Biology Benchmark
Diagram How much carbon (in g/m2) is released into the atmosphere as a result of the metabolic activity of herbivores? Give your answer to the nearest whole number.
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Diagram What percent of the biomass in the forest community represented above is tied up in the shrub layer? Give you answer to the nearest whole number.
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Graph Use the graph above to calculate the lag time in months between the change in densities of the prey and the predator populations. Give your answer to the nearest tenth of the month.
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Grid in: In a certain species of flowering plant, the purple allele P is dominant to the yellow allele p. A student performed a cross between a purple-flowered plant and a yellow-flowered plant. When planted, the 146 seeds that were produced from the cross matured into 87 plants with purple flowers. Calculate the chi-squared value for the null hypothesis that the purple flowered parent was heterozygous for the flower-color gene. Give your answer to the nearest tenth.
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Grid in: Use the graph above to calculate the mean rate of population growth (individuals per day) between day 3 and day 5. Give your answer to the nearest whole number
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The Hedgehog protein (Hh) plays a critical role during a certain period of embryo development, but it normally has no role in adults except for the maintenance of adult stem cells. However, the Hedgehog protein has been detected in 70 percent of pancreatic cancer cell samples. As illustrated in the figures below, the Hedgehog protein binds to an integral membrane protein receptor known as Patched (Ptc), thus initiating a pathway of gene expression. When Hedgehog is absent, Ptc inhibits another protein known as Smoothened (Smo), which, in turn, blocks the activation of a group of proteins collectively known as the Hedgehog signaling complex (HSC). The inactivation is the result of proteolytic cleavage of one component of the HSC complex, a transcription factor known as Cubitus interruptus (Ci). When Hedgehog is present, it binds to Ptc, which prevents the inhibition of Smo by Ptc. The result is that Ci remains intact and can enter the nucleus, where it binds to and activates certain genes. One approach to treating patients with pancreatic cancer and other cancers in which the Hedgehog protein is detected is to modify the Hedgehog signaling pathway. Which of the following is the most useful approach? a. Treating patients with a molecule that is structurally similar to Hedgehog and that will bind to and interact with Ptc in the same fashion as Hedgehog b. Injecting patients with embryonic cells so that Hedgehog will bind to those cells instead of the cancer cells c. Treating patients with a membrane-soluble compound that can bind to Smo and block its activity d. Injecting patients with a preparation of purified membrane-soluble Ci that will enter the nuclei of the cancer cells and induce gene transcription
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In a population od certain frogs in which the allele for brown skin is dominant to the allele for green skin, a drought leads to selection against green-skinned frogs. When the drought ends, 12 percent of the remaining frogs exhibit the green-skin phenotype. If the population is now in Hardy-Weinberg equilibrium, what will be the frequency of the green-skin allele in the next generation? Provide your answer to the nearest hundredth.
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A culture of Spirogyra (an autotrophic alga) is maintained is a water solution containing dissolved carbon dioxide and a source of phosphates but lacking nitrogen compounds. A researcher determines the rates of synthesis of several organic compounds found in the Spirogyra before and after several weeks in the water solution. Which of the following graphs best illustrates a likely result of the experiment? Answer choices are graphs
B. only one with equal before and after carbs
Y=Algae population X=time Graph I: positive slope, then levels horizontally Graph II: + slope, levels, phosphate added, + slope, levels Figure I shows the growth of an algal species in a flask of sterilized pond water. If phosphate is added as indicated, the growth curve changes as shown in Figure II. Which of the following is the best prediction of the algal growth if nitrate is added instead of phosphate? Answer choices are graphs
C. looks like Graph I
Which of the following correctly illustrates a dipeptide and an amino acid in the optimal position to form a tripeptide? Answer choices are molecules
a. main line of first molecule: N-C-C-N-C-C
An individual's humoral response to a particular antigen differs depending on whether or not the individual has been previously exposed to that antigen. Which of the following graphs properly represents the humoral immune response when an individual is exposed to the same antigen more than once? Answer choices graphs Y=amount of antibody X=time
a.
Complex diagram of embryo cells The diagram above shows a developing worm embryo at the four-cell stage. Experiments have shown that when cell 3 divides, the anterior daughter cell gives rise to muscle and gonads and the posterior daughter cell gives rise to the intestine. However, if the cells of the embryo are separated from one another early during the four-cell stage, no intestine will form. Other experiments have shown that if cell 3 and cell 4 are recombined a"er the initial separation, the posterior daughter cell of cell 3 will once again give rise to normal intestine. Which of the following is the most plausible explanation for these findings? a. A cell surface protein on cell 4 signals cell 3 to induce formation of the worm's intestine. b. The plasma membrane of cell 4 interacts with the plasma membrane of the posterior portion of cell 3, causing invaginations that become microvilli. c. Cell 3 passes an electrical signal to cell 4, which induces differentiation in cell 4. d. Cell 4 transfers genetic material to cell 3, which directs the development of intestinal cells.
a. A cell surface protein on cell 4 signals cell 3 to induce formation of the worm's intestine.
An experiment to measure the rate of respiration in crickets and mice at 10 degrees C and 25 degrees C was performed using a respirometer, an apparatus that measures changes in gas volume. Respiration was measured in mL of O2 consumed per gram of organism over several five-minute trials and the following data were obtained. Chart: Organism__Temperature__Average Respiration Mouse _________10 ____________0.0518 Mouse__________25____________0.0321 Cricket_________10_____________0.0013 Cricket_________25_____________0.0038 During anaerobic cellular respiration, oxygen gas is consumed at the same rate as carbon dioxide gas is produced. In order to provide accurate volumetric measurements of oxygen gas consumption, the experimental setup should include which of the following? a. A substance that removes carbon dioxide gas b. A plant to produce oxygen c. A glucose reserve d. A valve to release excess water
a. A substance that removes carbon dioxide gas
The first diagram below shows the levels of mRNA from two different genes (bicoid and caudal) at di#erent positions along the anterior-posterior axis of a Drosophila egg immediately before fertilization. The second diagram shows the levels of the two corresponding proteins along the anterior-posterior axis shortly after fertilization. Graph 1: mRNA distribution before fertilization bicod anterior, caudal evenly dispersed Graph 2: mRNA distribution after fertilization bicod anterior to middle, caudal middle to posterior Which of the following conclusions is best supported by the data? a. Bicoid protein inhibits translation of caudal mRNA. b. Bicoid protein stabilizes caudal mRNA. c. Translation of bicoid mRNA produces caudal protein. d. Caudal protein stimulates development of anterior structures.
a. Bicoid protein inhibits translation of caudal mRNA.
