Author: Anonymous

Phytoplankton (black line) are important because they occupy the bottom of the food web absorbing CO2, functioning as a carbon sink. A scientist suggests that an El Niño event in early 1998 caused a significant decrease in the abundance of phytoplankton that year in the equatorial Pacific Ocean. The horizontal axis is labeled Year, and the years 1990 through 2000, in increments of 2, are indicated. The vertical axis is labeled, Relative Plankton Density. A key indicates that one line represents zooplankton and the other line represents phytoplankton. The data represented in the graph are as follows. Note, all data are approximate. Data for zooplankton. The line begins approximately one third of the way up the vertical axis above the origin and trends slightly upwards and to the right, fluctuating up and down across the length of the horizontal axis with upward spikes approximately every two years, and a significant downward spike at the year 1998 that falls to just above the horizontal axis. Data for phytoplankton. The line begins just below the midpoint on the vertical axis, above the origin, and trends slightly upwards and to the right, fluctuating up and down across the length of the horizontal axis, staying above the line for zooplankton and with a significant downward spike at the year 1998 that falls one third of the way up the vertical axis, comes back up by 1999, and remains fairly constant after that. Figure 1. Relative abundance of plankton over time in the eastern equatorial Pacific Ocean Which of the following observations would best support this alternative hypothesis?

The heterotroph hypothesis of the origin of life states that basic organic building blocks formed from inorganic molecules under the primitive conditions present early in Earth’s development. These building blocks combined to form polymers, such as crude proteins. Dr. Sidney Fox wished to add to the heterotroph hypothesis of the origin of life by synthesizing simple proteins from a mixture of amino acids. Which statement below best states an alternative hypothesis Fox could have used to frame his research?

Zebra mussels are an invasive species that has become widely established throughout the United States. Figure 1 shows the percent change in the population sizes of selected groups of organisms in the Hudson River since the introduction of zebra mussels. In this study chlorophyll-containing bacteria are considered phytoplankton and all other bacteria are considered bacterioplankton. The bars are labeled along the horizontal axis as follows: Phytoplankton, Native Mussels, Zooplankton, Open Water Fish, Bacterioplankton, Shoreline Bottom Animals, Shoreline Fish. Each bar belongs to one of two categories: Open Water Habitat, or Shoreline Habitat. The vertical axis is labeled Change After Zebra Mussel Invasion, in percent, and the numbers negative 100 through positive 150, in increments of 50, are indicated. Each bar is described as follows. Note that all values are approximate. Phytoplankton. Negative 80 percent, Open Water Habitat. Native Mussels. Negative 75 percent, Open Water Habitat. Zooplankton. Negative 74 percent, Open Water Habitat. Open Water Fish. Negative 26 percent, Open Water Habitat. Bacterioplankton. 48 percent, Open Water Habitat. Shoreline Bottom Animals. 24 percent, Shoreline Habitat. Shoreline Fish. 98 percent, Shoreline Habitat. Figure 1. Change in biomass of selected Hudson River organisms after the introduction of zebra mussels Which of the following hypotheses about the effect of zebra mussels on the Hudson River community is best supported by the data in Figure 1?

Phenotype is determined, in part, by which genes are expressed. The diagram below illustrates how the product of gene X regulates the expression of other genes. At the top of the figure is a rectangle in which the middle 60 percent is unshaded, and each end is shaded. The rectangle is labeled “Gene X.” An arrow points from Gene X to a squiggly line with an arrowhead labeled “3 prime” at one end. The other end of the line is labeled “5 prime.” Another arrow leads from the squiggly line to a coiled line labeled “Protein X.” Shown below Protein X are four rectangles, each of which is unshaded in the middle and shaded at each end. From left to right, the rectangles are labeled “Gene 1,” “Gene 2,” “Gene 3,” and “Gene 4”. Arrows point from Protein X to Gene 1, Gene 2, and Gene 4, and the Protein X symbol is superimposed on the left shaded area of Gene 1, Gene 2, and Gene 4. Arrows point from Gene 1, Gene 2, and Gene 4 to squiggly lines below each of the genes. Each of the squiggly lines has an arrowhead labeled “3 prime” at one end. The other end of each line is labeled “5 prime.” Nothing is present below the rectangle labeled Gene 3. Which of the following statements best explains how protein X regulates gene expression?

One of the oldest known mammalian fossils belongs to a small furry species, Hadrocodium wui, that lived 195 million years ago. For the following 100 million years, only a small number of groups of mammalian fossils are found in the fossil record. By 65 million years ago, the non-avian dinosaurs were extinct. By 55 million years ago, there were 130 mammal genera, including 4,000 different species that occupied a wide variety of habitats. Which of the following best describes the cause of the rapid increase in the number of mammalian species between 65 and 55 million years ago?

A model that represents a process occurring in a cell of a particular organism is shown in Figure 1. where the two strands in the middle portion of the helix have separated from each other. Twelve bases are indicated on each of the two strands. Seven complementary bases, with the sequence A U G A U C U, are shown bound to the bottom of the two DNA strands, starting from the left end of the strand. An arrow above the seven bases points from left to right. Figure 1. Process occurring in a cell Which of the following correctly explains the process shown in Figure 1?

A researcher hypothesizes that RNA molecules were present in the most recent common ancestor of all living Which of the following scientific questions would best test the hypothesis?

Over many generations, two populations of the same species can diverge into separate species through reproductive isolation. The figures below represent a model of speciation and show the results of matings between individuals from two diverging populations at four different stages of speciation. The males represented in the model are heterogametic, which means they have two different sex-determining chromosomes, (e.g., XY). The females are homogametic, which means they have two similar sex-determining chromosomes, (e.g., XX). The offspring from each mating are labeled interpopulation hybrids. Figure 1 shows the results of a mating between a male and a female from the two populations. In each subsequent figure, the males are from one of the diverging populations and the females are from the other population. The fertility and viability of the offspring from each mating are indicated in the figures. Population 1 males and females are represented by white circles. Population 2 males and females are represented by black circles. Interpopulation Hybrid males and females are represented by circles that are half black and half white. The first row shows a male from population 1 and a female from population 2. The second row shows six Interpopulation Hybrid individuals. From left to right, they are: fertile male, fertile male, fertile female, fertile male, fertile female, fertile female. The first row shows a male from population 1 and a female from population 2. The second row shows six Interpopulation Hybrid individuals. From left to right, they are: infertile male, infertile male, fertile female, infertile male, fertile female, fertile female. The first row shows a male from population 1 and a female from population 2. The second row shows six Interpopulation Hybrid individuals. From left to right, they are: infertile male, infertile male, infertile female, infertile male, infertile female, infertile female. The first row shows a male from population 1 and a female from population 2. The second row shows the words: No Viable Offspring. 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)?

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

Malaria is caused by several different species of Plasmodium, a protozoan parasite. Plasmodium resistance to the common drugs used to treat malaria has increased in recent years. In a scientific study, Plasmodium samples were analyzed in blood drawn from a large number of infected patients before drug treatment and subsequently from the subset of infected patients with drug-resistant Plasmodium. DNA sequences of four different Plasmodium genes thought to be involved in resistance were compared between samples from patients with drug-sensitive Plasmodium and patients with drug-resistant Plasmodium. Which of the following best supports the hypothesis that preexisting mutations confer drug resistance?