AP Bio Semester 1 Exam

If 30% of the nucleotides in a single-stranded RNA molecule are adenine, then what percent are expected to be thymine? A. 0% B. 20% C. 30% D. 70%

A. 0%

The energy required to run the Calvin cycle reactions of photosynthesis comes from which two substances produced during the light-dependent reactions? A. ATP and NADPH B. ADP and PO4 C. H+ and PO2 D. O2 and CO2 E. H2O and CO2

A. ATP and NADPH

An increase in the rate of oxygen production by algae would be accompanied by a comparable increase in the rate of production of which of the following substances? A. C6H12O6 B. CO2 C. CH4 D. NH3 E. H2O

A. C6H12O6

The diagram above represents a model of signal transduction pathways (I and II) in a cell that is targeted by two different hormones (H1 and H2). The components of the signal transduction pathways are identified in the figure legend. Each cellular molecule in both pathways can exist in an inactive or active form. When the components in pathway I are sequentially activated, the TAP molecules promote cell division. When the components in pathway II are sequentially activated, downstream signaling by the G protein is inhibited. Based on the model, which of the following mutations is most likely to result in a cell that will generate a cancerous tumor? A. A mutation in the gene encoding PP that results in a nonfunctional protein B. A mutation in the gene encoding G-PIP that results in a nonfunctional protein C. A mutation in the gene encoding R1 so that it is inactive even in the presence of H1 D. A mutation in the gene encoding R2 so that it is active even in the absence of H2

B. A mutation in the gene encoding G-PIP that results in a nonfunctional protein

Which of the following best describes the production of DMSP by coral and coral symbionts? A. A negative feedback mechanism that increases the environmental change B. A negative feedback mechanism that reverses the environmental change C. A positive feedback mechanism that increases the environmental change D. A positive feedback mechanism that reverses the environmental change

B. A negative feedback mechanism that reverses the environmental change

The diploid number of chromosomes in the cell of a domesticated dog is 78. Which of the following options includes the correct number of chromosomes in a cell after each cellular process (G2 checkpoint, meiosis, and fertilization, respectively)? A. After G2- 156, after meiosis- 78, fertilization 39 B. After G2- 78, after meiosis-39, after fertilization- 78 C. After G2- 156, after meiosis- 39, after fertilization- 78 D. After G2- 78, after meiosis- 78, after fertilization- 39

B. After G2- 78, after meiosis-39, after fertilization- 78

Which of the following organelles modified and packages for secretion the materials produced by the ribosomes? A. Chloroplast B. Golgi apparatus C. Nucleus D. Nucleolus E. Mitochondrion

B. Golgi apparatus

Based on the data shown, changes in the light intensity resulted in changes in the rate of which of the following processes? A. Excretion B. Photosynthesis C. Respiration D. Translation E. Transcription

B. Photosynthesis

The events listed below generally take play during meiosis: 1. Synapsis occurs 2. Crossing over is completed 3. Condensation of chromosomes begin 4. Separation of homologous chromosomes begin Which of the following is the correct sequence of these events? A. 1, 2, 3, 4 B. 2, 1, 3, 4 C. 3, 1, 2, 4 D. 3, 4, 2, 1 E. 4, 2, 3, 1

C. 3, 1, 2, 4

Which of the following describes a mutation that would lead to an increase in the frequency of nondisjunction? A. A mutation affecting checkpoint 1 proteins that forces cells to enter Go B. A mutation affecting checkpoint 2 proteins that allows cells to divide with DNA damage C. A mutation affecting checkpoint 3 proteins that prevents attachment of spindle fibers D. A mutation affecting checkpoint 2 proteins that prevents duplication of the chromosomes

C. A mutation affecting checkpoint 3 proteins that prevents attachment of spindle fibers

Which of the following is probably the genotype of the dark, short haired parent in cross 1? A. CcBb B. ccbb C. CCBB D. CCbb E. ccBB

C. CCBB

Which two cellular organelles in eukaryotes have both electron transport systems and chemiosmotic mechanisms? A. Ribosomes and endoplasmic reticulum B. Chloroplasts and endoplasmic reticulum C. Chloroplasts and mitochondria D. Mitochondria and nuclei E. Nuclei and Golgi apparatus

C. Chloroplasts and mitochondria

Used to carry the genetic code A. Proteins B. Carbohydrates C. Nucleic acids D. Lipids E. Steroids

