Solution Manual For Hole's Essentials of Human Anatomy and Physiology, 14th Edition

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1ANSWERS TOPRACTICE QUESTIONSChapter1Practice1.11.What factors probably stimulated an early interest in the human body?Factors include attempting to understand the causes of various injuries,illnesses,and theloss of function of body parts,and tryingto treat these conditions.2.What kinds of activities helped promote the development of modern medical science?Activities include dissection of cadavers, the production of prosthetic body parts,experimentation to improve medical knowledge and techniques, and the discovery of certainchemicals in nature as treatments for specific conditions.Practice1.21.Why is it difficult to separate the topics of anatomy and physiology?Structure is closely related to function; body parts are shaped and arranged (anatomy) insuch a way that they are able to perform their functions (physiology).2.List examples that illustrate how the structure of a body part makes possible itsfunction.The front teeth (incisors) are pointed for grasping and tearing food, while the back teeth(molars) are flattened for grinding food. Thejointedstructure of the bones of thefingersallow us to grasp objects. The cone-shaped, chambered heartpumps blood through theblood vessels. The tubular blood vessels transport blood to the cells of the body.Practice1.31.How does the human body illustrate levels of organization?Larger structures are composed of smaller and smaller components. For example, the bodyconsists of several systems, such as thecardiovascularsystem. Thecardiovascularsystemconsists of organs, such as theheartandblood vessels. Theheartis composed of tissues,which consist of layers of cells. Cellsare composedof organelles, whichconsist ofmolecules, andfinally,atoms.2.What is an organism?An organism is a complete unit of life. Organisms range in size fromasingle cell toacomplex living thing,likeahuman, whichiscomposed of trillions ofcells. Humans, ascomplex organisms, are composed of organ systems, organs, tissues, cells, molecules,andatoms

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23.How do body parts at different levels of organization vary incomplexity?Typically, the higher the level of organization a structure ispart of, the more complex it is.For example, a molecule is composed oftwoor more atoms; therefore,a molecule is morecomplex than an atom. An organ system, such as thecardiovascularsystem, is composedof organs, such as theheart and blood vessels. Therefore, an organ system is morecomplex than any of its organs.Practice1.41.What are the characteristics of life?The characteristics of life are properties that all living organisms exhibit. They includemovement,reproduction,responsiveness, growth,and metabolism, which in turn consists ofthe processes ofrespiration, digestion, circulation, and excretion.2.How are the characteristics of life dependent on metabolism?Metabolism is the sum of all of the chemical reactions that occur in the cells. Metabolismsupports life processes. For example, digestion of food is accomplished bymetabolicreactions that break down the food into smaller particles that can be absorbed across themembrane of the small intestine. Once absorbed, food particles are circulated,and used forgrowth, movement, and reproduction. Wastes from food are excreted.Practice1.51.Which requirements of organisms does the external environment provide?Theenvironment provides water, food, oxygen, heat,and pressure.2.Why is homeostasis important to survival?Homeostasis is the maintenance of a stable internal environment, whichconsists ofthe fluidaround our body cells.Changes in the external environment affect the internal environment,and therefore, the health of our cells. Cells, tissues, organs, and systems function properlyonly in the presence of certain concentrations of water, oxygen,hydrogen ions (pH),andnutrients, and specific conditions of heat and pressure.Having enough water in our cellsprevents dehydration, shrinkage of cell nuclei, and cell death. Homeostatic pH preventsirreversible alteration of enzyme structure (denaturation) and function.3.Describe two homeostatic mechanisms.Negative feedback is a common homeostatic mechanism.When a variable deviates from itsset point, this mechanism activates effectors that return the variable toward its normal range.For example, if a person is too hot, sweating and increased blood flow to the skinreturn thebody temperature to its normal range. A less common mechanism is positive feedback, inwhich a change in a variable leads to further change. During blood clotting, certainchemicals stimulate further blood clotting, to stop the bleeding.

