final exam study guide
final exam study guide BIL 226
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This 29 page Study Guide was uploaded by Annmarie Jaghab on Monday December 7, 2015. The Study Guide belongs to BIL 226 at University of Miami taught by Dr. Groff in Fall 2015. Since its upload, it has received 12 views. For similar materials see General Botany in Biology at University of Miami.
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BIL 226 Final exam study guide Section 1 material: Lecture 2 organism life cycle: a continuing process of growth, change, and reproduction Species concepts: MSC: different species are defined by differences in morphology (form). Uses type specimens to document the scientific names of species. Limitations: 1) form of organisms varies throughout the life cycle 2) even organisms in the same stage of the life cycle and reproduced from the same parent may be variable 3) how much difference in form, color, etc. makes a species a different species BSC: species are defined by the ability of their members to interbreed Limitations: 1) some organisms reproduce without sex (budding, sprouting, parthenogenesis) 2) some organisms we only know from fossil evidence so we can’t test if they interbreed 3) two once separate species can hybridize (cross breed) making phylogenies netlike (reticulate) ex. Cattle and bison can make fertile hybrid Lecture 3 Linnaeus’ idea of binomial nomenclature: two names for living things. The basic framework of classification used by biologists. Species names: consist of a genus and specific epithet Genus: species grouped together with other species Classification: grouping of living things into a hierarchically nested set of categories Linnaean hierarchy of ranks: Kingdom, Phylum, Class, Order, Family, Genus, Species Phylogenetic tree of life model: one common ancestor for Bacteria, Archaea, and Eucarya Web or network/reticulation: two once separate species hybridize (cross breed) making phylogenies netlike (reticulate). Due to the horizontal transfer of information between different lineages. Hybrids: denoted with x hybrida after the name. A mix of two species. DNA species barcoding: using the information contained in particular short regions of the DNA molecule as a barcode to identify species. Different DNA regions are needed to “barcode” plants vs. animals Lecture 4 Kingdoms: The original thought was that there were 5 kingdoms. The branch began at monera then protists and then branches into plants, animals, and fungi. Domains: there are three main ones. Bacteria, archaea, and eucarya Changing concepts of the Kingdoms: traditional kingdoms were separated based on the complexity of organization (1 celled or filaments/ simple or complex). Body constructed with many specialized cell types. Mode of nutrition. Why? There is more knowledge of the organisms (2 groups of prokaryotes: archaea and bacteria) and there are changes in biologists’ criteria for groups to recognize in a classification (monophyl vs paraphyl) Raven Table 124 Prokaryotes: no nucleus, circular DNA is in the cytoplasm. Internal structures are not organized into compartments, much smaller than eukaryotes, no cytoskeleton. One celled or filaments. Archaea live in extreme environments. Some bacteria are green and can use sunlight to make highenergy molecules. Eukaryotes: have a nucleus with linear DNA, internal structures are organized into compartments, 10 times larger than prokaryotes, cytoskeleton present, cytoplasm has organelles. One celled or multicellular. Characteristics of Kingdom Plantae: multicellular, have cell wall of cellulose, have multiple cell and tissue types, photosynthetic autotrophs that use energy from the sun to create energy rich organic molecules. Rarely use organic molecules from the environment. Characteristics of Kingdom Fungi: most species are multicellular, cell wall of chitin, some species have multiple cell and tissue types, not capable of photosynthesis, all species use organic molecules in the environment and digestion begins externally. Characteristics of group Protists: a few species are multicellular, some have a cell wall, some have multiple cell and tissue types, some are capable of photosynthesis, and some use organic molecules in the environment. Lecture 5 Monophyly: group that includes all the descendants of the most recent common ancestor of the group. Ex. Flowering plants Paraphyly: consists of a common ancestor but not all descendants of that ancestor. Ex. Gymnosperms (seed plants without flowers) ex. Reptiles. Ex.protists Polyphyly: a group with two or more ancestors but not including the true common ancestor of all its members. Groups are defined by a character trait that evolved more than once in the phylogeny of life. ex. Vertebrates with wings. Why are protists not a kingdom anymore? Protists are not a monophyletic group Clades: monophyletic groups. Visualized as one branch of the tree of life. Cladograms: branching diagrams showing the relationships among living things. One axis is time and top is most recent Using cladograms to specify a hypothesis of phylogeny: a cladogram is used to show evolutionary history. We use evidence of traits (morphological features, DNA sequences, physiology, behavior, etc) to explain the classification. One way we choose which hypothesis is most likely is by parsimony. We chose the trees that require fewer steps to describe the data. May not be true history but preferred until there is further evidence. Lecture 6 Eukaryotes: protists were the first eukaryotes concept of supergroups: a rank in the classification hierarchy between Domain and Kingdom. Each supergroup includes some Protists. One supergroup called “Plants and Algal relatives” includes the Plant Kingdom and another includes both Animal and Fungal Kingdoms called Opisthokonta. Early fossil Prokaryotes (including photosynthetic Cyanobacteria). Early fossil Eukaryotes (protists). Serial Endosymbiotic theory of the origin of the Eukaryotic cell: Started with a prokaryotic cell with a cell walllost cell wall which resulted in cell with flexible plasma membrane with many