BSC 116 Test 1 StudyGuide
BSC 116 Test 1 StudyGuide BSC 116
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This 33 page Study Guide was uploaded by Ashley Bartolomeo on Friday February 12, 2016. The Study Guide belongs to BSC 116 at University of Alabama - Tuscaloosa taught by Professor Harris in Spring 2016. Since its upload, it has received 266 views. For similar materials see Principles Biology II in Biological Sciences at University of Alabama - Tuscaloosa.
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Study Guide Test Number 1 Chapter 25 Vocabulary Adaptive Radiation period of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles in their community Alkaline Vent A deep sea hydrothermal vent that releases water that is warm (4090C) rather than hot and that has a high pH (is basic). These vents consist of tiny pores lined with iron and other catalytic minerals that some scientists hypothesize might have been the location of the earliest abiotic synthesis of organic compounds Cambrian Explosion A relatively brief time in geologic history when many presentday phyla of animals first appeared in the fossil record. This burst of evolutionary change occurred about535 525 million years ago and saw the emergence of the first large, hardbodied animals Endosymbiont Theory The theory that mitochondria and plastids, including chloroplast, originated as prokaryotic cells engulfed by a host cell. The engulfed cell and its host cell then evolved into a single organism Geologic Record A standard time scale dividing Earth’s history into time periods, grouped into four eons – Hadean, Archaean, Proterozoic, and Phanerozoic – and further subdivided into eras, periods and epochs Half Life The amount of time it takes for 50% of a sample of a radioactive isotope to decay Heterochrony Evolutionary change in the timing or rate of an organism’s development Homeotic Gene Any of the master regulatory genes that control placement and spatial organization of body parts in animals, plants, and fungi by controlling the developmental fate of groups of cells Hydrothermal Vent An area on the deep seafloor where heated water and minerals from Earth’s interior gush into the seawater Macroevolution Evolutionary change above the species level. Examples of macroevolutionary change into include the origin of a new group of organisms through a series of speciation events and the impact of mass extinctions on the diversity of life and its subsequent recovery Mass Extinction The elimination of a large number of species throughout Earth, the result of global environmental changes Paedomorphosis The retention in an adult organism of the juvenile features of its evolutionary ancestors Plate Tectonics The theory that the continents are part of great plates of Earth’s crust that float on the hot, underlying portion of the mantle. Movements in the mantle cause the continents to move slowly over time Protocell An abiotic precursor of a living cell that had a membranelike structure and that maintained an internal chemistry different from that of its surroundings Radiometric Dating A method for determining the absolute age of rocks and fossils, based on the halflife of radioactive isotopes Ribozyme An RNA molecule that functions as an enzyme, such as intron that catalyzes its own removal during RNA splicing Serial Endosymbiosis A hypothesis for the origin of eukaryotes consisting of a sequence of endosymbiotic events in which mitochondria, chloroplasts and perhaps other cellular structures were derived from small prokaryotes that had been engulfed by large cells Shared Ancestral Character A character, shared by members of a particular clade, that originated in an ancestor that is not a member of that clade Shared Derived Character An evolutionary novelty that is unique to a particular clade Stromatolite Layered rock that results from the activities of prokaryotes that bind thin films of sediment together Key Points Experiments stimulating possible early atmospheres have produced organic molecules from inorganic precursors. Amino acids, lipids, sugars and nitrogenous bases have also been found in meteorites Amino acids and RNA nucleotides polymerize when dripped onto hot sand, clay or rock. Organic compounds can spontaneously assemble into protocells, membrane bounded droplets that have some properties of cells The first genetic material may have selfreplicating, catalytic RNA. Early protocells containing such RNA would have increased through natural selection The fossil record, based largely on fossils found in sedimentary rocks, documents the rise and fall of different groups or organisms over time Sedimentary strata reveal the relative ages of fossils. The absolute ages of fossils can be estimated by radiometric dating and other methods The fossil record shows how new groups of organisms can arise via the gradual modification of preexisting organisms In plate tectonics, continental plates move gradually over time, altering the physical geography and climate of Earth. These changes lead to extinctions in some groups of organisms and bursts of speciation in others Evolutionary history has been punctured by five mass extinctions that radically altered the history of life. Some of these extinctions may have been caused by changes in continent positions, volcanic activity, or impacts from meteorites or comets Large increases in the diversity of life have resulted from adaptive radiations that followed mass extinctions. Adaptive radiations have also occurred in groups of organisms that possessed major evolutionary innovations or that colonized new regions in which there was little competition from other organisms Developmental genes affect morphological differences between species by influencing the rate, timing, and spatial patterns of change in an organism’s form as it develops into an adult The evolution of new forms can be caused by changes in the nucleotide sequences or regulation of developmental genes Novel and complex biological structures can evolve through a series of incremental modifications, each of which benefits the organism that possesses it Evolutionary trends can be caused by factors such as natural selection in a changing environment or species selection. Like all aspects of evolution, evolutionary trends result from interactions between organisms and their current environments Chapter 26 Vocabulary Analogy Similarity between two species that is due to convergent evolution rather than to descent from a common ancestor with the same trait Basal Taxon In a specified group of organisms, a taxon whose evolutionary lineage diverged early in the history of the group Binomial A common term for the twopart, latinized format for naming a species, consisting of the genus and specific epithet; also called a binomen Branch Point