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AP Biology Exam #4

Enzymes, Plant and Animal Nutrition, Cellular Respiration

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones? catabolism
Which of the following is (are) true for anabolic pathways? They consume energy to build up polymers from monomers.
Which of the following is a statement of the first law of thermodynamics? Energy cannot be created or destroyed.
Whenever energy is transformed, there is always an increase in the entropy of the universe.
Which of the following statements is a logical consequence of the second law of thermodynamics? Every chemical reaction must increase the total entropy of the universe.
Which of the following statements is representative of the second law of thermodynamics? Cells require a constant input of energy to maintain their high level of organization.
Which of the following types of reactions would decrease the entropy within a cell? dehydration reactions
The organization of organisms has become increasingly complex with time. This statement is consistent with the second law of thermodynamics.
Which of the following best describes enthalpy (H)? the heat content of a chemical system
Which is ATP an important molecule in metabolism? It provides energy coupling between exergonic and endergonic reactions.
When chemical, transport, or mechanicalwork is done by an organism, what happens to the heat generated? It is lost to the environment.
Which of the following statements is (are) true about enzyme-catalyzed reactions? The reaction is faster than the same reaction in the absence of the enzyme.
How can one increase the rate of a chemical reaction? Add a catalyst.
Sucrose is a disaccharide, composed of the monosaccharides glucose and fructose. The hydrolysis of sucrose by the enzyme sucrase results in breaking the bond between glucose and fructose and forming new bonds from the atoms of water.
Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as activation energy.
A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because the activation energy barrier for this reaction cannot be surmounted.
Which of the following statements regarding enzymes is true? Enzymes increase the rate of a reaction.
The active site of an enzyme is the region that is involved in the catalytic reaction of the enzyme.
According to the induced fit hypothesis of enzyme catalysis, which of the following is correct? The binding of the substrate changes the shape of the enzyme's active site.
Increasing the substrate concentration in an enzymatic reaction could overcome which of the following? competitive inhibition
Which of the following is true of enzymes? Enzymes increase the rate of chemical reaction by lowering activation energy barriers.
Competitive inhibitors block the entry of substrates into the active site of an enzyme. On which of the following properties of an active site does this primarily depend? the ability of an enzyme to form a template for holding and joining molecules
Which of the following is likely to lead to an increase in the concentration of ATP in a cell? an increase in a cell's catabolic activity
When you have a severe fever, what may be a grave consequence if this is not controlled? change in the folding of enzymes
How does a noncompetitive inhibitor decrease the rate of an enzyme reaction? by changing the shape of a reactant
The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is known as feedback inhibition.
Which of the following statements describes enzyme cooperativity? A substrate molecule bound to an active site affects the active site of several subunits.
Some enzymatic regulation is allosteric. In such casesm which of the following would usually be found? feedback inhibition
Among enzymes, kinases catalyze phosphorylation, while phosphatases catalyze removal of phosphate(s). A cell's use of these enzymes can therefore function as an on-off switch for various processes. Which of the following is probably involved? the change in a protein's charge leading to a conformational change
Besides turning enzymes on or off, what other means does a cell use to control enzymatic activity? compartmentalization of enzymes into defined organelles
An important group of peripheral membrane proteins are enzymes, such as the phospholipases that attack the head groups of phospholipids leading to the degradation of damaged membranes. What properties must these enzymes exhibit? water solubility
What is the term for metabolic pathways that release stored energy by breaking down complex molecules? catabolic pathways
The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction loses electrons and loses energy
When electrons move closer to a more electronegative atom, what happens? The more electronegative atom is reduced & Energy is released.
Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy? Electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O).
When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecules becomes oxidized.
When a molecule of NAD+ gaibs a hydrogen atom (not a hydrogen ion) the molecule becomes reduced.
Which of the following statements describes NAD+? NAD+ is reduced to NADH during both glycolysis and the citric acid cycle.
Where does glycolysis take place? cytosol
The ATP made during glycolysis is generated by substrate-level phosphorylation.
The oxygen consumed during cellular respiration is involved directly in which process or event? accepting electrons at the end of the electron transport chain
Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present of absent? glycolysis
An electron loses potential energy when it shifts to a more electronegative atom.
Wjy are carbohydrates and fats considered high energy foods? They have a lot of electrons associated with hydrogen.
Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed during glycolysis? 10%
During glycolysis, when glucose is catabolized to pyruvate, most of the energy of glucose is retained in the pyruvate.
In addition to ATP, what are the end products of glycolysis? NADH and pyruvate
The free energy for the oxidation of glucose to CO2 and water is -686 kcal/mole and the free energy for the reduction of NAD+ to NADH formed during glycolysis when it appears that as many as a dozen could be formed? Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
In glycolysis, for each molecule of glucose oxidized to pyruvate 2 molecules of ATP are used and 4 molecules of ATP are produced.
A molecule that is phosphorylated has an increased chemical reactivity; it is primed to do cellular work.
What kind of metabolic poison would most directly interfere with glycolysis? an agent that closely mimics the structure of glucose but is not metabolized
Why is glycolysis described as having an investment phase and a payoff phase? It uses stored ATP and then forms a net increase in ATP.
How does pyruvate enter the mitochondrion? active transport
Which of the following intermediary metabolites enters the citric acid cycle and is formed, in part, by the removal of a carbon (CO2) from one molecule pyruvate? actyl CoA
During cellular respiration, actyl CoA accumulates in which location? mitochondrial matrix
How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate? 2
Starting with one molecule of isocitrate and ending with fumarate, what is the maximum number of ATP molecules that could be made through substrate-level phosphorylation? 1
Carbon skeletons for amino acid biosynthesis are supplied by intermediates of the citric acid cycle. Which intermediate would supply the carbon skeleton for synthesis of a five-carbon amino acid? α-ketoglutarate
How many molecules of carbon dioxide (CO2) would be produced by five turns of the citric acid cycle? 10
How many reduced dinucleotides would be produced with four turns of the citric acid cycle? 4 FADH2 and 12 NADH
Starting with citrate, which of the following combinations of products would result from three turns of the citric acid cycle? 3 ATP, 6 CO2, 9 NADH, and 3 FADH2
Carbon dioxide (CO2) is released during which of the following stages of cellular respiration? oxidation of pyruvate to acetyl CoA and the citric acid cycle
For each molecule of glucose that is metabolized by glycolysis and the citric acid cycle, what is the total number of NADH + FADH2 molecules produced? 12
94. A young animal has never had much energy.He is brought to a veterinarian for help and is sent to the animal hospital for some tests. There they discover his mitochondria can use only fatty acids and amino acids for respiration, and his cells produce m
