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Name ____________________________ A.P. Biology Mid-Term Exam (Chapters 1-20) Among the following statements, only 22 are incorrect. Label 22 with “False” (4 points each) and the remainder as “True” (1 point each). Chemistry (8) 1. _____ The properties of carbon that influence it’s role in biological systems include its normal valence of 6, unequally distributed charges, and its inability to form long chains. FALSE 2. _____ Functional groups are clusters of elements typically found together in particular molecules, and they are usually involved in chemical reactions. 3. _____ The building blocks of proteins are triglycerides of fatty acids. FALSE 4. _____ Amino groups and carboxyl groups are the main functional groups of proteins. 5. _____ Side chains (variable or R groups) distinguish one amino acid from another. 6. _____ The primary structure is a protein’s sequence of fatty acids. FALSE 7. _____ A protein’s amino acids are linked by peptide bonds involving the amino group of one amino acid and the carboxyl of another. 8. _____ A protein’s secondary structure describes how hydrogen bonds form between amino acids that are fairly close together, usually as a helix or pleated sheet. 9. _____ A protein’s tertiary structure describes the folding of a protein molecule due to other attractions within the molecule, often involving the variable (R) groups. 10. _____ A protein’s quaternary structure describes the bonding of two or more polypeptide chains, such as in hair or the collagen in connective tissues. 11. _____ Functions of proteins include parts of plasma membranes (channels, gates, enzymes, facilitators of diffusion, etc), enzymes, and transport molecules (such as hemoglobin). 12. _____ Carbohydrates are often simply referred to as sugars, but are often much more complex (such as cellulose or starch). 13. _____ Monosaccharides are single protein units of 3 to 5 amino acids long. FALSE 14. _____ Monosaccharide have many functions including energy sources, markers on cell surfaces, and are the identifying factor of ABO blood groups. 15. _____ In aldehyde sugars (end in –ose) such as glucose and ribose, the terminal carbon on the adlehyde group has a double bonded oxygen and a hydrogen attached. 16. _____ In ketone sugars (end in –ulose) such as levulose (usually called fructose), the ketone group has the double bonded carbon and oxygen between two other carbons. 17. _____ Disaccharides are double protein units that serve as energy sources. FALSE 18. _____ Polysaccharides have multiple sugar units that function as energy sources, cell wall components (cellulose; pectin; etc.), and energy storage (starch in plants or glycogen in animals). 19. _____ Lipids are organic molecules in cells that are not water soluble, and include fats, oil, waxes, and steroids. 20. _____ Triglycerides consist of three fatty acids and one glycerol, and function in energy storage. 21. _____ Fatty acids are said to be saturated (with hydrogen) if all the carbons in the chain have single bonds between them in saturated fatty acids. 22. _____ In unsaturated fatty acids, some of the carbons have double bonds between them, so there are fewer hydrogen atoms. 23. _____ Steroids are based on cholesterol molecules, and include hormones such as the sex hormones. 24. _____ Steroid hormones are lipid soluble, and that means they pass freely through the plasma membrane and are able to act directly on DNA to turn genes on or off. 25. _____ Phospholipids are composed of two amino acid chains, a phosphate group and a hydrophobic protein head. FALSE 26. _____ Phospholipids are the major component of the plasma membrane. 27. _____ The phosphate group is on the hydrophilic head portion of the molecule, while the fatty acids constitute the hydrophobic tails. 28. _____ The function of an enzyme and its active site are influenced by temperature, pH and ion concentration, and inhibitors. 29. _____ Enzymes are catalysts that usually consist of omega-3 fatty acids. FALSE 30. _____ In an enzyme reaction, the rate of reaction increases as the temperature increases until the optimal temperature is reached. After that, the rate of reaction decreases as the enzyme denatures. 31. _____ Most enzymes become totally denatured at 60o C. 32. _____ Enzymes reduce the activation energy, the energy necessary to start a chemical reaction. 