The last part of metamorphosis of a tadpole to an adult frog results in the disappearance of the tail. This stage of development most likely occurs by a. cells of the tail dying and the nutrients being absorbed and reused by the body. b. shedding of the tail so energy is not spent on maintenance of an unneeded part. c. bilateral division of the tail and fusion with the developing hind limbs. d. individual cells of the tail migrating to the developing gonads.
a. Cells of the tail dying and nutrients being absorbed and reused by the body
The figures below illustrate the similarities between aTP synthesis in mitochondria and chloroplasts. Figures Mitochondria uses NADH, released Water; then ADP is used to make ATP Chloroplasts uses Water, makes NADPH; the ADP is used to make ATP The figures can best assist in answering which of the following questions? a. Do electron transport chains create a gradient so that ATP synthase and generate ATP molecules? b. What are the sources of energy that drive mitochondrial and chloroplast electron transport systems? c. What is the optimal temperature at which ATP synthase chemically converts ADP and a phosphate group into one molecule of ATP? d. What is the evolutionary relationship between the ATP synthase in mitochondria and the ATP synthase in chloroplasts
a. Do electron transport chains create a gradient so that ATP synthase and generate ATP molecules?
Picture of trees Mainly grasses -> oak trees and shrubs-> tall oak trees and small other trees and shrubs-> tall oak trees and medium sized other trees -> tall other trees and smaller oak trees The diagram above shows the progression of ecological events after a fire in a particular ecosystem. Based on the diagram, which of the following best explains why the oak trees are later replaced by other trees? a. Eventually the other trees grow taller than other oak trees and form a dense canopy that shades the understory. b. Oak trees alter the pH of the soil, making the forest better suited for shrubs and other trees. c. Roots and shrubs proliferate in the soil of the forest and prevent the oak trees from obtaining water. d. Oak trees succumb to environmental pollutants more readily than do either the shrubs or the other trees.
a. Eventually the other trees grow taller than other oak trees and form a dense canopy that shades the understory.
A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It was determined that the average beak size (both length and mass) of finches in a certain population increased dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the number of plants producing thin-walled seeds. Which of the following statements might best explain the increase in average beak size in the finch population during the drought? a. Finches with bigger beaks are better able to crack thick-walled seeds and produce more surviving offspring. b. Finches with bigger beaks can attack and kill finches with smaller beaks. c. Finches with bigger beaks possess more powerful flight muscles and are able to find more food. d. Finches that crack large seeds develop larger beaks over time.
a. Finches with bigger beaks are better able to crack thick-walled seeds and produce more surviving offspring.
Anabaena is a simple multicellular photosynthetic cyanobacterium. In the absence of fixed nitrogen, certain newly developing cells along a filament express genes that code for nitrogen-fixing enzymes and become nonphotosynthetic heterocysts. The specialization is advantageous because some nitrogen-fixing enzymes function best in the absence of oxygen. Heterocysts do not carry out photosynthesis but instead provide adjacent cells with fixed nitrogen, in exchange receiving fixed carbon and reduced energy carriers. Diagram As shown in the diagram above, when there is low fixed nitrogen in the environment, an increase in the concentration of free calcium ions and 2-oxyglutarate stimulates the expression of genes that produce two transcription factors (NtcA and HetR) that promote the expression of genes responsible for heterocyst development. HetR also causes production of a signal, PatS, that prevents adjacent cells from developing as heterocysts. Based on your understanding of the ways in which signal transmission mediates cell function, which of the following predictions is most consistent with the information given above? a. In an environment with low fixed nitrogen, treating the Anabaena cells with a calcium-binding compound should prevent heterocyst differentiation. b. A strain that overexpresses the patS gene should develop many more heterocysts in a low fixed nitrogen environment. c. In an environment with abundant fixed nitrogen, free calcium levels should be high in all cells so that no heterocysts develop. d. In environments with abundant fixed nitrogen, loss of the hetR gene should induce heterocyst development.
a. In an environment with low fixed nitrogen, treating the Anabaena cells with a calcium-binding compound should prevent heterocyst differentiation.
Simple cuboidal epithelial cells line the ducts of certain human exocrine glands. Various materials are transported into or out of the cells by diffusion. (The formula for the surface area of a cube is 6 ¥ S2, and the formula for the volume of a cube is S3, where S = the length of a side of the cube.) Which of the following cube-shaped cells would be most efficient in removing waste by diffusion? a. S = 10 μm b. S = 20 μm c. S = 30 μm d. S = 40 μm
a. S = 10 μm
Arctic foxes typically have a white coat in the winter. In summer, when there is no snow on ht aground, the foxes typically have a darker coat. Which of the following is most likely responsible for the seasonal change in coat color? a. The decrease in the amount of daylight in winter causes a change in gene expression, which results in the foxes growing a lighter-appearing coat. b. The diet of the foxes in summer lacks a particular nutrient, which causes the foxes to lose their white coat and grow a darker-colored coat. c. Competition for mates in the spring causes each fox to increase its camouflage with the environment by producing a darker-appearing coat. d. The lower temperatures in winter feature the pigment molecules in the arctic fox coat, causing the coat to become lighter in color.
a. The decrease in the amount of daylight in winter causes a change in gene expression, which results in the foxes growing a lighter-appearing coat.
Five new species of bacteria were discovered in Antarctic ice core samples. The nucleotide (base) sequences of rRNA subunits were determined for the new species. !e table below shows the number of nucleotide di"erences between the species. Chart: Species 1 2 3 4 5 1: - 3 19 18 27 2: __- 19 18 26 3: __ __ - 1 27 4: __ __ __ - 27 5: __ __ __ __ __ Which of the following phylogenetic trees is most consistent with the data?
c.
