If you do not understand the meaning or intention of a question, please sk. Please put away your cell phones, blackberries, ''Pods, laptop computers, etc. , otherwise you will receive a grade of O. Please separate the last sheet from the rest of the exam. Write the answer to only the last question on the last sheet. The last sheet is graded separately from the rest of the exam. Each multiple-choice question is worth 2 points. Note that a correct statement is not necessarily the best answer to a multiple-choice question.
If a question states "Select all that apply'' then select all of the correct choices. For each multiple-choice question write the letter for the best nswer in the space provided (circling your answer, a 0, or an x won''t count). You will receive ZERO credit for any question for which we cannot tell what your final answer is. If you cross out an answer, please be clear as to what your final answer is. Please pace yourself and use your time efficiently; allow time for the essay type questions.
If a question states "Answer either a or b, not both": if you answer both, then we will read only the answer to a, regardless of how much better your answer to b might be. Write your answers using a pen. Answers written using pencils will not be graded. Bonus Points: Write your name and lab section on all sheets. 1 . Populations of frogs, toads, and other amphibians around the world are in dramatic decline with more than a third of the world''s amphibian species threatened with extinction. A number of factors may be involved, and one possible cause may be the effects of agricultural pesticides and herbicides.
Several studies have shown that many of these pesticides and herbicides tested at the concentrations usually found where the amphibians live the University of California at Berkeley looked further into this problem to determine hether these agricultural poisons can affect the amphibians without necessarily killing them. He focused on atrazine, the most widely used herbicide in the world and a common contaminant in fresh water. Every year more than 70 million pounds of atrazine are applied to farmland in the United States alone.
Atrazine is applied to farmland in the spring, when many amphibians are breeding and thousands of tadpoles swim in the ponds and streams that receive runoff from farms, contaminated with atrazine. Total Points: In their laboratory Hayes and his associates looked at tadpoles of leopard frogs, species Rana pipiens. They hatched the eggs and the tadpoles were separated into 6 separate tanks. Three tanks contained water containing no atrazine (O ppb), and three tanks contained water with atrazine (concentration of 0. 1 ppb). ppb = parts per billion.
The tanks were the same size, had the same volume of water, and were kept at the same temperature and light cycle. They placed 30 tadpoles in each tank. After the tadpoles had developed into adults, they evaluated the reproductive tissues of the adults. They looked at the testes of the adult males. They looked for evidence of abnormal development of the testes, which might explain why the populations are eclining. If the testes don''t develop fully, then the male cannot mate, and without reproduction, the population will decline.
If there are eggs (instead of sperm) developing inside the male testes (called testicular oogenesis), this is a significant abnormality that prevents the males from mating also. For each tank they counted the number of the male frogs that showed some kind of testicular abnormality and calculated what proportion of the male frogs was thus affected. There is one measurement per tank (proportion of males with testicular abnormality). Their data are shown in the table below. Proportion of male frogs with testicular abnormalities (%) Concentration of atrazine (ppb) Mean Standard Deviation 3 0. 35 5. 0 a. 2 points: What is the question being asked? Do herbicides such as atrazine cause abnormalities in amphibians such as leopard frogs that might lead to declines in the population? b. 2 points: What is one alternative hypothesis? Atrazine causes testicular abnormalities in male leopard frogs. c. 2 points: What is the null hypothesis for the alternative hypothesis you wrote above? Atrazine does not cause testicular abnormalities in male leopard frogs. d. 2 points: What is the xperimental prediction? If we grow tadpoles of leopard frogs in tanks containing water with 0. ppb Atrazine or no Atrazine, then a higher proportion of the adult males grown in tanks containing water with Atrazine will show testicular abnormalities compared to those grown in tanks containing water with no Atrazine. e. 8 points: Use the data shown in the table above to draw a column graph of the mean ± standard deviation of the proportion of frogs subject to atrazine or no atrazine that had testicular abnormalities. Make sure to label the axes of the graph; include the treatments and the units where appropriate. Make sure to identify the means versus the standard deviations as such. Propor%on of male frogs with tes%cular abnormali%es 25 20 15 10 5 Atrazine Concentra%on (ppb) f. 2 points: What are the independent and dependent variables in this experiment? Independent: Atrazine levels Dependent: Proportion of male frogs with testicular abnormalities g. 2 points: List two (only two, not three or four) standardized variables in this experiment. Ex. Same size tank, same light cycle, etc. h. 2 points: What are the sample sizes and the number of replicates? Sample size: 3 per treatment 1 replicate Remember that the sample is the smallest unit on which you take a measurement. . 2 points: Without doing any statistical tests, do the data look like they support the alternative hypothesis you wrote above? Yes or No? 2. Which of the following results from unequal sharing of electron(s) between atoms? a. hydrophobic interaction b. nonpolar covalent bond d. polar covalent bond e. hydrogen bond Answer: d 3. 6 points: Each of the following three diagrams shows a monomer that can be used to make one of the types of molecules listed below. Write the correct letter (a, b, c, or d) in the space marked "Answer: next to the structure for the monomer. Total a. Nucleic acid b.
