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Mid-Term Exam, ECOL 340, March 8th 2007 This exam is 25% of your class grade or 250 points. Name________________________________________________ (1) Matching (14.4% of point total) 36 points ____Calyx ____Seed Plants ____Clade ____Cooksonia ____Origination rate A. Sugar Maple B. Oaks C. All organisms that share a common ancestor D. Autopolyploidy E. Early ‘experimental’ reproductive structures of gymnosperms. No longer present. ____Ring Porous F. Archegonium has been reduced and is absent ____Diffuse Porous G. Change in gene frequencies in a population ____Sympatric speciation H. First recognizable Embryophyte from fossil record ____Allopatric speciation I. Restriction of gene flow between populations due to a physical barrier ____Archegonia J. ‘Jacket’ of cells surrounding developing zygote ____Pollen grain K. Immature microgametophyte ____Angiosperms L. Chromosome duplication ____Salpinx M. Together with extinction important for influencing standing stocks of diversity. ____Heterospory N. All sepals ____Strobili O. Ovary ____An integumented megasporangium P. Reproductive structures that contain a high concentration of sporangia ____Polyploidy Q. Retain megaspores within their megasporangia ____Evolution R. Evolved independently in the microphyll and megaphyll lines of evolution N,Q,C,H,M,B,A,D,I,J,K,F,E,R,P,O,L,G (2) Names (7.2% of point total) 18 points ____Plank ____G.G. Simpson ____G.L. Stebbins ____R. Fisher ____S. Wright ____Dixon ____V. Grant ____C. Darwin ____ Malthus A. Concept of the ‘fitness landscape’ B. Evolution of Angiosperms is an “abominable mystery” C. Cohesion Tension Theory D. Fundamental Theorum of Natural Selection E. Only Botanist in the Evolutionary Synthesis F. Hybrid speciation G. Essay on “the principle of the population” H. Important in the Evolutionary Synthesis I. Light can be particle like (quanta). Energy in quanta is proportional to the wavelength I,H, E, D, A, C, F, B, G, 1 Short Answer (16% of point total) 40 points 4 POINTS (3) The earliest vascular plants diverged into two major lines of tracheophyte evolution. What were the names of these two **initial** lines of tracheophyte evolution? B and C a) Rhyniophyta b) Zosterophylophyta c) Trimerophytophyta d) Lycophyta e) Progymnospermata 3 POINT EACH – For #4-6 (4) The following five statements refer to the Rosids and the Asterids, as presented in class. Which statement is not true. B (a) species with a tubular corolla can be found in either clade. (b) the Rosid clade is the more primitive of the two. (c) triaperturate pollen can be found in either clade. (d) they possess double fertilization. (e) alkaloid secondary compounds can be found in either clade (5) Seed plants and Progymnosperms share a common ancestor within this ancient group of land plants. A (a) Rhyniophyta ; (b) Zosterophylophytes; (c) Archiofructus; (d) Lycophyta (6) Enations are an example of – C (a) a megaphyll, (b) a trait associated with the seed plants, (c) differing ways of evolving leaf-like structures, (d) plays an important role in the reproduction of the sporophyte, (e) none of the above 5 POINTS (7) List the following groups in order of the number of extant species (e.g. 1 = most diverse, 5 = least diverse) _2_Bryophytes, _3_Pteridophytes, _1_Angiosperms, _4_Gymnosperms, _5_Zosterophylophytes 2 4 POINTS (8) Describe in at least three sentences what the (i) Antenna and the (ii) Reaction Center is and what it does. Also, use a simple drawing to also help you answer the question. The antenna complex consists of Many chlorophyll molecules that ‘harvest’ light energy and then channels the excitation energy to the Reaction center. The RC is a special pair of chloropyll molecules that transfer excited electron to acceptor molecule. The arrangement of the antenna and reaction center is spatial with several light harvesting antenna arranged around a reaction center. 6 POINTS (9) List three plant taxa that dominated Carboniferous forests (hint Fossil Fuel!) Here are five acceptable taxa – Lycophytes (club mosses), Spenophytes (Horsetails), Pteridophytes (ferns), Progymnosperms, Eary seed plants 3 POINTS EACH (#10-13) (10) What is the currently accepted date for the first appearance of photosynthesis? ~3.6 billion years (plus or minus 0.5 billion) (11) What is the currently accepted date for the first appearance of land plants? ~430 millioin years ago (plus or minus 50 million) (12) What is the currently accepted date for the first appearance of Angiosperms? ~140 million years ago (plus or minus 30 million) (13) The gametophyte generation retains its eggs and juvenile diploid embryos within the ____ Archegonium ____ Longer Answer (24% of point total) 60 points (14) Outline the essential 6 steps for Evolution by Natural Selection to occur 12 POINTS 1-many offspring or potential for exponential growth 2-competition for space and resources 3-offspring differ in their ability to compete and obtain resources 4-differential survival/reproduction 5-variation in heritable 6-mean phenotype (genotype) of next generation has changed 3 (15) List three main functions of photosystems I and II? 6 POINTS HERE -stealing electrons -capturing light energy -producing high energy compounds -producing proton gradient to produce ATP (16) List three major trends associated with the basic land plant life-cycle (Hint, think changes that have occurred from the life-cycle of a typical Green Algae). 6 POINTS i) Reduction in size of the gametophytic portion of the life cycle ii) Elaboration in size of the sporophytic portion of the life-cycle iii) Less reliance on water for dispersal of spores and male gametes (17) During class many examples of convergent evolution were given. List 3 likely (and differing) examples of convergent evolution within land plants. 