In a transformation experiment, a sample of E. coli bacteria was mixed with a plasmid containing the gene for resistance to the antibiotic ampicillin (ampr). Plasmid was not added to a second sample. Samples were plated on nutrient agar plates, some of which were supplemented with the antibiotic ampicillin. The results of E. coli growth are summarized below. The shaded area represents extensive growth of bacteria; dots represent individual colonies of bacteria. Pictures No ampicillin: Wild ecoli=full of bacteria (plate I), Ecoli and ampr=full of bacteria(Plate III) Ampicillin: Wild E. coli=no bacteria (plate II), E. coli and ampr= a few colonies (plate IV) Which of the following best explains why there is no growth on plate II? a. The initial E. coli culture was not ampicillin-resistant. b. The transformation procedure killed the bacteria. c. Nutrient agar inhibits E. coli growth. d. The bacteria on the plate were transformed.
a. The initial E. coli culture was not ampicillin-resistant.
An experiment to measure the rate of respiration in crickets and mice at 10 degrees C and 25 degrees C was performed using a respirometer, an apparatus that measures changes in gas volume. Respiration was measured in mL of O2 consumed per gram of organism over several five-minute trials and the following data were obtained. Chart: Organism__Temperature__Average Respiration Mouse _________10 ____________0.0518 Mouse__________25____________0.0321 Cricket_________10_____________0.0013 Cricket_________25_____________0.0038 According to the data, the mice at 10 degrees C demonstrated greater oxygen consumption per gram of tissue than did the mice at 25 degrees C. This is most likely explained by which of the following statements? a. The mice at 10 degrees C had a higher rate of ATP production than the mice at 25 degrees C. b. The mice at 10 degrees C had a lower metabolic rate than the mice at 25 degrees C. c. The mice at 25 degrees C weighed less than the mice at 10 degrees C. d. The mice at 25 degrees C were more active than the mice at 10 degrees C.
a. The mice at 10 degrees C had a higher rate of ATP production than the mice at 25 degrees C.
The regulatory sequences of the operon controlling arabinose metabolism (ara operon) were studied to determine whether bacteria can respond to changes in nutrient availability. It is predicted that if those regulatory sequences are functioning properly, the bacteria will produce the enzymes involved in arabinose metabolism (structural genes B, A, and D) in the presence of arabinose. If a gene that encodes a green fluorescent protein (GFP) is substituted for the structural genes of the operon, activation of the regulatory sequences can be assayed by GFP expression. A culture of E. coli cells underwent a transformation procedure with a plasmid containing the regulatory sequences of the ara operon directly upstream of the gene encoding the GFP. The plasmid also confers ampicillin resistance to bacteria. Samples were then plated on different types of culture media. (Note: The GFP fluoresces only under UV light, not under white light.) The table below shows the results. Which of the following can best be used to justify why the GFP is expressed by E. coli cells after transformation with the plasmid? a. The presence of arabinose in the nutrient agar activated the expression of the genes located downstream of the ara operon regulatory sequences. b. The combination of ampicillin and arabinose in the nutrient agar inhibited the expression of certain gene products, resulting in the increased expression of the GFP. c. The nutrient agar without arabinose but with ampicillin activated the expression of the genes located downstream of the ara operon regulatory sequences. d. Both arabinose and ampicillin were required in the nutrient agar to activate the expression of genes located downstream of the ara operon regulatory sequences.
a. The presence of arabinose in the nutrient agar activated the expression of the genes located downstream of the ara operon regulatory sequences.
Both myoglobin and hemoglobin are proteins that bind reversibly with molecular oxygen. The graph below shows the oxygen-binding saturation of each protein at different concentrations of oxygen. Graph: Y=Saturation with Oxygen X=Partial pressure of O2 Myoglobin has a steep positive slop, then levels at the top Hemoglobin has a less positive slop and doesn't level until the near end of graph Strenuous exercise lowers the blood pH, causing the curves for both hemoglobin and myoglobin to shift to the right. This shift results in a. an unloading of O2 at higher partial pressures b. an increase in the number of O2-binding sites c. the capture of more O2 by hemoglobin d. the capture of more O2 by myoglobin
a. an unloading of O2 at higher partial pressures
In a transformation experiment, a sample of E. coli bacteria was mixed with a plasmid containing the gene for resistance to the antibiotic ampicillin (ampr). Plasmid was not added to a second sample. Samples were plated on nutrient agar plates, some of which were supplemented with the antibiotic ampicillin. The results of E. coli growth are summarized below. The shaded area represents extensive growth of bacteria; dots represent individual colonies of bacteria. Pictures No ampicillin: Wild ecoli=full of bacteria (plate I), Ecoli and ampr=full of bacteria(Plate III) Ampicillin: Wild E. coli=no bacteria (plate II), E. coli and ampr= a few colonies (plate IV) Plates I and III were included in the experimental design in order to a. demonstrate that the E. coli cultures were viable b. demonstrate that the plasmid can lose its ampr c. demonstrate that the plasmid is needed for E. coli growth d. prepare the E. coli for transformation
a. demonstrate that the E. coli cultures were viable
A student placed 20 tobacco seeds of the same species on moist paper towels in each of 2 petri dishes. Dish A was wrapped completely in an opaque cover to exclude all light. Dish B was not wrapped. The dishes were placed equidistant from a light source set to a cycle of 14 hours of light and 10 hours of dark. All other conditions were the same for both dishes. The dishes were examined after 7 days, and the opaque cover was permanently removed from dish A. Both dishes were returned to the light and examined again at 14 days. The following data were obtained. ______________________(Dish A) _______Dish B _________________Day7__Day14___Day7_Day14 _____________(Covered)_(uncovered)__[c]_[u] Germinated ______(12)__(20)________[20]_[20] seeds Green-leaved ______(0)_(14)_________[15]__[15] Seedlings Yellow-leaved _____(12)_(6)___________[5]__[5] seedlings Mean stem length __(8)_(9)____________[3]_[3] below first set of leaves According to the results of this experiment, germination of tobacco seeds during the first week is a. increased by exposure to light b. unaffected by light intensity c. prevented by paper towels d. accelerated in green-leaved seedlings
a. increased by exposure to light
Sickle-cell anemia results from a point mutation in the HBB gene. The mutation results in the replacement of an amino acid that has a hydrophilic R-group with an amino acid that has a hydrophobic R-group on the exterior of the hemoglobin protein. Such a mutation would most likely result in altered a. properties of the molecule as a result of abnormal interactions between adjacent hemoglobin molecules b. DNA structure as a result of abnormal hydrogen bonding between nitrogenous bases c. fatty acid structure as a result of changes in ionic interactions between adjacent fatty acid chains d. protein secondary structure as a result of abnormal hydrophobic interactions between R-groups in the backbone of the protein
a. properties of the molecule as a result of abnormal interactions between adjacent hemoglobin molecules
The area covered by tropical rainforest is reduced by millions of hectares per year due to agriculture and logging. Which of the following best describes a result of tropical rainforest deforestation? a. Populations of plants and animals will decrease as more rainforest disappears, leading to a decrease in biodiversity. b. An increase of soil moisture will lead to a rapid increase in new vegetation coverage. c. An increase in atmospheric carbon dioxide will lead to higher levels of ultraviolet radiation reaching the surface of the Earth. d. More oxygen will be available to other organisms as plant numbers decrease.
