AP Bio Final Study Guide

(C) 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? (LO 3.2, EK 3.A.1) (A) Simple carbohydrate (B) Amino acid (C) DNA (D) Polypeptide

R only

Cells in which region of the graph are ready to enter mitosis as the next step in the cell cycle?

No change to the protein/// A premature stop codon or an amino acid with different biochemical characteristics

Comparison of DNA sequences in Table II suggests that a functional GULO gene in lemurs can have a G, C, or T at position 21 but only a G at position 22. Which of the following pairs of predictions is most helpful in explaining the discrepancy? A substitution at position 21 would result in //// A substitution at position 22 would result in

(B) II only

Enzymes with their highest activity at an alkaline (basic) pH are represented by which of the following graphs? (A) I only (B) II only (C) III only (D) I and III only

(d.) I, II , and III only

Graphs representing enzymes sensitive to changes in pH include which of the following? (a.) I only (b.) IV only (c.) II and III only (d.) I, II , and III only

B

Lactose digestion in E. coli begins with its hydrolysis by the enzyme -galactosidase. The gene encoding -galactosidase, lacZ, is part of a coordinately regulated operon containing other genes required for lactose utilization. Which of the following figures correctly depicts the interactions at the lac operon when lactose is NOT being utilized? (The legend below defines the shapes of the molecules illustrated in the options.)

Golgi apparatus

Liver cells manufacture glycoproteins, while adipose cells store fat. Which of the following subcellular structures is likely to be more prominent in liver cells than in adipose cells?

1,133

The TAS2R38 gene encodes a receptor protein that influences the ability to taste bitterness. The gene has two alleles: a dominant, wild-type allele that enables an individual (taster) to taste bitterness and a recessive, mutant allele that interferes with the ability of an individual (nontaster) to taste bitterness. In a sample of 2,400 people, 1,482 were found to have the dominant (taster) phenotype. Assuming that the population is in Hardy-Weinberg equilibrium, approximately how many individuals in the sample are expected to be heterozygous for TAS2R38? (LO 1.6, EA 1.A.3)

The mother cannot be the biological parent of all three children

The banding patterns of the DNA fragments reveal that

(a.) pH affects the shape of the active site of the enzyme

The most likely explanation for the results shown in Graph I is that (a.) pH affects the shape of the active site of the enzyme (b.) the enzyme has a quaternary structure (c.) the enzyme has disulfide bonds (d.) pH affects the primary structure of the enzyme

(D) Interactions between amino acids present in the polypeptide

The tertiary structure and function of a polypeptide is principally determined by the (A) Length of the polypeptide (B) Number of nucleotides present in the polypeptide (C) Repeated units of glycerol making up the polypeptide (D) Interactions between amino acids present in the polypeptide

Using a different restriction enzyme to treat the DNA of each individual

All of the following are likely steps that would lead to the production of these gel patterns EXCEPT

The end of the drought

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 that 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?

Finches with bigger beaks are better able to crack thick-walled seeds and produce more surviving offspring.

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?

The beak size in a large number of finches was measured every year from 1981 to 1987.

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?

no clue

A cell has a surface area of 32 μm2 and a volume of 8 μm3. A different cell has a surface area of 36 μm2 and a volume of 12 μm3. What is the ratio of surface area to volume for the cell that is predicted to exchange materials with the surrounding environment at a faster rate by diffusion? Enter your answer as a fraction or a whole number.

Golgi complex

A cell is treated with a drug that prevents the formation of new lysosomes. The cell continues to transcribe the genes that code for the hydrolytic enzymes that are normally found in lysosomes and continues to translate the mRNAs for those proteins on membrane-bound ribosomes. The hydrolytic enzymes are most likely to accumulate in which of the following cellular structures?

B

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?

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

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?

The field was composed primarily of light-colored soil and little vegetation, affording gray mice protection from predators

A group of mice was released into a large field to which no other mice had access. Immediately after the release, a representative sample of the mice was captured, and the fur color of each individual in the sample was observed and recorded. The mice were then returned to the field. After twenty years, another representative sample of the mice was captured, and the fur color of each individual in the sample was again recorded. Which of the following best explains the change in the frequency distribution of fur color phenotypes in the mouse population, as shown in the figures above?

Population A may undergo instantaneous speciation by the doubling of its chromosome numbers (polyploidy)

A large assemblage of land snails is subdivided into two populations (A and B) by a river that effectively isolates the two populations for an indefinitely long period. From an evolutionary standpoint, which of the following is the LEAST likely to occur in the two populations? (A) Populations A and B will eventually differ in their ecological requirements. (B) Population A may ultimately breed at a different time of the year than population B does. (C) Population A may undergo instantaneous speciation by the doubling of its chromosome numbers (polyploidy). (D) Under laboratory conditions, cross- fertilizations between members of the two populations may be successful even after a long period of geographical separation.

Promoter

A mutation that affects Pitx1 gene function in all tissue types is most likely to be at which of the following genetic loci? (A) Hindlimb enhancer (B) Pituitary enhancer (C) Jaw enhancer (D) Promoter

C

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 the response?

(B) Nitrogen, because it is an essential element of amino acids

A plant has stunted growth and yellowing leaves because it is unable to synthesize key proteins due to a nutrient deficiency. In which nutrient is the plant most likely deficient? (A) Carbon, because it is an essential element in all organic molecules (B) Nitrogen, because it is an essential element of amino acids (C) Oxygen, because it is an essential element in both nucleic acids and proteins (D) Phosphorus, because it is an essential element of nucleic acids

Paired chromatids will separate, and the new daughter chromosomes will move toward opposite poles of the cell.

