Alternation of Generations
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how did plants reproduce without water?-spores housed in sporangia -gametes housed in gametangia -internal fertilization -embryo attachedwhat are some characteristics of bryophytes (non-vascular plants)?-lack vascular tissue (hence they lack true organs, leaves, stems, and roots) -the relatively undifferentiated body of such plants is known as the thallus -root-like structures are called rhizoids (formed of single cells not tissues like roots) -have a very thin waxy cuticlewho formed the first forests?ferns and other seedless vascular plantswhat did vascular tissue do for plants?enhanced transport and favored erect growthwhat is vascular tissue made up of?-internal tubes that transport water (xylem) and nutrients (phloem), and lignin which is an organic polymer (wood)what does lignin do?strengthens cell walls of xylemhow did shoot and root systems help plants?improved the growth, photosynthesis, and support of themwhat other traits appeared in vascular plants?-life cycles switched to dominant sporophytes -thick waxy cuticle -fully functional stomata (can open and close)what was the ecological and economic importance of pterophytes?the evolution of vascular tissue, roots, and leaves accelerated photosynthesis rates ex) Carboniferous forests removed CO2 to such a degree that it caused global cooling and the spread of glaciers -the remains of these plants formed thick deposits of organic matter ---> pressure and heat gradually converted them to coal ---> today coal is mined and burned to generate much of the electricity used todaywhat are some trends in seedless vascular plants?-they need H2O for reproduction -the dominant generation is the sporophyte which grows on top of the gametophytethe diploid generation of the plant life cycle always produces __________sporesplants undergo alternation of generations in which ___________the sporophyte generation alternates with the gametophyte generationin mosses, gametes are produced by ____________. in ferns, gametes are produced by __________.mitosis; mitosisthe noticeable part of a fern plant is a _____________diploid sporophytethe innovation essential to the survival of mosses on land was the ______________retention of the embryo on the parent plantmicro=_________; mega=_________male; femalewhat are some characteristics of seed plants?-seed plants have tiny gametophytes that are dependent on sporophytes -there are two kinds of spores produced in separate sporangia -microspores develop into male gametophytes, called pollen grains -female gametophyte develops inside the ovule, after fertilization that ovule and everything inside of it becomes a seed there are 2 different kinds of gametophytes that develop attached to the sporophytewhat are some terrestrial adaptations of seed plants?-pollen grain (male gametophytes) travel by air *benefit: sperm no longer need water -seed protects embryo sporophyte with seed coat and provides nutrients for germination -development of seeds from ovuleswhat did the early ovule consist of?integument, megasporangium, megaspore -megaspore develops by mitosis into the female gametophyte ---> pollen grain lands at the micropyle (ovule opening)dispersal by seeds vs. spores:seeds: seed plants, vascular; needs food and protection spores: seedless, nonvascular; no food or protectionwhat are some trends in seed plants?-sporophyte is dominant generation -sporophyte disperses the seedswhat are a gymnosperm's seeds like?typically naked and on cones (strobilus) - male cone called POLLEN CONE & female cone called OVULATE CONEwhat are angiosperms?vascular plants that have seeds and flowers (seed covered with a fruit)male gametophyte=______________;female gametophyte=____________pollen grain; embryo sacwhat are some characteristics of angiosperms?-have double fertilization -develops fruithow does double fertilization in angiosperms work?1) pollen tube discharges 2 sperms into female gametophyte which makes a diploid (2n) 2) then a sperm and two nuclei meet making a triploid (3n) 3) ovule develops into seed 4) ovary develops into a fruitthe major difference between angiosperms and gymnosperms is the _______________presence or absence of a protective covering over the ovuleafter fertilization, the _________ develops into a seed and the ________ develops into a fruit.ovule; ovaryboth gymnosperms and angiosperms have _________________pollen, seeds, and ovulesthe male gametophytes of flowering plants are also referred to as ___________pollen grainswhat are the two angiosperm groups?monocot and dicotcharacteristics of a monocot:-one cotyledon -veins usually parallel -vascular bundles usually complexly arranged -fibrous root system -floral parts usually in multiples of 3characteristics of a dicot:-two cotyledons -veins usually netlike -vascular bundles usually arranged in ring -taproot usually present -floral parts usually in multiples of 4 or 5what are the 3 main parts of a plant's anatomy?roots, stems, and leaveswhat are the 3 unique parts of a plant cell?