a: Population of plants and animals will decrease as more rain forest disappears leading to a decrease in biodiversity.
A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It was determined that the average beak size (both length and mass) of finches in a certain population increased dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the number of plants producing thin-walled seeds. Which of the following best describes the mechanism behind the change in beak size in the finch population? a. The formation of two new finch species from a single parent species b. A change in gene frequencies in the finch population due to selective pressure from the environmental change c. A new allele appearing in the finch population as a result of mutation d. The achievement of dynamic equilibrium in the finch population as a result of homeostasis.
b. A change in gene frequencies in the finch population due to selective pressure from the environmental change
Complex picture with antibodies, acetylcholine, and receptors The illustration above depicts a neuromuscular junction of a patient with an autoimmune disorder. Acetylcholine is a stimulatory neurotransmitter. Which of the following would be the most likely result of the continued presence of the antibody? (new practice:57) a. An increase in action potentials in the motor neuron and constant nerve pain b. A decrease in action potentials in the muscle, causing muscle weakness and fatigue c. A decrease in the opening of sodium-gated channels in the muscle, causing less sodium to be released from the muscle. d. An increase in the opening of sodium-gated channels in the motor neuron because of the accumulation of acetylcholine in the junction.
b. A decrease in action potentials in the muscle, causing muscle weakness and fatigue
The mechanism of action of many common medications involves interfering with the normal pathways that cells use to respond to hormone signals. Which of the following best describes a drug interaction that directly interferes with a signal transduction pathway? a. A medication causes the cell to absorb more of a particular mineral, eventually poisoning the cell. b. A medication enters the target cell and inhibits an enzyme that normally synthesizes a second messenger. c. A medication enters the target cell's nucleus and acts as a mutagen. d. A medication interrupts that transcription of ribosomal RNA genes.
b. A medication enters the target cell and inhibits an enzyme that normally synthesizes a second messenger.
The endocrine system incorporates feedback mechanisms that maintain homeostasis. Which of the following demonstrates negative feedback by the endocrine system? a. During labor, the fetus exerts pressure on the uterine wall, inducing the production of oxytocin, which stimulates uterine wall contraction. The contractions cause the fetus to further push on the wall, increasing the production of oxytocin. b. After a meal, blood glucose levels become elevated, stimulating beta cells of the pancreas to release insulin into the blood. Excess glucose is then converted to glycogen in the liver, reducing blood glucose levels. c. At high elevation, atmospheric oxygen is more scarce. In response to signals that oxygen is low, the brain decreases an individual's rate of respiration to compensate for the difference. d. A transcription factor binds to the regulatory region of a gene, blocking the binding of another transcription factor required for expression.
b. After a meal, blood glucose levels become elevated, stimulating beta cells of the pancreas to release insulin into the blood. Excess glucose is then converted to glycogen in the liver, reducing blood glucose levels.
A group of students summarized information on five great extinction events. Large Chart The students are sampling a site in search of fossils from the Devonian period. Based on the chart, which of the following would be the most reasonable plan for the students to follow? a. Searching horizontal rock layers in any class of rock and trying to find those that contain the greatest number of fossils b. Collecting fossils from rock layers deposited prior to the Permian period that contain some early vertebrate bones c. Looking in sedimentary layers next to bodies of water in order to find marine fossils of bivalves and trilobites d. Using relative dating techniques to determine the geological ages of the fossils found so they can calculate the rate of speciation of early organisms
b. Collecting fossils from rock layers deposited prior to the Permian period that contain some early vertebrate bones
The chemical reaction for photosynthesis is 6 CO2+ 12 H2 O + light energy → C6 H12O6+ 6 O2+ 6 H2O If the input water is labeled with a radioactive isotope of oxygen, 18O, then the oxygen gas released as the reaction proceeds is also labeled with 18O. Which of the following is the most likely explanation? a. During the light reactions of photosynthesis, water is split, the hydrogen atoms combine with the CO2, and oxygen gas is released. b. During the light reactions of photosynthesis, water is split, removing electrons and protons, and oxygen gas is released. c. During the Calvin cycle, water is split, regenerating NADPH from NADP+, and oxygen gas is released. d. During the Calvin cycle, water is split, the hydrogen atoms are added to intermediates of sugar synthesis, and oxygen gas is released.
b. During the light reactions of photosynthesis, water is split, removing electrons and protons, and oxygen gas is released.