A researcher examining a root tip observes a plant cell with condensed sister chromatids, kinetochores with attached microtubules, and individual chromosomes that are aligned at the equatorial plate of the cell. Which of the following best describes what the next process will be in the cell? (A) Homologous chromosomes (each with two sister chromatids) will move toward opposite poles of the cell. (B) Paired chromatids will separate, and the new daughter chromosomes will move toward opposite poles of the cell. (C) The nuclear envelope will break down, and the spindle will begin to form. (D) The chromatin will decondense, and the daughter cell will enter interphase.

I don't know

A researcher proposes that the transmembrane portion of a certain protein consists of 24 amino acids. Based on the proposed model, calculate the number of nucleotides in the mRNA that encode only the amino acids in the transmembrane portion of the protein. (LO 3.4, EK 3.A.1)

Single-stranded DNA

A student analyzed a viral genome and found that the genome had the following nucleotide composition. 35% cytosine 20% thymine 28% adenine 17% guanine Which of the following best describes the structure of the viral genome?

Did Mars have the elements present in its atmosphere to support life?

A widely accepted hypothesis about the origin of life on Earth is that life arose approximately 3.5 billion years ago as the result of a complex sequence of chemical reactions that took place spontaneously in Earth's atmosphere. Another hypothesis about the origin of life suggests that life began somewhere else in the universe and arrived on Earth by chance. Which of the following questions might scientists ask to most reliably determine if there has ever been life on Mars? (LO 1.30, EK 1.D.1) (A) How far from Earth was Mars 3.5 billion years ago? (B) Is there scientific proof that Earth ever had an oxygen-free atmosphere? (C) Did Mars have the elements present in its atmosphere to support life? (D) Was there oxygen gas on Mars 3.5 billion years ago?

1.5 meters

According to the data above, what is the deepest water level at which light penetration is expected to be at least 200 μEin m-2 s-1? Give your answer to the nearest tenth of a meter.

mode of internal temperature regulation

According to the data, the crickets at 25°C have greater oxygen consumption per gram of tissue than do the crickets at 10°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

The mice at 10°C had a higher rate of ATP production than the mice at 25°C.

According to the data, the mice at 10°C demonstrated greater oxygen consumption per gram of tissue than did the mice at 25°C. This is most likely explained by which of the following statements?

(A) Bacteria growing in the presence of lactose will fluoresce under ultraviolet light.

Bacterial cells that contain green fluorescent protein GFP will fluoresce under ultraviolet light. Which of the following is the most likely outcome of replacing the lacZ gene in the E. coli lac operon with the gene encoding GFP? (A) Bacteria growing in the presence of lactose will fluoresce under ultraviolet light. (B) Beta-galactosidase will be made only when bacteria are cultured under ultraviolet light. (C) Ultraviolet light will cause a bond to form between glucose and galactose monomers. (D) Ultraviolet light will cause a duplication of the lac operon.

(A) Inflated pod shape is dominant to constricted pod shape.

Based on the data in Table I, which of the following best explains why there are no individuals with constricted pods in the F1 generation? (A) Inflated pod shape is dominant to constricted pod shape. (B) The inflated-pod offspring in the F1 generation are homozygous. (C) Constricted pod shape typically arises from a new mutation in the F1 generation. (D) The constricted-pod offspring are carriers for the inflated pod shape allele.

(D) A nucleic acid.

Based on the data in the table, the unknown molecule should be classified as which type of molecule? (A) A carbohydrate. (B) A protein. (C) A fatty acid. (D) A nucleic acid.

Hybrid individuals are less likely to pass their genetic information on to subsequent generations

Based on the model of speciation presented, which of the following describes the most likely consequence to the populations over time? (A) Hybrid individuals are less likely to pass their genetic information on to subsequent generations. (B) Hybrid individuals living together are physically unable to mate with each other. (C) Geographically isolated populations gradually acquire similar heritable traits. (D) Differences between hybrid individuals of a species disappear over time.

Different neurons in the same neural network can release different amounts of neurotransmitter.

Based on the model, which of the following best explains how regulation of neurotransmitter release might increase the range of responses to a stimulus in the nervous system? (A) In the absence of any stimulus, neurons can still release neurotransmitters. (B) Different neurons in the same neural network can release different amounts of neurotransmitter. (C) In the depolarization phase of an action potential, postsynaptic neurons can adjust the amount of neurotransmitter bound to receptors on their surface. (D) In the recovery phase following a stimulus, enzymes can be mobilized to degrade molecules present in the synaptic vesicles.

GFP* contained in synaptic vesicles moved into the synaptic cleft by exocytosis.

Based on the model, which of the following best explains why a bright green fluorescence was observed following stimulation of a presynaptic neuron? (A) GFP* synthesis was activated when a gene taken up by the neuron was switched on. (B) GFP* stored in the cytoplasm of the neuron was packaged into synaptic vesicles. (C) GFP* contained in synaptic vesicles moved into the synaptic cleft by exocytosis. (D) GFP* present in the synaptic cleft was reabsorbed by endocytosis into the neuron.

CDK5 alters the activity of other proteins involved in the movement of synaptic vesicles to the plasma membrane.

Based on the model, which of the following describes the most likely mechanism by which CDK5 regulates neurotransmitter release? (A) CDK5 adds methyl groups to DNA, altering expression of genes required for synthesis of neurotransmitters. (B) CDK5 promotes the rearrangement of the lipid molecules of two bilayers into a single membrane. (C) CDK5 alters the activity of other proteins involved in the movement of synaptic vesicles to the plasma membrane. (D) CDK5 binds to gated ion channels in the postsynaptic membrane, resulting in diffusion of calcium ions.

The blackcaps that migrate to the United Kingdom will become reproductively isolated from the blackcaps that migrate to Spain, resulting in speciation in the blackcap population.