A. His cells contain something that inhibits oxygen use in his mitochondria.
B. His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.
C. His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA.
D. His cells cannot move NADH from glycolysis into the mitochondria.
E. His cells lack the enzyme in glycolysis that forms pyruvate.
95. Cellular respiration harvests the most chemical energy from which of the following?
A. substrate -level phosphorylation
B. transferring electrons from organic molecules to pyruvate
C. generating carbon dioxide and oxygen in the electron transport chain
D. chemiosmotic phosphorylation
E. converting oxygen to ATP
96. During aerobic respiration, electrons travel downhill in which sequence?
A. food → citric acid cycle → ATP →
B. food → NADH → electron transport chain → oxygen
C. glucose → pyruvate → ATP → oxygen
D. food → glycolysis → citric acid cycle →
E. glucose → ATP → electron transport chain → NADH
97. Where are the proteins of the electron transport chain located?
A. mitochondrial inner membrane
B. mitochondrial matrix
C. mitochondrial outer membrane
D. cytosol
E. mitochondrial intermembrane space
98. During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?
E. ADP + Pi
99. The primary role of oxygen in cellular respiration is to
A. yield energy in the form of ATP as it is passed down the respiratory chain.
B. combine with carbon, forming CO2.
C. combine with lactate, forming pyruvate.
D. act as an acceptor for electrons and hydrogen, forming water.
E. catalyze the reactions of glycolysis.
100. Inside an active mitochondrion, most electrons follow which pathway?
A. glycolysis → NADH → oxidative phosphorylation → ATP → oxygen
B. pyruvate → citric acid cycle → ATP →
NADH → oxygen
C. electron transport chain → citric acid cycle → ATP → oxygen
D. citric acid cycle → FADH2 → electron transport chain → ATP
E. citric acid cycle → NADH → electron transport chain → oxygen
101. During oxidative phosphorylation, H2O is formed. Where does the oxygen for the synthesis of the water come from?
A. carbon dioxide (CO2)
B. molecular oxygen (O2)
C. pyruvate (C3H3O -)
D. glucose (C6H12O6)
E. lactate (C3H5O -)
102. In chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert ADP + Pi to ATP?
A. energy released as electrons flow
through the electron transport system
B. energy released from movement of protons through ATP synthase
C. No external source of energy is required because the reaction is exergonic.
D. energy released from substrate-level phosphorylation
E. energy released from ATP synthase
pumping hydrogen ions from the mitochondrial matrix
103. Energy released by the electron transport chain is used to pump H+ ions into which location?
A. mitochondrial outer membrane
B. mitochondrial intermembrane space
C. mitochondrial matrix
D. cytosol
E. mitochondrial inner membrane
104. The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation is
A. oxidation of glucose to CO2 and water.
B. the difference in H+ concentrations on opposite sides of the inner
mitochondrial membrane.
C. the thermodynamically favorable transfer of phosphate from glycolysis and the citric acid cycle intermediate molecules of ADP.
D. the final transfer of electrons to oxygen.
E. the thermodynamically favorable flow of electrons from NADH to the mitochondrial electron transport carriers.
105. When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the
A. creation of a proton gradient.
B. lowering of pH in the mitochondrial matrix.
C. reduction of NAD +.
D. restoration of the Na+/K+ balance across the membrane.
E. formation of ATP.
106. Where is ATP synthase located in the mitochondrion?
A. outer membrane B. inner membrane C. cytosol
D. electron transport chain
E. mitochondrial matrix
107. It is possible to prepare vesicles from portions of the inner membrane of the mitochondrial components. Which one of the following processes could still be carried on by this isolated inner membrane?
A. oxidative phosphorylation
B. reduction of NAD +
C. both the citric acid cycle and oxidative phosphorylation
D. glycolysis and fermentation
E. the citric acid cycle
108. Each time a molecule of glucose (C6H12O6) is completely oxidized via aerobic respiration, how many oxygen molecules (O2) are required?
A. 38
B. 1
C. 2
D. 12
E. 6
109. Which of the following produces the most ATP when glucose (C6H12O6) is completely oxidized to carbon dioxide (CO2) and water?
A. fermentation
B. oxidative phosphorylation
C. glycolysis
D. citric acid cycle
E. oxidation of pyruvate to acetyl CoA
110. Approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose (C6H12O6) in cellular respiration?
A. 15
B. 2
C. 76
D. 38
E. 4
111. Assume a mitochondrion contains 58 NADH and 19 FADH2. If each of the 77 dinucleotides were used, approximately how many ATP molecules could be generated as a result of oxidative phosphorylation (chemiosmosis)?
A. 36
B. 173
C. 212
D. 77
E. 1102
112. Approximately what percentage of the energy of glucose (C6H12O6) is transferred to storage in ATP as a result of the complete oxidation of glucose to CO2 and water in cellular respiration?
A. 4% B. 10% C. 40% D. 25% E. 2%
113. Recall that the complete oxidation of a mole of glucose releases 686 kcal of energy (ΔG = -686 kcal/mol). The phosphorylation of ADP to form ATP stores approximately 7.3 kcal per mole of ATP. What is the approximate efficiency of cellular respiration
than the usual 36-38 moles of ATP?
A. 0.4% B. 60% C. 30% D. 40% E. 25%
114. What is proton-motive force?
A. the transmembrane proton concentration gradient
B. the force required to remove an electron from hydrogen
C. the addition of hydrogen to NAD +
D. movement of hydrogen into the intermembrane space
E. movement of hydrogen into the mitochondrion
115. In liver cells, the inner mitochondrial membranes are about 5 X the area of the outer mitochondrial membranes, and about 17 X that of the cell's plasma membrane. What purpose must this serve?
A. It increases the surface for oxidative phosphoryation.
B. It increases the surface for substrate -level phosphorylation.
C. It allows the liver cell to have fewer mitochondria.
D. It allows for increased rate of the citric acid cycle.
E. It allows for increased rate of glycolysis.
Use the following to answer the following questions.
Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." These little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. If the memb
116. After the first disruption, when electron transfer and ATP synthesize still occur, what must be present?
A. the electron transport system is sufficient
B. the ATP synthase system is sufficient
C. plasma membranes like those bacteria use for respiration
D. all of the electron transport system and the ability to add CoA to acetyl groups
E. all of the electron transport proteins as well as ATP synthase
117. After the second agitation of the membrane vesicles, what must be lost from the membrane?
A. cytochromes
B. the contact required between inner and outer membrane surfaces
C. the ability of NADH to transfer electrons to the first acceptor in the electron transport chain
D. the prosthetic groups like heme from the transport system
E. ATP synthase, in whole or in part
118. It should be possible to reconstitute the abilities of the vesicles if which of the following is added?
A. cytochromes
B. intact ATP synthase
C. more electrons
D. a second membrane surface
E. extra NADH
119. Which of the following couples chemiosmosis to energy storage?
C. electron transport
D. ATP synthase
E. cytochromes
120. Which of the following describes ubiquinone?
A. a small hydrophobic coenzyme
B. a substrate for synthesis of FADH
C. a vitamin needed for efficient glycolysis
D. an essential amino acid
E. a protein in the electron transport chain
121. Which of the following normally occurs whether or not oxygen (O2) is present?
A. oxidation of pyruvate to acetyl CoA
B. glycolysis
C. fermentation
D. citric acid cycle
E. oxidative phosphorylation
122. Which of the following occurs in the cytosol of a eukaryotic cell?
A. oxidative phosphorylation
B. glycolysis and fermentation
C. oxidation of pyruvate to acetyl CoA
D. fermentation and chemiosmosis
E. citric acid cycle
123. Which metabolic pathway is common to both cellular respiration and fermentation?
A. glycolysis
B. the citric acid cycle
C. oxidative phosphorylation
D. the oxidation of pyruvate to acetyl CoA
E. chemiosmosis
124. The ATP made during fermentation is generated by which of the following?
A. the electron transport chain B. oxidative phosphorylation C. chemiosmosis
D. aerobic respiration
E. substrate -level phosphorylation
125. In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of
A. ATP, NADH, and pyruvate.
B. ATP, pyruvate, and acetyl CoA.
C. ATP, pyruvate, and oxygen.
D. ATP, CO2, and lactate.
E. ATP, CO2, and ethanol (ethyl alcohol).
126. In alcohol fermentation, NAD + is regenerated from NADH during which of the following?
A. oxidation of NAD+ in the citric acid
B. phosphorylation of ADP to form ATP
C. oxidation of pyruvate to acetyl CoA
D. reduction of acetaldehyde to ethanol
(ethyl alcohol)
E. reduction of pyruvate to form lactate
127. One function of both alcohol fermentation and lactic acid fermentation is to
A. reduce NAD + to NADH.
B. reduce FAD+ to FADH2. C. reduce FADH2 to FAD+. D. oxidize NADH to NAD+. E. none of the above
128. Glycolysis is thought to be one of the most ancient of metabolic processes. Which statement supports this idea?
A. Ancient prokaryotic cells, the most primitive of cells, made extensive use of glycolysis long before oxygen was present in Earth's atmosphere.
B. Glycolysis neither uses nor needs O2.
C. Glycolysis is the most widespread metabolic pathway.
D. The enzymes of glycolysis are found in the cytosol rather than in a
membrane-enclosed organelle.
E. Glycolysis is found in all eukaryotic cells.
129. Why is glycolysis considered to be one of the first metabolic pathways to have evolved?
A. It relies on chemiosmosis which is a metabolic mechanism present only in the first cells-prokaryotic cells.
B. It is found in the cytosol, does not involve oxygen, and is present in most organisms.
C. It requires the presence of membrane-enclosed cell organelles found only in eukaryotic cells.
D. It produces much less ATP than does
oxidative phosphorylation.
E. It is found in prokaryotic cells but not in eukaryotic cells.
130. Muscle cells, when an individual is exercising heavily and when the muscle becomes oxygen deprived, convert pyruvate to lactate. What happens to the lactate in skeletal muscle cells?
