Principles of Biology Study Guide
Principles of Biology Study Guide BIOL 002
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This 11 page Study Guide was uploaded by Emilly LaFleur on Wednesday February 10, 2016. The Study Guide belongs to BIOL 002 at University of Vermont taught by John J. Mitchell in Spring 2016. Since its upload, it has received 218 views. For similar materials see Principles of Biology in Biological Sciences at University of Vermont.
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Date Created: 02/10/16
BIO 002 Exam 1 Study Guide Science 1) Abody of established knowledge on a given subject 2) Away of thinking or method used to accumulate and test that knowledge The province of science is the physical or natural world Some consider science to be a complement to other human characteristics/endeavors such as aesthetics and ethics in determining our relationship to the world Scientific Method 1) Interest/gather data, verify this data 2) Ask a question, or formulate a hypothesis (if/then) 3) Test a) gather more data b) create an experiment The ‘Controlled’Experiment 2 groups - an experimental and a control group ex) 1000 people in group 1, 1000 people in group 2 Scientists conducting controlled experiments try to match up people as best they can. For example, 500 males in group 1, 500 males will also be in group 2 Experiment: Group 1 receives the drug, Group 2 receives a placebo * placebo effect - psychological Ideal experiments are double blind, meaning both the patient and the physician distributing the medication is blind to whether the pill is the treatment or a placebo. Experimental treatment vs. Control group placebo c) Natural Experiment *when unethical to perform an experiment ex)AIDS *used when it is impossible to perform said experiment 4)Accept, Reject, or Modify your hypothesis a) send to a journal > peer-reviewed by a board of specialists 5) Hypothesis 1,2,3 -> connect a few hypotheses that have been accepted as fact and produce a theory. 6) Theory made! 7) Theory is then tested until accepted or thrown out. *theories can be accepted for centuries/generations, and then later disproved. Plant Diversity “Plant” has many definitions: a. Chlorophyll containing b. Photosynthetic organisms Land plants: primary producers - they trap the energy and carbon needed by all land dwelling organisms, and they provide ecosystem services, such as formation soil, water storage, and gas exchange. Characteristics: Alteration of generations Walled spores produced in ‘sporangia’(in cell wall) - protectant Multicellular ‘gametangia’-> produces gametes, holds egg Apical meristems -> linking Multicellular ‘gametangia’ BIO 002 Exam 1 Study Guide Female - archegonium Male - antheridia Meiosis 2n->1n Greater genetic environment -> could fit into new environment Land Plant Varieties Nonvascular Plants Vascular Plants Liverworts Mosses Ferns Gymnosperms Angiosperms |____________________| |______________| ancestral griepalga seed plants |____________________________________| true vascular tissue + lignin |_____________________________| seeds + pollen |_______________________| flowers + fruits adaptations: cuticle, stomata, protected embryos (seeds), association with Fungi, production of secondary compounds stomata: openings in cell lignin Life Cycle of Moss: Male or Female gamete (sperm or egg) > fertilization (capsules) > meiotic cell division (spores) > gametophytes Newly evolved elements of the conducting system in vascular plants Tracheids are first to appear, long thin cells, as the cell matures the cytoplasm dies, leaving jus the cell wall. Life Cycle of a Fern: a ‘simple’vascular plant (Spores) Mitosis and development > (Gametophyte plant) Mitosis > (sperm and egg) Fertilization > (zygote) Mitosis and development > (mature sporophyte) Meiosis Life Cycle of a Pine: a Gymnosperm ‘seed plant’ Male or Female cone > ovule> fertilization (sperm or eggs) > embryo (seed, seedlings) > mature sporophyte Looking specifically atAngiosperms ‘Flower plants’are monocots or eudicots, categories are based on the number of seed leaves. Monocots: Flower parts are in 3s or multiples of 3, smooth leaf edges, narrow parallel veins, vascular bundles are scattered, fibrous roots. 