ribosomes inward folds of the flexible plasma membrane pinch off forming internal compartments one with DNA attached to it which is the precursor for the nucleusincreasing quantity of DNA becomes surrounded by flattened internal membranes, cisternal ER. Cytoskeletal elements add support to the growing cell and enable it to flex its plasma membranenow a primitive phagocyte with true nucleus, ER, and golgi apparatusprecursors of mitochondria and precursors of chloroplasts are engulfed photosynthetic eukaryotic cell is created Where did the nucleus come from? The plasma membrane folds pinched off forming internal compartments, one with DNA attached to it, which became a precursor of the nucleus Where did mitochondria come from? The mitochondria started as a bacterial endosymbiont, which ultimately transferred most of its DNA to the host’s nucleus Where did the Chloroplasts come from? Chloroplasts are the descendents of bacteria and also ultimately transferred their DNA to the host’s nucleus. Cyanobacterium was taken up via endosymbiosis and became a chloroplast. Raven Fig. 1211 Cell cycle in eukaryotes: G0 is the nondividing resting stage. G1 is when the cell doubles in size, organelles, enzymes, and other molecules increase in number. The S phase is when DNA is replicated and associated proteins are synthesized and two copies of the genetic information now exist. G2 is when the structures required for cell division begin to assemble and chromosomes begin to condense. The M phase is when the two sets of chromosomes are separated by mitosis and the cell divides via cytokinesis. Mitosis is a mode of cell division in eukaryotes and can build up a multicellular body without changing ploidy level. Mitosis in plants: A mode of nuclear division as well. Consists of interphase, prophase, metaphase, telophase and cytokinesis in which the phragmoplast forms and the cell plate matures. Then the cell plate is there in early interphase and in interphase there is both a mother and daughter cell wall and then there is cell enlargement. Concept of the cell plate partitioning the mother cell into two daughter cells during cytokinesis in the Plant Kingdom. Raven figs. 340, 348, 85,810 Lecture 7 Cladogram worksheets (Know how to use evidence from a data matrix to choose a preferred hypothesis of phylogeny, as shown in a cladogram, based on the criterion of parsimony. Be able to draw and label the most parsimonious cladogram and be able to interpret cladograms and compare them to see recency of most common ancestor and monophylyl of groups and number of steps and homoplasy.) Should we consider the most parsimonious hypothesis of phylogeny to be “true” or merely prefer it provisionally based on current available evidence? The most parsimonious hypothesis is not always true, but we accept it until further evidence is obtained. What evolutionary process was interpreted as homoplasy, but might have been better represented by a diagram with different geometry? The simplest hypothesis is that Darwin’s finches shared a more recent common ancestor with one another than with any other species. Monophyly: when all the descendants of the most recent common ancestor are included Parsimony: a cladogram should be constructed in the simplest, least complicated, and most efficient way. Homoplasy: either multiple origin of traits (convergence) or reversals/losses of traits. Characters: characteristics Taxa/ taxon: can be a group of any rank (species, family, phylum, etc) Lecture 8 Mitosis: mitosis is a mode of nuclear division in Eukaryotes followed by cytokinesis, which is cell division. Mitosis and cytokinesis can build up a multicellular body and does not change ploidy level. Mitosis does not produce genetic variation. For plants the cell plate is perforated and the cytoplasm of the two daughter cells are connected by plasmodesmata, which allows for communication between daughter cells. Phragmoplast is only found in plant cells and is part of the spindle that forms Meiosis: Meiosis is a form of cell division in Eukaryotes that may produce 4 gametes or spores with half the ploidy level of the original cell. Meiosis is two rounds of nuclear division so it halves the ploidy level and results in genetic variation with crossing over and independent assortment of chromosomes. Results in spores or gametes. Nuclei of daughter cells vary in which subsets of parental genes they carry. Variation in Eukaryotic life cycles Raven fig 127 Diagrams of life cycles identifying locations of” Gametes, Fertilization, Diploid Zygote, Meiosis, Spores, Multicellular bodies built by mitosis. Be able to examine a life cycle diagram to determine whether a particular stage is haploid or diploid. Spores: reproductive structure (usually unicellular) that develops into an adult organism of the same ploidy level (via mitosis if the adult organism is multicellular) without fusing with another cell (without fertilization) Gametes: a reproductive cell of ploidy n Across the many different types of eukaryotic life cycles, spores or gametes may be formed by either mitosis or meiosis. zygotic meiosis is found in fungi and some algae. A single cell DIPLOID immediately undergoes meiosis gametic meiosis is animals, some protists, and algae. After fertilization the zygote undergoes mitosis and remains 2n and then a cell goes under meiosis and forms gametes. sporic meiosis is alternation of generations, plants and many algae. There is a multicellular diploid and haploid stage! haploid gametophyte forms gametes via mitosis above the bar in the diagrams the ploidy is n and below is 2n Alternation of Generations in Kingdom Plantae: both haploid and diploid phases develop into a multicellular body; the haploid gametophyte stage (n) forms gametes via mitosis and the diploid sporophyte (2n) stage forms spores via meiosis. Both the haploid and diploid are multicellular The Vascular Plants: including for example the ferns, conifers, and the flowering plants have a life cycle in which the diploid sporophyte generation makes the larger, more conspicuous multicellular body (a large easily visible organism). The Nonvascular