-chloroplast: the sites of photosynthesis -central vacuole: contains fluid that helps maintain filaments -cell wall: made from the structural carbohydrate cellulosewhat are the 5 major types of cells found in plants?-parenchyma -collenchyma -sclerenchyma -water conducting cells of xylem -sugar conducting cells of phloemwhat do parenchyma cells do?-performs most of the metabolic functions of a plants (photosynthesis, cellular respiration, food storage) -remains active when mature and usually have only primary cell walls which are thin and flexible -can divide and differentiate into other types of plant cells under certain circumstanceswhat do collenchyma cells do?-provides flexible support from thick cell walls -no secondary cell wall, flexible support -support for still growing parts like young stems of a celery stalk -resemble parenchyma cells in lacking secondary walls but have unevenly thickened primary wall -living cell elongates as stems and leaves growwhat do sclerenchyma cells do?-provides support to non-growing areas -dead at maturity -has a primary and secondary cell wall -support but not flexible -cannot elongate -when dead they form a rigid skeleton that supports the plantfunction of water conducting cells of xylem:-water transport and support -they have rigid lignin containing secondary cell wall -the tubes are hollow because cells are dead when mature -2 kinds of cells: vessel elements and tracheidstracheids=_________;vessel elements=____________long, thin, tapered; wide, short, less taperedfunction of sugar conducting cells of phloem:-food conducting cells called sieve tube elements are arranged end to end -sieve tube elements remain alive at maturity -the reduction in cell contents allows for nutrients to pass more easily through the cellwhat are the 3 types of dermal tissue in plants?dermal, ground, vascularin what ways is pollination partly responsible for diversity?-flowers have coevolved with specific animals attracting them and ensuring pollination -bee pollinated flowers have nectar guides that reflect UV light -birds are attracted to bright red and orange but no particular scent -beetles are drawn to fruity odors but are indifferent to color -night pollinated flowers are large, light colored, and highly scented; some even produce the smell of rotting flesh to attract carrion flies and beetles -because all of this is costly to the plant, natural selection will favor certain plantsdermal tissuecover the outside of the plant *non-woody plants have one single layer called epidermis *woody plants have several layers that form the corkwhat are the functions and specializations of dermal tissue?-stems and leaves have waxy coating (cuticle) and trichomes -catch water -reduce air flow -produce waxwhat do the leaves' special cells do?they are guard cells that regulate the size of the stomatawhat do the roots do?have epidermis that forms root hairsmain functions of vascular tissue:transports materials and supports xylem: transports water and dissolved materials phloem: transports organic nutrients (sugars) *the arrangement of these tissues depends on the organ and whether the flower is a monocot or dicot roots: vascular tissue arranged in cylinder leaves: vascular tissue arranged as veins stems: vascular tissue arranged in bundlesmain functions of ground tissue:fills the area between epidermis and vascular tissue -ground tissue in leaves is called the mesophyll ---> to do photosynthesis -ground tissue in stem is called pith (center) or cortex (outside) ---> aids in support and food storage -ground tissue in roots also called cortex ---> stores sugarswhat are the 3 basic plant organs?roots, stems, and leaveswhat was the solution to the separation of resources on land for plants?the development of the 3 basic organswhat two systems are the organs divided into?root system and shoot systemwhat is the root system?taproot and root hairs: maximize surface area so water and minerals can be absorbedwhat is the shoot system?stem, leaves, node, flower, internode, terminal bud, and axillary bud: does photosynthesisroots:function- anchors plant to the soil; absorbs and transports minerals and water; stores food; near the root tips are root hairs; each root hair is an extension of an epidermal cell Monocot roots- consists of a mat of generally thin roots spread out shallowly in the soil Dicot roots- have one main vertical taproot with many small secondary lateral roots growing outwardstems:function- supports the leaves and flower; green stems also perform photosynthesis; in the case of a tree, the stems are the trunk and all the branches including the smallest twigs -a stem has nodes, the points at which leaves are attached and internodes, the portion of the stem between nodes -the buds are underdeveloped shootsleaves:function- photosynthesis; it is a large surface area to maximize light harvesting; they are thin so that light will penetrate through to the bottom cells -composed of the lamina (blade) and the petiole (stalk) -Monocots have parallel venation -Dicots have branched venationwhat is the internal structure of a leaf?