Chapter 3

Exam Name___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) When cancer develops in one tissue and spreads to another through the blood or the lymph, the cancer is said to have undergone what process? A) metastasis B) cytokinesis C) mutation D) differentiation Answer: A 2) The space that is surrounded by the tissue wall of hollow organs is known as the A) tract. B) lumen. C) extracellular space. D) peritoneal cavity. E) epidural space. Answer: B 3) The lumen of a hollow organ such as the stomach is considered to be part of the ________ environment. A) internal B) external Answer: B 4) The watery medium that surrounds a cell is known as A) extracellular fluid. B) protoplasm. C) intracellular fluid. D) cytosol. E) cytoplasm. Answer: A 5) Which term is NOT used to define the structure that separates the contents of a human cell from its surrounding medium? A) plasmalemma B) a cell membrane C) a cell wall D) plasma membrane E) All of the answers are correct. Answer: C 6) Which of the following is NOT a function of membrane proteins? A) produce energy B) anchor or stabilize the cell membrane C) act as transport molecules for various solutes D) creating junctions between cells E) respond to extracellular molecules Answer: A 1 Contact: 7) Cell membranes are said to be A) freely permeable barrier. B) only permeable to water soluble molecules. C) selectively permeable barrier. D) impermeable barrier. E) None of the answers are correct. Answer: C 8) What is/are the major role(s) of the phospholipid bilayer in the cellular membrane? A) to provide a framework for membrane proteins only B) the absorption of fats only C) the formation of a barrier that is a selective for lipid-soluble molecules and to provide a framework for membrane proteins D) the formation of a barrier that is selective for lipid-soluble molecules E) to carry water-soluble molecules through a hydrophobic environment Answer: C 9) Which of the following is NOT a membrane lipid? A) sphingolipids B) phospholipids C) cholesterol D) All are membrane lipids. Answer: D 10) Which structure is a lipid bilayer that controls which objects can leave or enter the cell? A) endoplasmic reticulum B) ribosome C) Golgi apparatus D) plasma membrane E) nucleus Answer: D 11) A liposome is a A) a structural part of cell membranes. B) a medium to deliver cosmetics and drugs. C) a type of lipid. D) medium to deliver drugs. E) medium to deliver cosmetics. Answer: B 12) An immunoliposome is a liposome that A) can recognize cancer cells. B) suppresses the immune system. C) stimulates the immune system. D) None of the answers are correct. Answer: A 13) Intermediate filaments A) provide the cell with strength. B) transport materials within the cytoplasm. C) form the neurofilaments in nerve cells. D) stabilize the position of organelles. E) All of the answers are correct. Answer: E 2 14) Which proteins assist in the movement of vesicles along microtubules? A) ribosomes B) kinesins C) mitochondria D) Golgi complex E) rough endoplasmic reticulum Answer: B 15) Which is an example of a membranous organelle? A) centriole B) ribosome C) cytoskeleton D) cilia E) lysosome Answer: E 16) The thickest protein fibers from the following group are A) neurofilaments. B) keratin filaments. C) myosin molecules. D) microtubules. E) microfilaments. Answer: D 17) Ribosomal RNA is formed by A) Golgi complexes. B) nucleoli. C) mitochondria. D) the endoplasmic reticulum. E) lysosomes. Answer: B 18) Which statement about mitochondria is FALSE? A) The matrix of the mitochondria contains metabolic enzymes involved in energy production. B) The mitochondria produce most of a cell's ATP. C) The intermembrane space plays an important role in mitochondrial ATP production. D) The mitochondrial cristae form the inner membrane forming separate compartments. E) The mitochondria do not contain DNA nor RNA. Answer: E 19) In humans, only ________ cells have flagella. A) stomach lining B) intestine lining C) respiratory tract lining D) uterine tube lining E) sperm Answer: E 20) Tay-Sachs is a disease caused by having defective A) mitochondria. B) rough endoplasmic reticulum. C) smooth endoplasmic reticulum. D) lysosomes. E) Golgi bodies. Answer: D 3 21) Microvilli are found A) on the inside of cell membranes. B) mostly in muscle cells. C) in large numbers on cells that secrete hormones. D) in cells that participate in absorption. E) only on cells lining the reproductive tract. Answer: D 22) Microtubules A) are hollow, filamentous structures. B) are composed of tubulin. C) are the largest cytoplasmic fibers. D) form cilia that aid in cell movement. E) All of the answers are correct. Answer: E 23) Centrioles A) are white blood cells outside of vessels. B) provide shape and stability to a cell. C) direct the movement of DNA during cell division. D) hold the cell's ribosomes in place. E) help move fluid through the cell. Answer: C 24) Most of the ATP required to power cellular operations is made in the A) endoplasmic reticulum. B) ribosomes. C) mitochondria. D) nucleus. E) Golgi apparatus. Answer: C 25) Which does NOT accurately complete the sentence? One of the major functions of BOTH types of endoplasmic reticulum (ER) is the A) storage of genetic material for the cell. B) transport of biomolecules. C) storage of biomolecules. D) synthesis of biomolecules. Answer: A 26) Which is NOT made in smooth or rough endoplasmic reticulum? A) proteins B) fatty acids C) steroids D) phospholipids E) RNA Answer: E 4 27) Which is NOT synthesized in the smooth endoplasmic reticulum (SER)? A) steroids B) lipids C) proteins D) fatty acids E) All are synthesized in the SER. Answer: C 28) Which consists of a network of intracellular membranes with attached ribosomes? A) mitochondria B) Golgi apparatus C) rough endoplasmic reticulum D) smooth endoplasmic reticulum