1 seed leaf. Eudicots: Flower parts are in 4s and 5s, leaves are palmate, oval, veins are net like, vascular bundles are in a ring, taproot system. Seed leaves. The Meristem + The Developmental Organization of Plants Indeterminate > growth can continue indefinitely (due to existence of a mass of pluripotent stem cells. (the meristem) at the apexes of the Plant body. Meristems: clumps of small cell with dense cytoplasm + proportionality large nuclei. They divide relatively frequently, giving rise to two cells, on remains meristematic, while other may ‘differentiate’to contribute to the plant body. Plant Cell Division (Cytokinesis) BIO 002 Exam 1 Study Guide Begins with formation of a cell plate, around which membrane deposits process continues with the incorporation of Cellulose + other Polysaccharides + the formation of the ‘primary’cell wall. Primary wall formation will continue (until growth elongation is complete) Division plate > right angles to the long axis of the plant, increases the ‘size’or width of the plant. (opposite plate will grow in height) Plant Systems Organs: leaves, stems, + roots VEGETATIVE Flowers + fruit/seed > ‘reproductive phase’organs Systems Individual roots are organized into root system the stem module is a component of the stem system (stem + leaf are in the ‘shoot system’)cytokinesis The Stem Organ System The growing stem consists of modules, one growing on top of one another. TheApical Meristem gives rise tot eh Stem Modules Growth, Deposition, + Differentiation of apical shoot meristem cells is responsible for the development + growth of the ‘stem’ Periodic side bulges can be left behind as the tip grows, these develop into finger like leaf primordia. Branches Lateral buds (left behind meristem cells) when stimulated by the right hormones the cells are activated + the bud will grow. Plant Tissues Apical meristem of stoma + root give rise to a set of cylindrical primary meristems Dermal Tissue Outer protective covering Tightly packed epidermal cells, often with a waxy coating called the cuticle, which protects the plant from excess water loss. Sieve-Tube *May be specialized structures ex) stoma guard cells Guard Tissue Cells Parenchymal Cells > classic plant cells, vacuoles, chloroplast, (carry on photosynthesis) dermal cells on surface take in light. Collenchyma > found in upright portion, thickens walls, supports weight, flexible (can have bend) why is this good? environmental conditions > for example, does not break in harsh winds. Sclerenchyma > also support (not as long) grow in stacks, lay down a thick layer (secondary cell wall) ex) nut’s shell *cement like Vascular Tissue - Xylem H2O + mineral conducting vascular tissue of plants Primary conducting all > tracheids Vessel elements > found in angiosperms Build up cell types somewhat complex secondary cells. *leaves hollow tube structure > for fluid transport Vascular Tissue - Phloem Located toward the outside of root/stem is the principle food + metabolic transporting system *Sieve-Tube elements (direct transport cells) live cells at functional maturity (unlike the xylem cells) HIGHLY MODIFIED BIO 002 Exam 1 Study Guide Internal Stem Organization as plant stems + their systems support/separate the leaves, they lift them + expose them to air (vulnerable) Leaves Major Photosynthetic Organ Extension of shoot + stem development *not committed to becoming leaves, yet they expand by enlargement + cell division once initiated. a) Simple leaf > single, undivided blade b) Compound leaf > Blade consists of multiple leaflets (no auxiliary bud) c) Double compound leaf > each leaflet is divided into smaller leaflets Leaf Structure Thin epidermis w/waxy cuticle to maintain water, often accompanied by guard cells. Vascular bundles ramify through the blade (so no cell is more than three to four cell diameters away) Photosynthetic Parenchyma (mesophyll) divided into two sections a) Upper layer > Elongated cells (palisade layer) *dense b) Lower layer > Irregularly shaped + distributed around air spaces *spongy Root System Anchors the plant - absorbs water + nutrients, may store food Taproot system: single, large, deep, less prominent lateral roots Fibrous root system: large surface area, many thin roots, clingy Internal root structure Root apical meristem > quiescent center cell, below the center divide + gives rise to root cap cells, which protect the tip + sense gravity. Cells ‘above’the center divide, and become the three primary meristems (zone of division) above this area > The cells elongate pushing the root deeper into the soil (zone of elongation) Farther along the root cylinder the cells