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3Practice1.61.Which organ occupies the cranial cavity?The vertebral canal?The brainoccupies the cranial cavity, and the spinal cord occupies the vertebral canal.2.What doesvisceramean?“Viscera” refers to the organs within the thoracic and abdominopelvic cavities.3.Name the cavities of the head.Thesmallcavities of the head include the oral cavity, nasal cavity, orbital cavities, andmiddle ear cavities.The cranial cavity is the large cavity of the head; it is occupied by thebrain.4.Describe the membranes associated with the thoracic and abdominopelviccavities.Double-layered serous membranes line thewalls of the thoracic and abdominopelviccavities and surround each organ. The parietal layer lines the wall of the cavity, and thevisceral layer surrounds an organ. Between the layers is a potential space, or cavity,filled with lubricating fluid. The pleural membranes surround the lungs, the pericardialmembrane surrounds the heart, and the peritoneal membrane surrounds theabdominopelvic organs.5.Name and list the organs of the major organ systems.Integumentary system: skin, hair, nails, sweat and sebaceous glandsSkeletal system: bonesMuscular system: musclesNervous system: brain, spinal cord, nerves,andsense organsEndocrine system: endocrine glandsCardiovascular system: heart, arteries, veins, capillaries,andbloodLymphatic system: lymph nodes, thymus,andspleenDigestive system: mouth, teeth, tongue, pharynx, esophagus, stomach, small intestine,large intestine, salivary glands, liver, pancreas,andgallbladderRespiratory system: nasal cavity, pharynx, larynx, trachea, bronchi,andlungsUrinary system: kidneys, ureters, urinary bladder,andurethraReproductive systemof male:scrotum, testes, epididymides, ductus deferentia, seminalvesicles, prostate gland, bulbourethral glands, penis, and urethra

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4Reproductive systemof female:ovaries, uterine tubes, uterus, vagina, clitoris, and vulva6.Describe the general functions of each organ system.Integumentary system:Protects internal structures, regulatesbody temperature, detectschanges in environment via sensory receptors, and synthesizes specific chemicals, such asvitamin DSkeletal system:Provides a framework for the body, supports and protects internal organsand soft tissues, helps with body movements, produces blood cells, and stores inorganicsalts, such as calcium saltsMuscular system:Provides force to move body parts, maintains posture, and produces mostofthebody heatNervous system:Regulates and adjusts organ function for homeostasis;communicates vianerve impulses tohelp detect changes in the environment, integrate information, andrespond to this information by stimulating muscles and glandsEndocrine system:Regulates and adjusts organ function for homeostasis, andcommunicates via hormone secretion into body fluids; each hormone alters metabolism ofspecific target cellsCardiovascular system:Transportsred and white blood cells, platelets,respiratory gases,nutrients, hormones, and wastes throughout the bodyLymphatic system:Defends the body against infection and disease, transports some tissuefluid back to the bloodstream, and carries large fats from the digestive system to the generalcirculationDigestive system:Receives nutrients from the environment, breaks down food particles intosmaller molecules that can be absorbed across cell membranes and enter body fluids,eliminates wastes, and produces hormones to regulate digestive processesRespiratory system:Moves air into and out of the lungs,and exchanges oxygen and carbondioxide between the lungs and the bloodUrinary system:Removes blood wastes, helps maintain water, electrolyte, and acid-basebalance, produces urine, and transports urine to the outside of the bodyReproductive system of male:Produces and maintains sperm, produces hormones thatdevelop male body type, and transfers sperm to the female reproductive tractReproductive systemof female:Produces and maintains oocytes (eggs), produces hormonesthat develop female body type, receivessperm for fertilization, supports development oftheembryo and fetus, functions in birth process, and nourishes infant