A. It produces CO2 and water.
B. It is converted to NAD+.
C. It is converted to alcohol.
D. It is taken to the liver and converted back to pyruvate.
E. It reduces FADH2 to FAD+.
131. When muscle cells are oxygen deprived, the heart still pumps. What must the heart cells be able to do?
A. remove oxygen from lactate
B. derive sufficient energy from fermentation
C. continue aerobic metabolism when skeletal muscle cannot
D. transform lactate to pyruvate again
E. remove lactate from the blood
132. You have a friend who lost 7 kg (about 15 pounds) of fat on a "low carb" diet. How did the fat leave her body?
A. It was broken down to amino acids and eliminated from the body.
B. It was converted to urine and eliminated from the body.
C. It was converted to ATP, which weighs much less than fat.
D. Chemical energy was converted to heat and then released.
E. It was released as CO2 and H2O.
133. Phosphofructokinase is an allosteric enzyme that catalyzes the conversion of
fructose-6-phosphate to
fructose-1,6-bisphosphate, an early step of glycolysis. In the presence of oxygen, an increase in the amount ATP in a cell would be expected to
A. activate the enzyme and thus slow the
rates of glycolysis and the citric acid cycle.
B. activate the enzyme and increase the rates of glycolysis and the citric acid cycle.
C. inhibit the enzyme and thus increase the rates of glycolysis and the citric acid cycle.
D. inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle.
E. inhibit the enzyme and thus increase the rate of glycolysis and the concentration of citrate.
134. In vertebrate animals, brown fat tissue's color is due to abundant mitochondria. White fat tissue, on the other hand, is specialized for fat storage and contains relatively few mitochondria. Brown fat cells have a specialized protein that dissipates
proton-motive force across the mitochondrial membranes. Which of the following might be the function of the brown fat tissue?
A. to increase the rate of oxidative
phosphorylation from its few mitochondria
B. to allow other membranes of the cell to perform mitochondrial function
C. to increase the production of ATP
D. to regulate temperature by converting energy from NADH oxidation to heat
E. to allow the animals to regulate their metabolic rate when it is especially hot
135. What is the purpose of beta oxidation in respiration?
A. control of ATP accumulation
B. feedback regulation
C. breakdown of fatty acids
D. oxidation of pyruvate
E. oxidation of glucose
136. Where do the catabolic products of fatty acid breakdown enter into the citric acid cycle?
A. malate or fumarate
B. α-ketoglutarate
C. acetyl CoA
D. pyruvate
E. succinyl CoA
137. Which of the following describes the fate of most of the water taken up by a plant?
A. It makes cell elongation possible.
B. It is used as a solvent.
C. It is lost during transpiration.
D. It is used to keep cells turgid.
E. It is used as a hydrogen source in photosynthesis.
138. A soil well suited for the growth of most plants would have all of the following properties except
A. abundant humus.
B. good drainage.
C. high cation exchange capacity.
D. a high pH.
E. air spaces.
139. In hydroponic culture, what is the purpose of bubbling air into the solute?
A. to inhibit the growth of aerobic algae
B. to provide oxygen to the root cells
C. to inhibit the growth of anaerobic bacteria
D. to provide CO2 for photosynthesis
E. to keep dissolved nutrients evenly distributed
140. What is the major function of nitrogen in plants?
A. component of lignin-biosynthetic enzymes
B. a component of chlorophyll
C. active in amino acid formation
D. required to regenerate phospophenolpyruvate in C4 and CAM plants
E. component of DNA and RNA
141. Which of the following best describes the general role of micronutrients in plants?
A. They are necessary for the formation of cell walls.
B. They are cofactors in enzymatic reactions.
C. They prevent chlorosis.
D. They are necessary for essential regulatory functions.
E. They are components of nucleic acids.
142. Which of the following is not true of micronutrients in plants?
A. They are the elements required in relatively small amounts.
B. They are required for a plant to grow from a seed and complete its life cycle.
C. Overdoses of them can be toxic.
D. They are the essential elements of small size and molecular weight.
E. They generally help in catalytic functions in the plant.
143. What is meant by the term chlorosis?
A. a contamination of glassware in hydroponic culture
B. release of negatively charged minerals such as chloride from clay particles in soil
C. the yellowing of leaves due to decreased chlorophyll production
D. the formation of chlorophyll within the thylakoid membranes of a plant
E. the uptake of the micronutrient chlorine by a plant
144. Nitrogen fixation is a process that
A. releases nitrate from the rock substrate.
B. converts nitrogen gas into ammonia.
C. recycles nitrogen compounds from dead and decaying materials.
D. converts ammonia to nitrate.
E. A and B
145. Why is nitrogen fixation such an important process?
A. Nitrogen-fixing capacity can be genetically engineered.
B. Nitrogen fixation can only be done by
certain prokaryotes.
