Author: Anonymous

The three-spined stickleback (Gasterosteus aculeatus) is a small fish found in both marine and freshwater environments. Marine stickleback populations consist mostly of individuals with pronounced pelvic spines, as shown in Figure 1. Individuals in freshwater stickleback populations, on the other hand, typically have reduced pelvic spines, as shown in Figure 2. Each figure shows an image of a stickleback fish with a genetic structure below it. The left figure is labeled Figure 1. Marine stickleback. A long Pelvic Spine on the fish is labeled. The genetic structure below the fish contains three enhancers, a promoter, and a gene. From left to right, the Enhancer Sequences are labeled Hindlimb, Pituitary, and Jaw. To the right of the Enhancer Sequences is a Promoter with an arrow moving up and to the right, over the top of the Pitx1 gene. The right figure is labeled Figure 2. Freshwater stickleback. A short Pelvic Spine on the fish is labeled. The genetic structure below the fish contains three enhancers, a promoter, and a gene. From left to right, the Enhancer Sequences are labeled Hindlimb, Pituitary, and Jaw. The Hindlimb enhancer is crossed out with an X, and it is labeled Disabled Due to Mutation. To the right of the Enhancer Sequences is a Promoter with an arrow moving up and to the right, over the top of the Pitx1 gene. As represented in Figure 1 and Figure 2, the phenotypic difference between marine and freshwater sticklebacks involves Pitx1, a gene that influences the formation of the jaw, pituitary gland, and pelvic spine. Enhancer sequences upstream of the Pitx1 genetic locus regulate expression of the Pitx1 gene at the appropriate times and in the appropriate tissues during development. Previous studies have found that a mutation in the hindlimb enhancer interferes with the formation of a pronounced pelvic spine. 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?

Figure 1 illustrates processes related to control of transcription and translation in a cell. Gene X is shown at the top of the diagram, and a vertical arrow extends down from Gene X to a line representing an m R N A, where 5 prime is indicated at the left end and 3 prime is indicated at the right end of the m R N A. An arrowhead is also present at the 3 prime end of the m R N A. Another vertical arrow extends down from the m R N A to a circle labeled Transcription Factor. Five arrows extend from the Transcription Factor to 5 genes, labeled from left to right as Gene A, Gene B, Gene C, Gene D, Gene E. All of the genes except Gene D are labeled on; Gene D is labeled off. Genes A, B, C, and E each have a vertical arrow extending down to a short line representing an m R N A. A vertical arrow extends from each m R N A to a circle. The labels under the circles from left to right are Protein A, Protein B, Protein C, and Protein E. No arrows extend from Gene D. Figure 1. Model of a relationship between a transcription factor and selected genes Which of the following scientific claims is most consistent with the information provided in Figure 1?

In an experiment on the effects of deforestation of a portion of a northern temperate deciduous forest, all the trees were removed from a small mountainside watershed area and herbicides were applied for three years to prevent regrowth. Measurements of the concentration of calcium (an important nutrient) in runoff water were taken both before and after the deforestation. Monthly measurements also were made in a similar watershed in another part of the same forest that had been left undisturbed. The findings are displayed in the graph below. The figure shows a graph in quadrant one titled Monthly Measurements Of Calcium Concentration In Runoff Water. The horizontal axis has every month from June, 1965 to May, 1968, with a tick mark at each month. The vertical axis is labeled calcium ion concentration in runoff water in milligrams per liter, from zero to eleven in increments of one. The time of deforestation is marked at December 1965. There is a dashed line labeled losses from undisturbed watershed that remains at one milligram per liter with only slight fluctuations from June 1965 until the end of the graph in May 1968. There is a solid line labeled losses from disturbed watershed. The calcium ion concentration in runoff water for losses from disturbed watershed is approximately one milligram per liter from June 1965 until May 1966. There is a sharp increase from May to July where the ion concentration reaches seven milligrams per liter, then drops to five in August, and continues rising with fluctuations until October 1966 when it reaches a concentration of nine milligrams per liter. There is a decrease over time, with fluctuations, to six milligrams per liter by May 1967, when the concentration increases rapidly to above eleven, peaking in September 1967, then decreasing steadily with small fluctuations to approximately four milligrams per liter in May 1968. Which of the following is best supported by the data?

In certain Native American groups, albinism due to a homozygous recessive condition in the biochemical pathway for melanin is sometimes seen. If the frequency of the allele for this condition is 0.06, which of the following is closest to the frequency of the dominant allele in this population? (Assume that the population is in Hardy-Weinberg equilibrium.)

In the year 2000, specimens of Caulerpa taxifolia, a green alga used in tropical aquariums, were found off the coast of California. Native to the Indian Ocean, C. taxifolia is known for aggressive growth and an ability to compete with sea grasses.It is currently on an international list of invasive species. Which of the following best predicts the consequences of the introduction of C. taxifolia to the California coast?