C. Nucleic acids

Which of the following best explains how higher concentrations of nitrogen and phosphorus contribute to eutrophication? A. An increase in the population of algae results in more nitrogen and phosphorus in the water, causing severe eutrophication. B. Both bacteria and algae require nitrogen and phosphorus, so the algae must grow faster to compete with bacteria C. Nitrogen and phosphorus stimulate oxidative phosphorylation, which consumes the available oxygen in the water D. Algae require nitrogen and phosphorus to build macromolecules, so higher concentrations of these nutrients can result in algal blooms

D. Algae require nitrogen and phosphorus to build macromolecules, so higher concentrations of these nutrients can result in algal blooms

The 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. 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. B. 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.

A student in a biology class crossed a male Drosophila melanogaster having a gray body and long wings with a female D. melanogaster having a black body and apterous wings. The following distribution of traits was observed in the offspring. Which of the following is supported by the data? A. The alleles for gray body and long wings are dominant B. The alleles for gray body and long wings are recessive C. Genes for the two traits are located on two different chromosomes, and independent assortment occurred D. Genes for the two traits are located close together on the same chromosome, and crossing over occurred between the two gene loci

D. Genes for the two traits are located close together on the same chromosome, and crossing over occurred between the two gene loci

All of the following are true statements about meiosis in mammals except A. It serves as a factor in bringing about variation among offspring B. It follows DNA replication C. It occurs only in reproductive structures D. It produces cells with the haploid number of chromosomes E. It produces four genetically identical gametes

E. It produces four genetically identical gametes

The synthesis of protein or carbohydrate polymers always produces which of the following as a byproduct? A. ATP B. oxygen C. Carbon dioxide D. Urea E. Water

E. water

Within a forest ecosystem, there is a large amount of diversity among members of a warbler species. Of the following stages of meiosis illustrated for a typical cell, which contributes most to diversity among the warblers?

When the chromosomes are together (allows for crossing over)

Antidiuretic hormone (ADH) is important in maintaining homeostasis in mammals. ADH is released from the hypothalamus in response to high tissue osmolarity. In response to ADH, the collecting duct and distal tubule in the kidney become more permeable to water, which increases water reabsorption into the capillaries. The amount of hormone released is controlled by a negative feedback loop. Based on the model presented, which of the following statements expresses the proper relationship between osmolarity, ADH release, and urine production? A. As tissue osmolarity rises, more ADH is released, causing less water to be excreted as urine B. As tissue osmolarity rises, less ADH is released, causing less water to be excreted as urine C. As tissue osmolarity rises, more ADH is released, causing more water to be excreted as urine D. As tissue osmolarity rises, less ADH is released, causing more water to be excreted as urine

A. As tissue osmolarity rises, more ADH is released, causing less water to be excreted as urine

A common test for liver function involves sprinkling sulfur powder onto a sample of urine (mostly water with dissolved bodily waste). Sulfur powder sprinkled on a sample from an individual with impaired liver function will sink because the urine contains a high level of bile salts, while the sulfur powder sprinkled on normal urine samples will float. Which of the following best explains why bile salts cause the sulfur powder to sink? A. Bile salts decrease the surface tension of the urine sample. B. Bile salts increase the water potential of the urine. C. Bile salts increase the density of the urine sample. D. Bile salts decrease the strength of the covalent bonds within a water molecule.

A. Bile salts decrease the surface tension of the urine sample.

Butterflies of the genus Colias live in the Rocky Mountains, where they experience a wide range of temperatures. Different variants of a particular glycolytic enzyme in the flight muscles are optimally active at different temperatures. Within the same population, some individual butterflies fly most effectively at 29°C, while others fly most effectively at 40°C. Still others can be equally active at both temperatures. Which of the following claims is most consistent with the observed butterfly behavior? A. Butterflies that express two variants of the enzyme are active over a greater range of temperature. B. Butterflies that are active over a wide range of temperatures produce greater amounts of the enzyme C. Temperature has little effect on the activity of butterflies D. Butterflies that are active at warmer temperatures produce more offspring

A. Butterflies that express two variants of the enzyme are active over a greater range of temperature.

In cross II, the genotype of the dark, short-haired parent is A. CcBb B. ccbb C. CCBB D. CCbb E. ccBB

A. CcBb

The diagram above illustrates which of the following processes? (The diagram is showing 2 homologous chromosomes exchanging pieces of each other) A. Crossing over B. Base pair substitution C. Duplication D. Deletion E. Posttransciptional processing