33. _____ Most enzymes work best around a pH of 7. Enzymes can be denatured by deviations from the optimal pH. 34. _____ Competitive inhibitors are similar in shape to the normal substrate and bond with the active site of the enzyme. 35. _____ Competitive inhibitors are similar in shape to the enzyme and bond with the active site of the substrate. FALSE 36. _____ Noncompetitive inhibitors link to the enzyme molecule at a site other than the active site, changing the shape of the active site making it unavailable. Cells 37. _____ Cell size is largely influenced by the ratio of surface area to volume, which affects gas and nutrient exchange. 38. _____ Cellulose in the cell membrane (the plasma membrane) provides structural support for the cell. FALSE 39. _____ The plasma membrane regulates all that enters and leaves a cell. 40. _____ The cytoplasm is everything inside the cell, outside the nucleus. 41. _____ The cells structures within the cytoplasm are often suspended in a series or web of protein fibers (microtubules and microfilaments) called the cytoskeleton. 42. _____ All cells have ribosomes, which serve as the site for synthesis of proteins. 43. _____ All cells have DNA, which provides the instructions for making proteins, regulating cell activities, and enabling cells to reproduce. 44. _____ DNA of mitochondria are more similar to prokaryotic DNA and ribosomes than the DNA of the cell in which they reside. 45. _____ The nucleus directs cell activities and stores DNA. 46. _____ There are many small openings or channels on the nuclear membrane called nuclear pores, which allow ribosomal proteins and RNA to leave the nucleus. 47. _____ The ribosomal proteins are manufactured in the nucleolus and form ribosomes when they are assembled in the cytoplasm. 48. _____ Eukaryotes store DNA in the nucleus, and the DNA is in long stands wound tightly around proteins. 49. _____ Just before the cell divides, however, the DNA strands wind up into dense, compact structures called chloroplasts. FALSE 50. _____ An Endoplasmic Reticulum (ER) processes lipids made by the mitochondria. FALSE 51. _____ Ribosomes in the cytoplasm make proteins that are designed to remain in the cell to make new organelles. 52. _____ Ribosomes attached to the surface of the rough endoplasmic reticulum make proteins that are designed to be exported from the cell. 53. _____ The ER is a network of membranes that move carbohydrates and other substances through the nucleus. FALSE 54. _____ The ER membranes are also made of a lipid bilayer with embedded proteins. As a protein is made, it crosses the ER membrane and that portion of the ER pinches off and forms a sac called a vesicle that protects the protein from other proteins in the cytoplasm. 55. _____ The smooth portion of the ER lacks ribosomes and appears smooth in an electron microscope, and it functions in making lipids and breaking down toxic substances. 56. _____ The Golgi Apparatus (Bodies) packages and distributes ribosomes produced by the lysosomes. FALSE 57. _____ Vesicles from the ER carry the proteins to the Golgi apparatus, which appear as flattened sacs. 58. _____ Enzymes in the Golgi apparatus modify the proteins, which are then encased in new vesicles that bud from the surface of the Golgi. 59. _____ Some of the vesicles produced by the Golgi are lysosomes, which are small spherical organelles that contains the cell’s digestive enzymes. 60. _____ Lysosomes digest and recycle the cells used components by breaking down macromolecules (lipids, carbohydrates, nucleic acids and proteins). 61. _____ Mitochondria produce ATP through cellular respiration (including the Kreb’s cycle, the electron transport chain, and oxidative phosphorylation). 62. _____ Nearly all eukarotic cells contain mitochondria, and cells with high energy needs (e.g., muscle cells) have many (hundreds or thousands) mitochondria. 63. _____ Glycolysis takes place inside the mitochondria, with or without oxygen. FALSE 64. _____ Mitochondria also have two membranes. The outer is smooth, and the inner membrane has many folds. The two compartments formed by these membranes are where the chemical reactions take place. 