The representation on a phylogenetic tree of the divergence of two or more taxa from a common ancestor. A branch point is usually shown as a dichotomty in which a branch representing the ancestral lineage splits (at the branch point) into two branches, one for each of the two descendant lineages Clade A group of species that includes an ancestral species and all of its descendants. A clade is equal to a monophyletic group Cladistics An approach to systematics in which organisms are placed into groups called clades based primarily on common descent Class In Linnaean classification, the taxonomic category above the level or order Family In Linnaean classification, the taxonomic category above genus Genus A taxonomic category above the species level, designated by the first word of a species’ twopart scientific name Homoplasy A similar (analogous) structure or molecular sequence that has evolved independently in two species Horizontal Gene Transfer The transfer of genes from on genome to another through mechanisms such as transposable elements, plasmid exchange, viral activity and perhaps fusions of different organisms Ingroup A species or group of species who evolutionary relationships are being examined in a given analysis Kingdom A taxonomic category, the second broadest after domain Maximum Likelihood As applied to DNA sequence data, a principle that states that when considering multiple phylogenetic hypotheses, one should take into account the hypothesis that reflects the most likely sequence of evolutionary events, given certain rules about how DNA changes over time Maximum Parsimony A principle that states that when considering multiple explanations for an observation, one should first investigate the simplest explanation that is consistent with the facts Molecular Clock A method for estimating the time required for a given amount of evolutionary change, based on the observation that some regions of genomes evolve at constant rates Monophyletic A common ancestor and all of its descendants Order In Linnaean classification, the taxonomic category above the level of family Orthologous Genes Homologous genes that are found in different species because of speciation Outgroup A species or group of species from an evolutionary lineage that is know to have diverged before the lineage that contains the group of species being studied. An outgroup is selected so that its members are closely related to the group of species being studied, but not as closely related as any studygroup members are to each other Paralogous Genes Homologous genes that are found in the same genome as a result of gene duplication Paraphyletic Consists of a common ancestor and some of its descendants Phylogenetic Tree A branching diagram that represents a hypothesis about the evolutionary history of a group of organisms Phylogeny The evolutionary history of a species or group of related species Phylum In Linnaean classification, the taxonomic category above class Polyphyletic Includes distantly related organisms but does not include their most recent common ancestor Polytomy In a phylogenetic tree, a branch point from which more than two descendant taxa emerge. A polytomy indicates that the evolutionary relationships between the two descendant taxa are not yet clear Rooted Describing a phylogenetic tree that contains a branch point representing the most recent common ancestor of all taxa in the tree Sister Taxa Groups of organisms that share an immediate common ancestor and hence are each other’s closest relatives Systematics A scientific discipline focused on classifying organisms and determining their evolutionary relationships Taxon A named taxonomic unit at any given level or classification Taxonomy A scientific discipline concerned with naming and classifying the diverse forms of life Key Points Linnaeus’s binomial classification system gives organisms two pat names: a genus plus a specific epithet In the Linnaean system, species are grouped in increasingly broad taxa: related genera are placed in the same family, families in orders, orders in classes, classes in phyla, phyla in kingdoms, and kingdoms in domains Systematists depict evolutionary relationships as branching phylogenetic trees. Many systematists propose that classification to based entirely on evolutionary relationships Unless branch lengths are proportional to time or genetic change, a phylogenetic tree indicated only patterns of descent Much information can be learned about a species from its evolutionary history; hence, phylogenies are useful in a wide range of applications Organisms with similar morphologies or DNA sequences are likely to be more closely related than organisms with very different structures and genetic sequences To infer phylogeny, homology (similarity due to shared ancestry) must be distinguished from analogy (similarity due to convergent evolution) A clade is a monophyletic grouping that includes an ancestral species and all of its descendants Clades can be distinguished by their shared derived characters Among phylogenies, the most parsimonious tree is the one that requires the fewest evolutionary changes. The most likely tree is the one based on the most likely patter of changes Orthologous genes are homologous genes found in different species as a result of speciation. Paralogous genes are homologous genes within a species that result from gene duplication; such genes can diverge and potentially take on new functions Distantly related species often have many orthologous genes. The small variation in gene number in organisms of varying complexity suggests that genes are versatile and may have multiple functions Some regions of DNA change at a rate consistent enough to serve as a molecular clock, in which the amount of genetic change is used to estimate the date of past evolutionary events Molecular clock analyses suggest that the most common strain of HIV jumped from primates to humans in the early 1900s Past classification systems have given way to the current view of the tree of life, which consists of three great domains: Bacteria, Archaea, and Eukarya Phylogenies based in part on rRNA genes suggest that eukaryotes are most closely related to archaea, while data from some other genes suggest a closer relationship to bacteria Genetic analyses indicate that extensive horizontal gene transfer has occurred throughout the evolutionary history of life Chapter 27 Vocabulary Aerobic Respiration A catabolic pathway for organic molecules, using oxygen as the final electron acceptor in an electron transport chain and ultimately producing ATP. This is the most efficient catabolic pathway and is carried out in most eukaryotic cells and many prokaryotic organisms Anaerobic Respiration A catabolic pathway in which inorganic molecules other than oxygen