1. Two populations of a species of squirrel are geographically isolated from each other. Although they have the same population density, one population is significantly larger in number than the other. A new bacterial disease, which is easily spread and extremely virulent, affects both populations at the same time. Which of the following is the best prediction of how the new disease will affect the two populations?
(A) The two populations will be equally affected, because the ability to trigger an immune response is randomly distributed among all squirrels of that species.
(B) The larger population will be less affected by the disease than will the smaller population, because the mutation rate of the larger population is higher than the mutation rate of the smaller population.
(C) The smaller population will be more affected than will the larger population, because the smaller population has less genetic variation than the larger population has.
(D) The smaller population will be less affected than will the larger population, because the smaller population exhibits more genetic drift than the larger population exhibits.
2. 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?
(A) The mitochondrion is the only location in which eukaryotic cells can synthesize ATP.
(B) An ancestral cell most likely engulfed an aerobic prokaryote in a relationship that proved beneficial for both cells.
(C) Mitochondrial membranes provide abundant surface area for reactions because of the infoldings called cristae.
(D) The mitochondrion plays a role in respiration, but it also stores the cell’s extra mRNA.
3. 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
4. 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?
(A) Without natural herbivores or competitors, C. taxifolia will grow rapidly and crowd out native species of producers.
(B) C. taxifolia will have a hard time establishing itself because it will have to compete against native species of sea grasses, which are better adapted to the environment.
(C) C. taxifolia will grow rapidly, leading to an increase in the diversity of producers.
(D) Because it is not in the Indian Ocean, its natural environment, C. taxifolia will not be able to grow efficiently.
1. In an investigation of the effect of a particular insecticide on plant growth and development, researchers established 20 test plots containing mature Haplopappus squarrosus shrubs. H. squarrosus is pollinated by certain species of insects and is eaten by other species of insects. Ten test plots were sprayed with the watersoluble insecticide, and ten test plots were sprayed with water only. The researchers recorded the numbers of plants or plant parts at different life stages in each test plot. The results of the investigation are shown in the table.
(a) Identify the control treatment in the original experiment. Provide reasoning to support the researcher’s decision to not use a set of unsprayed plants as a control.
(b) A student incorrectly plotted one value from the table on a graph (Figure 1). Identify the error in the student-constructed graph. Provide reasoning to support the student’s choice of a logarithmic scale on the Y axis.
(c) Using the template provided, calculate the percent of plants or plant parts remaining from one life stage to the next life stage. Round your answer to one decimal place. Based on your calculations, identify the plant life stage at which the insects have the greatest impact on the life cycle of the plant. Justify your answer. Describe the most likely interaction between the insects and the plants.
(d) In a second experiment, researchers used a different insecticide that affects a different group of insects. In this treatment, the number of seeds formed was greatly reduced compared to the control. Based on this observation, describe the most likely interaction between the affected insects and the plants in this experiment. Justify your response.