land plants: “Bryophytes” including mosses have a life cycle in which the haploid gametophyte generation makes the larger more conspicuous multicellular body in the life cycle of those organisms. Three organs of the sporophyte in vascular plants: root, stem, and leaf. stem+leaf= shoot. What are their usual functions? Shoots and roots add to their length, and form new organs such as the leaves on shoots at their tips, via their apical meristems (open growth). Shoots do photosynthesis and have reproductive structures. Roots uptake water, minerals, and anchor plant. Where do new shoot branches tend to form and how can you use that positional relationship to figure out if a structure is a leaf or a shoot? In many vascular plants, a new shoot develops from the axil of a leaf. An axil is the spot just above the point of insertion of the leaf on the stem. In the axil of a leaf, new stems and leaves are made. The lower structure is the leaf and the one above is the shoot (looks like a little bud or can look like a thorn). The leaf below the axil is the subaxilary bud Concept of a subtending leaf, leaf axil, and axillary bud/axillary shoot: Keep in mind that the stem, leaves, and roots of some plants have evolved “atypical” functions; for example, not all leaves are green; stems or roots! Rather than leaves of some unusual species do most of the photosynthesis; leaves or entire shoots may sometimes have evolved the form and function of sharp defensive structures. Section 2 material: Lecture 11: “Land plants and algal relatives.” What is a eukaryote: plant, animal, fungi, and protist kingdoms what is a supergroup? A rank in classification between domain and kingdom, all supergroups include some protists. “Land plants and algal relatives” is the supergroup of some protists and the plant kingdom what is an alga? Photosynthetic eukaryotes lacking multicellular sex organs. They are often aquatic “green algae”: closely related to the land plants. Land plants: Kingdom Plantae = Embryophytes. What are the Chlorophytes (including Ulva, Chlamydomonas, Volvox) and how are they related to the land plants, based on the phylogeny presented in lecture and in your Raven text? The Chlorophytes are green algae but not the green algae that are most closely related to the land plants. The cholorophytes are a subgroup of the green algae and not very closely related to land plants. Chlamydomonas are unicellular and motile. Volvox are motile, spheroidal, colonial, oogamous. An ulva is a sea lettuce and is a green alga, has a multicellular alteration of generations meaning that the sporophyte and gametophyte are multicellular. Know the life cycle, morphology, and development of Ulva: life cycle is an isomorphic alternation of generations. What is a gametangium? a cell or multicellular structure in which gametes are formed What is a sporangium? A cell or multicellular structure in which spores are formed Isogamy: gametes are both motile and same size Anisogamy: gametes are both motile and different size Oogamy: gametes include a larger non-motile egg and a smaller motile sperm Two green algae that are even more closely related to the Land Plants and what characters do they share with Land Plants: 1) Chara: a green alga in the class charophyceae that resembles the plant kingdom since it has apical growth, a phragmoplast in cytokinesis, plasmodesmata, is oogamous, and the egg is retained on the parent gametophyte, has sporeollenin 2) Coleochaete: multicellular gametophyte. Several shared, derived characters in common with the land plants (Phragmoplast, cell plate, plasmodesmata, oogonium and antheridium) They both don’t have an alteration of multicellular generations. “Bryophytes” (liverworts, mosses, and hornworts): the nonvascular land plants. A paraphyletic group. Gametophyte generation is large, green, most visible, grows independently. Lecture12: Know the NVLP classification (named taxa), Phylogeny, Characters, Life cycles. -The gametangia of bryophytes includes archegonia and antheridia formed by the gametophyte (n) -fertilization takes place in the archegonium by motile sperm -the 2n embryo is dependent on the mother for nutrients (matrotrophy) -the 2n sporophyte grows out of the archegonium -the sporophyte generation consists of a foot, seta, and sporangium that undergoes meiosis -the gametophyte consists of a calyptra (made of gametophyte tissue) -the meiospores can be air-dispersed and there are sporopollenin walled spores (relation to zygote of coleochaete) -the spores germinate and in some protonema (early filamentous stage of growth in mosses) form and there are different forms of mature gametophytes in different bryophytes -the gametophytes of byrophytes have thalloid and leafy -the mosses can either be cushion or feathery -gemmae perform asexual reproduction and are part of the gametophyte generation -non vascular plants have a gametophyte with hadrom and leptom while the vascular sporophyte have the xylem and phloem -there are stoma in some non vascular land plants and some have pores on gametophyte and some have apical meristems on gametophyte (the hornworts have meristem between foot and sporangium in sporophyte) while in vascular plants the meristem is on the sporophyte. -bryophytes are ecologically important because they were pioneers and have peat bogs and C storage (carbon storage, allow them to uptake carbon) 1) Mosses (Bryophyta): peat mosses (Sphagridae), granite, true (Bryidae) 2) Liverworts (Marchantiophyta): thalloid and leafy 3) Hornworts (anthoceratophyta): Have a much longer lived sporophyte than the other bryophytes What are the “problems” that a green alga (an aquatic photosynthetic organism) would encounter in adapting to life “on dry land” (in the combined air/soil terrestrial environment)? What features of morphology, physiology, and life cycle allow “bryophytes” to live on land? Multicellular bodies are being exposed to air but for photosynthesis they need light and gases so dispersal through air or along the surface of the ground is done via spores that resist drying but only a small percent of spores find a good site. So the