Planning Time------10 minutes
Writing Time------80 minutes
Directions: Questions 1 and 2 are long free-response questions that require about 22 minutes each to answer and are worth 10 points each. Questions 3–8 are short free-response questions that require about 6 minutes each to answer. Questions 3–5 are worth 4 points each and questions 6–8 are worth 3 points each.
Read each question carefully and completely. Write your response in the space provided for each question. Only material written in the space provided will be scored. Answers must be written out in paragraph form. Outlines, bulleted lists, or diagrams alone are not acceptable.
1.Trichomes are hairlike outgrowths of the epidermis of plants that are thought to provide protection against beingeaten by herbivores (herbivory). In a certain plant species, stem trichome density is genetically determined.
To investigate variation in stem trichome density within the plant species, a student counted the number oftrichomes on the stems of six plants in each of three different populations. The student used the data to calculatethe mean trichome density (numbers of hairs per square centimeter) for each population. The results are providedin the table below.
(a) On the axes provided, create an appropriately labeled graph to illustrate the sample means of the three populations to within 95% confidence (i.e., sample mean±2 SEM).
(b) Based on the sample means and standard errors of the means, identify the two populations that are most likely to have statistically significant differences in the mean stem trichome densities. Justify your response.
(c) Describe the independent and dependent variables and a control treatment for an experiment to test the hypothesis that higher trichome density in plants is selected for in the presence of herbivores. Identify an appropriate duration of the experiment to ensure that natural selection is measured, and predict the experimental results that would support the hypothesis.
2. Mammalian milk contains antibodies that are produced by the mother’s immune system and passed to offspring during feeding. Mammalian milk also contains a sugar (lactose) and may contain proteins (protein A, protein B, and casein), as indicated in the table.
(a) Using the data in the table, construct a cladogram on the template provided to indicate the most likely evolutionary relationships among the different mammals. Indicate on the cladogram where each of thecharacters most likely arose in the evolutionary process, and justify the placement of the characters on the cladogram.
(b) Describe FOUR steps in the activation of the mother’s specific immune response following exposure to a bacterial pathogen. Predict how the mother’s immune response would differ upon a second exposure to the same bacterial pathogen a year later.
Plus symbol indicates the presence of character, and minus absence character. Plus symbol indicates the presence of character, and minus absence character. Plus symbol indicates the presence of character, and minus absence character. Plus symbol indicates the presence of character, and minus absence character. Plus symbol indicates the presence of character, and minus absence character. Plus symbol indicates the presence of character, and minus absence character.
(c) Predict the most likely consequence for a nursing infant who is exposed to an intestinal bacterial pathogen (e.g., Salmonella) to which the mother was exposed three months earlier. Justify your prediction.
3. As part of a new suburban development, a sports complex consisting of athletic fields and buildings is constructed in a formerly wooded area.
(a) Predict ONE ecological consequence on the local plant community that is likely to result during the site preparation and construction of the sports complex. Justify your prediction.
(b) To maintain the playing fields, large quantities of water and chemicals are applied regularly to the grass-covered areas. Predict ONE effect on the local animal community that might result from regular use and maintenance of the playing fields. Justify your prediction.
4. Adult male guppies (Poecilia reticulata) exhibit genetically determined spots, while juvenile and adult female guppies lack spots. In a study of selection, male and female guppies from genetically diverse populations were collected from different mountain streams and placed together in an isolated environment containing no predators.The study population was maintained for several generations in the isolated area before being separated into two groups. One group was moved to an artificial pond containing a fish predator, while a second group was moved to an artificial pond containing no predators. The two groups went through several generations in their new environments. At different times during the experiment, the mean number of spots per adult male guppy was determined as shown in the figure below. Vertical bars in the figure represent two standard errors of the mean (SEM).
(a) Describe the change in genetic variation in the population between 0 and 6 months and provide reasoning for your description based on the means and SEM.
(b) Propose ONE type of mating behavior that could have resulted in the observed change in the number of spots per adult male guppy between 6 and 20 months in the absence of the predator.
(c) Propose an evolutionary mechanism that explains the change in average number of spots between 6 and 20 months in the presence of the predator.
5. Genetically modified crops have been developed that produce a protein that makes the plants resistant to insect pests. Other genetic modifications make the crops more resistant to chemicals that kill plants (herbicides).
(a) Describe TWO potential biological risks of large-scale cultivation and use of such genetically modified plants.
(b) For each of the risks you described in part (a), propose a practical approach for reducing the risk.