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5Practice1.71.Describe the anatomical position.A person intheanatomical position is standing up straight, facing forward, has upper limbsat the sides, and the palms are facing forward.2.Using the appropriate terms, describe the relative positions of several body parts.The head is superior to the neck.The foot is inferior to the knee.Thetoes areanterior to theheel.Thebrain is posterior to the nose.The great toe is medial to the smallest toe.The thumb is lateral to the smallest finger.The kidneys are bilateral.The left kidney and the spleen are ipsilateral.The left kidney and the right kidney are contralateral.The knee is proximal to the foot.The knee is distal to the thigh.The skin is superficial to the subcutaneous layer.The lens of the eye is deep to the cornea.3.Describe the three types of body sections.A sagittal section divides the body into left and right portions.If the portions are equal, it iscalled a median or midsagittal plane. If the portions are unequal, it is called a parasagittalplane.A transverse or horizontal plane divides the body into top and bottom portions.A frontal or coronal section divides the body into front and back portions.4.Name the nine regions of the abdomen.Epigastric, left and right hypochondriac, umbilical, left and right lateral (lumbar), pubic(hypogastric), and left and right inguinal (iliac) regions

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1ANSWERS TOPRACTICE QUESTIONSChapter2Practice2.21.What are elements?Elements are pure substances, either found in nature or artificially produced, whichrepresent the simplest forms of matter that have certain chemicalcharacteristics.2.Which elements are the most common in the human body?The 4 most common elements are oxygen, carbon, hydrogen, and nitrogen. Together, theymake up about 95% of the human body.3.Where are electrons, protons, and neurons located in an atom?Protons and neutrons are found in the centrally located nucleus of an atom, whileelectronsarein constant motion around the nucleus.4.What is the difference between atomic number and atomic weight?The atomic number of an atom is the number of protons in its nucleus. All atoms of aparticular element have the same atomic number. The atomic weight is approximately equalto the number of protons plus the number of neutrons.Atoms of the same element mayhave different numbers of neutrons, and therefore, different atomic weights.Practice 2.31.What is an ion?An ionis anatom that hasgained or lost one or more electrons in a chemical reaction, andnow carriesa positive or negative charge.2.Describe two ways that atoms bond with other atoms.Atoms can form ionic bonds, in whichoppositely charged ions attract each other and unite,forming arrays or crystals, instead of discreet molecules. Atoms can also share electrons,forming covalent bonds. As the shared electrons move around the nuclei of both atoms,both achieve stability.3.Distinguish between an ion and a polar molecule.An ion contains unequal numbers of protons and electrons. A polar molecule contains equalnumbers of protons and electrons, but the shared electrons reside closer tothe nucleus ofone of the bonded atoms than to the other.This results in the polar molecule having oneslightly negativeendandone slightly positive end.

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2Practice2.41.Distinguish between a molecule and a compound.A molecule is anyparticle formed by the bonding oftwoor more atoms. The atoms may beeither identical or different. If the bound atoms are different elements, the molecule is calleda compound.2.What is amolecularformula? Astructural formula?A molecular formula shows the types of atoms in a particular molecule, and the number ofeach type of atom. The formula for water is H2O; this shows that a water molecule containstwoatoms of hydrogen andoneatom of oxygen. A structural formula shows thearrangement of atoms within a molecule, and uses lines to represent pairs of sharedelectrons.The structural formula for a molecule of hydrogen is H–H; this shows thattwoatoms of hydrogen are bound together by sharingonepair of electrons.3.Describe threetypes of chemical reactions.In a synthesis reaction,twoor more atoms (reactants) bond together, forming a larger ormore complex particle (product). For example,twoatoms of hydrogen andoneatom ofoxygen bind to synthesize a molecule of water. In a decomposition reaction, bonds breakwithin a reactant molecule, resulting in the formation of smaller or simpler particles.Decomposition occurs when a large starch molecule is broken down intoindividual glucosemolecules during the digestion process.During an exchange reaction betweentwomolecules, chemical bonds are broken and new ones are formed. Parts of the reactantsswitch places, producing new molecules. When an acid and base react, producing waterand a salt, this is an exchange reaction.Practice2.51.Compare the characteristics of an acid with those of abase.Acids are electrolytes that release H+ions in water, and have a pH of <7.Bases areelectrolytes that release ions that can bind toH+ions in water, and have a pH of >7.2.What does pH measure?The pH is a measurement of H+ion concentration in a solution.The lower the pH ofthesolution, the higher the H+concentration is, and the more acidic the solution is. The higherthe pH, the lower the H+concentration is, and the more basic, or alkaline, the solution is.3.What is a buffer?A buffer isa chemical that resists or minimizes pH changes.Buffer componentsbind to H+ions when they are present in excess, andrelease them when they are deficient.