sporophyte generation makes the spores and the zygote undergoes more mitoses thus a larger multicellular sporophyte is formed and the number of spores that result from each fertilization event is increased. To allow bryophytes to live on land, they developed a waxy cuticle to prevent desiccation and the development of gametangia provides protection for the gametes. They also have embryonic development, which is only seen in land plants and not green algae. Know the characters important in phylogeny: Heteromorphic alternation of generations. The sporophyte is 2n and the gametophyte is n and both are multicellular but differ in morphology The gametangia of the gametophyte consists of a multicellular antheridium with a sterile jacket that makes sperm and the archegonium which has sterile cells like stalk, venter, and neck and forms the egg -the zygote develops into a multicellular embryo sporophyte initially within the archegonium and dependent on the gametophyte (matrotrophy) -the multicellular sporophyte develops from a zygote and embryo stages into a structure that forms sporangia where meiosis occurs to form spores -in bryophytes, spores can disperse through the air and the single cells have hard sporopollenin walls to resist drying and decay Liverworts: thalloid vs. leafy: thalloid are undifferentiated bodies not differentiated into roots, leaves, and stems. They are thin and may facilitate uptake of water and CO2. Thalloid are probably paraphyletic and leafy are probably a clade. Leafy ones resemble mosses. Leafy have 2 rows, lobed, no midrib, colorless seta, no teeth around mouth). Leafy liverworsts have perianth and androecium on gametopyte so they are not comparable to sporophyte leaves. Pores vs. gemma cups of thalloid liverworts (the pore of a liverwort gpt is not the same as the stomata found on spts of some other kinds of plants): pores are on the thallus. Gemma cups multicellular bodies and are for asexual dispersal and make new gametophytes that are identical to the parent Life cycle of Marchantia, a thalloid liverwort: Moss Life cycle Lecture'14: Overview of Vascular Plants. How are their defining features related to life on land? They have tracheary elements which are water conducting cells with water conducting tissue called xylem. They have lignin which gives structural strength to cell walls. They have a waxy cutile on the dominant sporophyte generation to prevent dessication. Cutin is found in cuticle to help block pathogens. Their stomata open and close freely and allow gas exchange while minimizing water loss. Organography and development of the vascular plant sporophyte: Roots, Stems, Leaves. A stem and leaf make a shoot. Shoot functions: photosynthesis, intercept light and gas exchange, reproductive structures like sporangia are on the sporophyte Root functions: uptake water, minerals, anchor plant apical meristems: plants add new organs to body through open growth from apical meristems primary growth: at the tip/apex of a growing shoot or root an apical meristem adds new length to the stem or root and initiates new leaves via open growth secondary growth: shoots and or roots growth in thickness/girth. Caused by cell division and happens in lateral meristems adding growth inside and outside of them like hollow cylinders and specifically vascular cambium (wood) and cork cambium (bark) Know all the phyla, clades, and informal (non monophyletic) groupings listed in the classification of Kingdom Plantae as shown in Raven Table 12-4. Which are clades, which are not? How does each group disperse (primary mode of reproduction, whether spore or seed)? Which are vascular (xylem and phloem in spt), which are not? Lycophyta, Monilophyta, Seed Plants are all vascular. Lecture'15: Vascular Plant Life Cycles compared. What structures disperse in vascular plants? Spores (haploid meiospores, single celled and dessication resistant) vs. seeds (complex multicellular structures with particular features). Homospory (e.g. Polypodium, Equisetum, Lycopodium): one kind of spore Heterospory (e.g. Selaginella also seed plants): two kinds of spores different in morphology, germination, the kind of gametophyte they grow into, and the sex of the gametes produced. Seed plants: “Gymnosperms” (non flowering seed plants, naked seed) vs. Angiosperms (Phylum Anthophyta, flowering plants). The sporophyte of the vascular plants grows out of the archegonium, branches, and becomes independent. Clades (monophyletic groups) vs. “grades” (levels of organization, non monophyletic) Sporophylls and strobili: strobilus is a cone. Sporophylls are special leaves bearing the sporangia and they are part of sporophyte (2n). phylum lycophyta has them Heterosporous life cycle: microspores vs. megaspores; microsporangia vs. megasporangia; microgametophyte vs. megagametophyte; endosporic development; which gametophyte is female, which male? Microspores (n) are small, formed by microsporangia (2n) of the sporophyte and become the male microgametophye (n). Megaspores(n) are larger formed by megasporangia (2n) of the sporophyte and become the female megagametophye (n). Seed plants. The seed is a fertilized ovule; ovule is an integumented megasporangium. In flowering plants, the seed is enclosed in a structure called a fruit that develops out of the ovary of the flower. Know the seed plant life cycle (e.g. Pinus): The gametophytes of pine are much reduced and nutritionally dependent on the sporophyte. The immature male gametophytes consist of only four cells are the pollen grains that are transferred by the wind to the vicinity of the female gametophyte within an ovule. The non-motile sperm produced by the germinating pollen grains are conveyed to the eggs of the archegonia by pollen tubes. Water is not necessary as a medium for the sperm to reach the egg. The ovule, which encloses the megagametophyte, matures after fertilization and becomes the seed. The elaborate suspensor, which is characteristic of pines, disintegrates by the time the embryo is fully developed. The pine seed is made up of an embryo, seed coat, and stored food consisting of the megagametophyte. Pollen = the male gametophyte (differs from a spore in being multicellular) Pollination vs. fertilization. Pinus: a “Gymnosperm” (seeds “naked”) Phylum Anthophyta: (Angiosperms = flowering plants), ovules are enclosed by the ovary of the flower. The fertilized ovule is enclosed by the mature fruit (which develops out of the ovary wall). Seeds in flowering plants are not “naked” as in “Gymnosperms.” ' Lecture'17 and Lecture'18: More on vascular plants without seeds. Phylum Monilophyta (ferns, including Polypodium, Psilotum, etc; and horsetails, Equisetum). In the phylogeny of vascular plants, be able to identify examples of extinct taxa, convergent evolution (multiple origin of traits), loss of a trait in the course of evolution, monophyletic groups, paraphyletic groups, and polyphyletic groups. Ferns (some epiphytes). Prothallus, Sorus, indusium, fern life cycle. Prothallus is another name for gametophyte of ferns. Sorus are clusters of sporangia on a fern leaf and can be naked meaning they are not covered by an umbrella shaped indusium. Psilotum (whisk fern): no roots; large sporangia (3 sporangia fused together); once thought to be a primitive vascular plant similar to Devonian fossils; now thought to be a fern that has lost the ability to make roots. They have rhizome but those are not roots! Psilotum gametophyte: subterranean and mycoheterotrophic. Polypodium, Psilotum, and Equisetum are homosporous (all spores the same size). Some fossil forms (you do not need to know the names of all the fossils, but be aware that many fossil types exist; shown on the cladogram with an asterisk). Some resemble modern taxa of Phylum Monilophyta, others resemble modern Lycophyta (etc.). Phylum Lycophyta: Lycopodium (club moss, homosporous), Selaginella (spike moss, heterosporous), and Isoetes (quillwort, heterosporous). Do understand that Isoetes, like some fossil forms of Lycophyta, has secondary growth. Isoetes is in the phylum lycophyta and is heterosporous and has secondary xylem Section 3 material: Lecture 20 The seed plants. Know the phyla, clades, informal groups: Raven, Table 12-4. Review of Heterospory in Selaginella. Seed plants also have a heterosporous life cycle. Has two types of spores that are different in morphology, germination, type of gametophyte they grow into, and the sex of the gametes that are produced by those gametophytes. Microspores are small, formed by microsporangia (2n) of the sporophyte and form male microgametophyte that form sperm and Megaspores are large, formed by the megasporangia (2n) of the sporophyte, germinate inside the large spore wall (endosporic) and form the female megagametophyte that forms the archegonia which forms an egg and fertilization happens in the archegonium to form zygote (2n). The microspores and megaspores are haploid and are formed in the sporangia of the diploid sporophyte. Seeds, embryos, seedlings. Seedling – what is it, where does it come from, what does it develop into? A seed is a fertilized ovule and is a complex, multicellular reproductive structure that can often disperse an entire embryo sporophyte, inside other protective tissues. A seedling is a young sporophyte. Review of ovule structure, seed plant life cycle, and embryo formation. An ovule is an integumented megasporangium formed on the diploid sporophyte of the seed plant. It has a micropyle for pollen to enter, it is surrounded by an integument (2n), it contains a megasporangium which is also called the nucellus, and inside the megasporangium is a functional megaspore. The megasporangium forms a megaspore (n) via meiosis. The megaspore stays on the parent sporophyte and develops into the megagametophyte inside the megasporangium (2n). Pollination is when a pollen grain (microgametophyte, n) often from another sporophyte is transported to the ovule. The pollen grain germinates inside the ovule and releases sperm. In fertilization, the sperm fertilizes the egg to form the zygote which divides to form a multicellular embryo. Seeds of “Gymnosperms” and angiosperms – similarities, differences. Gymnosperm: naked seed, no flowers, paraphyletic group Angiosperm: flowering plants, ovules are enclosed in the ovary of the flower, seeds are enclosed in the fruit, do not have the megagametophyte as stored food for the embryo. 3n endosperm is food source Lecture 21 Both Gymnosperms and Angiosperms have seeds and seedlings. Both multicellular, both have multicellular embryo sporophyte, both have food source for embryo sporophyte, both have protective structures originating from the parent sporophyte (2n) which is usually different genetically from the embryo Seedling morphology: root, hypocotyl, cotyledonary node (and cotyledons), epicotyl. Epicotyl is above the first node and part of the shoot The first node is the cotyledon (“seed leaves” can be 1,2, or more) Hypocotyl is below the first node (stem) Root (radicle) Variation in seedling morphology (cotyledons can vary greatly in structure and function, for example). Can be one, two, or more cotyledons. Seed plants without flowers (Gymnosperms). What traits separate them from non-seed plants? What traits separate them from the Phylum Anthophyta (flowering plants)? Gymnosperms differ from the non seed plants since they contain seeds. They differ from the flowering plants because they lack flowers and have naked seeds. Angiosperms have seed in vessel called ovary or fruit and have a flower/strobilus How do the ovules of gymnosperms and angiosperms differ (which is “naked”) Gymnosperm has naked ovules how do the strobili differ (compare the 2 kinds of “cones” in Pinus to the diagram of an angiosperm flower)? (We will add to the list of gymnosperm/angiosperm differences later). Pinus (gymnosperm) can have microsporangiate strobili (pollen cone) with many microsporohylls bearing microsporangia which have pollen grains Pinus can have ovulate strobilus (seed cone) Angiosperm strobilus is the flower What are the main groups (Phyla) of gymnosperms? Know the four phyla of extant (living) gymnosperms and one genus as an example of each. Phylum Coniferophyta (conifers, pinus) Phylum Cycadophyta (cycas) Phylum Ginkgophyta (ginkgo) Phylum Gnetophyta (gnetum) Are all gymnosperms (including the extinct forms known only from fossils) a clade (monophyletic group)? Gymnosperms are paraphyletic. The progymnosperms (extinct fossil wood like modern gymnosperms that reproduce with spores not seeds) and pteridophytes (ferns) are represented as paraphyletic. What are the 3 alternative hypotheses of phylogeny (3 cladograms) shown in Raven, Fig. 18-10, about the relationships of the living groups of gymnosperms to angiosperms? In a, the angiosperms and gymnosperms are a clade. In b the angiosperms and gymnosperms are a clade, in c the gymnosperms are not monophyletic. Do all of these show the living gymnosperms as a clade? No, in hypothesis c the gymnosperms are not shown as a clade. Know the life cycle of Pinus (pine) in detail, as diagrammed in Raven Fig. 18-19 and discussed in lecture. Long leaf pine Lecture 22 How are seeds of gymnosperms and angiosperms similar? -multicellular, contain multicellular embryo sporophyte, have food source for the embryo sporophyte, have protective outer structures originating from the parent sporophyte (2n) which is genetically different from the embryo Flowering plants (angiosperms, Phylum Anthophyta). What characters distinguish the flowering plants from the gymnosperms? Flowering plants have ovules enclosed in the ovary of the flower. The seed is not naked and is enclosed in a fruit that develops out of the ovary. Angiosperms have endosperm which is not in gymnosperms! Are the flowering plants a clade? Yes, they are monophyletic Flower is the strobilus of the angiosperms – great range of variation in structure, often associated with co-evolution with different species of pollinating animals (insects, birds, etc). Animal pollinators can help pollinate. Wind pollination can also occur. Parts of a flower: Floral “whorls” – what is a whorl? Flower is a shoot with successive nodes called whorls. A whorled leaf arrangement is 3 or more leaves at each node. “Classical” concept of a flower interprets the sepals, petals, stamens, and carpels as comparable (homologous) to leaves. Refers to flower parts as different whorls Leaf arrangement: alternate, opposite, whorled. “Alternate” sometimes described as “spiral” (more accurately, “helical”). Alternate: 1 leaf inserted at node Opposite: 2 leaves inserted at same node Whorled: 3 or more leaves inserted at same node “Whorls” of flowers: calyx, corolla, androecium, gynoecium. Calyx: sepals Corolla: petals Corolla and Calyx make up perianth Androecium: anther and filament (collectively stamen) Gynoecium: ovary, ovules, stigma, and style (collectively carpel) Lecture 23 Know examples of flower parts taking different forms in various species of angiosperms. A pistil is a separate part of the gyncoecium and depending on the flower it can be one or many carpels if they are fused or not. Concept of the fusion of parts (for example, syncarpous vs. apocarpous gynoecium). Syncarpous gynoecium: several carpels fused together into a single structure in the gynoecium Apocarpous gynoecium: separate carpels The gynoecium may be one or more pistils, and may be one or more carpels; even if only one pistil is present, that may be composed of two or more fused carpels. What evidence can help us figure out how many carpels are present in a single pistil? Look at the cross section to see the number of carpals Ovary position and fusion of parts to form a hypanthium. Hypogenous: ovary is superior. Sepals, petals and stamen are below ovary Epigynous: ovary is inferior. Sepals, petals, and stamen are above ovary Perigynous: ovary is superior. Hypanthium, cuplike structure, formed from fused bases of calyx, corolla, and androecium Concept of the fruit, developed from the ovary of the flower. The seed of angiosperms is enclosed in a fruit that develops out of the ovary. Lecture 24 Microlab in class: we dissected fruits of strawberry, tomato, green bean, apple. Tomato has a superior ovary Apple has an inferior ovary Each seed in a strawberry has its own ovary Fruits can be dry or fleshy, and can disperse seeds in many ways. Green beans are a dry fruit while an orange, apple, strawberry, etc would be fleshy. Fleshy fruits usually are dispersed by animals whereas dry fruits are adapted to air, water, or animal dispersal. Inflorescences (clusters of flowers grouped together on a shoot). A structure that appears to be one flower is really a composite structure of many flowers clustered together in the flowering region of a shoot aka inflorescence Lecture 25 Review of the angiosperm life cycle; concepts of double fertilization and the endosperm. Angiosperms have endosperms. Double fertilization is when the sperm fertilizes both the polar nuclei and the egg. The endosperm becomes 3n, while the zygote is 2n. Contrast the food stored for seedling growth in the seed of a typical gymnosperm (Pinus) and a typical angiosperm. The gymnosperms have the megagametophyte as the stored food for the embryo. Angiosperms have endosperm (3n) as the stored food source. 19-22 angiosperm life cycle Monocots and Dicots – what morphology feature of the seedling is referenced in those names? Monocots (including grasses, palms, lilies, etc) also tend to have parallel-veined leaves and flower parts in groups of 3 (for example, 3 sepals, 3 petals, 6 stamens in 2 whorls of 3, 3 carpels). Monocots have one cotyledon where as dicots have two. Monocots are considered a clade. Are “all the angiosperms that are not monocots” a clade (monophyletic group)? See Raven Fig. 20-7. No, they are not a clade. Dicots are paraphyletic Lecture 26 Form and function in roots and shoots. Roots: structural features, functional features. How are they different from shoots? Where do roots originate in the embryo? What are the structure, developmental origin, and function of the root cap, root hairs, and lateral roots? Roots have apical meristems that do not form leaves, they form a root cap and root hairs. Roots have lateral roots that grow out endogenously. Roots have no sporangia. For roots, xylem and phloem are not in a circular ring. Shoots