E) nucleoli Answer: C 29) Which structure is NOT involved in storage? A) lysosomes B) mitochondrial cristae C) peroxisomes D) storage vesicles E) All are involved in cellular storage. Answer: B 30) The proteins synthesized in the rough endoplasmic reticulum are then sent to the A) cell membrane for secretion. B) nucleus for cellular use. C) lysosome for modification. D) Golgi complex for packaging. E) smooth endoplasmic reticulum for storage. Answer: D 31) You discovered a new cell that lacks lysosomes. This cell would NOT be able to A) destroy H2O2. B) synthesize lipids. C) transport water-soluble molecules. D) synthesize enzymes. E) digest cellular wastes and bacteria. Answer: E 32) Which activates digestive enzymes inside lysosomes? A) water B) enzymes C) acid D) base E) air Answer: C 33) Peroxisomes A) are sites for synthesis of fatty acids, steroids, and phospholipids. B) are a type of lysosome. C) use an enzyme to destroy H2O2 that is toxic to the cell. D) are responsible for the atrophy of unused muscles. E) All of the answers are correct. Answer: C 5 34) The number of mitochondria in skeletal muscle cells is ________ the number of mitochondria in adipose (fat) cells. A) less than B) equal to C) greater than Answer: C 35) The control center for cellular operations is the A) ribosomes. B) nucleus. C) Golgi complex. D) endoplasmic reticulum. E) mitochondria. Answer: B 36) The beta cells of the pancreas produce insulin, a protein hormone. Which organelle would be found in higher levels in the beta cells? A) lysosomes B) ribosomes C) microvilli D) mitochondria Answer: B 37) If the adrenal cortex produces lipid hormones such as aldosterone, which organelle would be higher in cells of the adrenal cortex? A) mitochondria B) rough endoplasmic reticulum C) smooth endoplasmic reticulum D) Golgi apparatus E) ribosome Answer: C 38) The nucleus stores DNA that encodes the sequence of which molecules? A) phospholipids B) proteins C) lipids D) carbohydrates E) All of the answers are correct. Answer: E 39) The term secretion refers to A) the process by which a cell releases a substance into the extracellular space. B) storage of a material, until it is time for it to leave the cell. C) the manufacture and assembly of a material. D) synthesis of a protein for export from the cell. E) None of the answers describe secretion. Answer: A 40) Which cellular organelle is considered the powerhouse of the cell because it produces most of the ATP? A) ribosome B) Golgi apparatus C) nucleus D) mitochondria E) endoplasmic reticulum Answer: D 6 41) Arrange the following events in protein secretion in the proper sequence. 1. The polypeptide chain enters the lumen of the endoplasmic reticulum. 2. A secretory vesicle is formed. 3. A transport vesicle is formed. 4. The polypeptide chain enters the lumen of the Golgi complex. A) 3, 1, 4, 2 B) 1, 2, 3, 4 C) 1, 3, 2, 4 D) 4, 3, 1, 2 E) 1, 3, 4, 2 Answer: E 42) Movement of material between cells is known as the ________ pathway. A) cisendothelial B) transcellular C) transendothelial D) paracellular E) metacellular Answer: D 43) Which is NOT a type of cell junction? A) loose junctions B) tight junctions C) adherens junctions D) gap junctions E) desmosomes Answer: A 44) The esophagus is a tube that carries food from the mouth to the stomach. It does not secrete any enzymes or absorb any nutrients, but it does need to stand up to significant friction and stress. The type of epithelium most likely lining the esophagus would be A) transitional epithelium. B) stratified squamous epithelium. C) cuboidal epithelium. D) simple squamous epithelium. E) simple columnar epithelium. Answer: B 45) The type of protein found in gap junctions is the A) integrin. B) cadherin. C) connexin. D) claudin. E) occludin. Answer: C 46) Disappearance of which type of junction most likely contributes to the metastasis of cancer cells throughout the body? A) anchoring B) gap C) tight Answer: A 47) The types of junction proteins important in nerve growth and development are A) integrins. B) connexins. C) claudins. D) immunoglobulin superfamily. E) occludins. Answer: D 7 48) Which is NOT a primary tissue type? A) neural tissue B) connective tissue C) osseous tissue D) muscle tissue E) epithelial tissue Answer: C 49) Which is NOT a function of epithelia? A) producing specialized secretions B) movement C) regulating exchange D) providing physical protection E) storing energy reserves Answer: E 50) Epithelial cells adapted for membrane transport of large quantities of materials, such as ions and nutrients, usually have ________ on their apical surface. A) lysosomes B) mitochondria C) cilia D) flagella E) microvilli Answer: E 51) Epithelia are connected to underlying connective tissues by A) a basal lamina. B) the apical surface. C) desmosomes. D) basal body. E) gap junctions. Answer: D 52) Glands that secrete hormones into the blood are A) exocrine glands. B) unicellular glands. C) mixed glands. D) endocrine glands. E) None of the answers are correct. Answer: D 53) Exocrine glands A) may make either mucous or serous secretions. B) may release their secretions through open tubes, called ducts. C) release their secretions into the external environment. D) may work as single cells or as a multicellular organ. E) All of the statements are true. Answer: E 8 54) Every substance that enters or leaves the internal environment of the body must cross an epithelium. A) True B) False Answer: A 55) Epithelia are more likely to develop genetic mutations associated with cancer because they divide frequently. A) True B) False Answer: A 56) The function of microvilli on the apical membrane of transporting epithelia is to A) allow the cell to move through a fluid medium. B) increase the movement of extracellular fluid. C) increase the cell's surface area. D) increase the toughness of