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3Practice2.61.How do inorganic and organic molecules differ?Organic molecules contain carbon and hydrogen;inorganic molecules do not.2.How do electrolytes and nonelectrolytes differ?Electrolytes are substances thatdissolve anddissociate in water and release ions; mostinorganic substances are electrolytes.Nonelectrolytes are substances that dissolve inwater, but do not release ions; this includes many organic substances.3.Name the inorganic substances common in body fluids.Water, oxygen, carbon dioxide, and salts are common inorganic substances in cells.4.Compare the chemical composition of carbohydrates, lipids, proteins, and nucleicacids.Carbohydrates consist of carbon, hydrogen,and oxygen, with approximately a 2 to 1 ratio ofhydrogen to oxygen atoms. Lipids (triglycerides) also consist of carbon, hydrogen,andoxygen, but they contain a much higher ratio of hydrogen to oxygen atoms.Some lipids alsocontain phosphorus.Proteins are also mainly composed ofcarbon, hydrogen, and oxygen,but they also contain nitrogen, and some contain sulfur. Nucleic acids consist of carbon,hydrogen, oxygen, nitrogen,and phosphorus.5.How does an enzyme affect a chemical reaction?An enzyme catalyzes a chemical reaction, meaning thatit greatly increases the reaction rate.Metabolic reactions are able to occur quickly enough to support life processes only becauseof the presence of enzymes.6.What is the chemical basis of the great diversity of proteins?All proteins are composedofvarious combinations of 20 different amino acids. Proteinscontain chains of <100 to >5000 amino acids. Some consist of only one polypeptide chain,while others consist of several. The length and order of amino acids, as well as the pleatedor coiled secondary structure and the 3-deminsional shape, or conformation, of the protein,all contribute to the great diversity of proteins in the body.7.What are the functions of nucleic acids?Deoxyribonucleic acid, or DNA, stores the genetic information, or genetic code,onchromosomes. This information is used to construct proteins for the cell.Various types ofribonucleic acid, or RNA,function in the process of protein synthesis.

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1ANSWERS TOPRACTICE QUESTIONSChapter3Practice3.11.What is a cell?A cell is the smallest unit of life. To be classified as a cell, the structure mustdisplay all ofthe characteristics of life: responsiveness, respiration, digestion, growth, absorption,assimilation, circulation, excretion, movement,and reproduction.An organism may consistof one cell ortrillions, as in humans.2.Give three examples of how a cell’s shape makes possible the cell’s function.A skeletal muscle cell is long and cylindrical; this enables it to shorten during musclecontraction, leading to a specific type of body movement. A cell in the alveoli (air sacs) ofthe lungs is broad and flattened; this provides a large surface area forthe rapid exchange ofoxygen into the blood.The many branches (dendrites and axons) and threadlike shape ofneurons (nerve cells) allow them to communicate with several other cells at the same time.Practice3.21.Name the three major parts of a cell and their functions.The 3 major parts of a cell are the cell membrane, nucleus,and cytoplasm. The cellmembrane is the outer boundary of the cell; it protects the structural integrity of the cell,regulatesentryand exitof substances,communicates and interacts with other cells, andtransports messages into the cell. The nucleus stores the DNA, or genetic material, directsthe cell’s activities,and produces ribosomes. The cytoplasm consists of fluid and organelles,whichperform basic cell functions, such as processing and using nutrients, and producingsubstancesfor the cell or for export.2.Define organelles and explain their general functions in a cell.Organelles are tiny structures found in the cytoplasm,whichperform specific functions forthe cell.They conduct activities such as food breakdown to produce energy and heat,protein and lipid productionand packaging, and maintenance of cell shape.3.What is a selectively permeable membrane?Aselectively permeable membrane is one that regulates which substances enter or leavethe cell.