-upper and lower epidermis: protective function -lower epidermis generally contains more stomata -epidermal cells lack chloroplastswhat is palisade mesophyll?tightly packed cells on the upper surface which contain 3-5 times as many chloroplasts as those of spongy parenchyma -chloroplasts usually remain near the cell wall since this adjustment guarantees optimal use of lightwhat is spongy mesophyll?loosely arranged cells; creates air spaces to facilitate gas exchangewhat are the 2 main ways plants and their cells transport things?active transport and osmosiswhat part of the root cells control mineral uptake?plasma membraneshow does cell transport work?-minerals are dissolved in water -they must move through the epidermis and cortex (xylem tissue) -membranes of root cells are selectively permeable (they only let certain solutes cross them) -this selectivity helps regulate the mineral composition of a xylem's cap -minerals and water cross a membrane at the epidermis or at the endodermiswhat is the intracellular route?epidermal cell membrane and soluteswhat is the extracellular route?caparian strip (wax barrier) forces solution to cross epidermal cell's membranewhat pulls water up through xylem vessels?transcriptionhow does transcription work?-xylem sap flows up the shoot system through the tracheids and vessel elements -root pressure: the upward push of xylem sap by the active pumping of minerals into xylem by root hairs and cells -transpiration (evaporation from plants): the pull of xylem sap by the loss of water from the leaves -transpiration is allowed by two special properties of water: cohesion and adhesionhow does the transpiration-cohesion-tension mechanism work?1) transpiration exerts a pull along a string of water molecules held together by 2) cohesion: stickiness of water molecules and helped upward by 3) adhesion: stickiness to xylem cell walls -transpiration is an efficient way of moving large volumes of water -a single corn plant, transpires 125 L of water in a growing season -requires no energy expenditure by the planthow do guard cells control transpiration?-large leaf surface areas ---> benefit and disadvantage -as long as water moves up from soil fast enough to replaces the water that is lost, transpiration presents no problems -but if the soil dries out and transpiration exceeds the delivery of water to the leaves, the leaves will wilt -the guard cells control the opening of a stoma by changing shape, widening or narrowing the gap between the two cellshow does the phloem transport sugars?-phloem sap moves in various directions -a sugar source is a plant organ that is a producer of sugar, by photosynthesis or by breakdown of starch ex) leaves -a sugar sink is an organ that is a consumer of the storage of sugar ex) growing roots, buds, stems, and fruitswhat is the pressure flow mechanism?At the sugar source: 1) sugar is loaded into a phloem tube by active transport which raises the solute concentration inside the phloem 2) the high solute concentration draws water in the tube by osmosis ---> increase water pressure At the sink: 3) sugar leaves the phloem tube 4) water follows by osmosis ---> lower water pressure -the building of water pressure at the source end and the reduction of that pressure at the sink end causes water to flow from source to sink -xylem tubes recycle the water back from sink to sourcehow does primary growth in plants lengthen shoots and roots?-growth is possible by tissues called meristems -apical meristems are at the tips of buds and roots -they allows the plant to increase in length -this process is called primary growthhow does primary growth work in roots?-the root tip is covered by a cap that protects the meristematic tissue -growth in length occurs just behind the root tip -there are 3 zones: zone of cell division, zone of elongation, zone of maturation (differentiation) -there are no sharp boundaries between them -elongation pushes the meristem region downhow does secondary growth increase the diameter of woody plants?