A. Crossing over

Which of the following best describes the role of mitosis in the cell cycle? A. Distributing replicated chromosomes to daughter nuclei B. Dividing the cytoplasm to form four gametes C. Producing organelles and replicating chromosomes D. Exchanging genetic material between homologous chromosomes

A. Distributing replicated chromosomes to daughter nuclei

The diagram below shows energy changes in a specific chemical reaction with and without the addition of an enzyme to the reaction. Which of the following questions can best be answered by the diagram? A. Does the addition of an enzyme reduce the activation energy required for a reaction? B. Does the addition of an enzyme result in the formation of covalent bonds? C. Does the addition of an enzyme produce a greater amount of products? D. Does the addition of an enzyme change the pathway for the reaction?

A. Does the addition of an enzyme reduce the activation energy required for a reaction?

Which of the following describes the most likely location of cholesterol in an animal cell? A. Embedded in the plasma membrane B. Dissolved in the cytosol C. Suspended in the stroms of the chloroplasts D. Bound to free ribosomes

A. Embedded in the plasma membrane

Which of the following best explains why a cell's plasma membrane is composed of two layers of phospholipids rather than just a single layer? A. Having two oppositely oriented layers of phospholipids allows only the hydrophilic heads to interact with water inside and outside of the cell B. Having two oppositely oriented layers of phospholipids allows the hydrophilic heads to repel water both inside and outside of the cells C. Having two identically oriented layers of phospholipids gives cells more protection from the exterior environment than just a single layer would. D. Having two identically oriented layers of phospholipids allows for the production of vacuoles while still maintaining a protective barrier.

A. Having two oppositely oriented layers of phospholipids allows only the hydrophilic heads to interact with water inside and outside of the cell

Which of the following correctly describes the relationship of the dark-coat-color allele to the albino condition? A. It is dominant B. It is recessive C. It is codominant D. It is a polygenic inheritance pattern E. The alleles are linked

A. It is dominant

Which of the following occurs in all species of living organisms and may lead to an increase in genetic variation? A. Mutations in the genome B. Crossing-over in meiosis C. Random assortment of chromosomes D. Alternative splicing of mRNA

A. Mutations in the genome

A typical bag of fertilizer contains high levels of nitrogen, phosphorus, and potassium but trace amounts of magnesium and calcium. Which of the following best matches the fertilizer component with the molecule in which it will be incorporated by organisms in the area? A. Nitrogen will be incorporated into nucleic acids B. Phosphorus will be incorporated into amino acids C. Potassium will be incorporated into lipids D. Magnesium will be incorporated into carbohydrates

A. Nitrogen will be incorporated into nucleic acids

Carbon dioxide most likely enters a cell through which of the following processes? A. Simple diffusion through the membrane B. Facilitated diffusion through membrane proteins C. Active transport through membrane proteins D. Active transport through aquaporins

A. Simple diffusion through the membrane

To investigate bacterial metabolism, a researcher divided a population (culture) of Staphylococcus capitis bacteria into two sets of culture tubes containing glucose. The researcher added a chemical to one set of tubes and measured the pH of the cultures at 5-minute intervals as the bacteria metabolized the glucose into lactic acid. Which of the following best describes the process by which the bacteria are breaking down the glucose to produce lactic acid? A. The bacteria are breaking down sugars in the absence of oxygen. B. The bacteria are creating a H✶ gradient to synthesize more ATP C. The bacteria are using their mitochondria to break down glucose in the presence of oxygen D. The bacteria are producing CO2 in the Krebs cycle that is then converted into lactic acid.

A. The bacteria are breaking down sugars in the absence of oxygen.

Which of the following was the dependent variable in the researcher's study? A. The concentration of chlorophyll a B. The concentration of total nitrogen and phosphorus C. The slope of the trend line showing the rate of change D. The variance of the data points from the trend line

A. The concentration of chlorophyll a

Which of the following correctly illustrates a dipeptide and an amino acid in the optimal position to form a tripeptide? A. The dipeptide's OH-C=O is closest to the amino acid's H-N-H B. The dipeptide's and amino acid's OH-C=O are closest to each other C. The dipeptide's and amino acid's H-N-H are closest to each other D. The dipeptide's H-N-H is closest to the amino acid's CH3