the cell. E) increase the resistance of the cell to viruses. Answer: C 57) The simple squamous epithelial lining of blood vessels is called A) the vasa recta. B) luteal cells. C) endothelium. D) basolateral epithelium. E) None of the answers are correct. Answer: C 58) Which tissue has extensive extracellular matrix? A) muscle B) epithelial C) connective D) neural E) epithelial, neural, and muscle Answer: E 59) Functions of connective tissue include A) establishing a structural framework for the body. B) storing energy reserves. C) providing protection for delicate organs. D) transporting fluids and dissolved materials. E) All of the answers are correct. Answer: E 60) Cells that store fat are called A) mast cells. B) liposomes. C) fibroblasts. D) melanocytes. E) adipocytes. Answer: E 61) Loose connective tissue A) surrounds muscles and nerves. B) attaches muscle to bone. C) supports small glands. D) All of the answers are correct. Answer: C 9 62) Which is NOT a characteristic of plasma? A) the fluid portion of blood B) part of the ECF C) a sticky solution containing glycoproteins and proteoglycans D) a watery extracellular matrix E) a dilute solution of ions and dissolved organic molecules Answer: C 63) The term meaning "programmed cell death" is A) diuresis. B) necrosis. C) apoptosis. D) oncogenesis. E) cytocide. Answer: C 64) The definition "less specialized cells that retain the ability to divide" applies to A) totipotent cells. B) stem cells. C) gametocytes. D) nurse cells. E) apoptosis. Answer: B 65) Groups of tissues that carry out related functions may form structures known as A) organs. B) organelles. C) organisms. D) cells. E) Impossible to tell from the information given. Answer: A 66) The heaviest organ in the body is the A) brain. B) liver. C) skin. D) urinary bladder. E) stomach. Answer: C 67) This organelle is the site of most ATP synthesis in the cell. A) endoplasmic reticulum B) Golgi apparatus C) lysosomes D) mitochondria E) peroxisomes Answer: D 68) These degrade long chain fatty acids and toxic foreign molecules. A) endoplasmic reticulum B) Golgi apparatus C) lysosomes D) mitochondria E) peroxisomes Answer: E 10 69) This is the digestive system of a cell, breaking down old organelles or bacteria. A) endoplasmic reticulum B) Golgi apparatus C) lysosomes D) mitochondria E) peroxisomes Answer: C 70) This modifies proteins and packages them into secretory vesicles for export from the cell. A) endoplasmic reticulum B) Golgi apparatus C) lysosomes D) mitochondria E) peroxisomes Answer: B 71) The simplest cell-cell junction is called a(n) A) anchoring junction. B) gap junction. C) desmosome. D) neuromuscular junction. E) tight junction. Answer: B 72) This junction contributes to the blood-brain barrier. A) gap junction B) desmosome C) anchoring junction D) tight junction E) neuromuscular junction Answer: D 73) These junctions can be cell-matrix junctions. A) anchoring junction B) connexin C) neuromuscular junction D) tight junction E) gap junction Answer: A 74) The loss of these junctions are a characteristic of cancer. A) neuromuscular junction B) anchoring junction C) gap junction D) tight junction E) claudin constructed junction Answer: B 11 75) This tissue is made up of adipocytes. A) dense, irregular connective tissue B) dense, regular connective tissue C) fat D) bone E) cartilage Answer: C 76) Fibroblasts that secrete collagen-rich matrix are the main cell type in this tissue. A) cartilage B) bone C) blood D) fat E) loose connective tissue Answer: E 77) Chondrocytes secrete a firm but flexible matrix to form what tissue? A) cartilage B) blood C) bone D) fat E) loose connective tissue Answer: A 78) An osteocyte is a main cell type in which tissue? A) adipose B) loose connective tissue C) bone D) blood E) cartilage Answer: C 79) Which plays a role in temperature regulation in infants? A) brown fat B) bone C) collagen D) white fat E) cartilage Answer: A 80) Nucleoli function in the production of A) DNA that controls all cell functions. B) peroxisomes. C) proteins. D) secretory vesicles. E) RNA for ribosomes. Answer: E 81) Cell membranes are said to be ________ because they allow some substances to pass but not others. A) structural B) metabolically active C) selectively permeable D) hydrophilic E) a physical barrier Answer: C 12 82) The nucleus is surrounded by a(n) A) plasmalemma. B) adhesion molecule. C) cell wall. D) nuclear envelope. E) protein coat. Answer: D 83) Communication between the nucleus and cytosol occurs through A) nucleoli. B) plasmalemma. C) nuclear pores. D) desmosomes. E) sodium channels. Answer: C 84) Cells are transformed into specialized units during A) programed cell death. B) apoptosis. C) differentiation. D) transcription. E) mitosis. Answer: C 85) The lining of the heart is called A) ciliated epithelium. B) endothelium. C) transporting epithelium. D) protective epithelium. E) secretory epithelium. Answer: B 86) ________ is the extracellular component of connective tissues. A) Cartilage B) Ground substance C) Cytoplasm D) Mucous E) Blood Answer: B 87) The combination of fibers and ground substance in supporting connective tissues is known as A) mucous. B) extracellular matrix. C) micelles. D) blood. E) cytoplasm. Answer: B 13 88) The fluid substance of blood is called A) peroxide. B) plasma. C) cytoplasm. D) endothelium. E) interstitial fluid. Answer: B 89) The study of tissue structure and function is called A) remodeling. B) physiology. C) plasticity. D) differentiation. E) histology. Answer: E 90) Structures composed of epithelial cells that produce secretions are called A) micelles. B) nuclear pores. C) ducts. D) cell junctions. E) glands. Answer: E 91) ________ is a tissue that is modified to transmit chemical and electrical signals from one cell to another. A) Exocrine tissue B) Endothelium C) Epithelia