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24.Describe the chemical structure of a cell membrane.The cell membrane consists of a double layer, or bilayer, of phospholipids. The phospholipidmoleculesareoriented such that their water-soluble heads face the surfaces of themembrane, and theirlipid-soluble tails face the membrane interior.The membranealsoincludes proteins that span the width of the bilayer or are associated with one of thesurfaces, and smaller amounts of cholesterol and carbohydrates.5.What are the functions of ribosomes, the endoplasmic reticulum, vesicles, and theGolgi apparatus?Ribosomes provide a physical site on which amino acids bond together during proteinsynthesis, and the enzymatic function to support the process. Vesicles store substances in acell, or transport them throughout a cell or from one cell to another. Endoplasmic reticulumprovides a transportation system for molecules in the cell, and also performs protein and lipidsynthesis. The Golgi apparatus modifies proteins produced on the ribosomes of the roughendoplasmic reticulum, packages them, and transports them in vesicles to other organellesor to the cell membrane for export.6.Explain how organelles and other structures interact to secrete substances from thecell.The rough endoplasmic reticulum, which contains ribosomes, produces proteins. Thesmooth endoplasmic reticulum produces lipidsand some sugars. Some of these substancesare directly secreted from the cell in vesicles consisting of cell membrane. Others enter theGolgi apparatus, are combined with other molecules, and are then secreted from the cellinside vesicles that bud offthe Golgi apparatus.7.What is the function of mitochondria?Mitochondriabreak down food molecules for energy and heat. The energy is stored mainlyin a molecule called ATP (adenosine triphosphate).The heat is used to maintain normalbody temperature.8.What are the functions of lysosomes and peroxisomes?Lysosomes and peroxisomesuse their enzymes to break down certain cellcontents andcomponents. Lysosomes maintain acidic pH for optimal activity of theirenzymes, and breakdown nutrient molecules,some drugs and toxins, and damaged cell parts. Peroxisomescontain different enzymes than lysosomes; they break down hydrogen peroxide, fatty acids,and alcohol.9.How do microfilaments and microtubules differ?Both are thin and threadlike, and both help form the cytoskeleton of the cell. Butmicrofilaments consist of the protein actin, and help in cellular movements. Microtubules

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3consist of the protein tubulin, are 2-3 times the diameter of microfilaments, and participate incell division.10.What is a centrosome and what does it do?A centrosome is an organelle that is composed oftwohollow, cylindrical centrioles. It linesup and distributes the dividing chromosomes to the forming daughter cells during mitosis.11.Locate cilia and flagella and explain what they are composed of and what they do.Cilia and flagella are bothfingerlikeextensions from the cell membrane of certain cells.When cilia are present, they occur in large numbers; theybeat in a coordinated pattern, tomove fluids, such as mucus, in a certain direction. A flagellum is much longer than a cilium,and is used to propel the cell. Most cells have onlyoneflagellum, but some microorganismshave more than one. The only human cell with a flagellum is a sperm cell.12.Identify the structure that separates the nuclear contents from the cytoplasm.The nuclear envelope separates the nuclear contents from the cytoplasm.It isdouble-layered,and contains nuclearpores, which regulate whichsubstances enter and leave thenucleus.13.What is produced in the nucleolus?The nucleolus produces ribosomes.14.Describe chromatin and how it changes.Chromatin is composed of DNA and protein in a loose array of coiled fibers. Thisis theform in which DNAexists when the cell is at rest.When the cell enters cell division, thefibers condense and coil tightly, formingDNAstrands called chromosomes.Practice3.31.What types of substances diffuse most readily through a cell membrane?Lipid-soluble substances diffuse most readily through a cell membrane, since they can easilypass through the phospholipid bilayer. Also, substances that are present in higherconcentration on one side of the cell membrane diffuse more readily than thoseof equalconcentrations.2.Explain the differences among diffusion, facilitated diffusion, and osmosis.Diffusion is the passiverandommovement of a substance from a region of higherconcentration to a region of lower concentration.Lipid-soluble substances diffuse across cellmembranes.Facilitated diffusion is similar to diffusion, but requires the help of a membraneprotein, such as an ion channel, to help transport the substance across the cell membrane.Water-soluble substances, such as ions, cross cell membranes by this method. Osmosisrefers to the movement of water molecules across a cell membrane, into a region containing