Protein c. Polysaccharide d. Lipid Answer: c Answer: b 4. 6 points: Consider the functional groups amino, carbonyl, carboxyl, phosphate, hydroxyl, sulfhydryl, and methyl. On the diagram below circle and label/identify three different functional groups (write the name of the functional group next to each unit you circle). If the molecule has several of the same functional group (for example 3 phosphate groups), then they count as one functional group and you only have to label one of them, but you need to find two other functional groups for a total of 3 ifferent functional groups.
Methyl Hydroxyl Carbonyl 5. The structure shown above has a basic functional group that can accept a H+ and become positively charged. a. True b. False 6. ß-pleated sheets are examples of bonds. a. primary, peptide b. secondary, hydrogen bonds structure of a protein and are formed by c. tertiary, disulfide bonds d. primary, ionic bonds e. secondary, peptide f. tertiary, hydrogen 4 7. 6 points. Answer either a or b, not both: a. Describe the role of the clay particles in the soil and the proton pump in root cells in acquisition of Ca2+ and Mg2+ by plant roots. Clay particles have negative charges.
Ca2+ and Mg2+ tend to stick to clay particles due to the opposite charges. When roots use their proton pumps to pump out H+ to the soil solution, the H+s will displace Ca2+ and Mg2+ from Clay (cation exchange) and release them into the soil solution and the roots can then take up the Ca2+ and Mg2+. b. Explain how nitrate (N03-) in acid rain affects soil fertility as well as toxicity to plants. Nitrate with its negative charge will attract Ca2+ and Mg2+ away from the clay particles and then drag them into the soil solution and they then leach out of the soil long with the nitrate as nitrate drains out of the soil and into the local streams.
This reduces the fertility of the soil. The acid rain also causes Aluminum to become more 8. Select all that apply: An aqueous solution at pH 7 a. has 10 times as many hydrogen ions as a solution at pH 6 b. has 1/10 the number of hydrogen ions as a solution at pH 6 c. has twice as many hydrogen ions as a solution at pH 6 d. has half as many hydrogen ions as a solution at pH 6 e. has equal concentration of hydrogen and hydroxide ions f. has 7 times as many hydrogen ions as hydroxide ions Answer: b and e 9. 6 points.
Answer either a or b, not both: . In response to the problems acid rain has caused for forests three remedies were discussed in the article you reviewed in class. Pick one (liming, wetlands, or pollution reduction) and explain what this remedy will do that would be beneficial and what the limitations of this remedy are. • Liming with Ca and Mg will help to reverse the acidification process and the mineral imbalance in the soil. However, this is not a cure as pollution continues to pour acid rain on the forests.
And, some microbes that can degrade lignin and other carbon structures in the soil are stimulated and begin to break down these ompounds and release C02 into the atmosphere, which is the opposite of what we want a forest to do. Other microbes that turn ammonium into nitrate are also stimulated and thus the nitrate formed can aggravate the leaching of cations such as Ca and Mg from the • Denitrifying bacteria in wetlands will break down nitrates and clean the water of surface springs. This will not solve the problem the trees are facing from acid rain for the following reason.
Wetlands are downstream from the forests. The nitrate and nutrients leaching out of the forest soils enter runoff and reach these wetlands where the bacteria get rid of the itrate and reduce the amount of nitrate that would otherwise enter surface springs. However, this does not do anything for any organism upstream of the wetlands. So, the malnourished forests do not benefit from this process. • As air pollution and acid rain are reduced, there is less nitrate entering the soil, and so less of these essential nutrients will be leached out of the soil.
