6) ________ are hollow tubes made of spherical protein subunits called tubulins. Answer: 7) Aerobic cellular respiration occurs in the ________. Answer: 8) Two very important second messengers used in the G protein­linked receptor mechanism are cyclic AMP and ________. Answer: 9) The most common extracellular ion is ________. Answer: 10) The process of discharging particles from inside a cell to the outside is called ________. Answer: 11) A red blood cell would swell if its surrounding solution were ________. Answer: 6) ________ are hollow tubes made of spherical protein subunits called tubulins. Answer: Microtubules 7) Aerobic cellular respiration occurs in the ________. Answer: mitochondria 8) Two very important second messengers used in the G protein­linked receptor mechanism are cyclic AMP and ________. Answer: ionic calcium 9) The most common extracellular ion is ________. Answer: sodium 10) The process of discharging particles from inside a cell to the outside is called ________. Answer: exocytosis 11) A red blood cell would swell if its surrounding solution were ________. Answer: hypotonic 12) A ________ is a channel between cells. Answer: 13) Describe two important functions of the Golgi apparatus. Answer:. 14)W hy can we say that a cell without a nucleus will ultimately die? Answer: 15) Are Brownian motion, diffusion, and osmosis seen only in living tissue? Answer:. 16) W hat forces maintain a steady state "resting" membrane potential? Answer: 12) A ________ is a channel between cells. Answer: connexon 13) Describe two important functions of the Golgi apparatus. Answer: To modify, sort, and package proteins. 14)W hy can we say that a cell without a nucleus will ultimately die? Answer: W ithout a nucleus, a cell cannot make proteins, nor can it replace any enzymes or other cell structures (which are continuously recycled). Additionally, such a cell could not replicate. 15) Are Brownian motion, diffusion, and osmosis seen only in living tissue? Answer: No. Since they are passive processes that do not require energy, they can occur in the absence of any cellular processes. 16) W hat forces maintain a steady state "resting" membrane potential? Answer: Both diffusion and active transport mechanisms operate within the cell membrane to maintain a resting membrane potential. 17) Briefly describe the glycocalyx and its functions. Answer: 18) Explain the term genetic code. What does it code for? What are the letters of the code? Answer: 19) W hy are free radicals so dangerous to cells, and how are they dealt with by the body? Answer: 17) Briefly describe the glycocalyx and its functions. Answer: The glycocalyx is the sticky, carbohydrate­rich area on the cell surface. It helps bind cells together and provides a highly specific biological marker by which cells can recognize each other. 18) Explain the term genetic code. What does it code for? What are the letters of the code? Answer: The genetic code is the information encoded in the nucleotide base sequence of DNA. A sequence of three bases, called a triplet, specifies amino acid in a protein. The letters of the code are the four nucleotide bases of DNA designated as A, T, C, and G. 19) W hy are free radicals so dangerous to cells, and how are they dealt with by the body? Answer: Free radicals are highly reactive chemicals that cause havoc in any cellular environment by reacting with things they should not. Cells with peroxisomes have enzymes specific to reducing free radicals into less reactive chemicals 20) In all living cells hydrostatic and osmotic pressures exist. Define these pressures and explain how they are used in the concept of tonicity of the cell. Answer: 21) W hat is the common route of entry for flu viruses into a cell? Answer: 22) W hich organelles have their own DNA? Answer: 20) In all living cells hydrostatic and osmotic pressures exist. Define these pressures and explain how they are used in the concept of tonicity of the cell. Answer: Hydrostatic pressure is the pressure of water exerted on the cell membrane. Osmotic pressure is created by different concentrations of molecules in a solution separated by the cell membrane. Since these pressures are exerted on the membrane they can be used by the cell to change the shape of the cell, regulate substances entering and exiting the cell, and bring about the polarity of the cell. 21) W hat is the common route of entry for flu viruses into a cell? Answer: Flu viruses and diphtheria toxins use receptor­mediated endocytosis. The virus can attach to the receptors or to the substances the receptors accept to "hitch a ride" into the cell. 22) W hich organelles have their own DNA? Answer: Mitochondria, nucleus, and centrioles 23) How are the products of free ribosomes different from membrane­bound ribosomes? Answer: 24) How are peroxisomes different from lysosomes? Answer: 25) Briefly name the subphases of interphase and tell what they do. Answer: 23) How are the products of free ribosomes different from membrane­bound ribosomes? Answer: Free ribosomes make soluble proteins that function in the cytosol. Membrane­bound ribosomes produce proteins that are to be used on the cell membrane or exported from the cell. 24) How are peroxisomes different from lysosomes? Answer: Some of the peroxisomes are oxidases which use oxygen to detoxify harmful substances. They are very good at neutralizing free radicals. Peroxisomes divide by simply budding. Lysosomes have powerful hydrol ytic enzymes that will pretty much destroy anything they come in contact with. They are manufactured by the Golgi apparatus. 25) Briefly name the subphases of interphase and tell what they do. Answer: G1 ­ growth phase. The cell is metabolically active and the centriole begins to divide at the end of this phase. S ­ DNA replicates itself. New histones are made and assembled into chromatin. G2 ­ Enzymes and proteins are synthesized and centriole replication is completed. This is the final phase of interphase ...
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