A student placed 20 tobacco seeds of the same species on moist paper towels in each of 2 petri dishes. Dish A was wrapped completely in an opaque cover to exclude all light. Dish B was not wrapped. The dishes were placed equidistant from a light source set to a cycle of 14 hours of light and 10 hours of dark. All other conditions were the same for both dishes. The dishes were examined after 7 days, and the opaque cover was permanently removed from dish A. Both dishes were returned to the light and examined again at 14 days. The following data were obtained. ______________________(Dish A) _______Dish B _________________Day7__Day14___Day7_Day14 _____________(Covered)_(uncovered)__[c]_[u] Germinated ______(12)__(20)________[20]_[20] seeds Green-leaved ______(0)_(14)_________[15]__[15] Seedlings Yellow-leaved _____(12)_(6)___________[5]__[5] seedlings Mean stem length below first set of leaves__(8)_(9)____________[3]_[3] The most probable cause for the difference in mean stem length between plants in dish A and plants in dish B is which of the following? a. Shortening of cells in the stem in response to the lack of light b. Elongation of seedlings in response to the lack of light c. Enhancement of stem elongation by light d. Genetic differences between the seeds
b. Elongation of seedlings in response to the lack of light
Graph: Y=oxido-reductase activity X=Woodruff or Apopka (Males or Females) Woodruff- males lower than females Apopka- males barely above females Testosterone oxido-reductase is a liver enzyme that regulates testosterone levels in alligators. One study compared testosterone oxido-reductase activity between male and female alligators from Lake Woodruff, a relatively pristine environment, and from Lake Apopka, an area that has su!ered severe contamination. The graph above depicts the findings of that study. The data in the graph best support which of the following claims? a. Environmental contamination elevates total testosterone oxido-reductase activity in females. b. Environmental contamination reduces total testosterone oxido-reductase activity in females. c. Environmental contamination elevates total testosterone oxido-reductase activity in males. d. Environmental contamination reduces total testosterone oxido-reductase activity in males.
b. Environmental contamination reduces total testosterone oxido-reductase activity in females.
Experimental evidence shows that the process of glycolysis is present and virtually identical in organisms from all three domains, Archaea, Bacteria, and Eukarya. Which of the following hypotheses could be best supported by this evidence? a. All organisms carry out glycolysis in mitochondria. b. Glycolysis is a universal energy-releasing process and therefore suggests a common ancestor for all forms of life. c. Across the three domains, all organisms depend solely on the process of anaerobic respiration for ATP production. d. The presence of glycolysis as an energy-releasing process in all organisms suggests that convergent evolution occurred.
b. Glycolysis is a universal energy-releasing process and therefore suggests a common ancestor for all forms of life.
In a transformation experiment, a sample of E. coli bacteria was mixed with a plasmid containing the gene for resistance to the antibiotic ampicillin (ampr). Plasmid was not added to a second sample. Samples were plated on nutrient agar plates, some of which were supplemented with the antibiotic ampicillin. The results of E. coli growth are summarized below. The shaded area represents extensive growth of bacteria; dots represent individual colonies of bacteria. Pictures No ampicillin: Wild ecoli=full of bacteria (plate I), Ecoli and ampr=full of bacteria(Plate III) Ampicillin: Wild E. coli=no bacteria (plate II), E. coli and ampr= a few colonies (plate IV) Which of the following statements best explains why there are fewer colonies on plate IV than on plate III? a. Plate IV is the positive control. b. Not all E. coli cells are successfully transformed. c. The bacteria on plate III did not mutate. d. The plasmid inhibits E. coli growth.
b. Not all E. coli cells are successfully transformed.
The following is a food web for a meadow habitat that occupies 25.6 km^2. The primary producers' biomass is uniformly distributed throughout the habitat and totals 1,500 kg/km^2. Picture of food web Developers have approved a project that will permanently reduce the primary producers' biomass by 50 percent and remove all debits and deer. Which of the following is most likely to result at the completion of the project? a. The biomass of coyotes will be 6 kg, and the biomass of hawks will be 0.5 kg. b. The biomass of coyotes will be dramatically reduced. c. The coyotes will switch prey preferences and out compete the hawks. d.There will be 5 percent fewer voles and 90 percent fewer hawks.
b. The biomass of coyotes will be dramatically reduced.
Graph: y=rate of contraction x=osmolarity of solution slope of -1 Paramecia are unicellular protists that have contractile vacuoles to remove excess intracellular water. In an experimental investigation, paramecia were placed in salt solutions of increasing osmolarity. The rate at which the contractile vacuole contracted to pump out excess water was determined and plotted against osmolarity of the solutions, as shown in the graph. Which of the following is the correct explanation of the data? a. At higher osmolarity, lower rates of concentration are required because more salt diffuses into the paramecia. b. The concentration rate increases as the osmolarity decreases because the amount of water entering the paramecia by osmosis increases. c. The con tactile vacuole is less efficient in solutions of higher osmolarity because of the reduced amount of ATP produced from cellular respiration. d. In an isosmotic salt solution, there is no diffusion of water into or out of the paramecia, so the concentration rate is zero.
b. The concentration rate increases as the osmolarity decreases because the amount of water entering the paramecia by osmosis increases.
In most freshwater fish, nitrogenous waste is primarily excreted as ammonia, which is highly soluble in water and is toxic at low concentrations. In terrestrial mammals, ammonia is converted to urea before it is excreted. Urea is also highly soluble in water but less toxic than ammonia at low concentrations. Which of the following best explains why freshwater fish do not convert ammonia to urea for excretion? a. The metabolic pathways of fish do not normally involve nitrogen consumption. b. The dilution of ammonia by direct excretion into freshwater conserves energy. c. Ammonia is concentrated in tissues, where it is stored prior to excretion. d. The nitrogen in ammonia is recycled for use in protein and nuclide synthesis.
b. The dilution of ammonia by direct excretion into freshwater conserves energy.
A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It was determined that the average beak size (both length and mass) of finches in a certain population increased dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the number of plants producing thin-walled seeds. The biologist discovered from 1988 to 1993, the average beak size declined to pre-1981 levels. The reversal in beak size from 1988 to 1993 was most likely related to which of the following events? a. The loss of food supply for the finches. b. The end of the drought. c. An increase in drought conditions. d. An increase in predators consuming finches.
b. The end of the drought.
During the infection cycle for a typical retrovirus, such as HIV, which uses RNA as genetic material, the genetic variation in the resulting population of new virus particles is very high because of a. damage to the virus particle from envelope loss during infection. b. errors introduced in the DNA molecule through reverse transcription. c. errors in protein molecules produced in translation. d. recombination of the genomes of free virus particles.
b. errors introduced in the DNA molecule through reverse transcription.
