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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