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4a dissolved substance(solute)that cannot cross the membrane. Water moves from higherto lower water concentration, and from lower to higher solute concentration.3.Distinguish among hypertonic, hypotonic, and isotonic solutions.Isotonic solutions have the same osmotic pressure; cells in an isotonicextracellular fluidneither gain nor lose water.A hypertonic solution is one with a higher osmotic pressure(higher solute concentration and lower water concentration) than that of the cells or anothersolution; cells in a hypertonic solution lose water by osmosis and shrink. A hypotonicsolution isone with a lower osmotic pressure (lower solute concentration and higher waterconcentration) than that of the cells or another solution; cells in a hypotonic solution will gainwater by osmosis and swell.4.How does filtration happen in the body?During diffusion, molecules pass through a membrane due to random molecular movement.During filtration, molecules are forced to move across a membrane due to pressure. Bloodpressure derived from the pumping action of the heart causes filtration ofwater and smallmolecules out of capillaries to deliver nutrients to the cells.5.Explain the mechanism that maintains unequal concentrations of ions on oppositesidesof a cell membrane.The sodium potassium pump uses the energy of ATP to move Na+and K+ions across cellmembranes at certain times. This movement occurs against the concentration gradients ofthese ions, and functions to maintain gradients that can be used by the cell for specificpurposes, such as the conduction of nerve impulses.6.How are facilitated diffusion and active transport similar and different?Facilitated diffusion and active transport both use membrane proteins to transportsubstances across cell membranes. Facilitated diffusion moves substances from higher tolower concentration, and does not require energy from ATP. Active transport movessubstances from lower to higher concentration, and requires ATPforenergy.7.How do endocytosis and exocytosis differ?Endocytosis moves molecules into a cell inside a vesicle composed of a small portion of thecell membrane. Exocytosis transports molecules stored inside a vesicle out of a cell, byfusion of the vesicle with the cell membrane and release of its contents into the extracellularfluid.8.Explain how receptor-mediated endocytosis is more specific than pinocytosis orphagocytosis.In pinocytosis, the cell indents when approached by droplets of liquid, forms a vesicle, andtakes in the liquid. Phagocytosis does the same with solid particles. These processesengage innonspecific uptake of moleculesfrom the extracellular fluid. In receptor-mediated