begin to differentiate taking on their ultimate functions (zone of maturation) ^Epidermal cells often produce exponentially long root hairs, increasing surface area + absorptive potential. Resources and Transport Primary resources 1) access to sunlight 2) access to gases CO2 +O2 3) access to H2O 4) access to minerals Phyllotaxy> growing tall + arrangement of leaves Root modifications ^ to enhance absorption of needed nutrients plants cannot use nitrogen in the N2 form that is abundant in the air. They absorb it from the soil as NO3 or NH4 (nitrogen fixing bacteria) About 80% of plants have Mycorrhizae, a mutualistic association between roots + fungi. The fungus increases the volume of soil available to the plant + renders some soil compounds more H2O soluble in exchange for sugars, amino acids + vitamins. (give + take) Cellular mechanism of Transport Requires a transport protein for hydrophilic subs against a lipid membrane. Plant cells have an array of such proteins. H+ATPase > primary controller of transport in plant cells BIO 002 Exam 1 Study Guide active transport protein uses energy inATP to generate a Hydrogen gradient + the membrane potential for plant cells little energy is required to pump hydrogen out Water movement H2O can move by diffusion down it’s concentration gradient (solute or osmotic potential of H2O) Water can also move from high pressure to low pressure. Transport pathways 1)Apoplast: the continuum of the extracellular space + porous cell walls of plant tissues as well as the dead interiors of Xylem cells. 2) Symplast: the cytoplasmic continuum, each plant cell is connected to its neighbors via plasmodesmata. Dissolved molecules can move from cell to cell throughout a tissue via this path. 3) Transmembrane Route: Here a substance must be transported across multiple cell membranes to transverse a tissue. Root Uptake Mechanisms Mineral solutes can enter the apoplast + passively diffuse through the outer regions of the root. Minerals can also be actively transported into cytoplasm of the root hairs (water will follow passively) They can diffuse through the symplast toward the center of the root.At the endodermis the apoplectic route is blocked by the hydrophobic casparian strip. The endodermal cell membranes are the ‘Gate Keepers’for mineral entry into the stele. *The endoderm prevents its return to the soil solution. Transportation + Guard CellAction 1) In the presence of light, potassium ions are actively transported into the guard cells from the epidermal cells. 2) Higher internal K+ and CI- concentrations give guard cells a more negative potential, causing them to take up water, increase in pressure, and stretch, opening the stoma. 3) In the absence of light, as K+ diffuses passively out of the guard cells, water follows by osmosis, the guard cells go limp, and the stoma changes. Xylem Transport (Transportation - Cohesion - Tension Mechanism) 1) Transportation: water vapor diffuses out of the stomata 2) Water evaporates from mesophyll cell walls 3) Tension pulls water from the veins into the apoplast of the mesophyll 4) Tension pulls the water column upward and outward in the xylem of veins in the leaves 5) Tension pulls the water column upward in the xylem of the root and stem 6) Water molecules from a cohesive water column from the roots to the leaves 7) Water moves into the xylem by osmosis 8) Water enters root from soil by osmosis *Reviewed cellular mechanisms of transport, transport pathways. root uptake mechanism, and guard cells, all information which is listed in Week 2 BIO 002 notes from the lecture on January 29th, 2016. The Pressure Flow Model of PhloemActivity Sucrose of amino acids are loaded into phloem - often diffuse out of source cells into the apoplast + are taken into sieve companion cells by secondary active transport before entry into phloem sieve tube. 1) Transcription pulls water up xylem vessels 2) Source cells load Sucrose into phloem sieve tubes, reducing their H2O potential *often an active process BIO 002 Exam 1 Study Guide 3) H2O is taken from xylem vessels by osmosis, raising the pressure potential in the sieve tube to sink cells 4) Internal pressure differences drive the sap down the sieve tube to sink cells. 