have apical meristems that form leaves, nodes, internodes, and axillary shoots. Leaves and axillary shoots grow exogenously from the surface of the parent shoot. For shoots, reproduction occurs in sporangia. In shoots, xylem, phloem are in a ring. What are the essential “collections data” needed to document a scientific collection? Review your VPC guidelines and think about this. Photographer name, unique number, date, place, description of plant parts, nearby conditions. Lecture 27 Review of roots. The banyan tree (Ficus benghalensis) and other fig trees that begin as epiphytes (“strangler figs”) and send down roots to the ground that may fuse and become multiple “tree trunks.” The banyan tree begins life as a “strangler fig” which is a kind of epiphyte in the fig genus ficus that germinates on another tree and sends down roots to the soil and these roots grow down and graft together encircling the host tree. More roots then originate from the shoots of the fig and grow downward and undergo much secondary thickening growth. Prop roots of corn (Zea mays), similar stilt roots of many tropical trees including red mangrove (Rhizophora). Knee roots in bald cypress (Taxodium). Pneumatophores (anti-geotropic breathing roots) in black mangrove (Avicennia). Plants (including species that we cultivate for human food) that store their own food in their roots: carrots, sweet potato, turnip, sugar beet. The complicated structure and growth of sweet potato (Ipomoea batatas). Forms both shoots from roots and roots from shoots (root borne shoots/adventitious roots) Lecture 28 Shoot apical meristem and how its growth forms leaves, internodes of the stem, and axillary shoot meristems – all exogenously. At the apex of a growing shoot or root there is an apical meristem (region of rapidly dividing cells) which adds new length to the stem or root and initiates new leaves. Leaf primordia, leaf arrangement. Parts of a leaf: blade (lamina), petiole, and leaf base. From bottom to top: leaf base (point of attachment to the node of the shoot. Base may have outgrowths called stipules) (the term base is sometimes used wrongly for lower part of blade where it meets petiole). Petiole (stem part, may be absent). Lamina (blade) Variation in leaf structure: blade may be simple (lobed or not), or compound. Simple just has axillary bud and can have leaf with lobed blades while compound has axillary bud, rachis, and leaflets. Rachis the part in between the leaflets Petiolate has a petiole Sessile does not have a petiole, leaf directly attached to stem Palmate leaflets are arranged in shape of a palm Pinnate leaflets are arranged on opposite sides like a feather How to tell if a structure is a compound leaf or a branch with several separate simple leaves? See if there are leaflets to determine compound (not attached to a separate axillary bud) Stipules may be present as elaborations of the leaf base region. Outgrowth on the leaf base region The amazing leaf of Nepenthes pitcher plants. Look like a sac, animals defecate in it. Collects nitrogen. Be able to interpret and describe different types of leaves, and know a leaf from a shoot system. Storage shoots: bulb of onion, green onion, etc (Allium spp.), corms of Gladiolus and Crocus, rhizome of ginger, underground shoot tuber of potato (Solanum tuberosum). Bulb is a fleshy, concentric, leaf base that forms a swollen structure around and above the shoot apical meristem, it is the part of the plant that stores food. Green onion base wraps around in a tube called a sheeting leaf base. Corm is a shoot and food for next season’s growth is stored in swollen stem tissue Crocus forms new corm Potato is an underground shoot tuber. The baby potato parts store food for the next season’s growth of the plant. Ginger: food is stored in a rhizome (thickened, horizontal stem) Hypocotyl tuber of radish (Raphanus sativa). When you eat radish, it is the hopocotyl Lecture 29 Be able to interpret and describe different types of leaves, and know a leaf from a shoot system. Potatoes are shoots and not roots because they have nodes and internodes Storage roots: carrot, beet, sweet potato (Ipomoea batatas). Storage shoots: bulb of onion, green onion, etc (Allium spp.), rhizome of ginger, underground shoot tuber of potato (Solanum tuberosum). Sheathing leaf bases of various types in celery (we eat the petiole!), onion (Allium), etc. Hypocotyl tuber of radish (Raphanus sativa). The shoot of the radish is both the green epicotyl and the red hypocotyl Section 4 material Lecture 30 Population Ecology: changes in the population due to births, deaths, age structure of the population. It is important to our understanding of mechanisms and history of evolution. Populations of species can be valuable to humans, or pose problems to humans, and human population can be problems for other species. Definitions of ecology: study of the relationships of living things to their environment (including other living things). Can also be defined as: the study of the distribution and abundance of organisms (living things) and the interactions that determine their distribution and abundance. Scales of ecology: organismal, population, community, ecosystem. How can we understand the interactions of organisms, populations, communities, and ecosystems that determine the distribution and abundance of living things? By following evolution and it’s mechanisms What can we measure, what experiments and analyses can illuminate those interactions? we can do thought experiments to look at doubling rates. We can think of the area covered by Duckweed for example, which also presents us with exponential growth in the number of individuals. Temperature and Saguaro cactus, analyzed geographically (mapped). Populations of organisms. Lemna (duckweed) example. If doubles every day and at day 30 the whole pond is covered, on the th th th 29 day ½ is covered, 28 ¼ is covered, 27 1/8 is covered. Exponential growth: population size (N) increases in such a way that N doubles in size again and again in each equal time interval (the doubling time) doubling time: time it takes for population to double in size growth rate: “r” which is the intrinsic rate of increase in population size (analogous to rate of compound interest) using the “rule of 70” as an approximation. Know how to solve problems using the rule of 70. 