65. _____ Mitochondria also have nucleic acids (DNA) and ribosomes. Membranes 66. _____ In the Fluid mosaic model , the plasma membrane consists of two layers of phospholipids with a variety of proteins within it. 67. _____ The fatty acid tails (hydrophobic tails) of the phospholipids are toward the inside of the membrane, while the phosphate group, and associated atoms, are on the outsides (hydrophilic heads). 68. _____ The membrane functions to regulate the passage of substances into and out of the cell, providing selective permeability. 69. _____ Substances that can diffuse freely through the plasma membrane are nonpolar (hydrophobic) molecules as well as very small molecules such as water, carbon dioxide and oxygen. In general, charged particles do not pass freely through the membrane. 70. _____ The ability of specific ions and polar molecules to pass through the membrane depends on transport proteins that are within the membrane. 71. _____ Simple diffusion is a type of passive transport in which a substance travels through the membrane from areas of high concentration to areas of low concentration. 72. _____ Facilitated diffusion is a type of passive transport in which membrane proteins assist some substances through the membrane along the concentration gradient. 73. _____ Active transport requires energy to transport substances against the diffusion gradient, allowing the cells to concentrate substances inside or outside. 74. _____ An example of active transport is the sodium-potassium pump. Cellular respiration 75. _____ Glycolysis takes place in the cytosol, splitting a 6 carbon sugar to two, three carbon pyruvate molecules without using oxygen. 76. _____ Glycolysis produces 2 NADH and a net gain of 2 ATP through substrate level phosphorylation. 77. _____ The Krebs cycle takes place in the thylakoids of the chloroplasts. FALSE 78. _____ In the Krebs cycle, pyruvate is reacted with coenzyme A (CoA), carbon dioxide is released, hydrogen ions are harvested in NADH and FADH and one ATP is generated per cycle by substrate level phosphorylation. 79. _____ The Electron transport chain takes place in the inner membrane of the mitochondrion, where hydrogen ions are actively transported between the membranes of the mitochondrion. 80. _____ The electron transport chain creates an electrochemical gradient that provides the energy for the production of ATP. 81. _____ As electrons are passed down the electron transport chain, molecular oxygen accepts the hydrogen ions and electrons, forming water. 82. _____ Lactic acid fermentation occurs in skeletal muscle cells with insufficient oxygen and produces lactic acid, causing muscle fatigue and an oxygen debt. 83. _____ When resting, lactic acid is carried to the liver via the bloodstream where it is converted back to pyruvate for use in other body functions. 84. _____ Alcoholic fermentation occurs in yeast and some bacterial cells, producing ethanol (ethyl alcohol) which eventually poisons the cells. Photosynthesis 85. _____ Photosynthesis is production of sugar by using sunlight energy. 86. _____ The reactions of photosynthesis are summarized as 6H2O + 6CO2 –(light) C6H12O6+ 6O2 87. _____ Photosynthesis occurs in membranes of thylakoids, which are sacs in stacks called grana, surrounded by the stroma of the chloroplast. 88. _____ The thylakoid sacs are the location of the light reactions of photosynthesis that produces ATP and NADPH. 89. _____ Stroma is comparable to the cytoplasm of the cell, and serves as the location of the Calvin cycle, in which ATP and NADPH provide energy and hydrogen ion electrons for the production of sugar, independent of light. 90. _____ Photosynthetic pigments include the primary pigment, chlorophyll a, and the accessory pigments chlorophyll b and carotenoids. 91. _____ The accessory pigments protect chlorophyll a from damage from UV light and absorb light at wavelengths not absorbed by chlorophyll a. 92. _____ The energy absorbed by accessory pigments are transferred to chlorophyll a in the photosystems, broadening the absorption spectrum for photosynthesis. 93. _____ The O2 released during photosynthesis comes from splitting water (H2O). 94. _____ The mesophyll of the leaf are involved in photosynthesis. 95. _____ In C3 plants (most plants), most of the photosynthesis occurs in the palaside mesophyll (palisade parenchyma) located on the upper side of the leaf. 96. _____ Spongy mesophyll is toward the lower side of the leaf, and is responsible for only some photosynthesis, but serves primarily in gas exchange with the atmosphere through openings called stomata. 