5) Sucrose is unloaded into sink cells *By passive or active transport mechanism 6) H2O moves back to xylem vessels Plant Responsiveness Respond to a wide variety of Physical and Biological stimuli, stimuli maybe be internal or derive from the environment of the plant. ^These often involve alterations in plant growth, reproduction of plant development Examples of Physical/Biological Stimuli Physical Biological Light Internal: Atmospheric gases Hormones Humidity Environmental: Temperature Herbivores Touch, wind Agricultural hormone applications Gravity Pathogens Soil water Organic chemicals emitted by plants Soil microorganisms Plants (since they can get up and go) usually respond by adjusting their pattern of development and growth These factors may include: 1) Environmental cues 2) Receptors for said cues 3) Hormonal release > in response, could mediate the plants response to the cue 4) Acellular signal transduction cascade to amplify the specific response to the hormone 5) Transcriptional induction or post-translational modification of metabolically active proteins 6) Aresultant change in all division, cell expansion, and or cell differentiation (specialized activities) Reviewing the process of Meiosis In changeable environments sexual reproduction is favored since meiosis and fertilization allow allele shuffling and more ready evolutionary change Meiosis I: Interphase > Prophase (Recombination occurs) > Metaphase (Homologues pair) >Anaphase (Sister chromatids remain attached) > Telophase (split) Meiosis II: repeats Meiosis I (without prophase) this time with the sister chromatids, and now ending with four haploid cells. *Diagrams of these processes can be found on the Bb site, under Course Materials, and Figures: Angiosperm Reproduction, Development and Hormones Plant Reproductions All sexual reproduction in plants, precedes by ‘alteration of generations’Land plants have two multicellular generations > Gametophytes + Sporophytes…. to be continued on February 3rd’s lecture! Plant Reproduction continued Diploid Sporophyte> the angiosperm flower made of modified leaves (separated by short internodes) BIO 002 Exam 1 Study Guide Calyx = all sepals Corolla = all petals Androecium = all stamens Gynoceciam = all carpels (pistil - a single carpel or group of fused carpels) Floral Organs Sepals: base of flower > green + leaf like (protect the bud) Petals: just above the sepals, brightly colored + scented (attract pollinators) Stamen: consist of a stalk called the filament supporting the anther > contains chambers (microsporangia) produce pollen carpels > female reproductive structures. pollen land on stigma, (held up by a long skinny neck , at the base is the ovary with one re more ovals. Composed of megapozgical tissue (responsible for egg production) Complete flowers have all four floral organs - Incomplete flowers luck one or more of these structures. Male 1. Microspore mother cells develop within pollen sacs of anther. 2. Meiotic cell division produces four haploid microspores 3. Each microspore produces an immature male gametophyte male gametophyte by mitotic cell division 4. After pollination, the generative cell produces two sperm calls by mitotic cell division. The male gametophyte is now mature Female 1. Megaspore mother cell develops within ovule 2. Meiotic cell division produces four haploid megaspores, three degenerate 3. Remaining megaspore forms eight nuclei by mitosis 4. Cytoplasmic division produces seven cells of mature female gametophyte Pollination + Fertilization Pollen is transferred from the anther to a receptive stigma of an individual of the same species. 80% of all pollination is biotic > employing animal go-betweens of the remains 20% (most by wind pollination) Once a pollen has landed on a suitable stigma > it absorbs water, germinates, + grows a pollen tube. Generative cells will form two sperm nuclei. (will follow the tube nuclear down the tube) Pollen tube grows between the cells of the stigma + style toward the ovary - process guided by chemoattractant. *produced by Snergids - GABA? Double Fertilization One sperm nuclear unites with the egg producing the zygote. The other unites with the two central nuclei producing a 3n cell that will expand into the endosperm tissue. Growth, Morphogenesis, + Cell Differentiation Produce the plant body Growth > cell replication + elongation Morphogenesis > cell positioning + associations that determine tissue + organ shape Differentiation > the process by which cells take on specific functions Asymmetrical divisions influence cell fate *effects all specialization + plant polarity Asingle gene mutation can effect hormone