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

Strengthen your understanding of key topics with Solution Manual For Hole's Essentials of Human Anatomy and Physiology, 14th Edition, a detailed textbook guide.

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    1 ANSWERS TO PRACTICE QUESTIONS Chapter 1 Practice 1.1 1. What factors probably stimulated an early interest in the human body? Factors include a ttempting t o understand the causes of various injuries , illnesses, and the loss of function of body parts, and try ing to treat these conditions . 2. What kinds of activities helped promote the development of modern medical science? Activities include d issection of cadavers, the production of prosthetic body parts, experimentation to improve medical knowledge and techniques , and the discovery of certain chemicals in nature as treatments for specific conditions . Practice 1.2 1. Why is it difficult to separate the topics of anatomy and physiology? S tructure is closely related to function ; body parts are shaped and arranged (anatomy) in such 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 its function. The front teeth (incisors) are pointed for grasping and tearing food, while the back teeth (molars) are flattened for grinding food. The jointed structure of the bones of the fingers allow us to grasp objects. The cone - shaped, chambered heart pumps blood through the blood vessels. The tubular blood vessels transport blood to the cells of the body. Practice 1.3 1. How does the human body illustrate levels of organization? Larger structures are composed of smaller and smaller components. For example, the body consists of several systems, such as the cardiovascular system. The cardiovascular system consists of organs, such as the heart and blood vessels . The heart is composed of tissues, which consist of layers of cells. Cells are composed of organelles, which consist of molecules , and finally , atoms. 2. What is an organism? An organism is a complete unit of life. Organisms range in size from a single cell to a complex living thing , like a human, which is com posed of trillion s of cells. Humans, as complex organisms, are composed of organ systems, organs, tissues, cells, molecules , a nd atoms

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    2 3. How do body parts at different levels of organization vary in complexity? Typically, the higher the level of organization a structure is part of , the more complex it is. For example, a molecule is composed of two or more atoms; therefore , a molecule is more complex than an atom. An organ system, such as the cardiovascular system, is composed of organs, such as the heart and blood vessels . Therefore, an organ system is more complex than any of its organs. Practice 1.4 1. What are the characteristics of life? The characteristics of life are properties that all living organisms exhibit. They include movement, reproduction , responsiveness, growth, and metabolism, which in turn consists of the processes of respiration, 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. Metabolism supports life processes. For example, digestion of food is accomplished by metabolic reactions that break down the food into smaller particles that can be absorbed across the membrane of the small intestine. Once absorbed, food particles are circulated, a nd used for growth , movement, and reproduction. Wastes from food are excreted. Practice 1.5 1. Which requirements of organisms does the external environment provide? The environment provides water, food, oxygen, heat , and pressure. 2. Why is homeostasis important to survival? Homeostasis is the maintenance of a stable internal environment , which consists of the fluid around 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 properly only in the presence of certain concentrations of water, oxygen, hydrogen ions (pH) , and nutrients, and specific conditions of heat and pressure. Having enough water in our cells prevents dehydration, shrinkage of cell nuclei, and cell death. Homeostatic pH prevents irreversible alteration of enzyme structure (denaturation) and function. 3. Describe two homeostatic mechanisms. Negative feedback is a common homeostatic mechanism. When a variable deviates from its set 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 skin return the body temperature to its normal range. A less common mechanism is positive feedback, in which a change in a variable leads to further change. During blood clotting, certain chemicals stimulate further blood clotting, to stop the ble eding.

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    3 Practice 1.6 1. Which organ occupies the cranial cavity? T he vertebral canal? The brain occupies the cranial cavity, and the spinal cord occupies the vertebral canal. 2. What does viscera mean? “Viscera” refers to the organs within the thoracic and abdominopelvic cavities. 3. Name the cavities of the head. The small cavities of the head include the oral cavity, nasal cavity, orbital cavities, and middle ear cavities. The cranial cavity is the large cavity of the head; it is occupied by the brain. 4. Describe the membranes associated with the thoracic and abdominopelvic cavities. Double - layered serous membranes line the walls of the thoracic and abdomin opelvic cavities and surround each organ. The parietal layer lines the wall of the cavity, and the visceral layer surrounds an organ. Between the layers is a potential space, or cavity, filled with lubricating fluid. The pleural membranes surround the lungs, t he pericardial membrane surrounds the heart, and the peritoneal membrane surrounds the abdominopelvic organs. 5. N ame and list the organs of the major organ systems. Integumentary system: skin, hair, nails, sweat and sebaceous glands Skeletal system: bones Muscular system: muscles Nervous system: brain, spinal cord, nerves, and sense organs Endocrine system: endocrine glands Cardiovascular system: heart, arteries, veins, capillaries, and blood Lymphatic system: lymph nodes, thymus, and spleen Digestive system: mouth, teeth, tongue, pharynx, esophagus, stomach, small intestine, large intestine, salivary glands, liver, pancreas, and gallbladder Respiratory system: nasal cavity, pharynx, larynx, trachea, bronchi, and lungs Urinary system: kidneys, ureters, urinary bladder, and urethra Reproductive system of male : scrotum, testes, epididymides, ductus deferentia, seminal vesicles, prostate gland, bulbourethral glands, penis, and urethra