A. The dipeptide's OH-C=O is closest to the amino acid's H-N-H

A student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. The student measured the mass of the peeled grapes. The student then placed each peeled grape into one of five solutions. After 24 hours, the student removed the peeled grapes from the solutions, measured their final mass, and calculated the percent change in mass. In a second experiment (Table 2), the student placed a peeled grape into a solution containing both small diffusible solutes and solutes to which the membrane is impermeable (nondiffusible solutes). Which of the following best explains why larger grapes have a different rate of water absorption per gram of mass than smaller grapes do? A. The rate is slower because smaller grapes have a larger surface-area-to-volume ratio than the larger grapes do B. The rate is slower because larger grapes have a larger surface-area-to-volume ratio than the smaller grapes do C. The rate is slower because smaller grapes can expand more than larger grapes to hold excess water D. The rate is slower because larger grapes have more volume to hold excess water than smaller grapes do

A. The rate is slower because smaller grapes have a larger surface-area-to-volume ratio than the larger grapes do

In an experiment, the efficiency of oxygen exchange across the plasma membrane is being assessed in four artificial red blood cells. The table above lists some properties of those artificial cells. Other conditions being equal, which artificial cell is predicted to be the most efficient in exchanging oxygen with the environment by diffusion? A. the cuboidal cell B. the tetrahedral cell C. the cylindrical cell D. the spherical cell

A. the cuboidal cell

Which of the following is evidence that eukaryotes and prokaryotes share a common ancestor? A. All eukaryotes and prokaryotes contain linear DNA B. All eukaryotes and prokaryotes contain ribosomes C. All eukaryotes and prokaryotes use organic molecules as an energy source D. All eukaryotes and prokaryotes are capable of mitosis

B. All eukaryotes and prokaryotes contain ribosomes

Amylase is an enzyme that converts carbohydrate polymers into monomers. Glycogen synthase is one of the enzymes involved in converting carbohydrate monomers into polymers. Which of the following best explains the reactions of these enzymes? A. Amylase aids in the removal of a water molecule to break covalent bonds whereas glycogen synthase aids in the addition of a water molecule to form covalent bonds. B. Amylase aids in the addition of a water molecule to break covalent bonds whereas glycogen synthase aids in the removal of a water molecule to form covalent bonds. C. Amylase aids in the addition of a water molecule to form covalent bonds whereas glycogen synthase aids in the removal of a water molecule to break covalent bonds. D. Amylase aids in the removal of a water molecule to form covalent bonds whereas glycogen synthase aids in the addition of a water molecule to break covalent bonds.

B. Amylase aids in the addition of a water molecule to break covalent bonds whereas glycogen synthase aids in the removal of a water molecule to form covalent bonds.

A researcher measured the temperature at which two different samples of double-stranded DNA denature (separate into single strands). Sample 1 denatured at a significantly lower temperature than sample 2 did. Based on the data, the researcher claims that the DNA in sample 2 is composed of a higher percentage of guanine and cytosine than the DNA in sample 1 is. Which of the following best supports the researcher's claim? A. The bonds between guanine and cytosine are covalent bonds, which require more energy to disrupt than those between adenine and thymine. B. Guanine-cytosine pairs denature at a higher temperature because they have more hydrogen bonds between them than adenine-thymine pairs do C. Adenine-thymine pairs require less energy to separate because adenine and thymine are both single-ring bases. D. Guanine-cytosine pairs require more energy to separate because one is a purine and one is a pyrimidine.

B. Guanine-cytosine pairs denature at a higher temperature because they have more hydrogen bonds between them than adenine-thymine pairs do

Students investigated the effect of light on the carbon cycle in aquatic ecosystems by performing the controlled experiment summarized below. The students placed equal amounts of water (pH 7.0) from a large aquarium in glass beakers. The students transferred aquatic plants from the aquarium to several of the beakers, and then they placed equal numbers of the beakers in the light or the dark. Similarly, the students transferred goldfish from the same aquarium to other beakers, and then they placed equal numbers of those beakers in the light or dark. Finally, the students placed an equal number of beakers containing water only in the light or dark. After exposing the samples to light or dark for one hour, the students recorded the pH of the water in each beaker. Carbon dioxide dissolved in water will lower the pH of an aqueous solution. In the experiment, the students used changes in pH to monitor changes in the amount of carbon dioxide in the water. For each treatment group, the students calculated the mean pH and standard error, as documented in the table below. Which of the following graphs is the most appropriate representation of the experimental results documented in the table? A. Pie chart B. Histogram C. Line graph D. Line of best fit