tissue D) Neural tissue E) Connective tissue Answer: D 92) ________ secretions are released onto an epithelial surface. A) Hormonal B) Exocrine C) Nuclear D) Endocrine E) Microtubular Answer: B 93) ________ secretions are released into interstitial space to diffuse into the blood. A) Mucous B) Serous C) Exocrine D) Endocrine E) Ribosomal Answer: D 94) ________ proteins extend all the way across the cell membrane. A) Transmembrane B) Peripheral C) Cytoskeletal D) Glycolipid E) Nuclear Answer: A 14 95) ________ proteins attach loosely to other membrane proteins or polar regions of phospholipids. A) Glycolipid B) Cytoskeletal C) Nuclear D) Peripheral E) Transmembrane Answer: D 96) ________ is a protective layer made up of mostly membrane carbohydrates. A) Epidermis B) Connective tissue C) Glycocalyx D) Cadherin E) Focal Adhesion Answer: C ESSAY. Write your answer in the space provided or on a separate sheet of paper. 97) Explain the relationship between microtubules, cilia, flagella, centrioles, spindle fibers, and the centrosome. Answer: Microtubules are a cytoskeletal protein made of tubulin. Microtubules form a major component of the internal scaffolding of the cell. Microtubules can also be assembled into cilia and flagella, which are organelles that produce cell-generated movements, and into centrioles and spindle fibers. Centrioles produce the spindle fibers, which are responsible for changing the position of chromosomes during nuclear division. Centrioles are part of a larger structure known as the centrosome, which also includes a darkly staining material and acts as the cell's microtubule organizing center. 98) List the four major tissue types. Give an example and location of each. Answer: See Table 3.4 and the "Tissues of the Body" section in the chapter. 99) Describe the structure of the cytoskeleton, and list its functions. Answer: The cytoskeleton consists of actin microfilaments, intermediate filaments, and microtubules and forms a scaffold throughout the cytoplasm. An interesting feature is that some of the proteins are relatively fixed in position, whereas others can be rapidly assembled or disassembled as necessary. The functions include providing mechanical strength and shape, stabilizing position of organelles, intracellular transport system, functional linkage to other cells and to extracellular space, and cell-generated movements. 100) Define, compare, and contrast each term listed and explain how the terms are related to each other: rough endoplasmic reticulum, smooth endoplasmic reticulum, ribosomes, and Golgi Apparatus. Answer: All are structures involved in synthesis of biomolecules. All but ribosomes are membranous structures. Ribosomes may be free or attached to ER, making it rough. See Figure 3.4 in the chapter. 101) Sketch a cell membrane. Label at least three components and briefly explain what each one does. Answer: See Figure 3.2 102) Describe the composition and function of the extracellular matrix. Answer: In any tissue, the extracellular matrix consists of two basic components: proteoglycans and insoluble proteins. The matrix plays an important role in processes ranging from growth and development to cell death. The matrix aids in cell communication with its environment by attaching to the cell membrane or cytoskeleton. 15 103) Define, compare, and contrast each term listed, and explain how the terms are related to each other: tendons, ligaments, cartilage, bone. Answer: Each term is a type or subtype of connective tissue. Tendons attach skeletal muscle to bone, whereas ligaments connect bone to bone. Cartilage and bone together are structurally supportive tissues. See Figure 3.12 and 3.13 in the chapter. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 104) If an animal cell lacked centrioles, it would not be able to A) synthesize proteins. B) undergo nuclear division. C) produce DNA. D) metabolize sugars. E) maintain its balance. Answer: B 105) Which cytoskeleton components are responsible for the movement of chromosomes during cell division? A) thick filaments B) intermediate filaments C) microfilaments D) microtubules E) All of the answers are correct. Answer: D 106) A flagellum moves a cell through a fluid medium. What moves the fluid medium across the surface of cells that are not free to move? A) centrioles B) thick filaments C) endoplasmic reticulum D) ribosomes E) cilia Answer: E 107) Which statement about mitochondria is FALSE? A) The intermembrane space is used in the production of ATP. B) The outer mitochondrial membrane is responsible for its shape. C) Mitochondria are responsible for providing energy to the cell. D) Mitochondria contain their own DNA and RNA. E) Mitochondria can replicate themselves only when directed by the cell's nuclear DNA. Answer: E 108) Plasma is to blood as ________ is to cytoplasm. A) protein B) serum C) inclusion D) cytosol E) organelle Answer: D 16 109) Examination of a sample of glandular cells shows an extensive network of smooth endoplasmic reticulum. Which would be a likely product of these cells? A) steroid hormones B) protein (peptide) hormones C) transport proteins D) digestive enzymes E) protein antibodies Answer: A 110) In a pancreatic cell producing digestive enzymes, you would expect to find a lot of A) smooth endoplasmic reticulum. B) rough endoplasmic reticulum. Answer: B 111) Chondrocytes are to cartilage as osteocytes are to A) blood. B) bone. C) epithelium. D) fat. E) neural tissue. Answer: B 112) The tissue(s) that is/are considered excitable because of the ability to generate electrical signals is/are called ________ tissue. A) muscle B) neural C) epithelial D) muscle tissue and neural E) muscle tissue, neural tissue, and epithelial Answer: D 113) You are looking at a slide of an unknown organ that has an empty lumen with stratified squamous epithelium