accept electrons at the “downhill” end of electron transport chains Biofilms A surfacecoating colony of one or more species or prokaryotes that engage in metabolic cooperation Bioremediation The use of organisms to detoxify and restore polluted and degraded ecosystems Capsule (1) In many prokaryotes, a dense and welldefined layer of polysaccharide or protein that surrounds the cell wall and is sticky, protecting the cell and enabling it to adhere to substrates or other cells. (2) The sporangium of a bryophyte (moss, liverwort or hornwort) Chemoautotroph An organism that obtains energy by oxidizing inorganic substances and needs only carbon dioxide as a carbon source Chemoheterotroph An organism that requires organic molecules for both energy and carbon Commensalism A symbiotic relationship in which one organism benefits but the other is neither helped nor harmed Conjugation (1) In prokaryotes, the direct transfer of DNA between two cells that are temporarily joined. When the two cells are members of different species, conjugation results in horizontal gene transfer. (2) In ciliates, a sexual process in which two cells exchange haploid micronuclei but do not reproduce Decomposer An organism that absorbs nutrients from nonliving organic material such as corpses, fallen plant material, and the wastes of living organisms and converts them to inorganic forms; a detritivore Endospore A thickcoated, resistant cell produced by some bacterial cells when they are exposed to harsh conditions Endotoxin A toxic component of the outer membrane of certain gramnegative bacteria that is released only when the bacteria die Exotoxin A toxic protein that is secreted by a prokaryote or other pathogen and that produces specific symptoms, even if the pathogen is no longer present Extreme Halophile An organism that lives in a highly saline environment, such as the Great Salt Lake or the Dead Sea Extreme Thermophile An organism that thrives in hot environments Extremophile An organism that lives in environmental conditions so extreme that few other species can survive there F Factor In bacteria, the DNA segment that confers the ability to form pili for conjugation and associated functions required for the transfer of DNA from donor to recipient. The F factor may exist as a plasmid or be integrated into the bacterial chromosome F Plasmid The plasmid form of the F factor Facultative Anaerobe An organism that makes ATP by aerobic respiration if oxygen is present but that switches to anaerobic respiration or fermentation if oxygen is not present Fimbria A short, hairlike appendage of a prokaryotic cell that helps it adhere to the substrate or to other cells Gram Stain A staining method that distinguishes between two different kinds of bacterial cell walls; may be used to help determine medical response to an infection Gram Negative Describing the group of bacteria that have a cell wall that is structurally more complex and contains less peptidoglycan than the cell walls of gram positive bacteria. Gram negative bacteria are often more toxic than gram positive bacteria Gram Positive Describing the group of bacteria that have a cell wall that is structurally less complex and contains more peptidoglycan than the cell walls of gram negative bacteria. Gram positive bacteria are usually less toxic than gram negative bacteria Heterocyst A specialized cell that engages in nitrogen fixation in some filamentous cyanobacteria Host The larger participant in a symbiotic relationship, often providing a home and food source for the smaller symbiont Methanogen An organism that produces methane as a waste product of the way it obtains energy. All known methanogens are in domain Archaea Nitrogen Fixation The conversion of atmospheric nitrogen to ammonia. Biological nitrogen fixation is carried out by certain prokaryotes, some of which have mutualistic relationships with plants Nucleoid A nonmembrane enclosed region in a prokaryotic cell where its chromosome is located Obligate Anaerobe An organism that requires oxygen for cellular respiration and cannot live without it Parasite An organism that feeds on the cell contents, tissues or body fluids of another species (the host) while in or on the host organism. Parasites harm but usually do not kill their host Parasitism A symbiotic relationship is which one organism, the parasite, benefits at the expense of another, the host, by living either within or on the host Pathogen An organism or virus that causes disease Peptidoglycan A type of polymer in bacterial cell walls consisting of modified sugars cross linked by short polypeptides Photoheterotroph An organism that uses light to generate ATP but must obtain carbon in organic form Pilus In bacteria, a structure that links one cell to another at the start of conjugation; also called a sex pilus or conjugation pilus Plasmid A small, circular, doublestranded DNA molecule that carries accessory genes separate from those of a bacterial chromosome R Plasmid A bacterial plasmid carrying genes that confer resistance to certain antibiotics Symbiont The smaller participant in a symbiotic relationship, living in or on the host Symbiosis An ecological relationship between organisms of two different species that live together in direct and intimate contact Taxis An oriented movement toward or away from a stimulus Transduction A process in which phages (viruses) carry bacterial DNA from one bacterial cell to another. When these two cells are members of different species, transduction results in horizontal gene transfer Key Points Many prokaryotic species can reproduce quickly by binary fission, leading to the formation of populations containing enormous numbers of individuals. Some form endospores, which can remain viable in harsh conditions for centuries Because prokaryotes can often proliferate rapidly, mutations can quickly increase a population’s genetic variation. As a result, prokaryotic populations often can evolve in short periods of time in response to changing conditions Genetic diversity in prokaryotes also can arise by recombination of the DNA from two different cells (via transformation, transduction, or conjugation). By transferring advantageous alleles, such as ones for antibiotic resistance, genetic recombination can promote adaptive evolution in prokaryotic populations Nutritional diversity is much greater in prokaryotes than in eukaryotes. As a group, prokaryotes perform all four modes of nutrition: photoautotrophy, chemoautotrophy, photoheterotrophy, and chemoheterotrophy Among prokaryotes, obligate aerobes require O2, obligate anaerobes are poisoned by O, and facultative anaerobes can survive with or without O2 Unlike eukaryotes, prokaryotes can metabolize nitrogen in many different forms. Some can convert atmospheric nitrogen to ammonia, a