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Bio Orgs exam 1
| Question | Answer |
|---|---|
| dermal tissue | outer protective covering of the plant |
| dermal tissue | outer protective covering of the plant nonwoody= epidermis cuticle = waxy epidermal coating that helps prevent water loss guard cell = involved in gaseous exchange |
| vascular tissue | transport of materials through plant and provide mechanical support |
| xylem | conducts water and dissolved minerals upward (root 2 shoot); dead at maturity |
| tracheids | all vascular plants, long, thin cells with tapered ends, water move mainly though pits where it doesn’t have to cross secondary walls |
| vessel elements | wider, shorter, thinner walled, less tapered than tracheids, form long pipes known as vessels |
| phloem | -transports sugars from where they are made to where they are needed (alive at maturity) -sugar and other nutrients transported though long narrow cells called sieve cells (chains of cells = sieve tube elements) |
| sieve tube elements | lack nucleus/ribosomes/distinct vacuole/cytoskeletal elements to enable nutrients to pass more easily through the cell |
| companion cell | nonconducting cell that is connected to the sieve tube element by numbers plasmodesmata ; their nucleus and ribosomes serve the adjacent sieve tube |
| ground tissue | internal to the vascular tissue known as pith; external known as cortex |
| parenchyma | large central vacuole, perform most metabolic functions, photosynthesis occurs w/in chloroplasts of parenchyma cells, retain the ability to divide and differentiate into other types of plant cells under particular conditions |
| Collenchyma | help support young parts off the shoot, generally elongated cells that have thicker primary walls (unevenly thick), just below the epidermis in young stems/petioles, provide flexible support without restraining growth, living and flexible at maturity |
| Sclerenchyma cells | more rigid than collenchyma cells, function as support, secondary wall contains large amounts of lignin (strengthening polymer), cannot elongate and occur in areas that have stopped growing in length, dead at functional maturity |
| sclereids | boxier than fibers and irregular in shape, very thick lignified secondary walls |
| fibers | usually grouped in strands, long, slender, tapered (hemp used for fiber) |
| secondary growth | made possible by 2 lateral meristems extending along the the length of a shoot or root where primary growth has ceased (growth in thickness) |
| lateral meristem | vascular cambium/cork cambium; cylinders of dividing cells one cell thick |
| vascular cambium | adds vascular tissue called secondary xylem (wood) and secondary phloem |
| vascular rays | radial files of mostly parenchyma cells that connect the secondary xylem and phloem (move water and nutrients between secondary xylem and phloem, store carbs, wound repair) |
| cork cambium | replaces the epidermis with thicker tougher periderm |
| spring wood | usually has secondary xylem cells with large diameters and thin cell walls |
| summer wood | thick walled cells that provide more support |
| endodermis | innermost layer of cells in the root cortex that functions as a last checkpoint for selective passage of minerals from the corvette into the vascular cylinder |
| caspian strip | belt made of suberin prevents water and minerals from crossing the endodermis and entering the vascular cylinder via the apoplast, MUST cross endodermis |
| suberin | waxy material impervious to water/ dissolved minerals |
| bulk flow via the xylem | epidermis —> root cortex —> vascular cylinder —> xylem sap transported by bulk flow |
| xylem sap | water and dissolved minerals in the xylem |
| pushing xylem sap : root pressure | at night = no transpiration —> root cells actively pumping mineral ions into xylem of vascular cylinder/caspian strip prevent minerals from leaking back out into the cortex and soil —> water flows in from root cortex creating root pressure |
| guttation | more water entering leaves than transpired out |
| pulling xylem sap : cohesion -tension hypothesis | transpiration proves the pull of rate ascent of xylem sap, cohesion of water molecules transmits this pull along the entire length of xylem from shoots to roots (normally under negative pressure) |
| translocation | transport of products of photosynthesis |
| phloem sap | aqueous solution that flows through sieve tubes (mainly sugar/sucrose) |
| sugar source | plant organ that is a net producer of sugar |
| sugar sink | organ that is a net consumer or depository of sugar |
| phloem moving sugar | requires active transport via proton pumping and H+/sucrose cotransport |
