Midterm Second - BioSci 1C (Winter, 2006). Test form A Use: SCANTRON FORM NO. UCD 2000 Please read these instructions:
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1) Do not start the test until instructed to do so. These instructions, of course, are not actually part of the test, so you can go ahead and read them... I mean, they are sort-of part of the test, but not the important part... I mean, OK, so they are like, important, but not, like, test important, right? So, anyway.....
(We apologize for the previous segue into Valley speak, those responsible for this have been sacked.)
2) While you are waiting, fill in the following on your SCANTRON: - Write your name in the box labeled "NAME" (...am I going too fast for anybody?) - Put your student ID number in the ID number box - Fill in the bubbles corresponding to the digits in your ID number - Fill in the bubble for TEST FORM "A" 3) Be sure to close all backpacks/briefcases, remove all material except this test and the scantron (and, of course, pencil and eraser) from your desk, and if you want to wear a hat, turn it backwards (scientific research has shown that the presence of a hat causes a slight, but statistically significant reduction in blood flow to the brain, which may reduce your exam performance; but in a recent interview with Jerry Springer, a reliable source has claimed that turning the hat backwards will actually enhance the flow of positive cosmic forces to your brain, more than compensating for any negative effect, and this is our basis for requiring this orientation) This midterm will account for 25% of your class grade. Important: there are 3 pages at the end of the test, a gripe sheet and 2 short answer pages, with the point value for each short answer question indicated. The short answer pages must be turned in. Fill in your name at the top of the short answer pages, and hand them in along with your scantron form. The "gripe sheet" is for part 1 only - not just for any kind of gripes, but if there is any question in part 1 which you think is not clear, and want to explain your reasoning for the answer(s) that you chose, then this is the place to do it. There is no gripe sheet for the short answers because you should be explaining your reasoning as part of the short answer! If you have gripes, fill in your name at the top of the gripe sheet, and hand it in along with the scantron form. If we think your interpretation of the question and your answer to it are valid, then you will get credit. We suggest that you mark your answers on both the test and the scantron, and keep the test for your records. You should keep the test because we will be sending out the correct answers via email right after the exam, and you can check your answers against that, and also, you never know. You could become a famous scientist some day, and as part of your memorabilia, an old botany test could be worth something.... OK, so it's a long shot.
Second Midterm - BioSci 1C (Winter, 2006)
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1. Gametangia of algae are X. Because gametes are produced by the Y process of cell division, the ploidy (that is, chromosome number) of the cells of the gametangia that produce gametes is Z. The choices for X, Y and Z that make the statement above correct are: : a. X = specialized structures where gametes are formed, Y = meiosis and Z = n . b. X = specialized structures where gametes are formed, Y = mitosis Z = n. c. X = specialized structures where gametes are formed Y = mitosis and Z = 2n. d. X = specialized structures where gametes are formed, Y =meiosis and Z = 2n. e. This is a trick question. Gametangia are specialized structures where gametes are formed but there are no gametangia in algae. 2. While fungal cells have cell walls, their walls are different from those of higher plants because they lack cellulose. Instead of having cellulose as the primary structural component of their cell walls, fungal wall contain __X__, which is also an important component of the supporting structures of __Y__. This latter fact is often used by researchers who study the evolutionary relationships between fungi and other major groups of organisms. X and Y are: a. X= peptidoglycan , Y= Bacteria . b. X= chitin , Y= Protists c. X= endosymbionin , Y= Cyanobacteria . d. X= peptidoglycan , Y= Cyanobacteria. e. X= chitin, Y= Insects . 