Review Answers - Answer Section CHAPTER 1 INTRODUCTION...

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Unformatted text preview: Answer Section CHAPTER 1: INTRODUCTION: THEMES IN THE STUDY OF LIFE INTERACTIVE QU ESTIONS 1.1 1.2 1.3 1.4 a. The biosphere includes most regions of land and water and the atmosphere up to sev- eral kilometers: all of Earth that is inhabited by life. b. An ecosystem includes all the living organ- isms in an area, along with the nonliving parts of the environment with which they interact. c. A community consists of all the organisms inhabiting a particular area. d. A population includes the individuals of a single species in an area. e. An organism is an individual living entity. f. Organs and organ systems, found in more complex organisms, perform life’s functions. g. Tissues are collections of similar cells. Sev— eral tissues make up an organ. h. Cells are the fundamental unit of life. i. Organelles are the functional components that make up cells. j. Molecules are composed of two or more atoms. They are the chemical units of life. In predicting how a particular drug or treat- ment may affect various aspects of the' body; in predicting effects on various parts of the eCosystem as C02 concentration climbs. The order of nucleotides in a DNA molecule that makes up a gene "spells" the instructions, rewritten in RNA, for making a protein with a specific function. They are characterized to a large extent by their mode of nutrition. Plants are photosynthetic, fungi absorb their nutrients from decomposing organic material, and animals ingest other organisms. Most species tend to produce more offspring than can survive. Organisms with heritable / F./ 1.6 1.7 1. traits best suited to the environment will tend to leave more offspring. Over time, favorable adaptations will accumulate in a population. New species may arise as small populations are exposed to different environments and natural selection favors different traits. a. Since most encounters with coral snakes are fatal, predators didn't ”learn" to avoid them. But predators with genes that somehow made them instinctively avoid coral snakes would have been more likely to pass on those genes to offspring, gradually adapting the predator pop ulation to the presence of poisonous snakes in their area. b. This experiment could not control for the number of predators in each area and thus the total number of attacks on snakes. By present— ing data as the percent of total attacks, the effect of this variable was eliminated. a. A hypothesis is less broad in scope than a theory; it is a tentative explanation for a smaller set of observations. A theory can generate many testable hypotheses and is supported by a large body of evidence. Both hypotheses and theories are revised when new data do not support their predictions. b. Science seeks to understand natural phe- nomenon; technology is the practical use of sci- entific knowledge. SUGGESTED ANSWERS TO STRUCTURE YOUR KNOWLEDGE a. Evolution explains the unity and diversity of life. All organisms are modified descendants of common ancestors. Darwin’s theory of natural selection leading to differential reproductive 4:47 448 Answer Section a success accounts for the adaptation of popula- f. DNA is the molecule of inheritance, coding tions to Earth’s varying environments. information for proteins and the functions of a b. Nth every increase in biological level, the cell, and passed on from one generation to the. organization, and interactions of component next. parts lead to emergent; new properties of the g. Organisms regulate their internal environ. dynamic system. ment, usually through negative feedback c. Organisms exchange materials and energy mechanisms that slow down body processes, With the living and nonliving components of matching supply to demand. their environment. All organisms requireenergy. Energy flows through ecosystems from sunlight to chemical energy in producers and consumers ANSWERS T0 TEST YOUR KNOWLEDGE to escape as heat. (1. At each level of biological organization, Multiple Choice: structure and function are correlated. 