97. _____ The stomata are regulated by guard cells, which are triggered by CO2 concentration. 98. _____ In C3 plants, the stomata open during the day and close at night. CAM plants in arid regions open their stomata at night to conserve water. 99. _____ Photosystem I donates electrons that end up in NADPH 100. _____ Photosystem II splits water, and donates electrons that restore photosystem I, and water is ultimately the source of electrons that end up in NADPH. 101. _____ The light-independent reactions (also known as the dark reactions or the Calvin cycle) use NADPH from the light reactions to provide energy and hydrogen ions needed to produce sugar from carbon dioxide. 102. _____ The light-dependent reactions occur only during the day; the light-independent reactions occur only during the night. FALSE 103. _____ In the light-independent reactions the carbon dioxide acceptor is RuBP in a reaction catalyzed by the enzyme rubisco that eventually forms PGA. 104. _____ In the light-independent reactions the first stable compound, PGA, reacts with NADPH to produce PGAL, which is converted to glucose, and RuBP is restored with a series of reactions involving ATP and NADPH. 105. _____ Photorespiration occurs when the stomata of the leaf are closed and there is a shortage of carbon dioxide for photosynthesis; the enzyme rubisco reacts RuBP with oxygen instead of carbon dioxide to produce needed carbon dioxide. 106. _____ C3 plants are capable of trapping (fixing) carbon in the Calvin cycle only. 107. _____ C3 plants store the products of the Calvin cycle as starch and cellulose. 108. _____ C4 plant utilize the Calvin cycle, but have a series of added on reactions that allow carbon dioxide to be trapped in the early morning or late evening. 109. _____ CAM plants are desert plants that trap CO2 at night and store it as crassulacean acid to prevent water loss through the stomata since the stomata only open at night. 110. _____ The light-dependent reactions utilize CO2 and H2O; the light -independent reactions produce CO2 and H2O. FALSE 111. _____ The light-dependent reactions produce ATP and NADPH; the light-independent reactions use energy stored in ATP and NADPH. 112. _____ If plants are grown for several days in an atmosphere containing 14CO2 in place of 12CO2, one would expect to find very little radioactivity in the growing leaves. FALSE 113. _____ If plants are grown for several days in an atmosphere containing 14CO2 in place of 12CO2, one would expect to find large amounts of radioactive water released from the stomata. FALSE 114. _____ If plants are grown for several days in an atmosphere containing 14CO2 in place of 12CO2, one would expect to find a large increase in 14C in the starch stored in the roots. 115. _____ Carbohydrate-synthesizing reactions of photosynthesis directly require products of the light reactions. 116. _____ The carbon that makes up organic molecules in plants is derived directly from carbon fixed in photosynthesis. The Cell Cycle 117. _____ In the cell cycle, interphase refers to the G1, S and G2 phases collectively. 118. _____ The G1 phase features normal cell function and growth; and cells that do not pass the G1 checkpoint remain permanently in G1, sometimes referred to as G0. 119. _____ The S phase features the synthesis of RNA known as RNA replication. FALSE 120. _____ The G2 phase features additional production of proteins, and preparation for mitosis. 121. _____ Checkpoints in the cell cycle determine whether a cell is ready to proceed to the next phase of the cycle. 122. _____ Mitosis occurs in diploid somatic (body) cells and results in two identical daughter cells with the same number of somatic cells as the parent cell. 123. _____ Prophase of mitosis includes the disappearance of the nuclear membrane, the appearance of the replicated chromosomes, an in animal cells the replication of the centromere and migration of the duplicated centromeres to the opposite poles of the cell. 124. _____ Metaphase of mitosis features sister chromatids meeting along the equatorial plate of the cell and spindle fibers attaching to each chromatid. 125. _____ In anaphase of mitosis, chromatids are separated as the spindle fibers shorten. 126. _____ Telophase of mitosis features the formation of new nuclei. 