Blackcap birds (Sylvia atricapilla) migrate out of Germany before wintertime. Prior to the 1960s, all members of a particular blackcap population flew to Spain, which had an abundant natural food source. Now, some members of the same blackcap population fly to the United Kingdom, where food placed in feeders by humans is abundant. The blackcaps return to the same forests in Germany to nest during the breeding season. Some blackcaps that migrate to the United Kingdom have become distinguishable by certain physical and behavioral traits from blackcaps that migrate to Spain. Which of the following best predicts the effect on the blackcap population if humans in the United Kingdom continue to place food in feeders during the winter? (LO 1.22, EK 1.C.2) (A) The blackcaps that migrate to Spain will selectively mate with the blackcaps that migrate to the United Kingdom, resulting in increased genetic variation in the blackcap population. (B) The blackcaps that migrate to the United Kingdom will become reproductively isolated from the blackcaps that migrate to Spain, resulting in speciation in the blackcap population. (C) The blackcaps in Spain and the United Kingdom will migrate to other geographical locations in search of potential mating partners, resulting in a smaller blackcap population in Germany. (D) The blackcaps will begin nesting at their wintering sites in Spain or the United Kingdom, resulting in a larger blackcap population migrating back to Germany after the breeding season has ended.

A defect in a cell-cycle checkpoint prevents a cell from entering the S phase.

Cancer can result from a variety of different mutational events. Which of the following is LEAST likely to result in the initiation of a cancerous tumor? (A) A receptor mutation results in activation of a cell-division pathway in the absence of the appropriate ligand. (B) A mutation results in the loss of the ability to produce a tumor-suppressor protein. (C) A defect in a cell-cycle checkpoint prevents a cell from entering the S phase. (D) At the anaphase checkpoint, separation of chromatids occurs without all centromeres

They will be maintained at the same frequency.

If a population is at Hardy-Weinberg equilibrium, which of the following can be predicted for the recessive alleles in the population?

(c.) The change in absorbance over time in the solution will be less than that of the other samples.

If an additional sample containing the chloroplast/DCPIP solution was placed at a distance of 90 cm from the lamp, which of the following predictions would be most consistent with the experimental results? (a.) The concentration of DCPIP in the solution will increase exponentially. (b.) The absorbance at 60 minutes will be roughly equal to 1.4. (c.) The change in absorbance over time in the solution will be less than that of the other samples. (d.) The temperature of the solution will exceed 75°C.

A substance that removes carbon dioxide gas

During aerobic 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?

condensation of chromatin in preparation of nuclear division in both cells

If chemical signals in the cytoplasm control the progression of a cell to the M phase of the cell cycle, then fusion of a cell in G1 with a cell in early M phase would most likely result in the

The frequency of the Ellis-van Creveld allele is 0.0447 in the isolated population and 0.0026 in the general population, which suggests that genetic drift has occurred in the isolated population

Ellis-van Creveld syndrome is a recessive genetic disorder that includes the characteristics of short stature and extra fingers or toes. In the general population, this syndrome occurs in approximately 1 in 150,000 live births. In a particular isolated population, however, the incidence of this syndrome among live births is 1 in 500. Assume that both the isolated population and the general population are in Hardy-Weinberg equilibrium with respect to this syndrome. Which of the following best describes the difference between the frequency of the allele that causes the syndrome in the general population and the frequency of the allele in the isolated population?

After many generations, the offspring of the introduced guppies will mature at an older age and larger size because of selective pressure from the new predator.

Evolutionary biologists have observed variation in the average age and size of mature individuals in a population of small freshwater guppies. Guppies found in pools with pike cichlids—a predator fish that preys primarily on larger guppies—reproduce at a young age and are small at maturity. Guppies found in pools with killifish—a different predator fish that preys primarily on smaller guppies—reproduce at an older age and are larger at maturity. Which of the following predicts the most likely outcome of moving a population of guppies from a pool with pike cichlids to a pool with killifish? (LO 1.5, EK 1.A.2)

(D) Rr XtXt × Rr XTY

Eye pigment in a particular strain of fly is determined by two genes. An autosomal gene that controls the color of the pigments in the eye has two alleles: a dominant allele (R) that results in red eyes and a recessive allele (r) that results in sepia eyes. A sex-linked gene that controls the expression of the colored pigments also has two alleles: a dominant allele (T) that allows for expression of the colored pigments and a recessive allele (t) that does not allow for expression of the colored pigments. Individuals without a T allele have white eyes regardless of the alleles of other eye-color genes. Which of the following represents a cross between a white-eyed female and a red-eyed male? (A) Tt XRXR × tt XrY (B) Tt XrXr × tt XRY (C) RR XTXT × Rr XTY (D) Rr XtXt × Rr XTY

(B) During the light reactions of photosynthesis, water is split, removing electrons and protons, and oxygen gas is released.

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.

Proteases and RNases to rule out protein and RNA as the transforming factors

In 1944 Avery, MacLeod, and McCarty performed transformation experiments using live, harmless bacteria and extracts from virulent bacteria treated with various enzymes. Which of the following enzymes were used and why?

(A) The alleles for body color and wing shape assort independently, as predicted by Mendel's laws.

In Drosophila melanogaster the allele for wild-type tan body color (B) is dominant to the recessive allele for black body color (b). Similarly, the allele for wild-type wing shape (V) is dominant to the recessive allele for vestigial wing phenotype (v). In the cross diagrammed above, the expected and observed results are shown. Which of the following best explains the observed results of the cross? (A) The alleles for body color and wing shape assort independently, as predicted by Mendel's laws. (B) The genes for body color and wing shape are located close to each other on the same chromosome. (C) The traits of body color show complete dominance over the traits of wing shape. (D) The observed variations in body color and wing shape are detectable in males but not in females.

(C) on different chromosomes

In Table I, the ratio of phenotypes in the offspring from the testcross with F1 plants that had purple flowers and inflated pods suggests that the genes for flower color and pod shape are located (A) close together on the same autosome (B) on the X chromosome (C) on different chromosomes (D) on a mitochondrial chromosome

.35

In a population of 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.