1. d 3. b 5. a '7. e 9 e e. Cells are the basic units of life. They come in 2. d 4. b 6. d 8. c two distinct forms: prokaryotic and eukaryotic. CHAPTER 2: THE CHEMICAL CONTEXT OF LIFE INTERACTIVE QUESTIONS 2.7 a. H=1,0=2,N=3,C=4 2.1 calcium, phosphorus, potassium, sulfur, sodium, __ .. fl chlorinemgnesium b. H:HQ::9:N:::N:H:_C_:H H 2.2 neutrons; 15, 15, 16, 31 2'3 absorb; released 2.8 a. Nonpolar; even though N has a high elec tronegativity, the three pairs of electrons are shared equally between the two N atoms be- 2‘4 a. Carbon, 6C c. Oxygen, 80 cause each atom has an equally strong attraction for the electrons. ® 13. Polar; N is more electronegative than H and _ pulls the shared electrons in each covalent bond closer to itself. 17- Nitrogen, 7N d- Magnesium, 12Mg c. Nonpolar; C and H have similar electronega- tivities and share electrons fairly equally be- ' tween them. g d. The C=O bond is polar because 0 is more electronegative than C; the C—H bonds are relatively nonpolar. 2.9 a. CaClz in. Ca2+ is the cation. 2.5 Although each orbital can hold a pair of elec— trons, each electron fills a separate orbital until no empty orbitals remain. 2.6 a. protons b. atomic number c. element d. neutrons e. mass number or atomic mass 2.11 Water's two covalent bonds with H are spread f. isotopes apart at a 104.5" angle due to the hybridization \ g. electrons of the s and 3 p orbitals. .- h. electron shells 2.12 6, 6, 6 \ 1. valence shell \ NJ", (AJV SUGGESTED ANSWERS TO STRUCTURE . YOUR KNOWLEDGE 1. -——n orbitals in Electron —1 negligible electron shells 2. a. The atoms of each element have a character- istic number of protons in their nuclei, referred to as the atomic number. In a neutral atom, the atomic number also indicates the number of electrons. The mass number is an indication of the approximate mass of an atom and is equal to the number of protons and neutrons in the nucleus. The atomic mass is equal to the mass number and is measured in the atomic mass unit of dal- tons. Protons and neutrons both have a mass of Answer Section 449 c. The valence of an atom is most related to the chemical behavior of an atom because it is an indication of the number of bonds the atom will make, or the number of electrons the atom must share in order to reach a filled valence shell. . Ionic and nonpolar covalent bonds represent the two ends of a continuum of electron sharing between atoms in a molecule. In ionic bonds the electrons are completely pulled away from one atom by the other, creating negatively and positively charged ions (anions and cations). In nonpolar covalent bonds the electrons are equally shared between two atoms. Polar cova- lent bonds form when a more electronegative atom pulls the shared electrons closer to it, pro- ducing a partial negative charge associated with that portion of the molecule and a partial positive charge associated with the atom from which the electrons are pulled. ANSWERS TO TEST YOUR KNOWLEDGE approximately 1 dalton. Multiple Choice: mass number and 1. b 6. e 11. b 16. c 21. b atomic weight \12C 2. d 7. Cl 12. C 17. d 22. C 6 3. a 8. b 13. c 18. b 23. d . atomic number / . 4. e 9. e 14. b 19. a 24. e b. The valence, anindication of bonding capac- 5- a 10- C 15- E 20- C 25- B ity, is the number of unpaired electrons that an atom has in its valence shell. CHAPTER 3: WATER AND THE FITNESS OF THE ENVIRONMENT I INT E RACTIVE QU EST I 0 N S 3.2 a. polar water molecules b. absorbed c. released d. specific heat e. heat of vaporization f. evaporative cooling 3. solar heat 11. rain i. ice forms 3.3 a. olive oil: hydrophobic mostly nonpolar b. sugar: hydrophilic polar c. salt: hydrophilic ionic d. candle wax: hydrophobic nonpolar 3.4 a. The molecular mass of C3H503 is 90 d, the combined atomic masses of its atoms. A mole of 450 Answer Section lactic acid = 90 g. A 0.5 M solution would re- a. Bicarbonate acts as a base to accept EXCESS quire 1/2 11101 or 45 g. I-I+ ions when the pH starts to fall; the reaction b 3 01 X 1073 moves to the left. . b. When the pH rises, H" ions are donated by carbonic acid, and the reaction shifts to the right. 