Which of the following statements best supports the claim that organisms share fundamental processes as a result of evolution? a. All organisms that are introduced into new environments have the capacity to fill vacant ecological roles b. All organisms have the ability to utilize oxygen to harness energy from the chemical breakdown of organic compounds c. All organisms share a genetic code organized into triplet codons, making it possible for one organism to express a gene from another organism. d. All organisms possess structures such as chloroplasts and mitochondria within their cells that reflect past symbiotic relationships between prokaryotic precursors.
c. All organisms share a genetic code organized into triplet codons, making it possible for one organism to express a gene from another organism.
Both myoglobin and hemoglobin are proteins that bind reversibly with molecular oxygen. The graph below shows the oxygen-binding saturation of each protein at different concentrations of oxygen. Graph: Y=Saturation with Oxygen X=Partial pressure of O2 Myoglobin has a steep positive slop, then levels at the top Hemoglobin has a less positive slop and doesn't level until the near end of graph Which of the following statements is correct? a. At 10 mm Hg partial pressure, hemoglobin binds oxygen but myoglobin does not. b. At 20 mm Hg partial pressure, myoglobin and hemoglobin bind oxygen in equal amounts. c. At 40 mm Hg partial pressure, myoglobin has a greater affinity for oxygen than hemoglobin has. d. At 80 mm Hg partial pressure, myoglobin binds twice as much oxygen as hemoglobin binds.
c. At 40 mm Hg partial pressure, myoglobin has a greater affinity for oxygen than hemoglobin has.
In a second experiment, the plasmid contained the gene for human insulin as well as the ampr gene. Which of the following plates would have the highest percentage of bacteria that are expected to produce insulin? a. I only b. III only c. IV only d. I and III
c. IV only
In a transformation experiment, a sample of E. coli bacteria was mixed with a plasmid containing the gene for resistance to the antibiotic ampicillin (ampr). Plasmid was not added to a second sample. Samples were plated on nutrient agar plates, some of which were supplemented with the antibiotic ampicillin. The results of E. coli growth are summarized below. The shaded area represents extensive growth of bacteria; dots represent individual colonies of bacteria. Pictures No ampicillin: Wild ecoli=full of bacteria (plate I), Ecoli and ampr=full of bacteria(Plate III) Ampicillin: Wild E. coli=no bacteria (plate II), E. coli and ampr= a few colonies (plate IV) Plates that have only ampicillin-resistant bacteria growing include which of the following? a. I only b. III only c. IV only d. I and II
c. IV only
A pathogenic bacterium has been engulfed by a phagocytic cell as part of the nonspecific (innate) immune response. Which of the following illustrations best represents this response? a. Ribosome being used to fight bacterium b. Antibodies being used to fight bacterium c. Lysosomes taking in bacterium d. Mitochondria taking in bacterium
c. Lysosomes taking in bacterium
Membrane-bound organelles have been an important component in the evolution of complex, multicellular organisms. Which of the following best summarizes an advantage of eukaryotic cells having internal membranes? a. Eukaryotic cells are able to reproduce faster because of the presence of organelles. b. Some organelles, such as mitochondria and chloroplasts, are similar to prokaryotic cells in structure. c. Organelles isolate specific reactions, increasing metabolic efficiency. d. Compartmentalization leads to a higher mutation rate in DNA, which leads to more new species.
c. Organelles isolate specific reactions, increasing metabolic efficiency.
Two pictures of segments of DNA/RNA. Segment 1 is mainly A and T, while Segment 2 is mainly G and C The sequences for two short fragments of DNA are shown above. Which of the following is one way in which these two segments would differ? a. Segment 1 would not code for mRNA because both strands have T, a base not found in RNA. b. Segment 1 would be more soluble in water than segment 2 because it has more phosphate groups. c. Segment 1 would become denatured at a lower temperature than would segment 2 because A-T base pairs have two hydrogen bonds whereas G-C base pairs have three. d. Segment 1 must be from a prokaryote because it has predominantly A-T base pairs.
c. Segment 1 would become denatured at a lower temperature than would segment 2 because A-T base pairs have two hydrogen bonds whereas G-C base pairs have three.
A biologist spent many years researching the rate of evolutionary change in the finch populations of a group of islands. It was determined that the average beak size (both length and mass) of finches in a certain population increased dramatically during an intense drought between 1981 and 1987. During the drought, there was a reduction in the number of plants producing thin-walled seeds. Which of the following procedures was most likely followed to determine the change in beak size? (new practice: 7) a. A few finches were trapped in 1981 and again in 1987, and their beak sizes were compared. b. The beak size in fifteen finches was measured in 1987, and the beak size in the original finches was determined by estimation. c. The beak size in a large number of finches was measured every year from 1981 to 1987. d. Finches were captured and bred in 1981, and the beak size of the offspring was measured.
c. The beak size in a large number of finches was measured every year from 1981 to 1987.
By discharging electric sparks into a laboratory chamber atmosphere that consisted of water vapor, hydrogen gas, methane, and ammonia, Stanley Miller obtained data that showed that a number of organic molecules, including many amino acids, could be synthesized. Miller was attempting to model early Earth conditions as understood in the 1950s. The results of Miller's experiments best support which of the following hypotheses? a. The molecules essential to life today did not exist at the time Earth was first formed. b. The molecules essential to life today could not have been carried to the primordial Earth by a comet or meteorite. c. The molecules essential to life today could have formed under early Earth conditions. d. The molecules essential to life today were initially self-replicating proteins that were synthesized approximately four billion years ago.
c. The molecules essential to life today could have formed under early Earth conditions.
MRSA is the acronym for methicillin-resistant Staphylococcus aureus. Many of the strains of the common bacterium are also resistant to other antibiotics in use today. The resistance is linked to a collection of genes carried on plasmids that are passed from one bacterium to another by conjugation. Suppose a newly discovered, chemically different antibiotic is used in place of methicillin, Which if the following would be the most likely effect on Staphylococcus aureus antibiotic resistance? a. The gene for methicillin resistance, no longer needed, would disappear entirely from Staphylococcus aureus within a few generations. b. Transmission of the methicillin-resistance plasmid by conjugation would increase among the Staphylococcus aureus population as the genes would confer resistance to the new antibiotic. c. Transmission of the methicillin resistance plasmid would gradually decrease but the plasmid would not entirely disappear from the Staphylococcus aureus population. d. Transmission of the methicillin-resistant plasmid by conjugation would increase among the Staphylococcus aureus population due to the destruction of bacteria without the plasmid through use of the new antibiotic.
c. Transmission of the methicillin resistance plasmid would gradually decrease but the plasmid would not entirely disappear from the Staphylococcus aureus population.