contacting the lumen. Deep to the epithelium is a basement membrane and then two layers of smooth muscle. Which organ would this most likely belong to and why? A) The urinary bladder because it needs to stretch and constrict to store and eliminate urine. B) The esophagus because it is a passageway that needs to move but not absorb food products. C) The intestines because they need to move food along and absorb digested products. D) The liver because it secretes enzymes and bile and needs to move them to the gallbladder. Answer: B 114) A layer of proteoglycans and a network of filaments that prevents the movement of proteins and other large molecules from the connective tissue to epithelium describes A) areolar tissue. B) the basal lamina. C) endothelium. D) interfacial canals. E) the reticular lamina. Answer: B 17 115) The distinguishing characteristic of connective tissue is A) that it is always dividing, constantly being replaced throughout the body. B) that it is arranged in sheets of tissue that lie on body surfaces. C) the collagen fibers that offer support. D) the presence of extensive extracellular matrix containing widely scattered cells. E) All of these characteristics help make connective tissue unique. Answer: D 116) Which type of connective tissue does NOT fit with the typical characteristic of a dense ground substance? A) blood B) adipose C) tendons D) bone E) cartilage Answer: A 117) Close examination of an organ shows a lining of several layers of cells. The layers do not contain any blood vessels, and one surface of the cells faces the internal cavity of the organ. This tissue is probably A) epithelium. B) muscle tissue. C) fat tissue. D) connective tissue. E) neural tissue. Answer: A 118) Increasing muscle mass and decreasing fat content in your body can increase ones use of energy. Why is this? A) Fat cells have no blood supply. B) Adipocytes contain more cytoplasmic inclusions. C) Muscle cells have more mitochondria than fat cells. D) Fat is a connective tissue and not an excitable one. Answer: C 119) Microscopic examination of a tissue shows an open framework of fibers with a large volume of fluid ground substance and elastic fibers. This tissue would most likely have come from the A) tissue that separates skin from underlying muscle. B) inner wall of a blood vessel. C) muscle D) bony socket of the eye. E) larynx. Answer: A 120) Mature nerve cells are expected to lack which organelle(s)? A) endoplasmic reticulum B) Golgi bodies C) centrioles D) ribosomes E) nucleus Answer: C 121) Neurons in the CNS of the adult do not contain centrioles. What does that tell you about CNS neurons? A) They do not produce any products. B) It does not tell you much of anything. C) They do not carry nerve impulses. D) They do not replicate themselves. Answer: D 18 122) Only totipotent stem cells are capable of producing new cells in an adult. A) True B) False Answer: B 123) A lysosome is a(n) A) membranous organelle. B) transmembrane protein. C) inclusion. D) cytoskeletal protein. E) glycolipid. Answer: A 124) Mitochondria are a(n) A) membranous organelles. B) transmembrane proteins. C) inclusions. D) cytoskeletal proteins. E) glycolipids. Answer: A 125) A ribosome is a(n) A) membranous organelle. B) transmembrane protein. C) inclusion. D) cytoskeletal protein. E) glycolipid. Answer: C 126) Cilia are a(n) A) protein fibers. B) inclusions. C) membranous organelles. D) adherens. E) mitochondrial proteins. Answer: A 127) The endoplasmic reticulum is a(n) A) inclusion. B) glycocalyx. C) adheren. D) mitochondrial protein. E) membranous organelle. Answer: E 128) This type of epithelia is found in the epidermis, esophagus, and mouth, and these stacked layers of cells prevent exchange, while they resist chemicals, bacteria, and other destructive forces. A) exchange B) transport C) ciliated D) protective E) secretory Answer: D 19 129) This type of epithelia actively and selectively regulates the exchange of nongaseous material, such as ions and nutrients, and can be regulated in response to various stimuli. A) exchange B) transport C) ciliated D) protective E) secretory Answer: B 130) This type of epithelia is made up of thin, flattened cells that allow the rapid passage of O2 and CO2 in and out of the lungs and of certain blood vessels. A) exchange B) transport C) ciliated D) protective E) secretory Answer: A 131) This type of epithelia has cells that produce a substance and release it, either onto a surface or into the blood. A) exchange B) transport C) ciliated D) protective E) secretory Answer: E 132) This type of epithelia is made up of cells with membrane extensions that beat in a coordinated fashion to move fluid and particles across the tissue. A) exchange B) transport C) ciliated D) protective E) secretory Answer: C On the row of cells shown below, match A-E to the terms in the following question(s). Figure 3.1 133) Referring to Figure 3.1, which letter represents the apical membrane? A) A B) B C) C D) D E) E Answer: B 134) Referring to Figure 3.1, which letter represents the basolateral membrane? A) A B) B C) C D) D E) E Answer: E 135) Referring to Figure 3.1, which letter represents the basal lamina? A) A B) B C) C D) D E) E Answer: C 136) Referring to Figure 3.1, which letter represents the plasma membrane? A) A B) B C) C D) D E) E Answer: D 137) Referring to Figure 3.1, which letter represents the cytosol? A) A B) B C) C D) D E) E Answer: A 20 ESSAY. Write your answer in the space provided or on a separate sheet of paper. 138) Draw a concept map for the types of cell junctions and the proteins that compose them. Answer: This is discussed in the "Tissues of the Body" section of the chapter and shown in Figure 3.8a. SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 139) Cancer is abnormal, uncontrolled cell division. Which property of epithelial tissues makes them more likely to develop cancer? Answer: Epithelial tissues contain a population of dividing cells, which divide at a moderate rate. ESSAY. Write your answer in the space provided or on a separate sheet of paper. 