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5endocytosis, however, only molecules that can bind to specific receptors on the cellmembrane cause the membrane to indent, and form a vesicleto engulfthem.Practice3.41.Outline the cell cycle.During the lifecycleof a cell, it goes through a sequence of certain changes.The phases ofthe cell cycle are interphase, mitosis, and cytokinesis.After a cell forms, grows, andspecializes into a mature, functional cell, at a certain point, the cell divides intotwoidenticaldaughter cells. During interphase, a cell grows, metabolizes nutrients, and duplicates theDNA, organelles, membranes,and chemicals that it will need when it divides. In mitosis, thecontents of the nucleus divide, distributing the DNA to bothof theforming daughter cells.Cytokinesis involves the division of the cytoplasm that occurs during the latter portion ofmitosis.2.Explain regulation of the cell cycle.Hormones and growth factors can stimulate cell divisionat the proper times. Duringinterphase, restriction checkpoints determine if the cell lives, dies, or proceeds into celldivision.The telomeres on the ends of chromosomes limit the number of times a cell candivide by keeping a mitotic clock.3.Describe the events that occur during mitosis.Mitosis consists of 4 stages. During prophase, chromatin changes in chromosomes, thenuclear envelope disassembles, the centriole pairs migrate to opposite sides of the cell, andmicrotubules begin organizing into spindle fibers. During metaphase, the spindle fibersstretch between the centriole pairs,andthe chromosomes attach to them and line up alongthe midline of the cell.In anaphase, the chromosome pairs split; one chromatid from eachpair migrates along the spindle fibers to opposite sides of the cell. During telophase, thechromatids, now called chromosomes, reach the vicinity of the centrioles, and change backto their chromatin form. The spindle fibers disassemble, and a nuclear envelope formsaround each newly forming nucleus.4.Why must cells divide and specialize?Cells divide to provide new cells for growth of an organism, and to replace cells that havebeen damaged or lost by injury or disease, or have worn out.Cells must specialize, ordifferentiate, in order to become functional as one ofthealmost 300 cell types in the humanbody.

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65.Distinguish between a stem cell and a progenitor cell.A stem cell has the ability to divide over and over without specializing. A stem cell can dividetoformeithertwomore stem cells oronestem cell andoneprogenitor cell, which is partlydifferentiated (specialized). A progenitor cell can produce daughter cells that differentiateinto a limited number of cell types.6.How are new cells generated and how do they specialize?New cells are generated through the division of other cells, by the processes of mitosis andcytokinesis. Cells specializeby activating only the genes that synthesize the particular typesof proteins needed by that type of cell.7.How is cell death a normal part of development?Cell death, called apoptosis,occurs naturally during fetal development, to remove neurons inthe brain that have not established healthy nerve pathways, and prevent organs fromovergrowth. After birth, apoptosis removes skincells, damaged by sunburn,that maybecome cancerous, and helpsshape organs in growing children.

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1ANSWERS TOPRACTICE QUESTIONSChapter4Practice4.11.What is cellular metabolism?Cellular metabolism is a group of chemical reactions thatobtain, store, and release energy incells. Energy stored in the chemical bonds of nutrient molecules can beused by the cells fora variety of purposes, such as copying DNA for cell division, and transporting moleculesacross cell membranes during active transport.2.What are enzymes?Enzymes are proteins that catalyze, or speed up,all of the chemical reactions that occur incellular metabolism. They are necessary for reactions in the body to proceed at a rate thatcan maintain life.Practice4.21.What are the general functions of anabolism and catabolism?In anabolism, chemical bonds are formed, producing larger molecules that are used forgrowth and repair. These reactions require energy. Catabolism is the process by whichlarge nutrient molecules are decomposed into smaller ones, by breaking chemical bonds.These reactionsoccurinthe process ofdigestion, and provide the energy and buildingblocks needed for anabolism.2.What are the products of the anabolism of monosaccharides, glycerol and fatty acids,and amino acids?Anabolism of monosaccharides produces long chains of glucose, forming glycogen inanimals and starch in plants. When glycerol and 3 fatty acids bond together, they formtriglycerides. When anabolic reactions join amino acids together, dipeptides, polypeptides,and proteins are produced. Dipeptides contain 2 amino acids, and proteins contain 100 ormore amino acids.3.Distinguish between dehydration synthesis and hydrolysis.Dehydration synthesis is a type of anabolic reaction in which molecules are joined togetherbyremovinga H+ion from one molecule and a OH-ion from the other.The 2 ionsthenbindtogether to producea molecule of H2O, or water.This occurs when 2 molecules of glucosebind together to form the disaccharide maltose and a molecule of water. Hydrolysis is a typeof catabolic reaction in which a water molecule is split in order to break down another type ofmolecule. For example, inorder to decompose a molecule of maltose into 2 molecules ofglucose,onemolecule of water is split. Then, as the bond is broken in the maltosemolecule, the H+ion is added to one glucose molecule and the OH-ion is added to the other.

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