3.7 a. C02 + H20 = H2C03 == HC03- + H+ Increasing [C02] will drive these reactions to the right, increasing [H+]. b. HCOg" =EC03 — + H+ Increasing [H+] will drive this reaction to the left, thus decreasing [C0321 c. With less C03 — available to react with Ca2+, calcification rates would be expected to 3.5 Acidic, Basic, or Neutral? um 3-6 carbonic acid bicarbonate hydrogen ion decrease, as was shown in the study by Chris H2C03 # HCO; + H+ Langdon and colleagues. H+donor H+ acceptor , SUGGESTED ANSWERS TO STRUCTURE YOUR KNOWLEDGE 1. /—\ fl measures calculated by regulated by . maybe if higher i it higher on {n+1 WHOM I0“ which be... is is is to m mam..." 2. a. Cohesion, adhesion i. Floating ice insulates bodies of water so b. A water column is pulled up thrOugh plant they don't freeze solid. vessels. j. Versatile solvent c. Heatis absorbed or released when hydrogen 1:. Polar water molecules surround and dis— bonds break or form. Water absorbs or releases solve ionic and polar solutes. a large quantity of heat for each degree of tem— perature dlange. ANSWERS TO TEST YOUR KNOWLEDGE d. Highheat of vaporization e. Solar heat is dissipated from tropical seas. Multiple ChOlCB.‘ f. Evaporative cooling 1. c 6. cl 11. b 16. a 21. b g. Evaporation ofwater cools surfaces of plants 2. a '7. e 12. d 17. b 22. e and animals. 3. e 8. b 13. c 18. d h. Hydrogen bonds in ice space water mole— 4. e 9. e 14. c 19. d cules apart, making ice less dense. 5. b 10. d 15. e 20. e Answer Section 451 CHAPTER 4: CARBON AND THE MOLECULAR DIVERSITY OF LIFE INTERACTIVE QUESTIONS different bonding sequence and very different properties. Maleic acid and fumaric acid are geometric isomers whose double bonds fix the spatial arrangement of the molecule. Maleic acid is the cis isomer; both groups are on the same side of the double bond. Although the enantiomers L— and D—lactic acid look similar in a 4.2 Ethanol and dimethyl ether, structural isomers, flat representation of their structures, they are have the same number and kinds of atoms but a not superimposable. 4.1 A variety of organic compounds were pro- duced in Miller's apparatus, which attempted to simulate conditions on early Earth. The abi- otic synthesis of organic compounds may have been a first step in the origin of life. SUGGESTED ANSWERS TO STRUCTURE YOUR KNOWLEDGE 1. ISOMERS have same have different molecular molecular formulae shapes structural geometric different isomers three-dimensional isomers shapes chemical properties different have different have different are ”New” . atoms and arrangements images double bonds due to due to placement of atoms around asymmetric carbon Names and Characteristics of Organic Compounds Group Formula Containing Chemical Group Alcohols; polar group Aldehyde or ketone; polar group Carboxylic acid; release H+ —NH2 Amines; basic, accept I-I’r Thiols; cross-links stabilize protein structure Organic phosphates; involved in energy transfers, adds negative charge ‘ Methyl Methylated compounds; addition may alter function ANSWERS TO TEST YOUR KNOWLEDGE no rotation around double bond Multiple Choice: Matching: . 1. c 4. a 7. d 1. a,c 4. e 7 b,f 10. ad 2. b 5. d 8. d 2 b,f 5. e 8. e 11. e 3.e 6.a 9.c 3 a,d,e 6. a,c,d,e 9. a,c 12 c ‘\ 452 Answer Section CHAPTER 5: THE STRUCTURE AND FUNCTION OF MACROMOLECULES ————_,—_*T———fi INTERACTIVE QUESTIONS 5.5 a. fats, triacylglycexides 51 h dr xyl- ' b. phospholipids ' a. Y o c. glycerol 1). carbonyl (1. fatty acids c. aldose e. unsaturated: has someC= C bonds d‘ 1‘3”” r. saturated. no c=c all possible c—.H 2 bonds 5.2 3. phosphate group h. cell membranes i. steroids H0 ‘ " . j. animal cell membrane component (choles ' terol), hormones 5.6 a. CI)?! H CH3 H CH2 | l l | H—N—C-C- —-N—C—C—OH -—|- I n . .. H O H O alanine serine OH I HCI—Ia HCH2 II II H—N—C—(fi—N—Cl—C—OH . o .2; O 5.3 a. monosaccharides _ , dlpephd? . b. (CH20)n b. senne s R group is polar; alanme’s R group c. energy compounds 15 nonpolar _ :1. carbon skeletons, monomers c. a polypeptide backbone e. glycosidic linkages 5.7 a. hydrogen bond - f. disacchafides b. hydrophobic and van der Waals interactions 3. polysaccharides c. disulfide bridge h. glycogen d. ionic bond i. animals These interactions between R groups produce j. starch ’ tertiary structure. k. cellulose . . . . + l. chitin 5.8 a. Achange mpH alters the availablllty of H , OH', or other ions, thereby disrupting the hydrogen bonding and ionic bonds that main- tain protein shape. b. A protein in an organic solvent Would turn inside out as the hydrophilic regions became Hydrophilic clustered on the inside of the molecule and the head hydrophobic regions interacted with the non- polar solvent. c. The return to its functional shape indi— cates that a protein’s three-dimensional struc- ture is intrinsically determined by its primary structure——the sequence of its amino acids. . Hydrophobic tails . Answer Section 453 5.9 PROTEINS are polymers of function . epends on joined by consist of sequence is results from e tide primary FbEnds a carbon structure D'- helix, B pleated sheet is created by hydrophobic, hydrogen bonds within 'polar, charged, polypeptide backbone (acidic, basic) created by hydrophobic, van der Waals determine interacfions, H bonds, iom‘c bonds, disulfide bridges made of several polypeptide subunits hemoglobin, membrane proteins 5.10 DNA—aRNA—Wrotein b. pyrimidine; base has single ring 511 a. c. DNA; 2nd carbon m sugar 15 lackmg O Nitrogenous O 5 base Attachment Site Deoxyrjbose for phosphate of next nucleotide 5.12 NUCLEIC ACIDS are pol roots of DNA , . 15 consrst of double pentose and phosPhate helix (5—C sugar) group forms by either complementary . in in provides for used to code for self— code for ,5 amino acids replication RNA I in proteins may be phosphate—sugar backbone cytosine thymine uracil (in RNA) 454 Answer Section SUGGESTED ANSWERS TO STRUCTURE . YOUR KNOWLEDGE _ 2- a 1. The primary structure of a protein is the specific, genetically coded sequence of amino acids in a polypeptide chain. The secondary structure in- volves the coiling (a helix) or folding (B pleated sheet) of the protein, stabilized by hydrogen bonds along the polypeptide backbone. The ANSWERS TO TEST YOUR KNOWLEDGE Matching: LA 2.B 3.D 4. C 10. A 5. C 6. D Wm“ .B .C .A tertiary structure involves interactions between the side chains (R groups) of amino acids and produces a characteristic three—dimensional shape for a protein. Quaternary structure oc- curs in proteins composed of more than one polypeptide chain. amino acid (glycine) fatty acid nitrogenous base, purine (adenine) glycerol phosphate group sugar (pentose, ribose) sugar (triose) snappy.» Multiple Choice: 1. 2. 3. 4 5 e nmmn 11. c 16. 12. :1 1'7. . 18. 14. c 19. 15. d 20. PPPHP‘ ngmno‘ |-| m '3" U‘no‘fim N OJ p.111: CHAPTER 6: A TOUR OF THE CELL' . INTERACTIVE QU ESTIONS 6.1 6.2 6.3 a. the study of cell structure b. the internal ultrastructure of cells c. the three-dimensional surface topography of a specimen d. Light microscopy enables the study of liv— ing cells and may introduce fewer artifacts than do TEM and SEM. a. a phospholipid bilayer with the hydrophobic tails clustered in the interior and the phosphate heads facing the hydrophilic outside and inside of the cell; proteins are embedded in and at— tached to the membrane b. 102, or 100 times the surface area c. 103, or 1,000 times the volume The genetic instructions for specific proteins are transcribed from DNA into messenger RNA (mRNA), which then passes into the cytoplasm to complex with ribosomes where it is trans— lated into the primary structure of proteins. 