70= (doubling time) x (growth rate) Can exponential growth continue forever? No. the actual change in population size (N) in many natural populations has a more complicated trajectory than exponential growth Another simple model for population growth: the logistic equation (sigmoidal curve or “S” curve). Yeast example. Compare with exponential growth. Environmental factors can limit the number of yeast cells. Sigmoidal begins as exponential and then as saturation begins, the growth slows, and at maturity growth stops. The S curve/ logistic equation: initially population grows almost exponentially, doubling in size repeatedly. Population growth begins to slow down at the inflection point and then tapers off to a value of N that is just below the carrying capacity (K) Know the concepts (and units) of N, r, T, and K, and be able to interpret graphs of these equations. N: population size r: intrinsic rate of increase T: time K: the population size that the environment can maintain “r selection”: Characteristic of communities that are often disturbed with populations knocked down and regrowing exponentially. small size, rapid growth, short life span, early reproductive age, many small seeds, and good seed dispersal, weak competitive ability, high mortality of young, variable population size, low parental care. ex. Weeds and dandelions and many crops “K selection”: Characteristic of communities that are stable with populations usuall very near K. large size, slow growth, long life span, late reproductive age, few large seeds, poor seed dispersal, strong competitive ability, low mortality of young, fairly constant population size, high parental care. ex. Oak tree and other forest trees What is “K” for our human species, and how does our human population growth depend on populations of plants? we do not know the exact value of K for our human species. K is a property of the environment, so the K in Miami differs from that of another state. The human population depends on the population of plants because they feed what we eat and we eat them as well. Lecture 31 Concept of ecosystem: the biotic community plus the abiotic environment (energy, matter) and their interactions as a system. Energy flows through ecosystems (some energy lost, as heat, at each transfer due to 2 nd law of thermodynamics); matter cycles. When energy is converted from one form to another in a physical or chemical change, no energy is created or destroyed (1 law of thermodynamics). Whenever energy is changed from one form to another, we enndup with lower quality or less usable energy than we started with (2 law of thermodynamics) Energy flows; “who eats who.” Real energy flows through an ecosystem usually resemble a web rather than a chain Trophic levels: the highest amounts of free energy are present in the lowest trophic levels. Primary producers and then primary consumers, etc. primary producers (photo-autotrophs in most ecosystems): autotrophs that can capture energy from abiotic sources and store it in the chemical bonds of organic molecules. In some ecosystems, the primary producers are chemo-autotrophs. In most ecosystems, the primary producers are photosynthetic (photo-autotrophs) primary consumers: organisms that eat producers ex. herbivores secondary consumers: organisms that eat primary consumers ex. Carnivores and omnivores tertiary consumers: a carnivore at the topmost level in a food chain that feeds on other carnivores; feeds on secondary consumers decomposers/detritovores: ecological function involves the recycling of nutrients by performing the natural process of decomposition as it feeds on dead or decaying organisms Lecture 32 Cycling of matter: water cycle, carbon cycle, cycles of nitrogen, phosphorus, etc. Plants are critically involved in these cycles that supply matter to form the bodies of heterotrophs such as humans, and supply us with water and air, and also (via the green house effect) influence the global climate. Flows of energy: Plants are almost always primary producers and are crucially important in introducing abiotic energy into earth’s ecosystems. nd Due to the 2 law of thermodynamics, energy is never transferred in a useful form with 100% efficiency (some is lost as heat at each transfer). Thus most of the energy in an ecosystem is found in the lowest trophic levels – almost always the plants. All the rest of the system depends on them. Examples of energy flows through the trophic levels. Energy is lost (as heat) within each trophic level of the food chain due to the chemical reactions in the physiology of living things. In some ecosystems, there are fewer individuls present at lower trophic levels. Trophic pyramids of numbers (not always found); pyramids of biomass (not always found); pyramids of energy (always found). Understand these examples. Pattern of decreasing useful energy at higher trophic levels also is reflected in the number of individuals (trophic pyramid patterns). Even when there is an inverted pyramid of population numbers, there may be a pyramid of biomass (summed masses of all organisms) at each trophic level. Even the biomass of the lower trophic levels might be less than the biomass of higher trophic levels. Still, the free energy available per unit of time is greatest at the lowest trophic levels, but the energy is quickly passing through those levels to the higher levels. What trophic level do humans occupy? Does this depend on our diet? How does our diet interact with our trophic level, and with agricultural practices, energy use, conservation of biodiversity, and the carrying capacity (K) of earth for our human species? How we eat determines the way that the earth is used including: changes to the earth’s biomes that lead to extinctions and loss of ecoystem services. The potential carry capacity (K) of the earth for our human population.
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