process called nitrogen fixation Prokaryotic cells and even species may cooperate metabolically. Metabolic cooperation also occurs in surfacecoating biofilms that include different species Molecular systematics is helping biologists classify prokaryotes and identify new clades Diverse nutritional types are scattered among the major groups of bacteria. The two largest groups are the proteobacteria and grampositive bacteria Some archaea, such as extreme thermophiles and extreme halophiles, live in extreme environments. Other archaea live in moderate environments such as soils and lakes Decomposition by heterotrophic prokaryotes and the synthetic activities of autotrophic and nitrogen fixing prokaryotes contribute to the recycling of elements in the ecosystem Many prokaryotes have a symbiotic relationship with a host; the relationships between prokaryotes and their host range from mutualism to commensalism to parasitism People depend on mutualistic prokaryotes, including hundreds of species that live in our intestine and help digest food Pathogenic bacteria typically cause disease releasing exotoxins or endotoxins. Horizontal gene transfer can spread genes associated with virulence to harmless species or strains Prokaryotes can be used in bioremediation, production of biodegradable plastics, and the synthesis of vitamins, antibiotics and other products Chapter 28 Vocabulary “SAR” Clade One of four supergroups of eukaryotes proposed in a current hypothesis of the evolutionary history of eukaryotes. This supergroup contains a large, extremely diverse collection of protists from three major subgroups: stramenopiles, alveolates, and rhizarians. Alga A member of a diverse collection of photosynthetic protists that include both unicellular and multicellular forms. Algal species are included in three eukaryote supergroups (Excavate, SAR clade and Archaeplastida) Alternation of Generations A life cycle in which there is both a multicellular diploid form, the sporophyte and a multicellular haploid form, the gametophyte; characteristic of plants and some algae Alveolates One of the three major subgroups for which the “SAR” eukaryotic supergroup is named. This clade arose by secondary endosymbiosis; alveolate protists have membrane enclosed sacs (alveoli) located just under the plasma membrane Amoeba A protist characterized by the presence of pseudopodia Amoebozoan A protist in a clade that includes many species with lobe or tube shaped pseudopodia Apicomplexan A protist in a clade that includes many species that parasitize animals. Some apicomplexans cause human disease Archaeplastida One of the four supergroups of eukaryotes proposed in a current hypothesis of the evolutionary history of eukaryotes. This monophyletic group, which includes red algae, green algae and land plants, descended from an ancient protist ancestor that engulfed a cyanobacterium Blade A leaflike structure of a seaweed that provides most of the surface are for photosynthesis Brown Alga A multicellular, photosynthetic protist with a characteristic brown or olive color that results from carotenoids in its plastids. Most brown algae are mine and some have a plantlike body Cercozoan An amoeboid or flagellated protist that feeds with threadlike pseudopodia Ciliate A type of protist that moves by means of cilia Diatom Photosynthetic protist in the stramenopile clade; diatoms have a unique glasslike wall made of silicon dioxide embedded in an organic matric Dinoflagellate A member of a group of mostly unicellular photosynthetic algae with two flagella situated in perpendicular grooves in cellulose plates covering the cell Diplomonad A protist that has modified mitochondria, two equal sized nuclei and multiple flagella Endosymbiosis A relationship between two species in which one organism lives inside the cell or cells of another organism Euglenid A protist, such as Euglena or its relatives, characterized by an anterior pocket form which one or two flagella emerge Euglenozoan A member of a diverse clade of flagellated protists that includes predatory heterotrophs, photosynthetic autotrophs and pathogenic parasites Excavata One of four supergroups of eukaryotes proposed in a current hypothesis of the evolutionary history of eukaryotes. Excavates have unique cytoskeletal features, and some species have an “excavated” feeding groove on one side of the cell body Foram An aquatic protist that secretes a hardened shell containing calcium carbonate and extends pseudopodia through pores in the shell Golden Alga A biflagellated, photosynthetic protist named for its color, which results from its yellow and brown carotenoids Green Alga A photosynthetic protist, named for green chloroplasts that are similar in structure and pigment composition to the chloroplasts of land plants. Green algae are a paraphyletic group; some members are more closely related to land plants than they are to other green algae Heteromorphic Referring to a condition in the life cycle of plants and certain algae in which the sporophyte and gametophyte generations differ in morphology Holdfast A rootlike structure that anchors a seaweed Isomorphic Referring to alternating generations in plants and certain algae in which the sporophytes and gametophytes look alike, although they differ in chromosome number Kinetoplastid A protist, such a trypanosome, that has a single large mitochondrion that houses an organized mass of DNA Mixotroph An organism that is capable of both photosynthesis and hetertrophy Opisthokont A member of an extremely diverse clade of eukaryotes that includes funig, animals and several closely related groups of protists Parabasalid A protist, such as a trichomonad, with modified mitochondria Protist An informal term applied to any eukaryote that is not a plant, animal or fungus. Most protists are not unicellular, though some are colonial or multicellular Pseudopodium A cellular extension of amoeboid cells used in moving and feeding Radiolarian A protist, usually marine, with a shell generally made of silica and pseudopodia that radiate from the central body Red Alga A photosynthetic protist, named for its color, which results from a red pigment that maska the green of chlorophyll. Most red algae are multicellular and marine Rhizaria One of the three major subgroups for with the “SAR” eukaryotic supergroup is named. Many species in this clade are amoebas characterized by threadlike pseudopodia Secondary Endosymbiosis A process in eukaryotic evolution in which a heterotrophic eukaryotic cell engulfed a photosynthetic eukaryotic cell, which survived in a symbiotic relationship inside the heterotrophic cell Stipe A stemlike structure of a seaweed Stramenopila One of the three major subgroups for which the “SAR” eukaryotic supergroup is named. This clade arose by secondary