The FtsZ protein is present in prokaryotes and in chloroplasts. The protein is structurally and functionally similar to tubulin proteins of eukaryotic cells. Which of the following is a likely conclusion to draw from this information? a. FtsZ and tubulin proteins were both [resent in a common ancestor. b. Microtubules are involved in the mechanisms of photosynthesis. c. Tubulin genes are evolutionary derived from the gene that codes for the FtsZ protein. d. The sequences of the genes encoding the FtsZ and Tubulin proteins are identical.
c. Tubulin genes are evolutionary derived from the gene that codes for the FtsZ protein.
A sample of human blood was placed in a test tube containing a physiological saline solution (0.9% sodium chloride). This type of solution is often used intravenously to quickly rehydrate patients. A drop of blood from the test tube was placed on a slide and red blood cells were observed under a microscope. Three possible outcomes are diagrammed below. View 1: Shows shrunken RBCs View 2: Shows normal RBCs View 3: Shows Swollen RBCs Which of the following best predicts which diagrammed microscope view the laboratory worker would see and best explains why? a. View 1 because RBC membranes are freely permeable to water. b. View 2 because RBCs use energy to allow sodium entry and to pump water out. c. View 2 because the water of water movement into RBCs equals the rate of water movement out of the cells. d. View three because the sodium-potassium pumps in the RBC membranes use energy to keep the sodium out but allow water to freely flow into the cells.
c. View 2 because the water of water movement into RBCs equals the rate of water movement out of the cells.
An experiment to measure the rate of respiration in crickets and mice at 10 degrees C and 25 degrees C was performed using a respirometer, an apparatus that measures changes in gas volume. Respiration was measured in mL of O2 consumed per gram of organism over several five-minute trials and the following data were obtained. Chart: Organism__Temperature__Average Respiration Mouse _________10 ____________0.0518 Mouse__________25____________0.0321 Cricket_________10_____________0.0013 Cricket_________25_____________0.0038 According to the data, the crickets at 25 degrees C have greater oxygen consumption per gram of tissue than do the crickets at 10 degrees C. This trend in oxygen consumption is the opposite of that in the mice. The difference in trends in oxygen consumption among crickets and mice is due to their a. relative size b. mode of nutrition c. mode of internal temperature regulation d. mode of ATP production
c. mode of internal temperature regulation
A student placed 20 tobacco seeds of the same species on moist paper towels in each of 2 petri dishes. Dish A was wrapped completely in an opaque cover to exclude all light. Dish B was not wrapped. The dishes were placed equidistant from a light source set to a cycle of 14 hours of light and 10 hours of dark. All other conditions were the same for both dishes. The dishes were examined after 7 days, and the opaque cover was permanently removed from dish A. Both dishes were returned to the light and examined again at 14 days. The following data were obtained. ______________________(Dish A) _______Dish B _________________Day7__Day14___Day7_Day14 _____________(Covered)_(uncovered)__[c]_[u] Germinated ______(12)__(20)________[20]_[20] seeds Green-leaved ______(0)_(14)_________[15]__[15] Seedlings Yellow-leaved _____(12)_(6)___________[5]__[5] seedlings Mean stem length below first set of leaves__(8)_(9)____________[3]_[3] Additional observations were made on day 21, and no yellow-leaved seedling were found alive in either dish. This is most likely because a. yellow-leaved seedlings were unable to absorb water from the paper towels b. taller green-leaved seedlings blocked the light and prevented photosynthesis c. yellow-leaved seedlings were unable to convert light energy to chemical energy d. a higher rate of respiration in yellow-leaved seedlings depleted their stored nutrients.
c. yellow-leaved seedlings were unable to convert light energy to chemical energy
When DNA replicates, each strand of the original DNA molecule is used as a template for the synthesis of a second, complementary strand. Which of the following figures most accurately illustrates enzyme-mediated synthesis of new DNA at a replication fork?
d. (Answer choices are pictures) Multiple arrows leaving the molecule on the 5' strand
The figure above shows several steps in the process of bacteriophage transduction in bacteria. Which of the following explains how genetic variation in a population of bacteria results from this process? a. Bacterial proteins transferred from the donor bacterium by the phage to the recipient bacterium recombine with genes on the recipient's chromosome. b. The recipient bacterium incorporates the transduced genetic material coding for phage proteins into its chromosome and synthesizes the corresponding proteins. c. The phage infection of the recipient bacterium and the introduction of DNA carried by the phage cause increased random point mutations of the bacterial chromosome. d. DNA of the recipient bacterial chromosome undergoes recombination with DNA introduced by the phage from the donor bacterium, leading to a change in the recipient's genotype.
d. DNA of the recipient bacterial chromosome undergoes recombination with DNA introduced by the phage from the donor bacterium, leading to a change in the recipient's genotype.
Living cells typically have biosynthetic pathways to synthesize at least some of the amino acids used in making proteins. Some strains of E. coli, a prokaryote, can synthesize the amino acid tryptophan, while other E. coli strains cannot. Similarly, some strains of the yeast S. cerevisiae, a eukaryote, can synthesize tryptophan, while other S. cerevisiae strains cannot. Which of the following describes the most likely source of genetic variation found in the tryptophan synthesis pathways of both species? a. Exchange of genetic information occurs through crossing over. b. Viral transmission of genetic information required to synthesize tryptophan occurs. c. Random assignment of chromosomes leads to genetic variation. d. Errors in DNA replication lead to genetic variation.
d. Errors in DNA replication lead to genetic variation.