3. Even though the brown algae are not on the line of evolution that led to the true plants they have evolved specialized cells called trumpet cells that are a bit like the sieve cells of higher plants. Trumpet cells contain structures that look like sieve plates and are involved in the transport of sugar from the site of photosynthesis in the algal blades to important sink tissues that are well below the water's surface. The appearance of cells that look like food-conducting phloem cells in an organism that is off of the line of evolution to the higher plants is interpreted as an example of a. art imitating life b. cytomorphometry c. heterogamy d. evolutionary mimicry e. convergent evolution 4. When fungi are carrying out sexual reproduction, at one time or another an X nuclear condition is found in cells that have carried out the process of Y. The choices for X and Y that make this sentence correct are: a. X = n+n and Y = mitosis. b. X = 2n and Y = meiosis c. X = n+n and Y = plasmogamy d. X = heterokaryon and Y = karyogamy e. a and d are correct 5. In plant hormone biology, adding a methyl group to a hormone molecule's carboxyl function to make a methyl ester is important because a. esters smell good and this will attract pollinators to the voodoo lily that has grown up through the snow b. it converts jasmonic acid to a volatile form c. it converts volatile ethylene to a non-volatile form d. All of the above e. b and c
Second Midterm - BioSci 1C (Winter, 2006)
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6. The spores that are involved in asexual reproduction in fungi have the X chromosome number and are produced by the cell division process known as Y. The choices for X and Y that make this sentence correct are: a. X = n and Y = meiosis . b. X = n and Y = mitosis c. X = 2n and Y = meiosis d. X = 2n and Y = mitosis e. This is a trick question. All fungal spores are part of sexual reproduction events. You get a uniform batch of dwarf pea seeds (all the same variety), measure the dry weight of some representative seeds, and then grow the rest at different temperatures. At the end of 2 weeks you measure the total dry weight of your plants (including cotyledons, if present), and find the following: Initial seed dry weight = 1 g per seed (assume this represents the initial weight of all seeds used) Temperature (C) Final plant dry weight (g per plant) 5 0.5 10 4.3 15 8.7 20 9.2 25 5.5 30 2.8 40 (All dead)
7. Assuming that all other important environmental conditions (light, CO2, etc.,) were held constant, based on these data, and for this variety of dwarf peas, you could say: a. the plants were only under a condition of stress at 5C and 40C (low and high temperature stress) because a net growth occurred at all other temperatures b. temperature stress occurred at all temperatures except 20C c. temperature stress cannot be determined from these data because leaf photosynthesis was not measured d. the plants were only under a condition of stress at 40C (high temperature stress) because all other plants survived 8. How is it possible that the plants at 5C had less dry weight than when they started as seeds? a. at 5C the soil was too cold for the roots to take up water, so the plant desiccated b. cotyledon carbohydrate was used to support the growth and respiration of the seedling c. at 5C the air was too cold for any photosynthesis to occur d. a. and c. e none of the above 9. If rain or irrigation does not replace the soil water that plants transpire, then the soil will progressively dry out and the plants in that soil will typically respond to the drying by: a. opening the stomata to fix more CO2 and to prevent the leaves from overheating b. closing the stomata to restrict water loss c. changing sun leaves into shade leaves d. a. and c. e. b. and c. 10. The structure that allows a large kelp to remain anchored in place on the ocean floor near the shore is called a/an: a. Velcro pad b. air bladder. c. holdfast d. stipe e. slime layer
Second Midterm - BioSci 1C (Winter, 2006)
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11. Studies of plant developmental events often include attempts to determine where (that is, in what cells) particularly important molecules that control development are found. Choose the correct choices (1, 2, and 3) to fill the blanks in the following sentence and make it correct: By using a technique called _1_, developmental biologists use specific _2_ to locate specific _3_ in cells. a. 1 = cytomorphometry, 2 = plant hormones, 3 = genes. b. 1 = in situ hybridization, 2 = tagged complementary nucleic acids, 3 = mRNAs. c. 1 = immunolocalization, 2 = antibodies, 3 = proteins. d. All of the above are correct e. b and c are correct 12. At the light compensation point, what is "compensating" for what? a. CO2 uptake is compensating for H2O loss b. stomatal opening is compensating for guard cell closure c. the light dependent reactions are compensating for the light independent reactions d. light-driven CO2 uptake is compensating for respiratory CO2 loss 13. Tropisms are a. increases in plant photosynthesis involving light "perception" by chlorophyll b. responses to environmental stimuli that involve differential rates of growth on opposite sides of a stem or root c. seed germination stimulated by abscisic acid (ABA) d. All of the above e. a and c 14. When a cell differentiates it takes on specialized form in order to carry out specific functions. Which of the following statements about the processes associated with cellular differentiation is/are to likely be true? a. The