B. Histogram

A culture of Spirogyra (an autotrophic alga) is maintained in 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? A. Increased levels of carbohydrates and lipids, no change in proteins, increase in lipids B. No change in carbohydrates or lipids, decreased levels of proteins and nucleic acids C. Increased levels in carbohydrates, lipids, and nucleic acids, no change in proteins D. Decreased levels of carbohydrates and nucleic acids, increased level of proteins, no change in lipids

B. No change in carbohydrates or lipids, decreased levels of proteins and nucleic acids

A blue-flowered African violet of unknown ancestry self-pollinated and produced 50 seeds. These seeds germinate and grow into flowering plants. Of these plants, 36 produce blue flowers and 14 produce pink flowers. What is the best explanation for the pink-flowered offspring? A. Blue flowers are incompletely dominant to pink flowers. B. Pink flower color is a trait recessive to blue flower color C. Pink flower color is the result of somatic mutations in the flower color gene D. A previous generation of the blue-flowered parent must have included 50 percent pinkflowered plants

B. Pink flower color is a trait recessive to blue flower color

During mitosis, which of the following normally occur? A. Homologous chromosomes pair B. Replicated chromosomes line up on the equatorial plate C. Tetrads form D. Unreplicated chromosomes become oriented in the center of the cell E. Maternal and paternal chromatids pair

B. Replicated chromosomes line up on the equatorial plate

Coyote Hawk Deer Vole Rabbit Meadow Grasses Developers have approved a project that will permanently reduce the primary producers' biomass by 50 percent and remove all rabbits and deer. Which of the following is the most likely 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 outcompete the hawks. D. There will be 50 percent fewer voles and 90 percent fewer hawks

B. The biomass of coyotes will be dramatically reduced

Humans have a diploid number (2n) of 46. Which of the following statements best predicts the consequence if meiosis did not occur during gametogenesis? A. The gametes would get larger from one generation to the next B. The chromosome number would double with each generation C. The chromosome number would be halved with each generation D. The chromosome number would triple with each generation

B. The chromosome number would double with each generation

High levels of certain plant nutrients in runoff can lead to rapid growth of algae (an algal bloom) in aquatic ecosystems. These algal blooms are generally followed by algal death and decomposition, which consumes large amounts of dissolved oxygen in the water and results in oxygen levels insufficient to support aerobic respiration. This process is known as eutrophication. The amount of algae present in a body of water can be estimated from the amount of chlorophyll a in a sample of the water. A researcher studying eutrophication collected samples at different times of the year in a freshwater ecosystem. The samples were analyzed for total nitrogen and chlorophyll a concentration as well as total phosphorus and chlorophyll a concentration. Which of the following describes the relationship between the amount of chlorophyll a in a water sample and the concentration of nitrogen in that sample? A. As the concentration of chlorophyll a increases, the concentration of nitrogen decreases B. The concentrations of nitrogen and chlorophyll a are directly correlated C. The concentrations of chlorophyll a and nitrogen increase throughout the year D. There is no relationship between the concentrations of chlorophyll a and nitrogen.

B. The concentrations of nitrogen and chlorophyll a are directly correlated

Humans produce sweat as a cooling mechanism to maintain a stable internal temperature. Which of the following best explains how the properties of water contribute to this physiological process? A. The high specific heat capacity of water allows the body to absorb a large amount of excess heat energy. B. The high heat of vaporization of water allows the body to remove excess heat through a phase change of water from liquid to gas. C. The high surface tension of water contributes to the physical process by which water leaves the body. D. The high melting temperature of water allows the body to remove excess heat through a phase change of water from solid to liquid.

B. The high heat of vaporization of water allows the body to remove excess heat through a phase change of water from liquid to gas.

A mutation in the gene coding for a single-polypeptide enzyme results in the substitution of the amino acid serine, which has a polar R group, by the amino acid phenylalanine, which has a nonpolar R group. When researchers test the catalysis of the normal enzyme and the mutated enzyme, they find that the mutated enzyme has much lower activity than the normal enzyme does. Which of the following most likely explains how the amino acid substitution has resulted in decreased catalytic activity by the mutated enzyme? A. The substitution decreased the mass of the enzyme so that the mutated enzyme binds more weakly to the substrate than the normal enzyme does B. The substitution altered the secondary and tertiary structure of the enzyme so that the mutated enzyme folds into a different shape than the normal enzyme does. C. The substitution caused many copies of the mutated enzyme to cluster together and compete for substrate to bind. D. The substitution caused the directionality of the enzyme to change such that the amino terminus of the normal enzyme has become the carboxy terminus of the mutated enzyme

B. The substitution altered the secondary and tertiary structure of the enzyme so that the mutated enzyme folds into a different shape than the normal enzyme does.