endosymbiosis and includes diatoms and brown algae Unikonta One of four supergroups of eukaryotes proposed in a current hypothesis of the evolutionary history of eukaryotes. This clade, which is supported by studies of myosin proteints and DNA, consists of amoebozoans and opisthokonts. Key Facts Domain Eukarya includes many groups of protists, along with plants, animals and fungi. Unlike prokaryotes, protists and other eukaryotes have a nucleus and other membrane enclosed organelles, as well as a cytoskeleton that enables them to have asymmetric forms and to change shape as they feed, more or grow Protists are structurally and functionally diverse and have a wide variety of life cycles. Most are unicellular. Protists include photoautotrophs, heterotrophs and mixotrophs Current evidence indicated that eukaryotes originated by endosymbiosis when an archaeal host engulfed an alpha proteobacterium that would evolve into an organelle found in all eukaryotes, the mitochondrion Plastids are thought to be descendants of cyanobacteria that were engulfed by early eukaryotic cells. The plastidbearing lineage eventually evolved into red algae and green algae. Other protist groups evolved from secondary endosymbiosis events in which red algae or green algae were themselves engulfed In one hypothesis, eukaryotes are grouped into four supergroups. Each a monophyletic clade: Excavata, “SAR” clade, Archaeplastida and Unikonta Excavata include protists with modified mitochondria and spiral or crystalline rod inside flagella “SAR” clade includes protists with hairy and smooth flagella, membrane enclosed sacs beneath plasma membrane and amoebas with threadlike pseudopodia Archaeplastida includes protists like red and green algae with a photosynthetic pigment and plant type chloroplasts Unikonts include protists with lobe or tube shaped pseudopodia Protists form a wide range of mutualistic and parasitic relationships that affect their symbiotic partners and many other members of the community Photosynthetic protists are among the most important producers in aquatic communities. Because they are at the base of the food web, factors that affect photosynthetic protists affect many other species in the community Chapter 29 Vocabulary Angiosperm A flowering plant, which forms seeds inside a protective chamber called an ovary Anther In an angiosperm, the terminal pollen sac of a stamen, where pollen grains containing sperm producing male gametophytes form Antheridium In plants, the male gametangium, a moist chamber in which gametes develop Apical Meristem Embryonic plant tissue in the tips of roots and buds of shoots. The dividing cells of an apical meristem enable the plant to grow in length Archegonium In plants, the female gametangium, a moist chamber in which gametes develop Bryophyte An informal name for a moss, liverwort or hornwort; a nonvascular plant that lives on land but lacks some of the terrestrial adaptations of vascular plants Embryophyte Alternate name for land plants that refers to their shared derived trait of multicellular dependent embryos Gametangium Multicellular plant structure in which gametes are formed. Female gametangia are called archegonia, and male gametangia are called antheridia Gametophore The mature gameteproducing structure of a moss gametophyte Gametophyte In organisms (plants and some algae) that have alternation of generations, the multicellular haploid form that produces haploid gametes by mitosis. The haploid gametes unite and develop into sporophytes Gymnosperm A vascular plant that bears naked seeds seeds not enclosed in protective chambers Heterosporous Referring to a plant species that has two kinds of spores: microspores, which develop into make gametophytes and megaspores, which develop into female gametophytes Homosporous Referring to a plant species that has a single kind of spore, which typically develops into a bisexual gametophyte Hornwort A small, herbaceous, nonvascular plant that is a member of the phylum Anthocerophyta Leaf The main photosynthetic organ of vascular plants Lignin A strong polymer embedded in the cellulose matrix of the secondary cell walls of vascular plants that provides structural support in terrestrial species Liverwort A small, herbaceous, nonvascular plant that is a member of the phylum Hepatophyta Lycophyte An informal name for a member of the phylum Lycophyta, which includes club mosses, spike mosses and quillworts Megaphyll A leaf with a highly branched vascular system, characteristic of the vast majority of vascular plants Megaspore A spore from a heterosporous plant species that develops into a female gametophyte Microphyll In lycophytes, samll leaf with a single unbranched vein Microspore A spore from a heterosporous plant species that develops into a male gametophyte Monilophyte An informal name for a member of the phylum Monilophyta, which includes ferns, horsetails and whisk ferns and their relatives Moss A small, herbaceous, nonvascular plant that is a member of the phylum Bryophyta Peat Extensive deposits of partially decayed organic material often formed primarily from the wetland moss Sphagnum Peristome A ring of interlocking, toothlike structures on the upper part of a moss capsule (sporangium), often specialized for gradual spore discharge Phloem Vascular plant tissue consisting of living cells arranged into elongated tubes that transport sugar and other organic nutrients throughout the plant Protonema A mass of green, branched, one cell thick filaments produced by germinating moss spores Rhizoid A long, tubular single cell or filament of cells that anchors bryophytes to the ground. Unlike roots, rhizoids are not composed of tissues, lack specialized conducting cells, and do not play a primary role in water and mineral absorption Root An organ in vascular plants that anchors the plant and enables it to absorb water and minerals from the soil Seed An adaptation of some terrestrial plants consisting of an embryo packaged alone with a store of food within a protective coat Seedless Vascular Plant An informal name for a plant that has vascular tissue but lacks seeds. Seedless vascular plants form a paraphyletic group that includes the phyla Lycophyta (club mosses and their relatives) and Monilophyta (ferns and their relatives) Seta The elongated stalk of a bryophyte sporophyte Sorus A cluster of sporangia on a fern sporophyll. Sori may be arranged in various patterns, such as parallel lines or dots, which are useful in fern identification Sporophyll A modified leaf that bears sporangia and hence is specialized for reproduction Sporophyte In organisms (plants and some algae) that have alternation of generations, the multicellular diploid form that results from the union of gametes. The sporophyte produces haploid spores by meiosis that