However, the soil has already lost a large supply of these nutrients throughout the years that acid rain has been falling on these forests. The ions that are lost will not be replenished simply by reducing further pollution and reventing further leaching. So the malnourished forests are not being cured of their malnutrition. b. Consider the study performed by Hamburg et al. 2003 to determine whether the developmental stage and age of forests affect availability of calcium in the forest or whether the dominant effect is due to the acid rain that is falling on all of these forests.
These forests Total 6 are growing on similar soils in NH under similar conditions. What do the data in Figures 1 A and B tell us about calcium levels in forests of different age, and any changes over time for these forests? Explain. The data tell us that the calcium content of snails per m2 trap (Figure IA) increased over the 18 year interval in younger stands but decreased over the 18 year interval in older stands. Also, the highest levels were in the youngest stands and the lowest levels were in the older stands.
The data in Figure 1B tell us that the concentrations stands. Also, the data tell us that the concentrations of Ca in the forest floor increased over the 18 year time period in the younger stands but decreased over the 18 year time period in the older stands. 10. Select all that apply: All of the following ay be part of a prokaryotic cell except a. Golgi apparatus b. DNA c. pili d. plasma membrane e. ribosomes f. mitochondria Answer: a and f 1 1 . Select all that apply: Study of carbon deposits formed around 3. billion years ago suggests that there was probably life on earth back then because a. 13C is discriminated against by enzymes but not by inorganic reactions b. 12C is discriminated against by enzymes but not by inorganic reactions c. these deposits have a higher 12C : 13C ratio than older deposits d. these deposits have a higher 13C : 12C ratio than older deposits e. these deposits lack 12C f. hese deposits lack 13C Answer: a and c 12. Select all that apply: The seeding hypothesis a. Relates to how plants spread their seeds through dispersal by animal vectors b.
Explains that plants produce too many seeds that cannot be supported by the environment c. Relates to how meteorites may have brought certain microorganisms to earth d. Says the same thing as the hypothesis of biogenesis about origin of life e. Suggests some compounds such as amino acids may have been brought from outer space Answer: c and e 13. The mass number of an element can be easily approximated by adding together the number of n an atom of that element. a. protons and neutrons b. energy levels c. protons and electrons d. neutrons and electrons e. sotopes 7 Answer: a 14. What kind of chemical bond is involved in forming the primary structure of a protein? a. Hydrogen b. Ionic c. Covalent d. Van der Waals 15. Eukaryotic flagella lack the 9+2 microtubule structure found in bacterial flagella. 16. Select all that apply: Which of the following are present in both typical plant cells and typical animal cells? a. Mitochondria b. Chloroplasts c. Ribosomes d. Cell walls 17. (10 points) Compare and contrast the explanations provided for the origin of hloroplasts (from what did chloroplasts arise? in the theory of Autogeny as proposed by Taylor versus the Serial Endosymbiotic Theory as proposed by Margulis. Describe ONE piece of evidence that supports Margulis'' hypothesis and does not support Autogeny. According to autogeny, chloroplasts evolved from compartmentalization of part of the ancestral cell. The original ancestral cell was a photosynthetic bacterium with a complex system of membranes. As the cell compartmentalized, sections of the membranes broke away to form separate compartments, trapping small pieces of DNA and ribosomes inside.
The different compartments became specialized to accomplish specific tasks, including photosynthesis in the compartments we now call chloroplasts. According to SET, chloroplasts evolved from free-living photosynthetic bacteria. After the evolution of mitochondria, the aerobic cell with its mitochondria that carried out oxidative respiration could develop higher metabolic rates and be more efficient and grow larger and become predatory, and eventually in some lineages may have ingested without digesting some photosynthetic bacteria, which led to the evolution of hloroplasts in some but not all lineages of eukaryotes.
Example piece of evidence: DNA in chloroplasts and mitochondria is similar in structure to single circular chromosomes of bacteria. Supports the idea that the chloroplasts and mitochondria are derived from bacteria as Margulis suggests and that is why they have bacterial type DNA, but not the idea that the DNA is from the same original cell but got trapped in the organelle during compartmentalization as Taylor suggests. If that were the case, why would the nuclear and organellar DNA pieces be different from each other? Total
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