BIO 342 Spring 2004 Exam III Name This is a take-home exam. You may work alone or together, with resources or not, using the textbook or website, the library, whatever you feel will improve your answers. However, you may not write your exam onto any pages of your own, and all answers must fit within the spaces provided here. The exam is due no later than Monday at 5 PM. A plant grown from a seed in perlite watered with mineral solution deficient in a particular macronutrient element shows none of the expected symptoms and, in fact, is no different from a control plant watered with a complete mineral solution. What are two fundamentally-different possible/likely reasons for this lack of difference between treatment and control? The apical bud of a plant dies under mineral deficiency. The critical element causing death is: Mobile Immobile The leaf tips of older leaves grown under mineral deficiency show necrotic spots. The deficient element is Mobile Immobile A plant showing necrosis looks: A plant showing chlorosis looks: In cells, Nitrogen is a critical component of: In cells, Phosphorus is a critical component of: Why is it easier to show that a macronutrient is essential than it is to show that a micronutrient is essential? Page 1 of 7
In the graph space at right, plot the relationships between rate of oxygen processing and photon flux for both respiration and photosynthesis in a plant. Label the plot completely and be sure to tell what is happening to the plant at three fundamentally-different photon fluxes. Be sure to label both axes and include units for each! A leaf is placed in a cuvette and its oxygen production is measured as you did in the computer simulation and in laboratory. The instruments indicate oxygen evolution at 0.5 mg min -1. Assuming complete accuracy of the sensor, do you think it is legitimate to say that the rate of photosynthesis is 0.5 mg O 2 min -1? If not, is the true photosynthetic rate higher or lower than that? Explain! A leaf is placed in a cuvette and its oxygen production is measured as you did in the computer simulation and in laboratory. The gas in the cuvette is changed from typical atmospheric air to pure air (no carbon dioxide). Will the rate of photosynthesis increase or decrease--to what rate? Explain your prediction completely! In the remaining space, list the differences between RuBP carboxylase/oxygenase and PEP carboxylase. Page 2 of 7
In the space below, write a short essay about the process(es) providing organic material to mitochondria for the Kreb s (TCA, citric acid) cycle. Page 3 of 7
A tiny seed that you used in laboratory was from wild tobacco (Nicotiana sylvestris). This seed is so small, it makes you wonder how it can have any nutrition for the embryo. In the space below, tell what you speculate to be the storage material, where it would be stored within the cells of the seeds, and then describe how the embryo will convert that storage material into new cell walls as the embryo starts to grow. Page 4 of 7
The seeds of peaches contain cyanide. Explain why this chemical is found in the seed, how it is adaptive for the peach, include the mechanism of its adaptive action, and then tell how the peach embryo is able to germinate given its presence. In laboratory you observed the effect of Gibberellic Acid (GA) on dwarf pea plants. This chemical is roughly similar to steroids. Tell how this chemical might signal a cell to grow. In your pea plants, which cells responded? Given the response of those cells, how would you predict their cellulose microfibrils are oriented prior to growth. Then explain how you would expect to find the orientation of the microtubules in those cells. Page 5 of 7
Explain how phytochrome exists in two forms and how these forms are related to each other. Provide an absorption spectrum for them. Then describe which one is physiologically active, and what we know of its mechanism of stimulating the production of a particular protein in a cell. Page 6 of 7
Ross parents planted Chrysanthemum plants (SDP) along their driveway in about 1958. They never flowered in all the years from then until 1973 when Ross took Plant Physiology at the University of Michigan. In the space below, answer the following questions. At what time of year SHOULD these plants have flowered? What was the cause of the flowering failure? What were the possible solutions that Ross should have suggested to his parents to cover all the bases (hint: we may not have considered all of them in class THINK!)? What was the final solution that his parents accepted? What were the problems with each of the other possible solutions? Page 7 of 7