Ultraviolet (UV) radiation can damage DNA by breaking weak bonds. Which of the following best explains how this occurs? A. UV radiation disrupts the double helix structure by breaking the covalent bonds between the nitrogenous base pairs B. UV radiation disrupts the double helix structure by breaking the hydrogen bonds between the nitrogenous base pairs C. UV radiation is able to break DNA strands in two by breaking covalent bonds between the sugar-phosphate backbone molecules. D. UV radiation is able to break DNA strands in two by breaking hydrogen bonds between the sugar- phosphate backbone molecules.

B. UV radiation disrupts the double helix structure by breaking the hydrogen bonds between the nitrogenous base pairs

A genetic counselor is consulted by a young man who is worried about developing Huntington's disease, an inherited disorder caused by a dominant allele of a single gene. The young man explains that his cousin was recently diagnosed with Huntington's disease, and the news has caused him to consider his own risk of developing the disorder. Which of the following questions will best help the genetic counselor to evaluate the risk of the young man developing Huntington's disease and transmitting it to his children? A. Were you and your cousin born in the same geographical area? B. Were your parents or grandparents ever diagnosed with Huntington's disease? C. Were you in physical contact with a person diagnosed with Huntington's disease? D. Were you ever exposed to substances that are suspected of being mutagens?

B. Were your parents or grandparents ever diagnosed with Huntington's disease?

Carbohydrate-synthesizing reactions of photosynthesis directly require A. light B. products of the light reactions C. darkness D. O2 and H20 E. chlorophyll and CO2

B. products of the light reactions

A student analyzed a viral genome and found that the genome had the following nucleotide composition- 28% adenine, 20% thymine, 35% cytosine, 17% guanine. Which of the following best describes the structure of the viral genome? A. double stranded DNA B. single stranded DNA C. double stranded RNA D. single stranded RNA

B. single stranded DNA

Bacteriophages are viruses that infect bacteria. In an experiment, bacteriophages were labeled with either radioactive phosphorus or radioactive sulfur. The labeled bacteriophages were incubated with bacteria for a brief amount of time and then removed. The infected bacteria cells were found to contain significant amounts of radioactive phosphorus but not radioactive sulfur. Based on the results of the experiment, which of the following types of molecules did the bacteriophages most likely inject into the bacteria cells? A. simple carbohydrate B. amino acid C. DNA D. Polypeptide

C. DNA

Two types of cells, alpha and beta cells, produce signaling molecules that affect blood sugar levels in opposite ways (Figure 1). Epinephrine is a chemical, often released during periods of exercise, that ultimately causes an increase in blood sugar levels in the body. Based on Figure 1, which of the following best explains how exercise causes blood glucose levels to rise? A. Epinephrine inhibits alpha cells, causing the release of glucagon, and activates beta cells, blocking the release of insulin B. Epinephrine activates alpha cells, blocking the release of glucagon, and inhibits beta cells, causing the release of insulin. C. Epinephrine activates alpha cells, causing the release of glucagon, and inhibits beta cells, blocking the release of insulin D. Epinephrine inhibits alpha cells, blocking the release of glucagon, and activates beta cells, causing the release of insulin

C. Epinephrine activates alpha cells, causing the release of glucagon, and inhibits beta cells, blocking the release of insulin

Which of the following is responsible for the cohesive property of water? A. Hydrogen bonds between the oxygen atoms of two adjacent water molecules B. Covalent bonds between the hydrogen atoms of two adjacent water molecules C. Hydrogen bonds between the oxygen atom of one water molecule and a hydrogen atom of another water molecule D. Covalent bonds between the oxygen atom of one water molecule and a hydrogen atom of another water molecule E. Hydrogen bonds between water molecules and other types of molecules

C. Hydrogen bonds between the oxygen atom of one water molecule and a hydrogen atom of another water molecule

The amino acid in Figure 1 is found in a region of a polypeptide that folds away from water. Which part of the amino acid most likely contributes to the hydrophobic behavior of this region of the polypeptide? A. Amine (NH2) group B. Carboxyl (COOH) group C. Methyl (CH3) group D. Hydrogen (H) atom