| pressure flow | phloem sap moved though sieve tubes of angiosperms by bulk flow driven by this |
| apoplast | consists of everything external to the plasma membranes of living cells and includes cell walls, extracellular spaces, interior of dead cells (vessel elements / tracheids) |
| apoplectic route | water and solutes move along the continuum of cell walls and extracellular spaces |
| symplast | entire mass of cytosol of all the living cells in a plant, as well as the plasmodesmata , the cytoplasmic channels that interconnect them |
| symplastic route | water and solutes move along the continuum of cytosol (cross a plasma membrane once when they first enter the plant) once in the cell move around via plasmodesmata |
| transmembrane route | water and solutes move out of one cell, across the cell wall, into the neighboring cell which may pass them to the next cell in the same way |
| bulk flow | movement of liquid in response to a pressure gradient |
| carbon, oxygen | if lacking cause poor growth |
| hydrogen | if lacking causes wilting and poor growth |
| nitrogen | component of nuclei acids, proteins, chlorophyll ; if lacking can cause chlorosis at tips of older leaves |
| potassium | enzyme cofactor, major solute functioning in water balance , operation of stomata ; if lacking can cause mottling of older leaves, drying of leaf edges, roots poorly developed |
| calcium | important component of middle lamella and cell walls, maintains membrane function, signal transduction ; if lacking —> crinkling of young leaves, death of terminal buds |
| magnesium | component of chlorophyll, cofactor of many enzymes ; if lacking —>chlorosis between veins, found in older leaves |
| phosphorous | component of nucleic acids, phospholipids, ATP; if lacking —> healthy appearance but very slow development, thin stems, purpling of veins, poor flowering |
| chlorosis | yellowing of leaves |
| nitrification | oxidation of ammonia to nitrite followed by oxidation to nitrate; mediated by nitrifying bacteria |
| nitrogen fixation | nitrogen fixing bacteria convert gaseous nitrogen (N2) into NH3, which then picks up another H+ forming NH4 |
| ammonification | decomposers convert the organic nitrogen from fead organic material into NH4+ |
| rhizobium | form efficient an intimate associations with the roots of legumes; create nodules on roots -inside each nodule rhizobium bacteria form bacteroids which are contained within vesicles formed in the root cells |
| parasitic | absorb water, minerals, products for photosynthesis from living hosts; many have roots that function as haustoria (nutrient absorbing projection that tap into host plant) |
| carnivorous | supplement mineral diet by capturing insects and small animals, live in habitats where soils are poor in nitrogen/other minerals |
| embryo sac | female gametophyte that develops inside each ovule |
| Flower life cycle step 1 | in megaspornagium the megasporocyte divides by meiosis producing 4 megaspores. it undergoes 3 mitotic divisions and produces a female gametophyte |
| Flower life cycle step 2 | In the anther of a stamen, each microsporangium contains many microsporocytes. Each microsporocyte divides by meiosis producing 4 microspores |
| flower life cycle step 3 | a microspore develops into a pollen grain. generative cell of the gametophyte will divide forming two sperm. tube cell will produce the pollen tube |
| flower life cycle step 4 | each pollen tube elongates thought the style. When reaching an ovule it discharges its two sperm |
| flower life cycle step 5 | double fertilization occurs, one sperm fertilizes the egg forming a zygote. the other sperm fertilizes the central cell forming the endosperm |
| flower life cycle step 6 | the zygote develops into an embryo that is packaged along with food into a seed |
| flower life cycle step 7 | when a seed germinates the embryo develops into a mature sporophyte |
| imbibition | uptake of water due to low water potential of dry seed ; can initiate germination |
| apomixis | asexual production of seeds |
| totipotent | any cell that can divide and asexually generate a clone of the original organism |
| etiolation | physical adaptations for growing in dark |
| hormone | signaling molecule that is produced in low concatenations by one part of an organisms body and transported to other parts where either binds to a specific receptor and triggers responses in target cells and tissues |
| auxin | apical meristems/developing seeds; regulates plant growth, allows plant to bend toward light |
| cytokinins | roots ; cell division, counters senescence, makes new plant organs (roots vs. shoots) |