transcription of some genes may be turned on in the cell that is becoming specialized. b. New proteins may be produced in the cell that is becoming specialized. c. The transcription of some genes may be turned off in the cell that is becoming specialized. d. All of the above. e. a and c 15. A chemolithoautotrophic organism: a. uses light energy to make carbohydrates from CO2 b. uses chemical energy to make CO2 from carbohydrates c. obtains energy by oxidizing inorganic compounds d. makes carbohydrates from CO2 e. c. and d. 16. The so-called "Wilty" mutants of tomato plants and corn plants can be identified because their leaves wilt when plants are exposed to mild water stress. The leaves wilt because the mutants can't produce the hormone __X __ and, as a result the plant can't make __Y__ happen. X and Y are: a. X = Gibberellin , Y= opening of stomata b. X= ABA Y= closing of stomata c. X= Gibberellin, Y= production of additional root hairs d. X= Auxin , Y= loss of guard cell turgor e. b and d
Second Midterm - BioSci 1C (Winter, 2006)
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17. Red algae are often found anchored to the ocean floor in the neritic zone. What adaptation makes it possible for the red algae to carry out photosynthesis in this low light environment? a. Red algae have pigments that allow them to "harvest" the energy in the high energy red light that is able to penetrate through substantial depths of water. b. Red algae use air bladders that contain particularly high concentrations of CO2. The high CO2 concentrations mean that RUBISCO can function at very high efficiency, thus photosynthesis in red algae produces a great deal of sugar in spite of the weak light c. Red algae have pigments that allow them to "harvest" the energy in the high energy green and blue light that is able to penetrate through substantial depths of water. d. a and b are correct. e. b and c are correct. 18. Streptomycin is a broad spectrum antibiotic against bacteria because: a. it interferes with the bacterial 80s ribosome b. it interferes with the assembly of chitin into the bacterial cell wall c. it interferes with the bacterial 70s ribosome d. it interferes with the bacterial plasma membrane 19. Diatoms and Dinoflagellates are both "planktonic," which means that: a. they are green, photosynthetic organisms b. they are composed of small wooden planks c. they are carried passively by water currents d. none of the above 20. The stem-like structures of mosses are called X. These structures cannot be called stems because their waterconducting cells are not Y. The correct identities for X and Y are: a. X = caulids and Y = hydroids. b. X = phyllids and Y = stomata. c. X = caulids and Y = true vascular elements. d. X = phyllids and Y = hydroids. e. X = hydroids and Y = true vascular tissues 21. Important adaptations for water management and conservation that are first seen in the Bryophytes include: a. cuticles b. stomata c. water-conducting hydroids with lignin-reinforced cell walls d. All of the above e. a and b
Second Midterm - BioSci 1C (Winter, 2006)
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22. A plant growing under high light conditions will typically develop thicker leaves with higher maximum rates of photosynthesis than would be developed on the same plant if it were growing under low light conditions. The change from one leaf type to another in response to the environment is an example of: a. Acclimation b. Adaptation c. Evolution d. Symbiosis 23. Life is never simple. In the above question, the leaves that produce the benefits of a high rate of photosynthesis in high light also carry with them a cost or costs. That cost is (those costs are): a. a high rate of carbon supply to the plant b. a high light compensation point c. a low rate of respiration in the dark d. all of the above e. none of the above 24. The gametophores of mosses and the sporangiophores of fungi both serve to raise important reproductive structures above the soil surface. Which of the statements about gametophores and sporangiophores below is/are not correct? a. both are involved in processes of asexual reproduction b. the important reproductive structures supported by gametophores and sporangiophores are both structures in which meiotic cell divisions occur c. the important reproductive structures supported by gametophores and sporangiophores are locations where gametes are produced d. All of the statements above are not correct. e. a and c are incorrect. 25. The gametangia of mosses in which sperm cells are produced are called a. antheridia b. spermatagonia c. archegonia d. calyptria e. This is a trick question. Mosses do not have gametangia.
Second Midterm - BioSci 1C (Winter, 2006)
PART 2 (short answer): Tear off these sheets and turn them in with your scantron form Your Name _________Key______________
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Your TA's Name ______________________
Short Answer Scores 1. 2. 3. 4.