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    4 R eproductive system of female: ovaries, uterine tubes, uter us, vagina, clitoris, and vulva 6. Describe the general functions of each organ system. I ntegumentary system: Protects internal structures, regulate s body temperature, detects changes in environment via sensory receptors, and synthesizes specific chemicals, such as vitamin D Skeletal system: Provides a framework for the body, supports and protects internal organs and soft tissues, helps with body movements, produces blood cells, and stores inorganic salts, such as calcium salts Muscular system: Provides force to move body parts, maintains posture, and produces most of the body heat Nervous system: Regulates and adjusts organ function for homeostasis ; communicates via nerve impulses to help detect changes in the environment, integrate information, and respond to this information by stimulating muscles and glands Endocrine system: Regulates and adjusts organ function for homeostasis, and communicates via hormone secretion into body fluids; each hormone alters metabolism of specific target cells Cardiovascular system: Transports red and white blood cells, platelets, respiratory gases, nutrients, hormones, and wastes throughout the body Lymphatic system: Defends the body against infection and disease, transports some tissue fluid back to the bloodstream, and carries large fats from the digestive system to the general circulation Digestive system: Receives nutrients from the environment, breaks down food particles into smaller molecules that can be absorbed across cell membranes and enter body fluids, eliminates wastes, and produces hormones to regulate digestive processes Respiratory system: Moves air into and out of the lungs, and exchanges oxygen and carbon dioxide between the lungs and the blood Urinary system: Removes blood wastes, helps maintain water, electrolyte, and acid - base balance, produces urine, and transports urine to the outside of the body Reproductive system of male: Produces and maintains sperm, produces hormones that develop male body type, and transfers sperm to the female reproductive tract R eproductive system of female: Produces and maintains oocytes (eggs), produces hormones that develop female body type, receive s sperm for fertilization, supports development of the embryo and fetus, functions in birth process, and nourishes infant

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    5 Practice 1. 7 1. Describe the anatomical position. A person in the anatomical position is standing up straight, facing forward, has upper limbs at 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. The toes are anterior to the heel. The brain 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 is called a median or midsagittal plane. If the portions are unequal, it is called a parasagittal plane. 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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    1 ANSWERS TO PRACTICE QUESTIONS Chapter 2 Practice 2 . 2 1. Wh at are elements ? Elements are pure substances, either found in nature or artificially produced, which represent the simplest forms of matter that have certain chemical characteristics. 2. Which elements are the most common in the human body? The 4 most common elements are oxygen, carbon, hydrogen, and nitrogen. Together, they make 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, whi le electrons are in 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 a particular element have the same atomic number. The atomic weight is approximately equal to the number of protons plus the number of neutrons. Atoms of the same element may have different numbers of neutrons, and therefore, different atomic weights. Practice 2. 3 1. What is an ion? An i on is an atom that ha s gained or lost one or more electrons in a chemical reaction, and now carr ies a positive or negative charge. 2. Describe two ways that atoms bond with other atoms. Atoms can form ionic bonds, in which oppositely 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 equal numbers of protons and electrons, but the shared electrons reside closer to the nucleus of one of the bonded atoms than to the other. This results in the polar molecule having one slightly negative end and one slightly positive end.