Intermediate stage (Figure 2)

In a separate investigation, individual mice from two populations that in nature are geographically isolated from each other are mated in the laboratory. The hybrid offspring were then mated with individuals from either of the original populations. Only the female hybrid offspring were fertile. The experimental results are most consistent with which of the stages that are depicted in the model? (A) Initial population (Figure 1) (B) Intermediate stage (Figure 2) (C) Late stage (Figure 3) (D) Terminal stage (Figure 4)

Translation of ferritin mRNA is stimulated by iron.

In individuals with iron-rich diets, intracellular levels of iron are higher than in individuals with iron-poor diets. Which of the following best explains how organism (A) Translation of ferritin mRNA is inhibited in the presence of iron. (B) Translation of ferritin mRNA is stimulated by iron. (C) Ferritin protein is more stable in the presence of iron. (D) Ferritin protein is less stable in the presence of iron.

The jaw does not develop normally, but a pronounced pelvic spine does develop because the Pitx1 gene is expressed in the developing pelvis but not in the developing jaw.

In sticklebacks, which of the following is most likely to occur if the jaw enhancer is disabled instead of the hindlimb enhancer? (A) The jaw and a pronounced pelvic spine develop normally because the Pitx1 gene is expressed in both developing tissues. (B) Neither the jaw nor a pronounced pelvic spine develop normally because there is no Pitx1 gene expression in either developing tissue. (C) The jaw develops normally, but a pronounced pelvic spine does not develop because the Pitx1 gene is expressed in the developing jaw but not in the developing pelvis. (D) The jaw does not develop normally, but a pronounced pelvic spine does develop because the Pitx1 gene is expressed in the developing pelvis but not in the developing jaw.

DNA is made up of four different types of nucleotides, whereas proteins are made up of 20 different types of amino acids, enabling proteins to create many more chemical messengers than DNA can.

In the 1930s, most scientists agreed that proteins are the genetic material in cells. Which statement would scientists from the 1930s most likely cite as the strongest evidence that proteins, and not DNA, store genetic material in cells

(C) The cells that are exposed to hypotonic solutions will expand as water moves osmotically into the cells from the blood

Intravenous (IV) solutions administered to patients are normally isotonic. Which of the following is most likely if an IV of distilled water is administered to a patient? (A) The cells that are exposed to hypotonic solutions will shrink as a result of salt moving into the blood. (B) The liver will secrete additional bile salts into the blood to raise the tonicity of the administered fluid. (C) The cells that are exposed to hypotonic solutions will expand as water moves osmotically into the cells from the blood. (D) The patient's respiration rate will slow to compensate for the higher levels of circulating blood.

Comparing the arrangements of bones in the fins of lobe-finned fishes and limbs of the earliest tetrapods

Lobe-finned fishes were present in the oceans of the world approximately 400 million years ago. The first tetrapods (vertebrates that had limbs and could move on land) date to about 365 million years ago. One hypothesis states that early tetrapods evolved from lobe-finned fishes. Which of the following is the best plan for testing the hypothesis? (A) Determining the number of fins found on lobe-finned fishes from different geographical locations (B) Measuring the proportion of radioisotopes found in fossils of early tetrapods (C) Comparing the arrangements of bones in the fins of lobe-finned fishes and limbs of the earliest tetrapods (D) Sequencing DNA isolated from fossils of lobe-finned fishes to determine the size of the genome

(B) An ancestral cell most likely engulfed an aerobic prokaryote in a relationship that proved beneficial for both cells.

Mitochondria are found in most eukaryotic cells and contain their own DNA and ribosomes that are similar to those typical of many prokaryotic cells. Which of the following statements is justified by these observations?

(B) Lava has separated the population into two areas: an upland forest and a lowland marsh

On a large volcanic island, researchers are studying a population of annual herbaceous plants. Which of the following observations best supports the prediction that speciation will occur within the existing plant population? (A) Individuals of the species sometimes reproduce asexually by producing runners. (B) Lava has separated the population into two areas: an upland forest and a lowland marsh. (C) Multiple groups of birds depend on the fruit produced by the plants as a source of food. (D) The plants produce more seeds during warm summers than they do during cool summers.

Natural selection over multiple generations is favoring antibiotic resistance in the population of bacteria

Over several years, bacteria were isolated from members of a human population and tested for antibiotic resistance. The percent of bacterial isolates that were found to be antibiotic resistant is presented in the graph above for each year of the study. Which of the following conclusions is best supported by the information presented in the graph?

The warning bark changes the behavior of the related prairie dogs nearby, allowing the prairie dog's family to have increased survival and reproductive success

Prairie dogs are small mammals that live in large colonies in burrows in the ground. Prairie dogs that are near their own relatives when a predator approaches are much more likely to issue a warning bark than those that are near unrelated prairie dogs. The prairie dogs that hear a warning bark are more likely to hide in their burrows than to remain above ground. However, the prairie dog that gives the warning bark is putting itself at increased risk of being identified and killed by the predator. Which of the following presents the most likely evolutionary explanation for the behaviors described?

Degradation of p35 results in increased synaptic activity.

Previous experiments indicate that CDK5 is active only when attached to a protein called p35. Which of the following best predicts how p35 might play a role in regulating neuron function? (A) Elevated intracellular levels of p35 result in increased synaptic activity. (B) Degradation of p35 results in increased synaptic activity. (C) Reabsorption of p35 from the synaptic cleft results in increased synaptic activity. (D) Attachment of p35 to synaptic vesicles results in increased synaptic activity.

The basic molecular structure is a helix.

Rosalind Franklin's x-ray diffraction images taken in the 1950s most directly support which of the following claims about DNA?

It has a cell wall exterior to the plasma membrane and contains ribosomes.

Which of the following is true about the structure of the prokaryotic cell represented in the figure?