Phytochromes are molecules that change light stimuli into chemical signals, and they are thought to target light-activated genes in plants. A study was conducted to determine how certain cell proteins were made in a plant cell using a phytochrome. Figures 1 and 2 represent findings from the study. In the first part of the diagram, inactive phytochrome P r in the cytoplasm becomes active phytochrome P f r that enters the nucleus in the presence of red light. The next part of the diagram shows that P f r is bound to P I F 3 that is bound to a G Box Promoter and that P f r is also bound to a Transcriptional Complex that is bound to a T A T A box on DNA. A bent arrow above a shaded rectangle to the right of the T A T A box points to the right and is labeled Transcription. An arrow points from the shaded box to a circle labeled M Y B. In the last part of the diagram, the M Y B labeled circle is bound to another Promoter and also contacts a Transcriptional Complex that is bound to a T A T A box on DNA. A bent arrow above a shaded rectangle to the right of the T A T A box points to the right and is labeled Transcription. An arrow points from the shaded box to the label Cell Proteins. Figure 1. Phytochrome response to exposure to red light In the first part of the diagram, active P f r in the cytoplasm becomes inactive P r in the presence of far red light. The next part of the diagram shows an arrow labeled Far Red Light pointing to free P r in the nucleus and away from both P I F 3 bound to a G Box Promoter and a Transcriptional Complex bound to a T A T A box on DNA. A label above a shaded rectangle to the right of the T A T A box reads No Transcription. A second label below the shaded box reads M Y B Type Transcription Factor. The last part of the diagram shows another Promoter and a T A T A box on DNA. Nothing is bound to the promoter, and a Transcriptional Complex is bound to the T A T A box. A label above a shaded rectangle to the right of the T A T A box reads No Transcription. A label below the shaded rectangle reads Other Genes. Figure 2. Phytochrome response to exposure to far‑red light Use the response models shown in Figures 1 and 2 to justify the claim that phytochromes regulate the transcription of genes leading to the production of certain cellular proteins.

The graph below illustrates a logistic growth curve for a population of Euglena. with x-axis labeled time in days from zero to twenty, and y-axis labeled population size in organisms per milliliter. The growth curve starts with a population just above zero at zero days and increases exponentially to three-hundred organisms per milliliter at day ten, then flattening out and remaining at three-hundred. There is a point labeled Q on the curve at day twenty. The population would be most likely to remain at the level shown at Q under which of the following conditions?

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. The two apparatuses are the same except for the gases being used. The apparatuses are as follows, from top left clockwise: there is a horizontal pipe with an arrow pointing to the right. The pipe bends down into a round area labeled Gases. There are two wires carrying electric current into the gases, and a label indicating Spark Discharge where the wires enter the round area. From there, a pipe continues down through a condenser, with an arrow pointing straight down next to the pipe. Water Out to the right is indicated at the top of the condenser, and Water In to the left is indicated at the bottom of the condenser. Below the condenser, the pipe continues and there is another arrow pointing straight down. The pipe then curves to the left and bends around a trap, which is labeled Water Containing Organic Compounds. The pipe continues to the left to a round area labeled Boiling Water. The pipe continues up from there, and there is an arrow next to it pointing straight up. There is a branch in the pipe about halfway up the left side of the apparatus, labeled To Vacuum Line, with an arrow pointing to the left. The pipe continues past the branch to where it started. The Gases area in Experiment 1 is labeled: N 2, C H 4, N H 3, H 2 O, and C O 2. The Gases area in Experiment 2 is labeled: S O 2, H 2 S, H 2 O, C H 4, and C O 2. 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?

_______ is the enzyme used during replication to attach Okazaki fragments to each other.

Figure 1 shows the changing pattern of human population sizes in rural and urban areas from 1960 to 2016 with regard to the global population. The horizontal axis is labeled Year, and the years 1960 through 2010, in increments of 10, are indicated, as well as the year 2016. The vertical axis is labeled Number of People, and the numbers 0 through 4 billion, in increments of 1 billion, are indicated. The two curves are described as follows. Note that all values are approximate. The curve labeled Urban population, begins at a point with coordinates 1960, comma 1 billion, and curves upwards and to the right at a gradually increasing rate, passing through the point 2000, comma 2.8 billion. The curve ends at the point 2016, comma 4 billion. The curve labeled Rural population, begins above the curve labeled Urban population at the point 1960, comma 2 billion, and moves gradually upwards to the right passing through the point 2000, comma 3.2 billion. The curve then moves gradually upwards and to the right and ends at the point 2016, comma 3.35 billion. The Rural population curve intersects the Urban Population curve at the point 2007, comma 3.25 billion. Figure 1. Comparison of population size in urban and rural areas from 1960 to 2016. A scientist interested in investigating how human population trends might affect local animal species’ richness stipulates a null hypothesis that animal biodiversity in rural areas will be unaffected in the future by the human population trends shown in Figure 1. Which of the following would best refute this null hypothesis?