6 POINTS There are many potentially correct answers . . Here are a few - Succulent growth form (Aloe a Monocot and cactaceae a Carophylaceae) - Petal-like structureCaryophylaceae - Fused tubular flower (18) List the three ‘functions’ of xylem. For each ‘function’ please: 10 POINTS (5 points for Water transport function) (i) List the cell types and the associated specialized cell name(s) for that function; (ii) Indicate if a given cell type is restricted to a certain major land plant clade(s). (1) Water and fluid transport Vertical transport - Sclerenchyma (tracheids, vessels). Vessels (with the exceptions of the Gnetophytes(gymnosperm), are restricted to the angiosperms. Tracheids are found in all Tracheophytes. Horizontal transport - Parenchyma (Ray parenchyma). Schlerenchyma (Ray Tracheids – are found only in Gymnosperms. (2) Support 4 Sclerenchyma (Fibers) Fibers are only found within Angiosperm xylem. (3) Storage Parenchyma (Ray Parenchyma) (19) Please provide mathematical definitions for the following physical attributes of plants. Include in your answer: (a) What does this equation express? (2)(b) A short but complete description for each parameter within each mathematical definition (2); and (c) Provide at least three sentences why each mathematical equation is important for understanding land plant evolution (3). 14 Points (1) ri4 P Ji 8 li This is the Poiseuille equation. Ji is the flux of fluid within a tube. ri is the radius of a tube, is the fluid viscosity, li is the length of the tube. P/ li is the pressure gradients or the change in pressure over the change in length of pipe. Poiseuille equation is important for plant evolution as it describes how the flow rate of fluid through a pipe (such as a vessel or tracheid) is influenced by its dimensions (radius and length). Selection can act on flow rates of fluid through the xylem primarily through changes in radius and/or length. For example if the radius of a tube (vessel, tracheid) increases then flow rate will increase dramatically because of the 4th power dependence of flow rate on tube radius. This equation like explains why tracheid and vessel radius tends to have increased over evolutionary time as transport distance has increased. (2) This is Fick’s law. dS/dt is the rate of diffusion of a solute, S, . Di is the diffusion coefficient for a given solute (usually treated as a constant), A is the surface through which diffusion occurs. Ci/ x is the concentration gradient. Fick’s law is important as most resources within plants are transported by diffusion at some C dS Di A i x dt point. In order to maximize or minimize rates of diffusion selection can act on the area, A, over which solutes are diffused as well as the concentration gradient Ci/ x. Definitions (12% of point total) 30 Points 5 (20) For each term/character please provide a definition. (i) Make sure to write two sentences for each. (ii) Stress the functional and/or ecological, and/or evolutionary importance of each. 6 Points Each Cellulose A polymer of glucose consisting of Beta 1-4 bonds that are ‘unbreakable’ (cannot be digested) by animals. The most abundant biocompound on earth - crucial for increased biochemical stability and increased plant height over evolutionary time. Bordered pit A passage through the 20 cell wall of xylem elements (tracheids – common in conifers) which allows for the lateral conduction of water and helps minimize embolisms. The opening is surrounded by thickened 2 o cell wall to provide biochemical support from element collapse due to more negative water potential. Angiosperm seagrasses These are plants that have ‘come full circle’ and have reinvaded aquatic environments. They are of note evolutionarily as the main trend in Embryophyte evolution has been to constantly invade more xeric environments. Embolism – Results if the tension on the water column (driven by transpiration) within the xylem becomes so severe that the water column breaks. This is when the cohesive and adhesive forces on the water column are overcome. An embolism is a partial vacuum or an ‘air bubble’ in the xylem stream. The xylem (tracheid or vessel) becomes useless. Selection to minimize embolisms has been important in shaping xylem morphology. Hypanthium – A cup-like floral structure within Angiosperms that marks the fusion of petals, sepals and anthers. A trait that characterizes the Rosid clade. A hypanthium is an example of convergent evolution of a ‘tubular fused flower’ and likely reflects selection for specific types of animal pollination. QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture. 6 Long-answer (30% of point total) 72 points (21) On a separate sheet of paper please: (1) Draw the phylogeny of the land plants. (40) Only include the major extant land plant clades discussed in class. Include the following: Mosses, Flowering Plants (and all the major clades and grades within), Gymnosperms, Charophytes, Lycopods, Pteridophytes, hornworts, Sphenophyta (horsetails), Liverworts, Chlorophytes, Prokaryotic Photosynthetic bacteria (2) Label on your phylogeny – (14) (3) the BOTANICAL NAME for the clades that are the Seed Plants, Vascular Plants, Land Plants, and the Flowering Plants. Also, be sure to include the green algae and the likely extant green algae clade that shares a common ancestor with the land plants. Be sure to include the major clades and grades of the Flowering plants (3) At each node of your phylogeny please: (20) List the characters (or character) [also think adaptations here] associated with each group. Up to the angiosperm node, speculate on the likely selective pressures which led to the evolution of the characters associated with each node. Provide at least one to two sentences for each trait. Tree with some of the possible answers for character(s) for each node. There are others. Selective pressures depend on the characters listed, but generally revolve around the theme of adapting to more xeric environments. 7 Caryophyllales PSN Bacteria Chlorophytes Gymnosperms Angiosperms (flowering plants) Charophytes Carpel Spermatophytes Seed Egg retention Chlorophyll a,b Colochaete like ancestor 8