C. Nitrogen fixers are sometimes symbiotic with legumes.
D. Nitrogen fixation is very expensive in terms of metabolic energy.
E. Fixed nitrogen is most often the limiting factor in plant growth.
146. In what way do nitrogen compounds differ from other minerals needed by plants?
A. Only nitrogen is held by cation exchange capacity in the soil.
B. Only nitrogen is needed for protein synthesis.
C. Only nitrogen can be lost from the soil.
D. Only nitrogen can be absorbed by root hairs.
E. Only nitrogen requires the action of bacteria to be made available to plants.
147. Most crop plants acquire their nitrogen mainly in the form of
A. N2.
B. NH3.
C. CN2H2.
D. NO3..
E. amino acids absorbed from the soil.
148. The enzyme complex nitrogenase catalyzes the reaction that reduces atmospheric nitrogen to
A. NO-.
B. NO+.
C. N2.
D. NH3.
E. NO2.
149. In a root nodule, the gene coding for nitrogenase
A. is inactivated by leghemoglobin.
B. is found in the cells of the pericycle.
C. is absent in active bacteroids.
D. protects the nodule from nitrogen.
E. is part of the Rhizobium chromosome.
150. Among important crop plants, nitrogen-fixing root nodules are most commonly an attribute of
A. wheat.
B. corn.
C. legumes.
D. cabbage and other members of the brassica family.
E. members of the potato family.
151. If a plant is infected with Rhizobium, what is the probable effect on the plant?
A. It is supplied with phosphate from the soil.
B. It gets chlorosis.
C. It becomes flaccid due to the loss of water from the roots
D. It dies.
E. It probably will grow faster
152. You are weeding your garden when you accidentally expose some roots. You notice swellings (root nodules) on the roots. Most likely your plant
A. is developing offshoots from the root.
B. is infected with a parasite.
C. suffers from a mineral deficiency.
D. is benefiting from a mutualistic bacterium.
E. contains developing insect pupa.
153. Which of the following is a true statement about nitrogen fixation in root nodules?
A. The process is relatively inexpensive in terms of ATP costs.
B. The bacteria of the nodule are autotrophic.
C. The plant contributes the nitrogenase enzyme.
D. The process tends to deplete nitrogen compounds in the soil.
E. Leghemoglobin helps maintain a low O2 concentration within the nodule.
154. Which of the following is not a function of rhizobacteria?
A. carry out nitrogen fixation
B. supply growing roots with glucose
C. produce antibiotics that protect roots from disease
D. produce hormones that stimulate plant growth
E. absorb toxic metals
155. A woodlot was sprayed with a fungicide.
What would be the most serious effect of such spraying?
A. an increase in the number of decomposing bacteria
B. an increase in rates of wood decay
C. a decrease in food for animals that eat mushrooms
D. a decrease in tree growth due to the death of mycorrhizae
E. A and B
156. What is the mutualistic association between roots and fungi called?
A. root hair enhancement
B. Rhizobium infection
C. nitrogen fixation
D. parasitism
E. mycorrhizae
157. Hyphae form a covering over roots.
Altogether, these hyphae create a large surface area that helps to do which of the following?
A. protect the roots from ultraviolet light
B. aid in absorbing minerals and ions
C. maintain cell shape
D. increase cellular respiration
E. anchor a plant
158. Which of the following is a primary difference between ectomycorrhizae and endomycorrhizae?
A. Endomycorrhizae, but not ectomycorrhizae, form a dense sheath over the surface of the root.
B. There are no significant differences between ectomycorrhizae and endomycorrhizae.
C. Ectomycorrhizae do not penetrate root cells, whereas endomycorrhizae grow into invaginations of the root cell membranes.