1. (5 points) Illustrated below is a simplified diagram of the biosynthesis of growthpromoting gibberrellin in pea plants. A, B, C, and D are molecules similar in structure to E and assume that E is the only form of gibberrellin that will actually cause pea plant cells to elongate. The arrows between A, B, C, D and E represent the enzymes that convert A to B, B to C etc. In the genetic line of pea plants that you are working with the plants are short and the enzyme (arrow) required to convert C to D is mutated. Describe the test you would do to show that this particular enzyme is the one that is defective. Assume that you have samples of A, B, C, D and E available for use in your experiment.
A --> B --> C --> D --> E If the mutation that makes the plants short is in the enzyme that converts intermediate C into intermediate D, the dwarf plants should remain dwarf (i.e., not grow) when treated with A, B or C. For isolating the C to D enzyme as the crucial step, the experiment should be: Add some C to the dwarf plants. They should not grow. Add some D to the dwarf plants. They should grow. It would be nice if they gave some explanation such as the dwarf plants probably have a functional enzyme for D to E conversion, and so they convert added D to E and then grow in response to the added E. However, the question does not ask for an explanation. 2. (5 points) Draw a simple sketch illustrating a general life cycle of an organism having alternation of generations. Identify the points at which meiosis and mitosis occur. Indicate the points at which spores and gametes are produced. Indicate the general name given to the plants that produce gametes and spores. Show where fertilization occurs and where the zygote is produced. Identify the ploidy of each of the parts of the cycle that have been indicated above, in bold. This figure includes more than is required for the answer. The answer should identify Gametophyte, Sporophyte, Spores, and Gametes and identify the ploidy of each. The locations of these in the cycle should be given and the points at which meiosis, mitosis, fertilization/zygote formation occur should also be shown.
Second Midterm - BioSci 1C (Winter, 2006)
PART 2 (short answer): Tear off these sheets and turn them in with your scantron form Your Name _________Key______________
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Your TA's Name ______________________
3. (5 points) C3, C4, and CAM represent three contrasting pathways for CO2 to get fixed in plants, two of these pathways involve what you might call a "temporary fixation" step, one being temporary in location, the other being temporary in time. One of the pathways also involves a substantial change in the daily pattern of gas exchange between the plant and the atmosphere, compared to the other two. In the space below, describe each of these pathways in words (not diagrams), explaining what is meant by "temporary" versus "permanent" fixation, and how this relates to the daily pattern of gas exchange. C3: Stomata are open during the day and CO2 is fixed permanently (by RUBISCO) right away, so CO2 is fixed as it is taken up. C4: Stomata are open during the day, but CO2 is fixed temporarily in the mesophyll cells, then transported to the bundle sheath cells where it is released (`un-fixed') and then fixed permanently in the C3 pathway. CO2 is fixed as it is taken up. CAM: Stomata are open at night and CO2 is fixed temporarily. During the day it is released (in the same cells) and fixed permanently in the C3 pathway. CO2 is taken up at night, but fixed (permanently) during the day. 4. (5 points) . Following is a table of net photosynthesis data for 2 leaves collected from the same plant, where positive values of net photosynthesis indicate that CO2 is being taken up and negative values indicate that CO2 is being lost. Light intensity Net leaf photosynthesis (mg CO2 m-2 s-1) (% of full sunlight) Leaf #1 Leaf #2 0% (dark) -0.2 -0.5 10% +0.5 0.0 20% +1.0 +0.8 30% +1.5 +1.5 40% +1.5 +2.0 50% +1.5 +2.5 80% +1.5 +2.5 100% +1.5 +2.5 Based on these data, please answer the following: 4a. Define "low light stress" for photosynthesis, and indicate when that stress begins for each of the 2 leaves. Low light stress means any light level where the job (photosynthesis) is less than the maximum, so anything lower than 30% for leaf #1 and lower than 50% for leaf #2. 4b. If these leaves were both healthy, but just collected from different positions in a tree canopy, where do you think they each came from, and what is/are the reason(s) for your choice? Leaf #1 has less dark respiration but also less maximal photosynthesis than leaf #2, so leaf #1 would be typical of a shade leaf whereas leaf #2 would be typical of a sun leaf. Hence leaf #1 probably came from a shaded area (maybe interior of the canopy) and leaf #2 from the outer/upper part of the canopy.