C. Methyl (CH3) group

Scientists examined the folded structure of a purified protein resuspended in water and found that amino acids with nonpolar R groups were primarily buried in the middle of the protein, whereas amino acids with polar R groups were primarily on the surface of the protein. Which of the following best explains the location of the amino acids in the folded protein? A. Polar R groups on the surface of the protein can form ionic bonds with the charged ends of the water molecules. B. Polar R groups are too bulky to fit in the middle of the protein and are pushed toward the protein's surface. C. Nonpolar R groups that cannot form hydrogen bonds with water are pushed into the middle of the protein D. Nonpolar R groups from different parts of the protein form covalent bonds with each other to maintain the protein's structure

C. Nonpolar R groups that cannot form hydrogen bonds with water are pushed into the middle of the protein

Which of the following best describes the cellular process illustrated in Figure 1 ? A. Sister chromatids separating during anaphase of mitosis B. Chromosomes lining up along the midline of the cell during mitosis C.Reducing the chromosome number during anaphase I of meiosis D. Chromatids failing to separate during meiosis

C. Reducing the chromosome number during anaphase I of meiosis

Segment 1- ATATGAGTAGT TATACTCATCA Segment 2- GCGCAGACGAC CGCGTCTGCTG 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

Which of the follow best describes the hydrolysis of carbohydrates? A. The removal of a water molecule breaks a covalent bond between sugar monomers B. The removal of a water molecule forms a covalent bond between sugar monomers C. The addition of a water molecule breaks a covalent bond between sugar monomers D. The addition of a water molecule forms a covalent bond between sugar monomers

C. The addition of a water molecule breaks a covalent bond between sugar monomers

The diagram above depicts a karyotype of an individual human. Which of the following statements concerning the karyotype in the diagram is true? A. The diagram illustrates a genetic condition found in females. B. The diagram indicates a mechanism for increasing genetic diversity in subsequent generations C. The diagram illustrates the results of nondisjunction during gamete formation D. The diagram indicates Down syndrome, a genetic condition

C. The diagram illustrates the results of nondisjunction during gamete formation

The diagram above represents a typical rod-shaped bacterium. Which of the following best describes a feature shown in the diagram that is unique to archaea and bacteria? A. The organism is surrounded by a cell wall B. The organism contains ribosomes C. The organism does not have a nuclear membrane surrounding its genetic material D. The organism is not capable of making or providing itself with ATP

C. The organism does not have a nuclear membrane surrounding its genetic material

Which of the following best describes the cells that result from the process of meiosis in mammals? A. They are diploid B. They can be used to repair injuries C. They are genetically different from the parent cell D. They are genetically identical to all the other cells in the body E. They are identical to each other

C. They are genetically different from the parent cell

Which of the following best explains the most likely method by which this antitumor drug works? A. Trabectedin increases the production of cyclin proteins that signal the cancer cells to enter prophase B. Trabectedin interferes with the plasma membrane, causing it to break down and expose the DNA to damage C. Trabectedin interferes with the duplication of DNA during interphase and thus prevents cancer cells from passing the G2 checkpoint. D. Trabectedin interferes with the regulations of cyclin proteins, causing their levels to increase and creating errors in DNA.

C. Trabectedin interferes with the duplication of DNA during interphase and thus prevents cancer cells from passing the G2 checkpoint.

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

C. Treating patients with a membrane-soluble compound that can bind to Smo and block its activity

Based on the information provided, which of the following describes the most likely pattern of inheritance for the disorder? A. Autosomal recessive B. Autosomal dominant C. X-linked recessive D. Mitochondrial

C. X-linked recessive

A feature of organic compounds NOT found in inorganic compounds is the presence of A. ionizing chemical groups B. electrons C. carbon atoms covalently bonded to each other D. oxygen E. hydrogen bonds

C. carbon atoms covalently bonded to each other

In the F2 generation, the results are best explained by the fact that A. the test cross with the F1 flies resulted in sterile offspring B. these genes for eye color and wing shape do not pass through the F1 generation C. these genes for eye color and wing shape are found on the same chromosome D. crossing-over decreases variability E. the genes are sex-linked