D. Endomycorrhizae have thicker, shorter hyphae than ectomycorrhizae.
E. Ectomycorrhizae are found in woody plant species; about 85% of plant families form ectomycorrhizae.
159. The earliest vascular plants on land had underground stems (rhizomes) but no roots. Water and mineral nutrients were most likely obtained by
A. diffusion through stomata.
B. diffusion across the cuticle of the rhizome.
C. absorption by mycorrhizae.
D. osmosis through the root hairs.
E. absorption by hairs and trichomes.
160. Dwarf mistletoe grows on many pine trees in the Rockies. Although the mistletoe is green, it is probably not sufficiently active in photosynthesis to produce all the sugar it needs. The mistletoe also produces haustoria. Thus, dwarf mistletoe growing
is best classified as
A. a symbiotic plant.
B. a carnivorous plant.
C. a nitrogen-fixing plant.
D. an epiphyte.
E. a parasite.
161. What are epiphytes?
A. haustoria used for anchoring to host plants and obtaining xylem sap
B. aerial vines common in tropical regions
C. plants that have a symbiotic relationship with fungi
D. plants that live in poor soil and digest insects to obtain nitrogen
E. plants that grow on other plants but do not obtain nutrients from their hosts
162. Carnivorous plants have evolved mechanisms that trap and digest small animals. The products of this digestion are used to supplement the plant's supply of
A. minerals.
B. carbohydrates.
C. energy.
D. water.
E. lipids and steroids.
163. The body is capable of catabolizing many substances as sources of energy. Which of the following would be used as an energy source only after the depletion of other sources?
A. glucose in the blood
B. protein in muscle cells
C. glycogen in muscle cells
D. fat in adipose tissue
E. calcium phosphate in bone
164. An animal that migrates great distances
would obtain the greatest benefit from storing its energy as
A. amino acids.
B. minerals.
C. carbohydrates.
D. fats.
E. proteins.
165. Some nutrients are considered "essential" in the diets of certain animals because
A. only some foods contain them.
B. only those animals use the nutrients.
C. they cannot be manufactured by the organism.
D. they are subunits of important polymers.
E. they are necessary coenzymes.
166. Animals require certain amino acids in their diet. An amino acid that is referred to as nonessential would be best described as one that
A. is not found in many proteins.
B. can be made by the animal's body from other substances.
C. is less important than an essential amino acid.
D. must be ingested in the diet.
E. is not used by the animal in biosynthesis.
167. During the process of digestion, fats are broken down when fatty acids are detached from glycerol. In addition, proteins are digested to yield amino acids. What do these two processes have in common?
A. They are catalyzed by the same enzyme.
B. They involve the addition of a water molecule to break bonds (hydrolysis).
C. Both require the presence of hydrochloric acid to lower the pH.
D. Both occur intracellularly in most organisms.
E. Each requires ATP as an energy source.
168. To leave the digestive tract, a substance must cross a cell membrane. During which stage of food processing does this take place?
A. absorption
B. digestion
C. elimination
D. ingestion
E. hydrolysis
169. Intracellular digestion of peptides is usually immediately preceded by which process?
A. endocytosis
B. secretion
C. elimination D. absorption E. hydrolysis
170. Increasing the surface area directly facilitates which of the following digestive processes?
A. absorption B. elimination C. hydrolysis
D. A and B only
E. A, B, and C
171. Which of the following is an advantage of a complete digestive system over a gastrovascular cavity?
A. Extracellular digestion is not needed.
B. Extensive branching is possible.
C. Intracellular digestion is easier.
D. Digestive enzymes can be more specific.
E. Specialized regions are possible.
172. Extracellular compartmentalization of digestive processes is an evolutionary adaptation in many animal phyla. Which of the following phyla is correctly paired with the compartment that first evolved in that phylum?
A. Arthropodastomach
B. Molluscalarge intestine
C. Annelidacomplete alimentary canal
D. Chordataliver
E. Cnidariagastrovascular cavity
173. Foods eaten by animals are most often composed largely of macromolecules. This requires the animals to have methods for which of the following?