A single base-pair substitution in the gene encoding the beta subunit

Sickle-cell anemia is associated with a mutation in the gene encoding the beta subunit of hemoglobin that results in a change from glutamic acid to valine at position 6. All other amino acids are identical to a normal hemoglobin molecule. Based on the information above, which of the following mutations is the most likely cause of sickle-cell anemia? (A) A single base-pair substitution in the gene encoding the beta subunit (B) A single base-pair insertion in the gene encoding the beta subunit (C) A single base-pair deletion in the gene encoding the beta subunit (D) A translocation of DNA from one chromosome to another

(A) All properties of the molecule as a result of abnormal interactions between adjacent hemoglobin molecules

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) All 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

(D) In the presence of tryptophan, the trpR gene is inactive, preventing the production of the repressor that blocks expression of the operon.

The Trp operon is a coordinately regulated group of genes (trpA-trpE) that are required for tryptophan biosynthesis in E. coli. Based on the figure above, which of the following correctly describes the regulation of the Trp operon? (A) In the absence of tryptophan, the repressor is active and binds to the Trp operator, preventing RNA polymerase from transcribing the operon. (B) In the presence of tryptophan, the repressor is active and binds to the Trp operator, preventing RNA polymerase from transcribing the operon. (C) In the absence of tryptophan, the trpR gene is inactive, preventing the production of the repressor that blocks expression of the operon. (D) In the presence of tryptophan, the trpR gene is inactive, preventing the production of the repressor that blocks expression of the operon.

(D) DNA synthesis

The cells found in the region of the graph labeled Q are involved in what major cell cycle activity?

(D) The allele for blue is an X-linked dominant allele because there are no blue male offspring in cross 2.

The data above represent the results of three different crosses involving the inheritance of a gene that determines whether a certain organism is blue or white. Which of the following best explains the mechanism of inheritance of the gene? (A) The allele for white is an autosomal dominant allele because a 1:1 phenotype ratio of blue to white among both sexes is observed in cross 3. (B) The allele for blue is an autosomal dominant allele because an approximate 3:1 phenotype ratio of blue to white is observed in cross 1. (C) The allele for white is an X-linked dominant allele because no white females are produced in cross 1. (D) The allele for blue is an X-linked dominant allele because there are no blue male offspring in cross 2.

Iron increases ribosome binding to ferritin mRNA

The data can best be used to support which of the following claims about the mechanism for regulating ferritin gene expression? (A) Iron increases ribosome binding to ferritin mRNA. (B) Iron causes the ferritin mRNA to be degraded. (C) Iron increases the effect of actinomycin D on RNA polymerase. (D) Iron decreases the ability of ferritin mRNA to bind to ribosomes.

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

The diagram above depicts a karyotype of an individual human. Which of the following statements concerning the karyotype in the diagram is true?

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

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?

The activator is a sequence-specific DNA-binding protein that is present in some tissues but not in other

The figure above depicts the DNA-protein complex that is assembled at the transcriptional start site of gene X when the expression of gene X is activated in liver cells. Previous studies have shown that gene X is never expressed in nerve cells. Based on the diagram, which of the following most likely contributes to the specific expression pattern of gene X ? (A) Expression of gene X produces large amounts of tRNA but undetectable amounts of mRNA. (B) The general transcription factors inhibit the activation of gene X in liver cells by blocking the activator from (C) The activator is a sequence-specific DNA-binding protein that is present in some tissues but not in other (D) The enhancer is a unique DNA segment that is added to the nuclear DNA of some cells of an organism during the process of mitotic cell division but not other cells.

Structure Y is the location where proteins are synthesized.

The figure above represents a rough endoplasmic reticulum. Which of the following best describes the role of the structure labeled Y?

(C) crosses the endoplasmic reticulum membrane as it is translated, then moves to the Golgi apparatus, then to vesicles from which it is secreted

The figure above shows a series of microscope images taken over time of ovalbumin production in chick oviduct cells in response to stimulation with estrogen. The ovalbumin protein was detected using a fluorescent dye as shown by the white areas in the time-lapse sequence. The microscope images indicate that ovalbumin

The inner membrane has specialized proteins that create a hydrogen ion concentration gradient between the intermembrane space and the matrix.

The figure above shows an organelle typically found in eukaryotic cells. Which of the following best describes the function of the double membrane system of this organelle?

(B) To synthesize and isolate proteins for secretion or for use in the cell

The figure below illustrates a eukaryotic cell. Which of the following best describes how the three structures indicated by the arrows work together?

The reading frame of the sequence would shift, causing a change in the amino acid sequence after that point

The following DNA sequence is a small part of the coding (nontemplate) strand from the open reading frame of the -hemoglobin gene. Given the codon chart listed on page 6, what would be the effect of a mutation that deletes the G at the beginning of the DNA sequence? (LO 3.6, EK 3.A.1) 5'- GTT TGT CTG TGG TAC CAC GTG GAC TGA -3' (A) The mutation precedes the gene, so no changes would occur. (B) Lysine (lys) would replace glutamine (gln), but there would be no other changes. (C) The first amino acid would be missing, but there would be no other change to the protein. (D) The reading frame of the sequence would shift, causing a change in the amino acid sequence after that point.