6.4 a. smooth ER—in different cells may house enzymes that synthesize lipids; metabolize carbohydrates; detoxify drugs and alcohol; store and release calcium ions in muscle cells b. nuclear envelope—double membrane that encloses nucleus; pores regulate passage of ma- terials c. rough ER—attached ribosomes produce proteins that enter cisternae; produces secre- tory proteins and membranes d. transport vesicle—carries products of ER and Golgi apparatus to various locations e. Golgi apparatus—processes products of ER; makes polysaccharides, packages products in vesicles targeted to specific locations f. plasma membrane—selective barrier that regulates passage of materials into and out of the cell g. lysosome—houses hydrolytic enzymes to digest macromolecules 458 Answer Section CHAPTER 8: AN INTRODUCTION TO METABOLISM INTERACTIVE QUESTIONS e. The negatively charged phosphate groups ' are crowded together, and their mutual repul- 8°1 a. capacity to cause change sion makes this area instable. The chemical 13' kmetrc change to a more stable state of lower free en- lcl. 3:232:11 ergy accounts for the relatively high release of . . energy. 2. posmon f. conserved 8.5 a. free energy 3. created nor destroyed b. transition state h. first c. E A (free energy of activation) Without i. transformed or transferred enzyme 1'. entropy d. EA with enzyme k. second 2. AG of reaction Induced fit --_ High Free Energy Low Free Energy —_— _—_ 8.3 ACtive —‘° site Enzyme-substrate complex FRE— ENERGY measure o—f determined -by _ergyvailable AG 15 Tis AS' 15 free energy available to do work when when Substrates converted to products absolute change in tempera- entropy ture Change in total energy of system measure of 8.7 A competitive inhibitor would mimic the shape of the substrates and compete with them for the usually randomness active site. A noncompetitive inhibitor would be decrease in H reaction 15 _ a shape that could bind to another site on the en- l‘eaCtion is zyme molecule and would change the shape of the active Site such that the substrates could no longer fit. _xergonic _ndergonic spontaneous 8.4 a. adenine b. ribose c three phosphate groups d. A hydrolysis reaction breaks the terminal phosphate bond and releases a molecule of mor- ganic phosphate: ATP + H20 —) ADP + ®i 8.8 ATP would act as an inhibitor to catabolic pathways, slowing the breakdown of fuel mol— ecules if sufficient energy is available in the cell. ATP may act as an activator of anabolic path- ways that store resources in more complex molecules. / .l‘" SUGGESTED ANSWERS TO STRUCTURE YOUR KNOWLEDGE 1. Metabolism is the totality of chemical reactions that take place in living organisms. To create and maintain the structural order required for life requires an input of free energy—from sun- light for photosynthetic organisms and from energy-rich food molecules for other organisms. A cell couples catabolic, exergonic reactions (—AG) with anabolic, endergonic reactions (+AG), using ATP as the primary energy shuttle between the two. 2. Enzymes are essential for metabolism because they lower the activation energy of the specific reactions they catalyze and allow those reactions to occur extremely rapidly at a temperature conducive to life. By regulating the enzymes it produces, a cell can regulate which of the myriad of possible chemical reactions take place at any Answer Section 459 given time. Metabolic control also occurs through allosteric regulation and feedback inhi- bition. The compartments] organization of a cell facilitates a cell’s metabolism. ANSWERS TO TEST YOUR KNOWLEDGE Multiple Choice: 1. c 6. c 11. b 16. d 21. e 2. b 7. a 12. C 17. b 22. a 3. a 8. e 13. b 18. d 4. e 9. e 14. b 19. c 5. c 10. c 15. e 20. b Fill in the Blanks: 1. metabolism 6. free energy of activation 2. anabolic 7. competitive inhibitors 3. kinetic 8. coenzymes 4. allosteric 9. feedback inhibition 5. entropy 10. phosphorylated compound CHAPTER 9: CELLULAR RESPIRATION: HARVESTING CHEMICAL ENERGY //————fl . INTERACTIVE QUESTIONS 9.1 C6H1206; 6 C02; energy (ATP + heat) 9.2 a. oxidized b. reduced c. donates (loses) d. oxidizing agent e. accepts (gains) 9.3 a. oxygen b. glucose c. Some is stored in ATP and some is...
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