140) Describe the progression of a fertilized egg, from totipotent cell through pluripotent and multipotent stem cells. How might stem cells be of therapeutic value? What is plasticity? Answer: This is discussed in the "Tissue Remodeling" section of the chapter. 141) Describe the anatomical and fluid compartments of the body. How do the lumens of hollow organs fit into these classifications? Which fluid-containing cavities are considered to be internal and which are external? Of those that are external, why are they external (give examples)? You may wish to design a flow chart to help answer this. Answer: The anatomical compartments are the cranial cavity, containing the brain; the thoracic cavity, containing the heart and lungs; and the abdominopelvic cavity, containing organs of the digestive, urinary, and reproductive systems. The fluid compartments are the intracellular fluid (inside the cells) and the extracellular fluid (outside the cells). The extracellular fluids are found in the interstitial fluid between cells and the plasma of the blood, which is in the lumen of the circulatory system. Lumens of hollow organs such as the digestive and urinary tracts are part of the external environment, whereas the intracellular and interstitial fluids are internal. The lumen of the circulatory system is also internal. External lumens are those that open to the outside environment. These openings include the mouth, nostrils, anus, urethral, and vaginal orifices. 142) Describe the two general meanings of the term membrane, as used in biology. Which usage indicates layers of cells and which indicates layers of molecules? Answer: Prior to the use of microscopes, membranes were simply thin, flexible layers of cells that separated large compartments or lined large cavities. When microscopic study of cells allowed visualization of the cell envelope and organelles, the term membrane was additionally applied to thin layers of molecules. 143) Give three examples of structures whose formation involves molecular interactions that either increase or decrease contact with water molecules, explaining how they are similar and how they differ from each other. (Hint: They all involve molecules that have both polar and nonpolar portions.) Answer: Phospholipids have a polar portion that is attracted to water and a nonpolar portion that repels water. The molecules orient in water such that water is excluded from contacting the nonpolar portions. This is seen in: the bilayer arrangement of phospholipids in cell membranes, in which hydrophobic tails are in the middle of the layer; micelles, in which a single layer of phospholipids forms a sphere with the hydrophobic tails in the middle; and liposomes, which are hollow spheres made from phospholipid bilayers that can be filled with water-soluble molecules. 21 144) Your study partner is having difficulty understanding dense fibrous connective tissue, tendons, and ligaments. Explain to her how they are related to each other and how they are different from other categories of connective tissue. Answer: Dense fibrous connective tissue is a category of connective tissue, distinct from loose, adipose, blood, bone, and cartilage. It is not as dense as cartilage and bone but is denser than the other types listed. Like loose connective tissues, fibroblasts are the primary cell type, but unlike loose, the matrix consists of relatively more protein fibers and less ground substance. Like bone and cartilage, the fibers are primarily collagen. The fibers can be arranged randomly (irregular) or parallel to each other (regular). Tendons and ligaments are both composed of dense fibrous connective tissue. Tendons attach muscles to bones, whereas ligaments attach bones to bones; tendons lack elastic fibers, but they are present in ligaments; therefore ligaments are slightly stretchy. 145) Describe the difference between necrosis and apoptosis, and give specific examples of each. Answer: Necrosis is cell death as a result of damage from toxins, physical trauma, or lack of oxygen; damaged cells release chemicals that may damage neighboring cells. An example is death of skin cells as a result of sunburn. Apoptosis is programmed cell death, which is an internally regulated process and does not involve neighboring cells unless they too are so programmed. An example is the loss of skin webbing between fingers and toes in a fetus. 146) If a person who has not exercised regularly begins a consistent exercise routine, he/she will notice that their metabolism will seem to increase as their endurance improves. Why is this? Answer: Metabolism will increase with endurance because the number of mitochondria will increase with consistent exercise. The increase in mitochondria will improve endurance and increase metabolism of glucose because they will be metabolizing more glucose into ATP. 147) What is the benefit of having some of the cellular organelles enclosed by a membrane similar to the cell (plasma) membrane? Answer: The isolation of the internal contents of membrane-bound organelles allows them to manufacture or store secretions, enzymes, or toxins that could adversely affect the cytoplasm in general. Another benefit is the increased efficiency of having specialized enzyme systems concentrated in one place, for example, those necessary for energy production in the mitochondrion. In addition, the membranes themselves serve as "workspace," allowing the anchoring of enzymes or other proteins into a stabilized location. 