Examining the upper part of the lower rock layer for evidence of a catastrophic event, such as the presence of shocked quartz, iridium, or soot particles

The fossils in a layer of rock are significantly different from those in the rock layer directly above it. One hypothesis to explain the difference is that a major extinction event occurred at the point in time represented by the transition between the two rock layers. Which of the following is the best plan for collecting data to use in a test of the hypothesis? (LO 1.21, EK 1.C.1) (A) Examining the upper part of the lower rock layer for evidence of a catastrophic event, such as the presence of shocked quartz, iridium, or soot particles (B) Digging farther into the hillside to look for a section of sedimentary rock that has a third layer below the two layers that were already identified (C) Comparing the genomes of organisms from different evolutionary lineages to estimate the relative geologic age of the upper rock layer (D) Searching fossil collections in several museums for examples of the types of features once shared among organisms that are now extinct

(C) maternal mitochondrial mutations are inherited by all of a mother's offspring

The pedigree suggests that the gene is on a nuclear chromosome, and not on mitochondrial DNA, because (A) mitochondrial genes are not heritable (B) mitochondrial mutations cannot produce dominant traits (C) maternal mitochondrial mutations are inherited by all of a mother's offspring (D) mitochondrial DNA is circular, whereas chromosomal DNA is linear

Natural selection favors DDT-resistant mosquitoes that are already present in a population when DDT exposure occurs.

The pesticide DDT was widely used in the 1940s as a method of insect control. In the late 1950s the first DDT-resistant mosquitoes were discovered, and eventually DDT-resistant mosquitoes were found globally. When DDT is used now, the development of DDT resistance in mosquito populations occurs in months rather than years. Which of the following best explains the observations concerning DDT resistance in mosquitoes?

Is the EDA gene as representative of the differences between the populations as the 25 random genes that were examined for Figure 3?

The phylogenetic trees in Figures 2 and 3 depict two different phylogenies of the same populations of sticklebacks. Which of the following questions will best help determine which tree represents the most accurate phylogeny? (A) Is the EDA gene as representative of the differences between the populations as the 25 random genes that were examined for Figure 3? (B) Are the low-plated populations found only in freshwater and the high-plated populations found only in saltwater environments? (C) Is the common ancestor of the organisms represented in Figure 2 different from the common ancestor of the organisms represented in Figure 3? (D) Is the expression level of the EDA gene analyzed in Figure 2 significantly greater than the expression levels of the 25 genes analyzed in Figure 3?

During meiosis, crossing over leads to recombination of alleles between homologous chromosomes

The process depicted in the image above is best summarized by which of the following descriptions? (A) During the synthesis phase of the cell cycle, DNA molecules replicate to generate identical daughter cells. (B) Centromeres align specific gene sequences of homologous chromosomes during mitotic divisions. (C) The spindle apparatus attaches at chiasma during metaphase of mitosis. (D) During meiosis, crossing over leads to recombination of alleles between homologous chromosomes.

G1

The region on the graph labeled P represents cells in what stage of the cell cycle?

The HbA DNA contains a recognition site for the Mst II restriction enzyme.

The restriction endonuclease Mst II recognizes the sequence 5′ CCT(N)AG (where N = any nucleotide) and cuts DNA at that site, producing separate fragments. Which of the following best explains the banding patterns exhibited in Figure 1?

Single-celled organisms will use various mechanisms to counteract the increased flow of water from cells to the environment.

The salinity of a small inland lake has recently started to increase. Researchers are planning to study the lake over several decades to investigate how freshwater organisms survive significant changes in their natural habitat. Which of the following physiological mechanisms will the researchers most likely observe among the surviving organisms in the lake? (A) Prokaryotic organisms will use various mechanisms to counteract swelling of cells as a result of increased water uptake. (B) Single-celled organisms will use various mechanisms to counteract the increased flow of water from cells to the environment. (C) Eukaryotic organisms will use various mechanisms to counteract the diffusion of positively charged ions across the cell membrane. (D) Multicellular organisms will use various mechanisms to counteract the loss of cell adhesion as a result of calcium deficiencies

Eukaryotes have organelles that allow for compartmentalization of cellular processes, which increases the efficiency of those processes.

Which of the following best describes an advantage that eukaryote organisms have over prokaryote organisms?

C

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?

(B) 14C-labeled CO2, because atmospheric carbon is fixed to carbohydrates by photosynthesis

To test the hypothesis that a particular plant synthesizes storage lipids by using glyceraldehyde-3-phosphate from photosynthesis, a researcher plans to use radiolabeled precursors to track the molecules through the biosynthetic pathway. Which of the following radiolabeled precursors is most appropriate for the researcher to use? (A) 15N-labeled N2, because atmospheric nitrogen is fixed to amino acids by photosynthesis (B) 14C-labeled CO2, because atmospheric carbon is fixed to carbohydrates by photosynthesis (C) 35S-labeled methionine, because amino acids are incorporated into lipids during photosynthesis (D) 32P-labeled phosphate, because lipids are stored in plants as phospholipids

(B) The nitrogen (N2) gas and ammonia (NH3) gas in experiment 1 could provide the elemental nitrogen required for the formation of amino acids.

Two groups of students attempted to re-create the primitive atmospheric conditions of early Earth using the apparatus represented below. Each group ran the experiment with different gas mixtures in the apparatus. Which of the following statements best justifies the claim that the conditions in at least one of the experiments could generate the molecular building blocks essential for life? (A) The carbon dioxide (CO2) gas and water (H2O) vapor in experiment 1 could react spontaneously to produce the phospholipids required by the first life-forms. (B) The nitrogen (N2) gas and ammonia (NH3) gas in experiment 1 could provide the elemental nitrogen required for the formation of amino acids. (C) The sulfur dioxide (SO2) gas in experiment 2 could donate the excited electrons required to drive the process of photosynthesis. (D) The methane (CH4) gas in experiment 2 could act as the electron acceptor required to complete the process of cellular respiration.

The rate of proton pumping across the inner mitochondrial membrane is lower in the sample without oxygen

Two nutrient solutions are maintained at the same pH. Actively respiring mitochondria are isolated and placed into each of the two solutions. Oxygen gas is bubbled into one solution. The other solution is depleted of available oxygen. Which of the following best explains why ATP production is greater in the tube with oxygen than in the tube without oxygen?

Photosynthesis produces more oxygen than is consumed by respiration during the day.