-herbaceous plants do NOT grow in diameter -woody plants (trees, shrubs, vines) grow thicker -lateral meristems are responsible for this growth -two types of lateral meristems: vascular cambium and cork cambiumwhat is the vascular cambium?cylinder of meristem cells between the primary phloem and xylem -each year they produce secondary xylem and phloem -secondary xylem makes up the wood of a tree -sapwood is made of active xylem and heart wood is made of retired xylemwhat is cork cambium?meristem that produces cork -bark is anything outside of the vascular cambium -early spring: primary growth makes up the epidermis and cortex -late summer: epidermis is shed and replacedhow do plants respond to stimuli?tropisms orient plant growth toward or away from environmental stimuliwhat are gravitropisms?-growth of a plant in response to gravity -shoots grow upward (negative) and roots grow downward (positive)what are phototropisms?-the growth of the shoot in response to light -the hormone auxin is involved in phototropismwhat is thigmotropism?-growth in response to touch -the tendril of a pea plant coiling around a support -thigmotropism enables these plants to use such objects for support while growing toward sunlight -hormone is a chemical signal produced in one part of the body and transported to the other parts, where it acts on target cells to change their function -each hormone has multiple effects, this depends on: its site of action, its concentration, and the developmental stage of the plant -in most situations no single hormone acts alone -it is more of a balance of several plant hormones, that controls the growth and development of a planthow do auxins stimulate the elongation of cells in young shoots?-apical meristems are a major site of auxin synthesishow are auxins produced?by embryos within seeds application: due to lack of pollinators greenhouse tomatoes have fewer seeds and result in poorly developed fruits - spraying synthetic auxins on tomato vines promotes fruit developmenthow do cytokinins stimulate cell division?-promote cytokinins and cell differentiation -they are produced in actively growing roots -they promote seed germination -they also inhibit protein breakdown ---> shows aging -application: florists spray flowers with cytokinins to prevent aginghow do cytokinins and auxins work together?-auxin transported down the shoot from the terminal bud inhibits axillary buds from growing -shoot lengthens at the expense of lateral branching -cytokinins from the roots move into the shoot system signaling axillary buds to grow -cytokinins and auxins interact in the control of apical dominance (terminal bud suppresses the growth of axillary buds) -application: when gardeners cut the terminal bud of a planthow do gibberellins affect stem elongation, fruit growth, and seed germination?-more than 100 different gibberellins have been identified -young roots and leaves are major production sites -they stimulate cell elongation and cell division of leaves and stems, but not roots -in many plants, both auxins and gibberellins must be present for fruit development -embryo is rich in gibberellins after seed is soaked, gibberellins are released and break dormancyhow does abscisic acid (ABA) inhibit many plant processes?-the ratio of ABA to growth hormone determines the outcome of a plant -ABA slows growth and plays a role on seed dormancy and drought tolerance -ABA inhibits seed germination -in cold winter areas, long periods of cold can trigger ABA inactivation -during a drought, ABA accumulates in the plant and causes stomata to closehow does ethylene trigger fruit ripening and other aging processes?-ethylene stimulates fruit ripening and programmed cell death -it is also produced in response to stresses such as drought, flooding, injury, and infection -ethylene has a positive feedback effect -application: tomatoes are picked green and stored in huge storage bins piped with ethylene gaswhat is the reason leaves fall?abscissionwhat is abscission?-balance of auxin/ethylene -an old leaf produces less auxin cells at the abscission layer which is more sensitive to ethylene -before the leaf falls a protective layer formswhat do both auxin and gibberellins stimulate?cell elongationwhat 2 things does auxin inhibit?leaf abscission and axillary bud growthwhat does ethylene stimulate?leaf abscissionwhat do cytokinins stimulate?axillary bud growthwhat do gibberellins stimulate?seed dormancywhat does abscisic acid (ABA) stimulate?seed dormancywhat was the dominant lifecycle in bryophytes (nonvascular plants)?gametophytewhat was the dominant lifecycle in seedless vascular plants, gymnosperms, and angiosperms?sporophyteT or F: No energy is expended during water transport in plants.trueIn what direction does water flow in?from source to sinkwhat kind of growth is the apical meristem responsible for?primary growth and growth in length