127. _____ Division of the cell is called cellular lysis. FALSE Meiosis 128. _____ Meiosis occurs in reproductive cells and reduces the diploid parent cell to two haploid daughter cells, and then splits the daughter cells again to result in four haploid daughter cells. 129. _____ Mitosis and meiosis are both divisions of the nucleus, but serve different purposes. 130. _____ Mitosis most closely resembles the second stage of meiosis. 131. _____ Meiosis provides new cells for growth, repair or replacement. FALSE 132. _____ Crossing over takes place between prophase I and metaphase I of meiosis. 133. _____ Crossing over provides opportunities for variation between gametes. 134. _____ The independent assortment of chromosomes during metaphase I of meiosis provides opportunities for variation between gametes. 135. _____ The steps of meiosis below are in the correct order: .a. b. c. d. e. f. g. h. 136. _____ The nuclei in step d. are haploid. 137. _____ The nuclei in step e. are haploid. 138. _____ The nuclei in step h. are haploid. Genetics 139. _____ Alleles are alternative forms of a gene. 140. _____ Dominance is the expression of one allele masking the expression of another . 141. _____ Homozgyous individuals have identical alleles for a gene. 142. _____ Heterozygous individuals have two different alleles. 143. _____ Pleiotropy describes when one gene influences several other traits. 144. _____ A test cross is a cross between an unknown individual displaying the dominant trait and one that is a known homozygous recessive. 145. _____ Mendel’s Law of Segregation states that allele pairs separate during gamete formation (meiosis) and then randomly combine with the fusion of gametes during fertilization. 146. _____ Mendel’s Law of Independent Assortment states that the inheritance of one trait does not influence the inheritance of another as long as alleles for the trait are on separate chromosomes. 147. _____ If a couple’s first two children are female, the probability that the couple’s third child will be male is roughly 50%. 148. _____ If a couple’s first two children are female, the probability that all three of the couple’s children will be female is roughly 1/8 or 12.5%. 149. _____ A couple has 5 children, all sons. If the woman gives birth to a sixth child, the probability that the sixth child will be a son is 1/6 or 16.7%. FALSE Molecular Genetics 150. _____ Nucleotides are composed of a phosphate group, 5-carbon sugar (deoxyribose or ribose) and a nitrogenous base (adenine, guanine, cytosine, thymine, uracil). 151. _____ The phosphate of a nucleotide is attached to the 3' carbon of one sugar and the 5'carbon of the next, and the nitrogenous bases are linked to the 1' carbon of the sugar. 152. _____ In DNA, the nitrogenous bases are linked to each other by hydrogen bonds (cytosine with guanine; adenine with thymine). 153. _____ Adenine and guanine are purines, and are larger than thymine, cytosine and uracil, which are all pyrimadines. 154. _____ To form a double strand, one side of the DNA molecule must be upside down and backwards in relation to the other, which is referred to as antiparallel. 155. _____ In eukaryotes, DNA replication involves the creation of replication bubbles at various places in the DNA strand by the enzyme helicase, which breaks the hydrogen bonds between nitrogen bases. 156. _____ Purines always match with other purines, and pyrimadines match with pyrimadines. FALSE 157. _____ In DNA replication, RNA primase places a short sequence of RNA nucleotides called an RNA primer. 158. _____ In DNA replication on the leading strand, DNA polymerase adds nucleotides beginning at the 5' end of the newly forming strand that complements the leading strand. 159. _____ In DNA replication on the lagging strand, DNA polymerase adds nucleotides beginning at the 5' end but it builds short segments called Okazaki segments which are joined by the enzyme ligase. Protein Synthesis 160. _____ The genetic code is read as triplets of bases called a codon, and each codon codes for one amino acid. 161. _____ Because there are four bases, but are read only three at a time, there are 64 possible combinations. 162. _____ There are only 20 amino acids, so some of the codes are repetitive, and others do not code for anything and function as stop codons. 163. _____ Transcription takes place in the cytoplasm, in vesicles created by the Golgi. FALSE 164. _____ In transcription, the genetic code of the DNA is transcribed into a messenger RNA (mRNA) molecule. 