148) Sketch a short series of simple columnar epithelial cells. Label each of the three different borders. Briefly explain the different kinds of activities that may go on at each border, and tell how their structures and junctions support these functions. Answer: This is discussed in the "Tissues of the Body" section of the chapter. 149) Which type of epithelium would you expect to find in the alveoli (air sacs) in the lungs? Defend your answer. Answer: Since gases must diffuse across the alveoli and associated capillaries you would expect to find exchange epithelia, composed of very thin cells (simple squamous epithelium). Thicker types of epithelial cells would slow the process of gas diffusion to and from the blood. 150) During a lab practical, Laurant examines a tissue that is composed of densely packed protein fibers that are running parallel and form a cord. There are few nuclei and no striations, and there is no evidence of other cellular structures. Laurant identifies the tissue as skeletal muscle. Why is Laurant's choice wrong, and which tissue is he probably observing? Answer: Skeletal muscle tissue is made up of densely packed fibers running in the same direction, but since muscle fibers are composed of cells, they would have many nuclei and mitochondria. Skeletal muscle also has an obvious banding pattern or striations due to the arrangement of the actin and myosin filaments within the cell. Laurant is probably looking at a slide of tendon (dense connective tissue). 22 151) Cancer is not one disease but a group of related diseases, caused by abnormal genes, environmental factors, and/or viral infections. Describe the basic common characteristics of cancers, including the role of anchoring junctions and proteases. What is a tumor? What is metastasis? Is cancer usually considered to be contagious? Explain. Answer: Cancer results when cells begin to divide and grow and do not respond to normal controls that would limit their growth. Anchoring junctions eventually fail to keep the cancer cells together, allowing them to spread to other organs where they continue to grow uncontrolled. Some cancer cells secrete proteases that improve their ability to spread or metastasize. A tumor is a lump of cancerous cells. Cancer is usually not contagious, being caused instead by genetic mutations in an individual or exposure to environmental factors by that individual; exceptions are cancers caused by viruses, which are believed to be the minority. 152) In typical women of reproductive age, the epithelial cells lining the uterus (the endometrium) die and are shed from the body roughly once every month, in the process of menstruation. The triggers in this process include chemical (hormonal) changes and contraction of the blood vessels in the lining. Cell death may be a result of either apoptosis or necrosis. Describe the characteristics of each process. Develop an argument for classifying the process of menstruation as an example of apoptosis, and then argue for classifying it as necrosis. Which is correct? Answer: (Note to instructor: If students have not yet studied the reproductive system, they may not be able to answer the final question, therefore it could be omitted.) Necrosis is cell death as a result of damage from toxins, physical trauma, or lack of oxygen; damaged cells release chemicals that may damage neighboring cells. Apoptosis is programmed cell death, which is an internally regulated process and affects only the cell it occurs within. Menstruation may result from necrosis if the causative factor is changes in blood flow to the endometrium such that the oxygen supply is inadequate. Menstruation may result from apoptosis if it results from hormonal changes that directly kill the cells. While menstruation is a normal event and removes unneeded cells (characteristics of apoptosis), it results directly from the decrease in circulation, causing the cells to die from lack of oxygen; thus it is an example of necrosis. 153) The most common types of cancer in America include colon cancer, skin cancer, breast cancer, cervical cancer, and prostate cancer. What do all of these cancers have in common and why are they so prevalent in our society? Answer: All of these structures have epithelial tissue that is reproducing at a rapid rate. Because they undergo mitosis so often if a failure of apoptosis occurs or if a mutation alters the DNA of one of the cells, the new copies of the existing cells will cause an increase in the cancerous cells at a much faster rate than in other tissues that divide at a much slower rate. 154) Apoptosis and necrosis are described as the two ways cells die. Which one is "messy"? Which is "tidy"? Explain. Why do these forms of cell death exist? What are some advantages and/or disadvantages of each? Use the lining cells of the digestive tract in an example of an advantageous process. Answer: Necrosis is a result of damage to cells. The cells swell and rupture, and the enzymes that are released cause damage to other cells in the area; hence the descriptor "messy." Necrosis has the disadvantage of damaging cells that might otherwise have survived unscathed. Necrosis is not an advantageous process, but it is unavoidable because trauma to cells is unavoidable; we all get hurt sometimes. Apoptosis is "tidy" in that the cells do not rupture and release damaging enzymes; instead the cell breaks up into membrane-surrounded pieces that are consumed by immune cells. Apoptosis is advantageous in that it can shape a structure such as fingers and toes during development. In the case of the digestive tract, the harsh chemical environment would lead to frequent necrosis if it weren't for the programmed apoptosis occurring every day or so. 23 155) A. Define stem cells and differentiation, and describe the different types and the extent to which they are present during the life of an individual (include the fertilized egg as well as the adult that eventually