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    2 Practice 2 . 4 1. Distinguish between a molecule and a compound. A molecule is a ny particle formed by the bonding of two or more atoms. The atoms may be either identical or different. If the bound atoms are different elements, the molecule is called a compound. 2. What is a molecular formula? A structural formula ? A molecular formula shows the types of atoms in a particular molecule, and the number of each type of atom. The formula for water is H 2 O; this shows that a water molecule contains two atoms of hydrogen and one atom of oxygen. A structural formula shows the arrangement of atoms within a molecule, and uses lines to represent pairs of shared electrons. The structural formula for a molecule of hydrogen is H – H; this shows that two atoms of hydrogen are bound together by sharing one pair of electrons. 3. Describe three type s of chemical reactions. In a synthesis reaction, two or more atoms (reactants) bond together, forming a larger or more complex particle (product). For example, two atoms of hydrogen and one atom of oxygen bind to synthesize a molecule of water. In a decomposition reaction, bonds break within a reactant molecule, resulting in the formation of smaller or simpler particles. Decomposition occurs when a large starch molecule is broken down into individual glucose molecules during the digestion process. During an exchange reaction b etween two molecules, chemical bonds are broken and new ones are formed. Parts of the reactants switch places, producing new molecules. When an acid and base react, producing water and a salt, this is an exchange reaction. Practice 2.5 1. Compare the characteristics of an acid with those of a base. Acids are electrolytes that release H + ions in water, and have a pH of <7. Bases are electrolytes that release ions that can bind to H + 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 of the solution, the higher the H + concentration is, and the more acidic the solution is. The higher the pH, the lower the H + concentration is, and the more basic, or alkaline, the solution is. 3. What is a buffer? A buffer is a chemical that resists or minimizes pH changes . Buffer components bind to H + ions when they are present in excess, and release them when they are deficient.

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    3 Practice 2. 6 1. How do inorganic and organic molecules differ? Organic molecules contain carbon and hydrogen ; i norganic molecules do not. 2. How do electrolytes and nonelectrolytes differ? Electrolytes are substances that dissolve and dissociate in water and release ions; most inorganic substances are electrolytes. Nonelectrolytes are substances that dissolve in water, 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 nucleic acids. Carbohydrates consist of carbon, hydrogen , and oxygen, with approximately a 2 to 1 ratio of hydrogen to oxygen atoms. Lipids (triglycerides) also consist of carbon, hydrogen , and oxygen, but they contain a much higher ratio of hydrogen to oxygen atoms. Some lip i ds also contain phosphorus. Proteins are also mainly composed of carbon, 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 that it greatly increases the reaction rate. Metabolic reactions are able to occur quickly enough to support life processes only because of the presence of enzymes. 6. What is the chemical basis of the great diversity of proteins? All proteins are composed of various combinations of 20 different amino acids. Proteins contain 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 pleated or coiled secondary structure and the 3 - deminsional shape, or conformati on, 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, on chromosomes. This information is used to construct proteins for the cell. Various types of r ibonucleic acid, or RNA, function in the process of protein synthesis.

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    1 ANSWERS TO PRACTICE QUESTIONS Chapter 3 Practice 3 .1 1. What is a cell? A cell is the smallest unit of life. To be classified as a cell, the structure mus t display all of the characteristics of life: responsiveness, respiration, digestion, growth, absorption, assimilation, circulation, excretion, movement , and reproduction. An organism may consist of one cell or trillions, 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 muscle contraction, leading to a specific type of body movement. A cell in the alveoli (air sacs) of the lungs is broad and flattened; this provides a large surface area for the rapid exchange of oxygen into the blood. The many branches (dendrites and axons) and threadlike shape of neurons (nerve cells) allow them to communicate with several other cells at the same time. Practice 3 .2 1. 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 cell membrane is the outer boundary of the cell; it protects the structural integrity of the cell, regulates entry and exit of substances, communicates and interacts with other cells, and transports messages into the cell. The nucleus stores the DNA, or genetic material, directs the cell’s activities , and produces ribosomes. The cytoplasm consists of fluid and organelles , which perform basic cell functions, such as processing and using nutrients, and producing s ubstances for the cell or for export . 2. Define organelles and explain their general functions in a cell. Organelles are tiny structures found in the cytoplasm, which perform specific functions for the cell. They conduct activities such as food breakdown to produce energy and heat, protein and lipid production and packaging, and maintenance of cell shape. 3. What is a selectively permeable membrane? A selectively permeable membrane is one that regulates which substances enter or leave the cell.