165. _____ RNA differs from DNA because it contains ribose rather than deoxyribose, it contains the nitrogenous base uracil rather than thymine, and it is singled-stranded. 166. _____ After transcription, RNA processing removes noncoding portions called introns from the mRNA molecule, and the introns remain inside the nucleus. 167. _____ At the end of RNA processing, the coding portions called exons are joined by spliceosomes. 168. _____ After mRNA leaves the nucleus, it becomes attached to the ribosome between the subunits. 169. _____ The synthesis of protein from the mRNA at a ribosome is called translation. 170. _____ Amino acids are activated when attached to a tRNA molecule. 171. _____ In translation,, the anticodons of tRNA bond with a complementary mRNA codon at the ribosome, where the amino acid is attached to a growing chain of other amino acids. Evolution 172. _____ Linnaeus developed the system of binomial nomenclature for the classification of living things, giving each a specific scientific name (genus and species), usually in Latin and descriptive. 173. _____ Cuvier proposed that fossils are the remains of organisms that once lived and are found in sedimentary rocks. 174. _____ Hutton proposed that changes in the physical features of the earth were gradual (such as the formation of canyons), and Lyell said that the forces behind such events continue today. 175. _____ Lamarck believed that organisms have changed over time, and he proved that an organism needing a specific trait can acquire it and then passed it on to the offspring. FALSE 176. _____ Charles Darwin's theory of natural selection included that there are more offspring produced than can be supported. 177. _____ Darwin believed that variations exist in any population of organisms. 178. _____ Darwin believed that organisms compete with each other for essentials, such as food, water, mates, etc., and the individuals that are best fit (most adapted) tend to survive and have more offspring. 179. _____ Fossils represent ancestors of presently living organisms. 180. _____ Evidence that supports evolution includes comparative anatomy, which supports that related organisms have similar body parts. 181. _____ Evidence that supports evolution includes comparative embryology, which shows that related organisms have similar patterns of development. 182. _____ Evidence that supports evolution includes comparative biochemistry, which shows that related organisms have similar chemical pathways and chemical composition. Evolution of Populations 183. _____ The Hardy-Weinberg principle provides the conditions under which evolution occurs, but assumes that the population must be large, isolated without migration, with no natural selection or sexual selections, and no mutations. 184. _____ If p + q = 1 and p2 + 2 pq + q2 = 1, and p=.30, then 21% of the population are heterozygous. FALSE 185. _____ The Founder effect describes how an isolated small group of organisms leaves the main population to colonize in a new area, and changes to allele frequencies could occur. 186. _____ Genetic drift describes how random events in a small population can change allele frequencies. 187. _____ Gene flow describes how migrants can influence allele frequencies in the populations they visit. 188. _____ Prezygotic reproductive isolating mechanisms leading to speciation include gametic isolation, behavioral isolation, temporal isolation, mechanical isolation, and habitat isolation. 189. _____ Postzygotic isolating mechanisms include reduced hybrid viability, reduced hybrid fertility, and hybrid breakdown. 190. _____ Allopatric speciation involves reproductive isolation from a geographic barrier. 191. _____ Sympatric speciation involves reproductive isolation from a radical change in the genome of a population subgroup. 192. _____ Adaptive divergence or adaptive radiation is the result of the introduction of new environmental stresses presenting new problems and opportunities. 193. _____ Convergent evolution is the independent development of similar characteristics in different species as a result of similar ecological roles and selection pressures. 194. _____ Analogous structures are most closely associated with convergent evolution. 195. _____ Homologous structures are most closely associated with divergent evolution