A. demineralization
B. elimination
C. regurgitation
D. dehydration synthesis
E. enzymatic hydrolysis
174. Which of the following describes peristalsis in the digestive system?
A. the transport of nutrients to the liver through the hepatic portal vessel
B. smooth muscle contractions that move food through the alimentary canal
C. a common cause of loss of appetite, fatigue, and dehydration
D. a process of fat emulsification in the small intestine
E. voluntary control of the rectal sphincters regulating defecation
175. After ingestion, the first type of macromolecule to be worked on by enzymes in the human digestive system is
A. protein.
B. nucleic acid.
C. glucose.
D. carbohydrate.
E. cholesterol
176. What is the substrate of salivary amylase?
A. protein
B. starch
C. sucrose D. maltose E. glucose
177. Which of the following statements is true of mammals?
A. Enzyme production continues in the esophagus.
B. The epiglottis prevents food from entering the trachea.
C. All foods begin their enzymatic digestion in the mouth.
D. The trachea leads to the esophagus and then to the stomach.
E. After leaving the oral cavity, the bolus enters the larynx.
178. What part(s) of the digestive system have secretions with a pH of 2?
A. small intestine
B. liver
C. pancreas D. stomach E. mouth
179. Which of the following is true of bile salts?
A. They are normally an ingredient of gastric juice.
B. They are enzymes.
C. They emulsify fats in the duodenum.
D. They are manufactured by the pancreas.
E. They increase the efficiency of pepsin action.
180. Most nutrients absorbed into the lymph or bloodstream are in which form?
A. enzymes
B. monomers
C. disaccharides
D. polymers
E. peptides
181. Which of the following enzymes has the lowest pH optimum?
A. sucrase B. amylase C. pepsin
D. lipase
E. trypsin
The following questions refer to the digestive system structures in Figure 41.1.
Figure 41.1
182. Where are the agents that help emulsify fat produced?
A. 1
B. 8
C. 2
D. 9
E. 3
183. Where does the complete digestion of carbohydrates occur?
A. 4 only
B. 3 and 4
C. 1, 3, and 4
D. 3 only
E. 1 and 4
184. Where does the digestion of fats mostly occur?
A. 4 only
B. 3 only
C. 1, 3, and 4
D. 1 and 4
E. 3 and 4
185. Which structure is home to bacteria that produce vitamins as by -products of their metabolism?
A. 3
B. 7
C. 5
D. 4
E. 8
186. In general, herbivorous mammals have molars modified for
A. cutting. B. piercing. C. ripping. D. grinding. E. splitting.
187. In which group of animals would you expect to find a relatively long cecum?
A. carnivores
B. heterotrophs
C. herbivores D. omnivores E. autotrophs
188. Which of the following are adaptations to a carnivorous diet?
A. a rumen
B. broad, flat molars
C. amylase
D. ingestion of feces
E. bile salts
189. In which of the following would you expect to find an enlarged cecum?
A. tubeworms that digest via symbionts
B. humans and other primates
C. carnivorous animals
D. tapeworms and other intestinal parasites
E. rabbits, horses, and herbivorous bears
Use the following information to answer the following questions.
Mouse mutations can affect an animal's appetite and eating habits. The ob gene produces a satiety factor (the hormone leptin). The db gene product is required to respond to the satiety factor (the leptin receptor).
190. Leptin is a product of adipose cells. Therefore, a very obese mouse would be expected to
have which of the following?
A. increased gene expression of ob and decreased expression of db
B. decreased transcription of both ob and
C. increased gene expression of db and decreased expression of ob
D. mutation of ob or db
191. Most obese humans produce normal or increased levels of leptin without satiety. Which might provide an answer to at least some human obesity if a means to do so is found?
A. overexpression of the leptin receptor gene
B. inhibition of leptin receptors
C. activation of receptors for leptin
D. inactivation of leptin
E. supplementary leptin
192. Which of the following occurs when digestion of organic molecules results in more
energy -rich molecules than are immediately required by the animal?
A. The excess is eliminated.
B. The excess is stored as glycogen.
C. The excess is oxidized.
D. The excess is stored as starch.
E. The excess is hydrolyzed.
193. Which of the following hormone actions will occur when more energy is required by a human?
A. Both insulin and glucagon decrease.
B. Blood insulin increases.
C. Blood glucagon increases.
D. Thyroid hormone is increased.
E. Both insulin and glucagon increase.
194. When more energy sources are needed than are generated by diet, in which order does the animal draw on stored sources?
A. glycogen, protein, fat
B. muscle glycogen, fat, liver glycogen C. liver glycogen, muscle glycogen, fat D. fat, glycogen, protein
E. fat, protein, glycogen
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