develop into gametophytes Sporopollenin A durable polymer that covers exposed zygotes of charophyte algae and forms the walls of plants spores, preventing them from drying out Stoma A microscopic pore surrounded by guard cells in the epidermis of leaves and stems that allows gas exchange between the environment and the interior of the plant Strobilus The technical term for a cluster of sporophylls known commonly as a cone, found in most gymnosperms and some seedless vascular plants Tracheid A long, tapered waterconducting cell found in the xylem or nearly all vascular plants Vascular Plant A plant with vascular tissue. Vascular plants include all living plant species except liverworts, mosses and hornworts Vascular Tissue Plant tissue consisting of cells joined into tubes that transport water and nutrients throughout the plant body Xylem Vascular plant tissue consisting mainly of tubular dead cells that conduct most of the water and minerals upward from the roots to the rest of the plant Key Facts Morphological and biochemical traits, as well as similarities in nuclear and chloroplast genes, indicate that certain groups of charophytes are the closest living relatives of land plants A protective layer of sporopollenin and other traits allow charophytes to tolerate occasional drying along the edges of ponds and lakes. Such traits may have enabled the algal ancestors of plants to survive in terrestrial conditions, opening the way to the colonization of dry land Derived traits that distinguish the clade of land plants from charophytes, their closest algal relatives, include cuticles, stomata, multicellular dependent embryos and alternation of generations, apical meristems, multicellular gametangia and walled spores in sporangia Fossils show that land plants arose more than 470 million years ago. Subsequently plants diverged into several major groups, including nonvascular plants (bryophytes); seedless vascular plants, such as lycophytes and ferns and the two groups of seed plants: gymnosperms and angiosperms The three extant clades of nonvascular plants or bryophytes – liverworts, mosses and hornworts – are the earliest diverging plant lineages In bryophytes, the dominant generation consists of haploid gametophytes, such as those that make up a carpet of moss. Rhizoids anchor gametophytes to the substrate on which they grow. The flagellated sperm produced by antheridia require a film of water to travel to the eggs in the archegonia The diploid stage of the life cycle – the sporophytes – grow out of archegonia and are attached to the gametophytes and dependent on them for nourishment. Smaller and simpler than vascular plant sporophytes, they typically consist of a foot, seta (stalk_ and sporangium Fossils of the forerunners of today’s vascular plants date back about 425 million years and show that these small plants had independent, branching sporophytes and a vascular system Over time, other derived traits of living vascular plants arose, such as a life cycle with dominant sporophytes, lignified vascular tissue, welldeveloped roots and leaves, and sporophylls Seedless vascular plants include the lycophytes (phylum Lycophyta: club mosses, and quillworts) and the monilophytes (phylum Monilophyta: ferns, horsetails and whisk ferns and relatives). Current evidence indicated that seedless vascular plants, like bryophytes, do not form a clade Ancient lineages of lycophytes included both small herbaceous plants and large trees. Present day lycophytes are small herbaceous plants Seedless vascular plants formed the earliest forests about 385 million years ago. Their growth may have contributed to a major global cooling that took place during the Carboniferous period. The decaying remnants of the first forests eventually became coal Chapter 30 Vocabulary Arbuscular Mycorrhiza Association of a fungus with a plant root system in which the fungus causes the invagination of the host (plant) cells’ plasma membranes Ascocarp The fruiting body of a sac fungus (ascomycete) Ascomycete A member of the fungal phylum Ascomycota, commonly called sac fungus. The name comes from the saclike structure in which the spores develop Basal Angiosperm A member of one of three clades of early diverging lineages of extant flowering plants Carpel The ovuleproducing reproductive organ of a flower, consisting of the stigma, style and ovary Chitin A structural polysaccharide, consisting of amino sugar monomers, found in many fungal cell walls and in the exoskeletons of all arthropods Chytrid A member of the fungal phylum Chytridiomycota, mostly aquatic fungi with flagellated zoospores that represent an early diverging fungal lineage Complete Flower A flower that has all four basic floral organs: sepals, petals, stamens and carpels Conifer A member of the largest gymnosperm phylum. Most conifers are conebearing trees, such as pines and firs Cotyledon A seed leaf of an angiosperm embryo. Some species have one cotyledon, others two CrossPollination In angiosperms, the transfer of pollen from an anther of a flower on one plant to the stigma of a flower on another plant of the same species Deuteromycete Traditional classification for a fungus with no known sexual stage Dicot Refers to flowering plants that have two embryonic seed leaves, or cotyledons Dormancy A condition typified by extremely low metabolic rate and a suspension of growth and development Double Fertilization A mechanism of fertilization in angiosperms in which two sperm cells unite with two cell in the female gametophyte to form the zygote and endosperm Embryo Sac The female gametophyte of angiosperms, formed from the growth and division of the megaspore into a multicellular structure that typically has eight haploid nuclei Endosperm In angiosperms, a nutrient rich tissue formed by the union of a sperm with two polar nuclei during double fertilization. The endosperm provides nourishment to the developing embryo in angiosperm seeds Eudicot A member of a clade that contains the vast majority of flowering plants that have two embryonic seed leaves, or cotyledons Filament In an angiosperm, the stalk portion of the stamen, the pollenproducing reproductive organ of a flower Flower In an angiosperm, a specialized shoot with up to four sets of modified leaves, bearing structures that function in sexual reproduction Fruit A mature ovary of a flower. The fruit protects dormant seeds and often functions in their dispersal Haustorium In certain symbiotic fungi, a specialized hypha that can penetrate the tissues of host organisms Heterokaryon A fungal mycelium that contains two or more haploid nuclei per cell Hypha One of many connected filaments that collectively make up the mycelium of a fungus Incomplete Flower A flower in which one or more of the four basic floral organs (sepals, petals, stamens, or