What most likely causes the trends in oxygen concentration shown in the graph above?

The first polar body is produced in meiosis I, when the pairs of homologous chromosomes are separated into two cells. In meiosis II, the second polar body is generated when sister chromatids are separated into two cells to obtain the haploid number of chromosomes in the egg.

Which is the best explanation of the role of polar bodies during the formation of an egg?

Expression of the Pitx1 gene is affected by mutations at other genetic loci.

Which of the following best describes how sticklebacks in the same population with identical copies of the Pitx1 gene can still show phenotypic variation in the pelvic spine character? (A) The Pitx1 gene is carried on different chromosomes in different individuals. (B) Expression of the Pitx1 gene is affected by mutations at other genetic loci. (C) The genetic code of the Pitx1 gene is translated differently in males and females. (D) The subcellular location of the Pitx1 gene changes when individuals move to a new environment.

Sterile individuals make no genetic contribution to the next generation

Which of the following best describes the reason for excluding hybrid males when calculating the allele frequencies of two interbreeding populations at the intermediate stage of speciation (Figure 2)? (A) The process of mate selection in large groups often favors females over males. (B) The frequency of sex-determining chromosomes is usually equal to 0.5. (C) Sterile individuals make no genetic contribution to the next generation. (D) The chance of inheriting a recessive allele from a male is too small to calculate.

(B) To prevent the breakdown of the enzyme

Which of the following best describes why ice was used during this experiment? (A) To increase the activity of the enzyme (B) To prevent the breakdown of the enzyme (C) To slow the catalase molecules to increase the probability of contact with the hydrogen peroxide molecules (D) To increase the size of the active site on the enzyme

(D) The higher substrate concentrations in the more concentrated solutions speeded the reaction

Which of the following best describes why the disks rose to the surface faster in the more concentrated hydrogen peroxide solutions? (A) There was more enzyme present in the more concentrated solutions (B) A greater amount of heat was generated in the more concentrated solutions (C) The more concentrated solutions lowered the activation energy of the reaction (D) The higher substrate concentrations in the more concentrated solutions speeded the reaction

(D) The lacZ gene is highly expressed only when lactose is available.

Which of the following best explains the contribution of the lac operon to the metabolic efficiency of a bacterial cell? (A) Expression of the lac gene requires lactose. (B) RNA polymerase is rapidly degraded by the product of the lacP locus. (C) The repressor binds to DNA only when the cellular concentration of glucose is low. (D) The lacZ gene is highly expressed only when lactose is available.

RNA samples could be separated by size using agarose gel electrophoresis and incubated with labeled single-stranded DNA molecules that are complementary to the ferritin mRNA

Which of the following biotechnology approaches could be used to identify ferritin mRNA in a sample of total cellular RNA? (A) RNA samples could be directly cloned into a DNA plasmid, grown in bacteria, and tested for the ability to bind iron. (B) RNA samples could be separated by size using agarose gel electrophoresis and incubated with labeled single-stranded DNA molecules that are complementary to the ferritin mRNA. (C) RNA samples could be converted to protein and subsequently cut with a restriction endonuclease that recognizes DNA sequences. (D) RNA samples could be examined under a high-power microscope to visually identify the ferritin mRNA.

(d.) Light from a lamp can substitute for sunlight in stimulating chloroplast processes.

Which of the following can be reasonably concluded from the experimental results? (a.) Chloroplasts must be suspended in a buffer solution to function properly. (b.) The optimal temperature for activation of electron transfer is 25°C. (c.) DCPIP inhibits biochemical reactions in suspended chloroplasts. (d.) Light from a lamp can substitute for sunlight in stimulating chloroplast processes.

A

Which of the following correctly illustrates a dipeptide and an amino acid in the optimal position to form a tripeptide?

A buildup of lactic acid in the muscle tissue due to fermentation

Which of the following describes a metabolic consequence of a shortage of oxygen in muscle cells?

(C) Expression of the lac operon diminishes as lactose is depleted.

Which of the following describes the most likely consequence of a negative feedback pathway involving the lac operon? (A) The breakdown products of lactose block cell division. (B) Diffusion of lactose across the plasma membrane would stop in the presence of lactose. (C) Expression of the lac operon diminishes as lactose is depleted. (D) Binding of DNA by the repressor would increase in the presence of lactose.

(a.) Availability of electrons for transfer to DCPIP depends on light energy.

Which of the following descriptions of photosynthesis best explains the results of the experiment? (a.) Availability of electrons for transfer to DCPIP depends on light energy. (b.) Movement of DCPIP across chloroplast membranes occurs in less than 60 minutes. (c.) Chlorophyll molecules degrade rapidly in the presence of DCPIP. (d.) DCPIP can only be used to measure photosynthetic activity at low light levels.

C

Which of the following diagrams depicts the rate of an enzyme-catalyzed reaction from low substrate concentrations to saturating substrate concentrations?

(A) Place a catalase-soaked disk in a beaker of water

Which of the following experimental designs should the students use as a control for the experiment? (A) Place a catalase-soaked disk in a beaker of water (B) Poke the floating disks back down to the bottom of the beaker and retime the rise of the disks (C) Shake the beakers during the time disks are rising (D) Dip the disks in the 5% solution before putting them in any other solution

Cellular respiration

Which of the following is the best explanation for the pattern of change in mass of the organisms over time?

Beta-galactosidase will be produced, even in the absence of lactose.

Which of the following is the most likely consequence of a mutation at the operator locus that prevents binding of the repressor protein? (A) Expression of the structural genes will be repressed, even in the presence of lactose. (B) Beta-galactosidase will be produced, even in the absence of lactose. (C) RNA polymerase will attach at the Plac locus, but transcription will be blocked. (D) The operator locus will code for a different protein and thereby prevent transcription of the structural gene.