| gibberellins | meristems/developing seeds; seeds alarm clock (stimulates germination), promotes elongation at internodes |
| Abscisic acid | all plant cells; inhibits growth, promotes stomatal closure during drought, promotes seed dormancy and inhibits early germination |
| Ethylene | most parts of plant, produced in high concentrations during senescence; promotes ripening of fruit, leaf abscission, promotes root and root hair formation, promotes flowering in pineapple family |
| brassinosteroids | all plant tissues; cell expansion/division in shoots, root growth + at low - at high concentrations, promote xylem differentiation and inhibit phloem differentiation, promote seed germination and pollen tube elongation |
| Jasmonates | travel in phloem ; fruit ripening, floral development, pollen production, tendril coiling, root growth, seed germ, nectar secretion, produced in response to herbivory and pathogen invasion |
| Strigolactones | extracellular and produced in roots in response to low phosphate or high auxin flow ; seed germination, control apical dominance and attraction of mycorrhizal fungi to root |
| photomorphogenesis | light triggers many key event s in plant growth and development |
| phytochrome | pigments that absorb mostly red are far red light |
| red light vs far red light | red light increases germination whereas far red light (fast process) inhibited germination (slow process) |
| circadian rhythm | cycles of about 24 hours not controlled by a known environmental variable |
| photoperiodism | physchological response to specific night or day lengths |
| short day plant | required light period shorter than a critical length to flower |
| long day plant | only flower when the light period is longer than a certain number of hours |
| day neutral plants | unaffected by photoperiod and flower at age of maturity |
| thigmotropism | response to touch |
| PAMP (pathogen associated molecular patterns) Triggered immunity | chain of signaling events produces phytoalexins, plant cell walls are toughened |
| Effector Triggered immunity | disease resistance R genes code for R protein that can be activated by a specific effector; signal transduction pathways —> defense responses such as hypersensitive response and systematic acquired resistance |
| effectors | pathogen encoded proteins that cripple the plants innate immune system , directly into plant cells |
| hypersensitive response | formation of a ring of local cell death around the infection site |
| systemic acquired resistance | nonspecific, provides protection against a diversity of pathogens that can last for days; uses signaling molecule methyl salicylic acid around infection site and carries it via phloem throughout the plant and converts it to salicylic acid in remote areas |
| salicylic acid | activates a signal transduction pathway that poises the defense system to respond rapidly to another infection |
| root cap | protects the apical meristem as the root pushes through abrasive soil |
| endodermis | cylinder one cell think that forms the boundary with the vascular cylinder |
| pericycle | outer cell layer that surrounds and protects cylindrical bundles. also helps with nutrient and water transport |
| stomata | allow the exchange of CO2 and O2 |
| mesophyll | consists mostly of parenchyma cells specialized of photosynthesis |
| epidermis | dermal tissue of non woody plants |
| Cortex | function depends on type of cell. Could be parenchyma, collenchyma, or sclerenchyma |
| vascular cylinder | consists of phloem and xylem. Transports water, nutrients, carbohydrates |
| stamen | male part consisting of filament and anther; produce pollen grains which contain gametes needed for reproduction |
| pistil | female part. stigma, style, ovary. |
| anther | produces pollen |
| sepal | cover the flower bud, protecting it as it develops |
| petals | attract insects |
| stigma | top of the female portion that helps capture pollen |
| style | mediates pollination by providing a transmitting tissue for the pollen tube |
| ovary | develops ovules, protects and nourishes ovules and developing seeds, becomes the fruit that houses the seeds |
| ovule | in the event of successful pollination become seed or fruit |
| receptacle | connects the stalk to the flower and provides support |
| Angiosperm reproduction simplified | -mature pollen grain -> tube cell +gen cell -tube cell-> path through stigma down style to the ovary -gen cell divides into 2sperm -> down pollen tube 2 ovule -1 gen cell fertilizes egg -> zygote -1 gen cell bonds with 2 polar nuclei ->endosperm |
| endosperm | provides nutrients for developing plant |
Created by:
bouzianeju