carpels) are either absent or nonfunctional Integument Layer of sporophyte tissue that contributes to the structure of an ovule of a seed plant Karyogamy In fungi, the fusion of haploid nuclei contributed by the two parents; occurs as one stage of sexual reproduction, preceded by plasmogamy Magnoliid A member of the angiosperm clade that is most closely related to the combined eudicot and monocot clades Micropyle A pore in the integuments of an ovule Mold Informal term for a fungus that grows as a filamentous fungus, producing haploid spores by mitosis and forming a visible mycelium Monocot A member of a clade consisting of flowering plants that have one embryonic seed leaf, or cotyledon Mycorrhiza A mutualistic association of plant roots and fungus Nucleariid A member of a group of unicellular, amoeboid protists that are more closely related to fungi than they are to other protists Opisthokont A member of an extremely diverse clade of eukaryotes that includes fungi, animals and several closely related groups of protists Ovary In flowers, the portion of a carpel in which the eggcontaining ovules develop Ovule A structure that develops within the ovary of a seed plant and contains the female gametophyte Petal A modified leaf of a flowering plant Pheromone A small molecule released into the environment that functions in communication between members of the same species Plasmogamy The fusion of the cytoplasm of cells from two individuals; occurs as one stage of sexual reproduction, followed later by karyogamy Pollen Grain In seed plants, a structure consisting of the male gametophyte enclosed within a pollen wall Pollination The transfer of pollen to the part of a seed plant containing the ovules, a process required for fertilization Seed An adaptation of some terrestrial plants consisting of an embryo packaged along with a store of food within a protective coat Sepal A modified leaf in angiosperms that helps enclose and protect a flower bud before it opens Sporangium A multicellular organ in fungi and plants in which meiosis occurs and haploid cells develop Spore (1) In the life cycle of a plant or alga undergoing alternation of generations, a haploid cell produced in the sporophyte by meiosis. A spore can divide by mitosis to develop into a multicellular haploid individual, the gametophyte, without fusing with another cell. (2) In fungi, a haploid cell, produced either sexually or asexually, that produces a mycelium after germination. Stamen The pollenproducing reproductive organ of a flower, consisting of an anther and a filament Stigma The sticky part of a flower’s carpel, which receives pollen grains Style The stalk of a flower’s carpel, with the ovary at the base and the stigma at the top Yeast Single cells fungus. Yeasts reproduce asexually by binary fission or by the pinching of small buds off a parent cell. Many fungal species can grow both as yeasts and as a network of filaments; relatively few species grow only as yeasts. Zoospore Flagellated spore found in chytrid fungi and some protists Zygomycete A member of the fungal phylum Zygomycota, characterized by the formation of a sturdy structure called a zygosporangium during sexual reproduction Zygosporangium In zygomycete fungi, a sturdy multinucleate structure in which karyogamy and meiosis occur Key Facts Dominance of the sporophyte generation, the development of seeds from fertilized ovules, and the role of pollen in transferring sperm to ovules are key features of a typical gymnosperm life cycle Gymnosperms appear early in the plant fossil record and dominated many Mesozoic terrestrial ecosystems. Living seed plants can be divided into two monophyletic groups: gymnosperms and angiosperms. Extant gymnosperms include cycads, Ginkgo biloba, gnetophytes and conifers Flowers, generally consist of four types of modified leaves: sepals, petals, stamens (which produce pollen) and carpels (which produce ovules). Ovaries ripen into fruits, which often carry seeds by wind, water or animals to new locations Flowering plants originated about 140 million years ago, and by the midCretaceous (100 mya) had begun to dominate some terrestrial ecosystems. Fossils and phylogenetic analyses offer insights into the origin of flowers Several groups of basal angiosperms have been identified. Other major clades of angiosperms include magnoliids, monocots, and eudicots Pollination and other interactions between angiosperms and animals may have contributed to the success of flowering plants during the last 100 million years Humans depend on seed plants for products such as food, wood and many medicines Destruction of habitat threatens the extinction of many plant species and the animal species they support Chapter 31 Vocabulary Arbuscular Mycorrhizal Fungus A symbiotic fungus whose hyphae grow through the cell wall of plant roots and extend into the root cell (enclosed in tubes formed by invagination of the root cell plasma membrane) Ascus A saclike spore capsule located at the tip of a dikaryotic hypha of a sac fungus Basidiocarp Elaborate fruiting body of a dikaryotic mycelium of a club fungus Basidiomycete A member of the fungal phylum Basidiomycota, commonly called club fungus. The name comes from the clublike shape of the basidium Basidium A reproductive appendage that produces sexual spores on the gills of mushrooms Coenocytic Fungus A fungus that lacks septa and hence whose body is made up of a continuous cytoplasmic mass that may contain hundreds or thousands of nuclei Conidium A haploid spore produced at the tip of a specialized hypha in ascomycetes during asexual reproduction Dikaryotic Referring to a fungal mycelium with two haploid nuclei per cell, one from each parent Ectomycorrhizal Fungus A symbiotic fungus that forms sheaths of hyphae over the surface of plant roots and also grows into extracellular spaces of the root cortex Endophyte A harmless fungus, or occasionally another organism, that lives between cells of a plant part or multicellular alga Glomeromycete A member of the fungal phylum Glomeromycota, characterized by a distinct branching form of mycorrhizae called arbuscular mycorrhizae Lichen The mutualistic association between a fungus and a photosynthetic alga or cyanobacterium Model A physical or conceptual representation of a natural phenomenon Mycelium The densely branched network of hyphae in a fungus Mycosis General term for a fungal infection Soredium In lichens, a small cluster of fungal hyphae with embedded algae Key Facts All fungi (including decomposers and symbionts) are heterotrophs that acquire nutrients by absorption. Many fungi secrete enzymes that break down complex molecules Most fungi grow as thin, multicellular filaments called hyphae; relatively few species grow only as single celled yeasts. In their