The deletion of the single nucleotide causes a frame shift, changing the primary structure downstream of the mutation and resulting in a nonfunctional protein

Which of the following is the most likely effect of the mutation at nucleotide position 7 in the GULO gene of humans?

Inhibition of CDK5 activity in neurons increases the movement of synaptic vesicles to the plasma membrane in response to a specific stimulus.

Which of the following observations best supports the hypothesis that CDK5 negatively regulates neurotransmitter release? (A) Introduction of CDK5 protein into neurons results in the movement of synaptic vesicles to the plasma membrane in the absence of any stimulus. (B) Uptake of a gene encoding CDK5 by neurons results in the movement of synaptic vesicles to the plasma membrane in the absence of any stimulus. (C) Suppression of CDK5 expression in neurons inhibits the movement of synaptic vesicles to the plasma membrane in response to a specific stimulus. (D) Inhibition of CDK5 activity in neurons increases the movement of synaptic vesicles to the plasma membrane in response to a specific stimulus.

(b.) Comparing the observed results for sample 2 and sample 3

Which of the following provides the best indication that light is required for the activation of electron transfer reactions in chloroplasts? (a.) Calculating the rate of change of the absorbance for sample 1 (b.) Comparing the observed results for sample 2 and sample 3 (c.) Repeating the entire experimental procedure at night (d.) Including multiple trials for all the samples

(B) The purple allele is dominant to the white allele because all the offspring from the cross of purple-flowered and white- flowered plants had purple flowers.

Which of the following provides the best justification for an assumption that might have been used in the computer simulation (Table II)? (A) The broad allele is recessive to the narrow allele because broad leaves appear in every generation. (B) The purple allele is dominant to the white allele because all the offspring from the cross of purple-flowered and white- flowered plants had purple flowers. (C) The narrow allele is codominant with the purple allele because the purple-flower trait and the narrow-leaf trait segregate together. (D) The white allele is dominant to both the broad and narrow alleles because plants with either type of leaf shape can have white flowers.

Can simple organic molecules form spontaneously in an oxygen-free atmosphere?

Which of the following questions about the origin of life on Earth is most scientifically testable? (LO 1.28, EK 1.D.1) (A) Why were the earliest life-forms created using only twenty amino acids? (B) Did life originate to make the universe a better place? (C) Was catalytic RNA used by ancient organisms as a stepping stone to acquire protein enzymes? (D) Can simple organic molecules form spontaneously in an oxygen-free atmosphere ?

(A) Does the addition of an enzyme reduce the activation energy required for a 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?

(B) How is ATP used in the formation of 3-carbon carbohydrates?

Which of the following questions is most relevant to understanding the Calvin cycle?

Is the phosphorylation of ADP by ATP synthase dependent on the formation of a proton gradient?

Which of the following questions will best direct an investigation of the mechanism of ATP synthase?

(b.) What wavelength of light best activates electron transfer reactions in chloroplasts?

Which of the following scientific questions could be investigated using a similar experimental setup? (a.) How much carbon dioxide is required by a plant cell to produce one molecule of glucose? (b.) What wavelength of light best activates electron transfer reactions in chloroplasts? (c.) Which molecule in chloroplasts accepts activated electrons from DCPIP during photosynthesis? (d.) Are the same genes that are expressed in chloroplasts also expressed in mitochondria?

(A) Ions are unable to move through the phospholipid bilayer because the nonpolar tail regions of the phospholipids are hydrophobic

Which of the following statements is true regarding the movement of substances across cell membranes? (A) Ions are unable to move through the phospholipid bilayer because the nonpolar tail regions of the phospholipids are hydrophobic. (B) Ions are able to move through the phospholipid bilayer because the polar head regions of the phospholipids are charged. (C) Water is able to move through the phospholipid bilayer because the nonpolar tail regions of the phospholipids are charged. (D) Water is unable to move through the phospholipid bilayer because the polar head regions of the phospholipids are charged.

(D) Both samples are energy-releasing reactions, but the entropy in sample A is greater because ΔG is more negative than in sample B.

Which statement best explains the data? (A) Both samples are endergonic, but sample A shows a greater increase in entropy because ΔG is more negative than in sample B. (B) Both samples are energy-capturing reactions, but the total energy in sample A is greater because ΔG is more negative than in sample B. (C) Both samples are exergonic, but sample A shows a greater decrease in entropy because ΔG is more negative than in sample B. (D) Both samples are energy-releasing reactions, but the entropy in sample A is greater because ΔG is more negative than in sample B.

(B) This is a dehydration synthesis reaction because a hydrogen atom is removed from one amino acid and a hydroxyl group is removed from the other amino acid in order to form the dipeptide.

Which statement best explains this reaction? (A) This is a hydrolysis reaction because a water molecule is produced when the amino acids bond to form the dipeptide. (B) This is a dehydration synthesis reaction because a hydrogen atom is removed from one amino acid and a hydroxyl group is removed from the other amino acid in order to form the dipeptide. (C) This is a dehydration synthesis reaction because the hydroxyl group in the water molecule donates an electron to one of the amino acids, which is used to form the dipeptide. (D) This is a hydrolysis reaction because a water molecule is used to fuse two amino acids into a dipeptide.

(C) The excited electrons are replaced when an enzyme splits a water molecule into two electrons, an oxygen atom, and two hydrogen ions.

Which statement explains the process that occurs immediately after the electrons are excited in photosystem II? (A) The excited electrons are accepted by the terminal electron acceptor NADP+ and used to generate ATP. (B) The excited electrons release energy in the form of ATP as they are transported to another protein complex through a series of redox reactions. (C) The excited electrons are replaced when an enzyme splits a water molecule into two electrons, an oxygen atom, and two hydrogen ions. (D) The excited electrons are added to ADP+ to produce ATP, which is used to drive the reactions needed to produce sugar from carbon dioxide in the Calvin cycle.