transport, division symmetry + plant shape BIO 002 Exam 1 Study Guide Position-based mechanisms (rather than lineage based mechanisms, are responsible for determining all fate) (differentiation) Cell:cell contact and/or local gradients affect the activation or inactivation of specific genes. Embryo Development asymmetrical division of zygote a. larger basal cell (super-sensor) b. terminal cell (embryo proper) The Seed Develops from the ovule Endosperm: absorbs + stores nutrients integuments harden + form seed coat (protecting covering that surrounds/protects seed) AS the last stage occurs the seed dehydrates > no water, concentrating the abscise acid (hormone) this concentration causes the embryo’s metabolism to cease + the seed to enter dormancy Ovule > Developing Seed > Mature Seed Seed Dormancy + Germination During seed production, material tissues and the embryo increase the production of asbestic acid. The hormone slows metabolism + induces the expression of storage related proteins. This + dehydration induces dormancy in the seed. Gibberellins are involved in seed germination: Auxin + Elongation Indolacetic acid > (chemicallyAuxin is indolacetic acid) works through membrane bound receptor stimulates all elongation AH (Hydrophobic) < neutral Auxins + Tropisms Shoot apical meristems is the primary source of auxin production *carried down the shoot ___ concentration gradient that can function as a ‘morphogen’ *gravitropism: following gravity, seed growing in wrong orientation > gravitropism assists seeds in growing Auxin moves throughout the seed to help shoot/root elongation, all in relation to gravitropism Statoliths: Starch-heavy plastids, located in gravity sensing cells called statocytes found in endodermis- like cells of the shoot + in the center of the root cap. *Cell elongation response toAuxin carries with the differentiation state of the target cell. Reviewed: Seed Dormancy + Germination,Auxin + Cell Elongation (Indo. acid), + Gravitisophism The plant response to light > “photoreceptors” Phototrophin: main ‘blue-light’sensor. Made of protein kinase + a flavin pigment that can absorb blu- light. Flavin becomes linked to the protein activating it’s kinase function. *primary sensor involved in Phototropism. (a plant’s directional growth response to light) Phytochrome: plant’s ‘red-light’sensor. Two forms: Pr + Pfr BIO 002 Exam 1 Study Guide Pr: Only form in the dark + absorbs red light, converting into the active Pfr form. Pfr: Sends signals downstream, absorbs far-red light + converts back to Pr in sunlight, the equilibrium favors the Pfr form + signal generation Phytochrome signaling is involved in seed germination, greening, and shade avoidance + flowering. Phytochrome Greening (De-Etiolation) In germination the initial embryo looks nothing like a mature plant, it’s ‘seed leaves’are folded +white, and the root has no hairs. The root + stem are essentially specialized for rapid growth to penetrate the soil before reserves are exhausted. (Etiolation) are When the embryo breaks ground, it mist transform to a more ‘normal’status, this is DE-ETIOLATION + is a response to light exposure. The light sensor is Phytochrome. When the Embryo breaks ground & is exposed to light a signal cascade leads to: expression of greening components, including chlorophyll, enzymes in photosynthesis, and hormones that will regulate plant growth. Phototropism *Plants tend to bend toward their source of light. The Darwin's, Charles, + his son Francis first studies this. They choose to study grass seedlings (monocots) + noted that the plant was without it’s light sensor. The sensor was in the tip and influenced the rest of the plants growth. Deter Boysen-Jenson tests this ^ and cuts off the tips. The plants didn’t bend, he then reattached the tip in the dark, and the plant grew when he placed them in the sunlight, they grew toward the light. Concluded: the top produced a chemical that diffuses down plant + influences it’s growth. Frits Went confirms the existence + names a new hormoneAUXIN (mid 1920s) Auxin is a plant hormone that causes the elongation of cells in shoots and is involved in regulating plant growth. Auxin + Phototropism The shoot apical meristem is the primary source ofAuxin production. It is carried down the shoot creating a concentration gradient that can function as a ‘morphogen’and thus effect plant form. * the blue light photoreceptor traduces the response Cell