results). B. Which of the four tissue types contain populations of stem cells of known function, and what is that function? Which types of tissue have stem cells of unknown function? Do any types of tissue lack stem cells? C. How do fully differentiated cells differ from stem cells? How can stem cells be used in medical treatment? Give examples. Answer: A. Stem cells are cells that are mitotic and not fully differentiated. Differentiation is the process cells undergo as they become more and more specialized in structure and function as is typical of the specific tissues they compose. The fertilized egg and the cells resulting from the first few cleavage divisions after fertilization are totipotent, which means they can ultimately produce all the types of cells in an adult. Within the first week after conception, the cells begin differentiation and become capable of producing many types of cells but not all. These cells are pluripotent. By adulthood, stem cells can be described as multipotent, which are stem cells that can produce many of the cell types in a specific tissue, and committed stem cells, which can only become one specific cell type within that tissue. B. Epithelial and connective tissues have active populations of multipotent stems cells, which replace cells lost to damage or normal turnover. Muscle and nervous tissues contain stem cells but appear to be unable to replace lost cells. They were once thought to lack stem cells altogether. C. Once cells are fully differentiated, they can no longer divide to produce more cells. Disease conditions or injuries that result in cell loss may be remedied by treatment with appropriate stem cells. Examples are neurological injuries and diseases marked by irreversible damage to cells that cannot (yet) be replaced by new cells. 156) Stem cell research has become a political topic in the last few decades. Explain why the research is being done, why some cells are favored for this research over others, and what the factors are that cause some people not to support this type of research. Are any alternatives available that are less opposed? Answer: Stem cell therapy may remedy previously untreatable diseases and conditions such as those involving brain and spinal injury. It has become political because one source of stem cells that are highly desirable for research is those removed from human embryos and fetuses. These cells are less differentiated and therefore more likely to be able to yield the specific types of mature cells desired. Many people opposed to abortions of human pregnancies are opposed to the use of human embryos and fetuses as a source of stem cells because these embryos and fetuses are destroyed in the process. Use of umbilical cord blood from live births is less opposed, though these cells are somewhat limited in the types of cells they can produce and therefore may not be valuable for treating as large a variety of diseases and injuries. 157) Nervous tissue includes two types of cells: neurons and glial cells. Glial cells are mitotic, whereas neurons are not (except the small population of stem cells). Which type of cell is most likely to be involved in brain cancer, and why? Answer: Cancer results from uncontrolled cell division in mitotic cells. Therefore, glial cell cancers (gliomas) are the most common type of nervous system cancers, as they have the most mitotic activity. 158) Cell membranes are made up of lipid, protein, and carbohydrate in relative amounts that vary according to cell type. Describe the relative proportions of these substances in three structures, and relate these differences to cell function where possible. Answer: (Note to instructor: This may be a good question to use on a comprehensive final exam, as it ties together basic membrane composition with cell functions revealed in later chapters.) See Table 3.1 in the chapter. Red blood cells have nearly equal amounts of protein and lipid, with a small amount of carbohydrate, in this ratio of protein:lipid:carbohydrate: 49:43:8. Myelin is almost all lipid, followed by protein and carbohydrate in this ratio of lipid:protein:carbohydrate: 79:18:3. In later chapters on the nervous system, it will be seen that this preponderance of lipid results in electrical insulation, which is one of the main functions of myelin. The inner mitochondrial membrane is mostly protein, in this ratio of protein:lipid:carbohydrate: 76:24:0. This reflects the function of this membrane in chemical synthesis that relies on a variety of protein enzymes. 24 159) Nutrients undergo the last stages of digestion by enzymes located on the cells of the small intestine; then the nutrients are absorbed by these same cells by way of various membrane transport processes. Adipose cells absorb and store excess food energy in the form of fat. You and the other students in the physiology lab you are taking are doing an analysis of cell membrane composition, on unknown animal tissue samples labeled A and B. All lab groups determined that sample A contained, on average, 81% protein, 18% lipid, and 1% carbohydrate. Sample B contained 85% lipid, 10% protein, and 5% carbohydrate. Sketch a graph of the class data. You now have to make a logical conclusion as to which sample is more likely to be intestine and which is adipose tissue. What do you conclude, and why? Answer: A bar graph would be appropriate, as in the figure below. The presence of digestive enzymes and membrane transporters in small intestine cells indicate there should be a significant amount of protein present. Adipose cells, on the other hand, are relatively inactive and can passively absorb lipids by way of simple diffusion through the membrane phospholipids. Adipose tissue is expected, therefore, to consist primarily of lipids. Sample A is most likely small intestine, and sample B adipose. 25