Thee tiny blue-eyed Mary flower is often one of the first flowers seen in the spring in some regions of the United States. The flower is normally blue, but sometimes a white or pink flower variation is found. The following data were obtained after several crosses. Parents_________F1__________F2 Blue × white___ Blue_______ 196 blue, 63 white Blue × pink____ Blue________149 blue, 52 pink Pink × white___ Blue________ 226 blue, 98 ____________________________white, 77 pink Which of the following statements best explains the data? a. The appearance of blue in the F1 generation of the pink and white cross demonstrates that flower color is not an inherited trait but is determined by the environment. a. Flower color depends on stages of flower development, and young flowers are white, advancing to pink and then blue. c. Since the F1 and F2 phenotypes of the pink and white cross do not fit the expected genotypic and phenotypic ratios, blue-eyed Mary must reproduce by vegetative propagation. d. Flower color is an inherited trait, and the F1 and F2 phenotypes of the flowers arising from the pink and white cross can best be explained by another gene product that influences the phenotypic expression.
d. Flower color is an inherited trait, and the F1 and F2 phenotypes of the flowers arising from the pink and white cross can best be explained by another gene product that influences the phenotypic expression.
Which of the following statements most directly supports the claim that different species of organisms use different metabolic strategies to meet their energy requirements for growth, reproduction, and homeostasis? a. During cold periods pond-dewlling animals can increase the number of unsaturated fatty acids in their cell membranes while some plants make antifreeze proteins to prevent ice crystal formation in tissues. b. Bacteria lack introns while many eukaryotic genes contain many of these intervening sequences. c. Carnivores have more teeth that are specialized for ripping food while herbivores have more teeth that are specialized for grinding food. d. Plants generally use starch molecules for storage while animals use glycogen and fats for storage.
d. Plants generally use starch molecules for storage while animals use glycogen and fats for storage.
Lactose digestion in E. coli begins with its hydrolysis by the enzyme b-galactosidase. The gene encoding b-galactosidase, lacZ, is part of a coordinately regulated operon containing other gene required for lactose utilization. Which of the following figures correctly depicts the interactions at the lac operon when lactose is NOT beging utilized? (the legend below defines the shapes of the molecule illustrated in the options? a. RNA polymerase: at promoter, repressor protein and lactose: operator b. Repressor Protein and Lactose: Operator c. RNA Polymerase: Operator d. Repressor Protein: Operator
d. Repressor Protein: Operator
In a hypothetical population of beetles, there is a wide variety of color, matching the range of coloration of the tree trunks on which the beetles hide from predators. The graphs below illustrate four possible changes to the beetle population as a result of a change in the environment due to pollution that darkened the tree trunks. Graphs: I: Original-middle color, After-lighter II: Original-middle color, After-light or dark III: Original-middle, After-only middle color IV: Original-middle, After-Dark Which of the following includes the most likely change in the coloration of the beetle population after pollution and a correct rationale for the change? a. The coloration range shifted toward more light-colored beetles, as in diagram I. The pollution helped the predators find the darkened tree trunks. b. The coloration in the population split into two extremes, as in diagram II. Both the lighter-colored and the darker-colored beetles were able to hide on the darker tree trunks. c. The coloration range became narrower, as in diagram III. The predators selected beetles at the color extremes. d. The coloration in the population shifted toward more darker-colored beetles, as in diagram IV. The lighter-colored beetles were found more easily by the predators than were the darker-colored beetles.
d. The coloration in the population shifted toward more darker-colored beetles, as in diagram IV. The lighter-colored beetles were found more easily by the predators than were the darker-colored beetles.
A student placed 20 tobacco seeds of the same species on moist paper towels in each of 2 petri dishes. Dish A was wrapped completely in an opaque cover to exclude all light. Dish B was not wrapped. The dishes were placed equidistant from a light source set to a cycle of 14 hours of light and 10 hours of dark. All other conditions were the same for both dishes. The dishes were examined after 7 days, and the opaque cover was permanently removed from dish A. Both dishes were returned to the light and examined again at 14 days. The following data were obtained. ______________________(Dish A) _______Dish B _________________Day7__Day14___Day7_Day14 _____________(Covered)_(uncovered)__[c]_[u] Germinated ______(12)__(20)________[20]_[20] seeds Green-leaved ______(0)_(14)_________[15]__[15] Seedlings Yellow-leaved _____(12)_(6)___________[5]__[5] seedlings Mean stem length __(8)_(9)____________[3]_[3] below first set of leaves Which of the following best supports the hypothesis that the difference in leaf color is genetically controlled? a. The number of yellow-leaved seedlings in dish A on day 7 b. The number of germinated seeds in dish A on days 7 and 14 c. The death of all the yellow-leaved seedlings d. The existence of yellow-leaved seedlings as well as green-leaved ones on day 14 in dish B
d. The existence of yellow-leaved seedlings as well as green-leaved ones on day 14 in dish B
A human kidney !lters about 200 liters of blood each day.Approximately two liters of liquid and nutrient waste are excreted as urine. The remaining fluid and dissolved substances are reabsorbed and continue to circulate throughout the body. Antidiuretic hormone (ADH) is secreted in response to reduced plasma volume. ADH targets the collecting ducts in the kidney, stimulating the insertion of aquaporins into their plasma membranes and an increased reabsorption of water. If ADH secretion is inhibited, which of the following would initially result? a. The number of aquaporins would increase in response to the inhibition of ADH. b. The person would decrease oral water intake to compensate for the inhibition of ADH. c. Blood filtration would increase to compensate for the lack of aquaporins. d. The person would produce greater amounts of dilute urine.
d. The person would produce greater amounts of dilute urine.
Both myoglobin and hemoglobin are proteins that bind reversibly with molecular oxygen. The graph below shows the oxygen-binding saturation of each protein at different concentrations of oxygen. Graph: Y=Saturation with Oxygen X=Partial pressure of O2 Myoglobin has a steep positive slop, then levels at the top Hemoglobin has a less positive slop and doesn't level until the near end of graph Which of the following best describes the physiological significance of the different oxygen-binding capabilities of hemoglobin and myoglobin? a. They prevent muscles from depleting oxygen levels in the blood. b. They cause muscles to become anaerobic. c. They prevent glycogen depletion in muscles. d. They enhance movement of oxygen from the blood into the muscles.
d. They enhance movement of oxygen from the blood into the muscles.