elongation on the auxin concentrated side increases bending in the stem Process of Phototropism: 1) Auxin moves to the shaded side 2) Redistribution stopes asAuxin moves down the coleoptile 3) AhigherAuxin concentration causes more rapid growth on the shaded side. The tip curves toward the light. Apical Dominance + The control of Branching Auxin > produced by the shoot apical meristem + diffuses down the stem. It is inhibitory to the imitation of branches by auxiliary bud meristems (apical dominance) Cytokinins > produced b the root meristem + is carried up the root shaft into the stem. (apical dominance) But will stimulate lateral branch development. BIO 002 Exam 1 Study Guide The development of lateral branches + roots is significantly influenced by their position within the dual gradient (ratio) of these hormones. When auxin is high, the lateral buds are inhibited by the high levels. The lateral buds then develop into branches (optimal ratio of auxin to cytokinin) Later roots develop (w/ the optimal ration of cytokinin to auxin) When cytokinin levels are high, lateral roots are inhibited. Day length & flowering Timing of flowering is funded to the physiology of the plant + the demands of their environment. Day length / Light exposure The Phytochrome System, compared to the internal ‘Biological Clock’in order for the plant to determine the appropriate time in the season for flowering. The Light Signal & Flower Induction Phyotochromes within leaves sense the variation in the light signal. In response the leaf produces Florigen (The FT protein) The flowering hormone now moves via phloem. The FT binds with he transcription factor FD, + jointly they stimulate “Leafy” Floral identity genes > actions convert a leaf producing meristem to a reproductive meristem. TheABC Hypothesis Agene activity > Sepals + Petals B gene activity > Petals + Stamens C gene activity > Stamens + Carpels Ethylene + Senescence Ethylene > (a gas) activates a signal cascade that results in the introduction of a series of enzymes + factors (promote a apoptosis of the affected cell) Auxin + Gibberlin promote fruit development, while ethylene controls it’s ripening. The ratio ofAuxin to Ethylene controls the timing of abscission. Plant Growth Hormones AbscisicAcid > maintains seed dormancy, winter dormancy, and closes stomata Auxins > promote stem elongation, root initiation, fruit growth, inhibit axillary bud outgrowth, and leaf abscission Brassinosteroids > promote stem and pollen tube elongation Cytokinins > Inhibit leaf senescence, promote cell division, and axillary bud outgrowth Ethylene > Promotes fruit rippening and leaf abscission, inhibits stem elongation and gravitropism Gibberellin > Promote seed germination, stem growth, and fruit development, break winter dormancy, and mobilize nutrient reserves in grass seeds Defense against herbivores Toxins Secondary Metabolites Cyanogenic Glycosides: release cyanide in animal’s digestive tract *Enzymes shut them down, the predator gets sick, plant is no longer threatenedAlkaloids: Over stimulate the nervous system ex: Nicotine Tannins: Bind to and inactivate animal enzymes Oils: Repel predators with their order BIO 002 Exam 1 Study Guide ModifiedAminoAcids: Can be incorporated into animal protein and lead to their inactivation Defense: The systemin Wound Response releases systemic ^When it is chewed/attacked The hormone goes to the fruit, takes the systemin to the new leaves and binds to the new leaf, fruit, and flowers, now all the new cells have protease inhibitors which prevents the predators from digesting the plants (less attractive) DefenseAgainst Herbivores: Predator Recruitment . 1) Wounding 1) Chemical in Saliva . 2) Signal transduction pathway . 3) Synthesis + releases of volatile attractants . 4) Recruitment of parasitoid wasps + lay their eggs within caterpillars DefenseAgainst Pathogens 3 lines of defense . 1) Barriers > The epidermis + periderm with their toughened + water resistant cell walls are the first line of defense. . 2) The hypersensitive response: walls off invader. Ex) Bacteria eats its way through the cell wall (using enzymes) the cell ruptures is the enzymes are successful. The cell in defense sends signaling molecules “I’m about to be invaded” the cell will develop antibiotics to fight the bacteria. . 3) Thicken the cell wall + send warning signals to other cells to thicken.
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