multicellular form, fungi consist of mycelia, networks of branched hyphae adapted for absorption. Mycorrhizal fungi have specialized hyphae that enable them to form a mutually beneficial relationship with plants In fungi, the sexual life cycle involves cytoplasmic fusion (plasmogamy) and nuclear fusion (karyogamy), with an intervening heterkaryotic stage in which cells have haploid nuclei from two parents. The diploid cells resulting from karyogamy are short lived and undergo meiosis, producing genetically diverse hhaploid spores Many fungi can reproduce asexually as filamentous fungi or yeasts Molecular evidence indicates that fungi and animals diverged 11.5 billion years ago from a common unicellular ancestor that had a flagellum. However, the oldest fossils that are widely accepted as fungi are 460 million years old Chytrids, a group of fungi with flagellated spores, include some basal lineages Fungi were among the earliest colonizers of land; fossil evidence indicated that these included species that were symbionts with early land plants Fungi perform essential recycling of chemical elements between the living and nonliving world Lichens are highly integrated symbiotic associations of fungi and algae or cyanobacteria Many fungi are parasites, mostly of plants Humans use fungi for food and to make antibiotics Chapter 35 Vocabulary ABC HypothesisA model of flower formation identifying three classes or organ identity genes that direct formation of the four types of floral organs Apical Bud A bud at the tip of a plant stem; also called a terminal bud Apical Dominance Tendency for growth to be concentrated at the tip of a plant shoot, because the apical bud partially inhibits axillary bud growth Apical Meristem Embryonic plant tissue in the tips of roots and buds of shoots. The dividing cells of an apical meristem enable the plant to grow in length Axillary Bud A structure that has the potential to form a lateral shoot, or branch. The bud appears in the angle formed between a leaf and a stem Bark All tissues eternal to the vascular cambium, consisting mainly of the secondary phloem and layers of periderm Blade (1) A leaflike structure of a seaweed that provides most of the surface area for photosynthesis. (2) The flattened portion of a typical leaf Collenchyma A flexible plant cell type that occurs in strands or cylinders that support young parts of the plant without restraining growth Companion Cell A type of plant cell that is connected to a sievetube element by many plasmodesmata and whose nucleus and ribosomes may serve one or more adjacent sievetube elements Cork Cambium A cylinder or meristematic tissue in woody plants that replaces the epidermis with thicker, tougher cork cells Cortex (1) The outer region of cytoplasm in a eukaryotic cell, lying just under the plasma membrane, that has a more gellike consistency than the inner regions due to the presence of multiple microfilaments. (2) In plants, ground tissue that is between the vascular tissue and dermal tissue in a root or eudicot stem. Dermal Tissue System The outer protective covering of plants Determinate Growth A type of growth characteristic of most animals and some plant organs, in which growth stops after a certain size is reached Development The events involved in an organism’s changing gradually from a simple to a more complex or specialized form Endodermis In plant roots, the innermost layer of the cortex that surrounds the vascular cylinder Epidermis (1) The dermal tissue system of nonwoody plants, usually consisting of a single layer of tightly packed cells. (2) The outermost layer of cells in an animal Fiber A lignified cell type that reinforces the xylem of angiosperms and functions in mechanical support; a slender, tapered sclerenchyma cell that usually occurs in bundles Ground Tissue System Plant tissues that are neither vascular nor dermal, fulfilling a variety of functions, such as storage, photosynthesis and support Guard Cells The two cells that flank the stomatal pore and regulate the opening and closing of the pore Indeterminate Growth A type of growth characteristic of plants, in which the organism continues to grow as long as it lives Internode A segment of a plant stem between the points where leaves are attached Lateral Meristem A meristem that thickens the roots and shoots of woody plants. The vascular cambium and cork cambium are lateral meristems Lateral Root A root that arises from the pericycle of an established root Leaf Primordium A fingerlike projection along the flank of a shoot apical meristem, from which a leaf arises Lenticel A small raised area in the bark of stems and roots that enables gas exchange between living cells and the outside air Lignin A strong polymer embedded in the cellulose matrix of the secondary cell walls of vascular plants that provides structural support in terrestrial species Meristem Plant tissue that remains embryonic as long as the plant lives, allowing for indeterminate growth Meristem Identity Gene A plant gene that promotes the switch from vegetative growth to flowering Mesophyll Leaf cells specialized for photosynthesis. In C3 and CAM plants, mesophyll cells are located between the upper and lower epidermis; in C4 plants, they are located between the bundlesheath cells and epidermis Node A point along the stem of a plant at which leaves are attached Organ Identity Gene A plant homeotic gene that uses positional information to determine which emerging leaves develop into which types of floral organs Parenchyma Cell A relatively unspecialized plant cell type that carries out most of the metabolism, synthesizes and stores organic products, and develops into a more differentiated cell type Pattern Formation The development of a multicellular organism’s spatial organization, the arrangement of organs and tissues in their characteristic places in threedimensional space Periderm The protective coat that replaces the epidermis in woody plants during secondary growth, formed of the cork and cork cambium Petiole The stalk of a leaf, which joins the leaf to a node Phase Change In plants, a morphological change that arises from a transition in shoot apical meristem activity Phloem Vascular plant tissue consisting of living cells arranged into elongated tubes that transport sugar and other organic nutrients throughout the plant Pith Ground tissue that is internal to the vascular tissue in a stem; in many monocot roots, parenchyma cells that form the central core of the vascular cylinder Polarity A lack of symmetry; structural differences in opposite ends of an organism or structure, such as the root end and shoot end of a plant Primary Growth Growth produced by apical meristems, lengthening stems and roots Root An organ in vascular plants
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