C. these genes for eye color and wing shape are found on the same chromosome

Which of the following is most directly responsible for water's unique properties? A. It contains oxygen atoms B. It contains hydrogen C. It is an ionic compound D. It forms hydrogen bonds E. It is nonpolar

D. It forms hydrogen bonds

The rate of oxygen production equaled the rate of oxygen consumption during which of the following time periods? A. G to H B. H to I C. I to J D. J to K E. G to K

D. J to K

The manner in which several different ions and molecules move through a cell membrane is shown in the diagram above. For each ion or molecule, the relative concentration on each side of the membrane is indicated. Which of the following accurately describes one of the movements taking place? A. Glucose is transported into the cell by active transport B. Nat is transported into the cell by active transport. C. The movement of glucose through the membrane requires ATP hydrolysis. D. Na transport out of the cell requires ATP hydrolysis

D. Na transport out of the cell requires ATP hydrolysis

A series of crosses is performed with fruit flies (Drosophila melanogaster) to examine inheritance of the genes vestigial (vg) and cinnabar (cn). The recessive vg allele causes small, malformed wings called vestigial wings. The recessive cn allele causes bright-red eyes called cinnabar eyes. In the first cross, a female with wild-type wings and eyes is mated with a male with vestigial wings and cinnabar eyes. All the F1 individuals have wild-type wings and eyes. In the second cross, female F1 flies are mated with males with vestigial wings and cinnabar eyes. The phenotypes of 500 F2 individuals are shown in the table. Which of the following is the most likely explanation of the results? A. The two genes are located on two different chromosomes. B. The two genes are sex-linked. C. The two genes are located on mitochondrial DNA D. The two genes are linked on an autosome.

D. The two genes are linked on an autosome.

The diagram shows how water can adhere to the xylem in the stems of plants, which contributes to water movement in the plant. Which of the following best explains how water is able to move upward from the roots of a plant, through its xylem in the stem, and out to the leaves? A. Water is polar, and the walls of the xylem are nonpolar. Water molecules have the ability to form hydrogen bonds with one another but not with the xylem walls. B. Water is nonpolar, and the walls of the xylem are polar. Water molecules are able to form hydrogen bonds with the xylem walls, and they are pulled up the xylem. C. Water and the xylem are both nonpolar. Water molecules have the ability to form hydrogen bonds with one another but not with the xylem walls. D. Water and the xylem are both polar. Water molecules have the ability to form hydrogen bonds with each other and with the walls of the xylem.

D. Water and the xylem are both polar. Water molecules have the ability to form hydrogen bonds with each other and with the walls of the xylem.

Hydrangea flowers differ in color based on interactions between a pigment in the flower cells and aluminum ions dissolved in water absorbed from the soil. When aluminum ions are present, the pigment is blue; when aluminum ions are absent, the pigment is pink. The amount of aluminum ions the plant can absorb is dependent on the pH of the soil. Which of the following questions will best help a researcher design an experiment to learn about the relationship between hydrangea flower color, aluminum, and pH? A. How do aluminum-pigment interactions change the structure of the pigment and flower color? B. Can the pigment be used as an indicator of pH, because flower color depends on pH and aluminum? C. Does an increase in hydrogen ion concentration affect the ability of the pigment to dissolve in water? D. What will be the flower color of hydrangeas grown in soils of varying pH with or without aluminum?

D. What will be the flower color of hydrangeas grown in soils of varying pH with or without aluminum?

If in the F1 and F2 generations the same characteristics appeared in both males and females, it would be safe to assume that these traits for eye color and wing length A. are sex-linked B. vary in dominance according to sex C. are sex-influenced characteristics D. are autosomal characteristics E. follow the Mendelian rule of independent assortment

D. are autosomal characteristics

Which of the following is an important difference between light-dependent and light-independent reactions of photosynthesis? A. The light-dependent reactions occur only during the day; the light-independent reactions occur only during the night. B. The light-dependent reactions occur in the cytoplasm; the light-independent reactions occur in chloroplasts. C. The light-dependent reactions utilize CO2 and H2O; the light-independent reactions produce CO2 and H2O D. The light-dependent reactions depend on the presence of both photosystems I and II; the light-independent reactions require only photosystem I E. The light-dependent reactions produce ATP and NADPH; the light-independent reactions use energy stored in ATP and NADPH

E. The light-dependent reactions produce ATP and NADPH; the light-independent reactions use energy stored in ATP and NADPH

Site of modification and packing of proteins and lipids prior to export from cell

Golgi Apparatus