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    2 4. Describe the chemical structure of a cell membrane. The cell membrane consists of a double layer, or bilayer, of phospholipids. The phospholipid molecules are oriented such that their water - soluble heads face the surfaces of the membrane, and the ir lipid - soluble tails face the membrane interior. The membrane also includes proteins that span the width of the bilayer or are associated with one of the surfaces, and smaller amounts of cholesterol and carbohydrates. 5. What are the functions of ribosomes, the endoplasmic reticulum, vesicles, and the Golgi apparatus? Ribosomes provide a physical site on which amino acids bond together during protein synthesis, and the enzymatic function to support the process. Vesicles store substances in a cell, or transport them throughout a cell or from one cell to another. Endopl asmic reticulum provides a transportation system for molecules in the cell, and also performs protein and lipid synthesis. The Golgi apparatus m odifies proteins produced on the ribosomes of the rough endoplasmic reticulum, packages them, and transports th em in vesicles to other organelles or to the cell membrane for export. 6. Explain how organelles and other structures interact to secrete substances from the cell. The rough endoplasmic reticulum, which contains ribosomes, produces proteins. The smooth endoplasmic reticulum produces lipids and some sugars. Some of these substances are directly secreted from the cell in vesicles consisting of cell membrane. Others enter the Golgi apparatus, are combined with other molecules, and are then secreted from the cell inside vesicles that bud off the Golgi apparatus. 7. What is the function of mitochondria? Mitochondria break down food molecules for energy and heat. The energy is stored mainly in a molecule called ATP (adenosine triphosphate). The heat is used to maintain normal body temperature. 8. What are the functions of lysosomes and peroxisomes? Lysosomes and peroxisomes use their enzymes to break down certain cell contents and components. Lysosomes maintain aci dic pH for optimal activity of their enzymes, and break down nutrient molecules, some drugs and toxins, and damaged cell parts. Peroxisomes contain 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. But microfilaments consist of the protein actin, and help in cellular movements. Microtubules

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    3 consist of the protein tubulin, are 2 - 3 times the diameter of microfilaments, and participate in cell division. 10. What is a centrosome and what does it do? A centrosome is an organelle that is composed of two hollow, cylindrical centrioles . It lines up 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 both fingerlike extensions from the cell membrane of certain cells. When cilia are present, they occur in large numbers; they beat in a coordinated pattern, to move 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 only one flagellum, but some microorganisms have 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 is double - layered, and contains nuclear por e s , which regulate which substances enter and leave the nucleus. 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. This is the form in which DNA exists when the cell is at rest. When the cell enters cell division, the fibers condense and coil tightly, forming DNA strands called chromosomes. Practice 3 . 3 1. What types of substances diffuse most readily through a cell membrane? Lipid - soluble substances diffuse most readily through a cell membrane, since they can easily pass through the phospholipid bilayer. Also, substances that are present in higher concentration on one side of the cell membrane diffuse more readily than those of equal concentrations. 2. Explain the differences among diffusion, facilitated diffusion, and osmosis. Diffusion is the passive random movement of a substance from a region of higher concentration to a region of lower concentration. Lipid - soluble substances diffuse across cell membranes. Facilitated diffusion is similar to diffusion, but requires the help of a membrane protein, 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. Osmosis refers to the movement of water molecules across a cell membrane, into a region containing

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    4 a dissolved substance (solute) that cannot cross the membrane. Water moves from higher to 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 isotonic extracellular fluid neither 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 another solution; cells in a hypertonic solution lose water by osmosis and shrink. A hypotonic solution is one with a lower osmotic pressure (lower solute concentration and higher water concentration) than that of the cells or another solution ; cells in a hypotonic solution will gain water 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. Blood pressure derived from the pumping action of the heart causes filtration of water and small molecules out of capillaries to deliver nutrients to the cells. 5. Explain the mechanism that maintains unequal concentrations of ions on opposite sides of a cell membrane. The sodium potassium pump uses the energy of ATP to move Na + and K + ions across cell membranes at certain times. This movement occurs against the concentration gradients of these ions, and functions to maintain gradients that can be used by the cell for specific purposes, 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 transport substances across cell membranes. Facilitated diffusion moves substances from higher to lower concentration, and does not require energy from ATP. Active transport moves s ubstances from lower to higher concentration, and requires ATP for energy. 7. How do endocytosis and exocytosis differ? Endocytosis moves molecules into a cell inside a vesicle composed of a small portion of the cell membrane. Exocytosis transports molecules stored inside a vesicle out of a cell, by fusion of the vesicle with the cell membrane and release of its contents i nto the extracellular fluid. 8. Explain how receptor - mediated endocytosis is more specific than pinocytosis or phagocytosis. In pinocytosis, the cell indents when approached by droplets of liquid, forms a vesicle, and takes in the liquid. Phagocytosis does the same with solid particles. These processes engage in nonspecific uptake of molecules from the extracellular fluid . In receptor - mediated

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    5 endocytosis, however, only molecules that can bind to specific receptors on the cell membrane cause the membrane to indent, and form a vesicle to engulf them. Practice 3 . 4 1. Outline the cell cycle. During the life cycle of a cell, it goes through a sequence of certain changes. The phases of the cell cycle are interphase, mitosis, and cytokinesis. After a cell forms, grows, and specializes into a mature, functional cell, at a certain point, the cell divides into two identical daughter cells. During interphase, a cell grows, metabolizes nutrients, and duplicates the DNA, organelles, membranes , and chemicals that it will need when it divides. In mitosis, the contents of the nucleus divide, distributing the DNA to both of the forming daughter cells. Cytokinesis involves the division of the cytoplasm that occurs during the latter portion of mitosis. 2. Explain regulation of the cell cycle. Hormones and growth factors can stimulate cell division at the proper times . During interphase, restriction checkpoints determine if the cell lives, dies, or proceeds into cell division. The telomeres on the ends of chromosomes limit the number of times a cell can divide by keeping a mitotic clock. 3. Describe the events that occur during mitosis. Mitosis consists of 4 stages. During prophase, chromatin changes in chromosomes, the nuclear envelope disassembles, the centriole pairs migrate to opposite sides of the cell, and microtubules begin organizing into spindle fibers. During metaphase, the sp indle fibers stretch between the centriole pairs, and the chromosomes attach to them and line up along the midline of the cell. In anaphase, the chromosome pairs split; one chromatid from each pair migrates along the spindle fibers to opposite sides of th e cell. During telophase, the chromatids, now called chromosomes, reach the vicinity of the centrioles, and change back to their chromatin form. The spindle fibers disassemble, and a nuclear envelope forms around 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 have been damaged or lost by injury or disease, or have worn out. Cells must specialize, or differentiate, in order to become functional as one of the almost 300 cell types in the human body.

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    6 5. 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 divide to form either two more stem cells or one stem cell and one progenitor cell, which is partly differentiated (specialized). A progenitor cell can produce daughter cells that differentiate into 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 and cytokinesis. Cells specialize by activating only the genes that synthesize the particular types of 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 in the brain that have not established healthy nerve pathways, and prevent organs from overgrowth. After birth, apoptosis removes skin cells , damaged by sunburn, that may become cancerous, and helps shape organs in growing children.

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    1 ANSWERS TO PRACTICE QUESTIONS Chapter 4 Practice 4 .1 1. What is cellular metabolism? Cellular metabolism is a group of chemical reactions that obtain, store, and release energy in cells. Energy stored in the chemical bonds of nutrient molecules can be used by the cells for a variety of purposes, such as copying DNA for cell division, and transporting molecules across cell membranes during active transport. 2. What are enzymes? Enzymes are proteins that catalyze, or speed up , all of the chemical reactions that occur in cellular metabolism. They are necessary for reactions in the body to proceed at a rate that can maintain life. Practice 4 .2 1. What are the general functions of anabolism and catabolism? In anabolism, chemical bonds are formed, producing larger molecules that are used for growth and repair. These reactions require energy. Catabolism is the process by which large nutrient molecules are decomposed into smaller ones, by breaking chemical bo nds . These reactions occur in the process of digestion, and provide the energy and building blocks 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 in animals and starch in plants. When glycerol and 3 fatty acids b o nd together, they form triglycerides. When anabolic reactions join amino acids together, dipeptides, polypeptides, and proteins are produced. Dipeptides contain 2 amino acids, and proteins contain 100 or more amino acids. 3. Distinguish between dehydration synthesis and hydrolysis. D ehydration synthesis is a type of anabolic reaction in which molecules are joined together by remov ing a H + ion from one molecule and a OH - ion from the other. T he 2 ions then bind together to produc e a molecule of H 2 O , or water. This occurs when 2 molecules of glucose bind together to form the disaccharide maltose and a molecule of water. Hydrolysis is a type of catabolic reaction in which a water molecule is split in order to break down another type of molecule. For example, in order to decompose a molecule of maltose into 2 molecules of glucose, one molecule of water is split. Then, as the bond is broken in the maltose molecule, the H + ion is added to one glucose molecule and the OH - ion is added to the other.

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