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Biology 1030 Exam 2
| Question | Answer |
|---|---|
| Heterosporous | the production of spores of two different sizes and sexes by the sporophytes of land plants. ALL SEED PLANTS |
| Seed Plants | heterosporous gametophyte- reduced and dependent on sporophyte Seed Pollen as male gametophyte |
| Seed | “baby plant in a lockbox with its lunch”; highly resistant structures that allow for a dormant phase in the life cycle to wait out poor environmental conditions |
| Pollen | male gametophyte – many seed plants are no longer tied to external water for fertilization |
| Male Gametophyte | develop from microspores • become pollen grains • entire male gametophyte moved to the female as pollen grains • cannot perform photosynthesis, depends on nutrients that came from the parent sporophyte |
| Female Gametophyte | develop from megaspores within ovules ovule contains female gametophyte surrounded by nucellus (megasporangium) nucellus is surrounded by 1-2 integuments cannot perform photosynthesis, depends on nutrients from the parent sporophyte |
| micropyle | opening in integuments (allows sperm to get in) |
| Pollen Tube | means of transporting sperm to egg, does not require outside water |
| Pollination | moving pollen to vicinity of ovule. Agents: wind, animals |
| Seed Coat | Protects Embryo, an extra layer of hardened tissue derived from sporophyte tissue in the ovule |
| Gymnosperms | naked seed. all seed plants that are not angiosperms all lack flowers and fruits that are found in angiosperms ovule not completely enclosed by sporophyte tissue at time of pollination instead, ovule sits exposed on a scale (a modified leaf) |
| Angiosperms | covered seed. All flowering plants |
| Phylum Coniferophyta | monophyletic group worldwide distribution, more common in cold or dry regions needle-shaped leaves adapted to dry conditions thick cuticle stomata in pits soft wood tallest plants |
| Pines | over 100 species native to Northern hemisphere typically thick bark (survive fires, drought) secrete resin from leaves and bark response to wounding deters fungal and insect attacks source of turpentine and solid rosin |
| Phylum Cycadophyta | most resemble palm trees, but produce cones (female cones up to 45 kg, or 100 lbs!) have life cycle similar to pines unusual sperm: 1. have thousands of flagella arranged in spirals 2. swim within ovule to archegonium 3. largest sperm known |
| Phylum Ginkgophyta | Gingko 1 living species, Ginkgo biloba (also known as the maidenhair tree) no natural native populations; first cultivated in Japan and China deciduous – lose leaves flagellated sperm (similar to cycads) dioecious stinky seed coverings |
| Phylum Gnetophyta | the gnetophytes evidence that they form a clade with angiosperms 1.vessels in xylem (common in angiosperms, found only in these gymnosperms) 2.members of Gnetum have broad leaves similar to angiosperm leaves 3.some genetic similarity to angiosperms |
| Welwitschia | belong to gnetophyta bizarre plants of southwest African deserts 1.stem is shallow cup that tapers into a taproot 2.two leathery leaves (often split) grow continuously from base 3.conelike reproductive structures at leaf base 4.dioecious |
| Dioecious | separate male and female plants |
| Ephedra | belong to gnetophyta common in Mexico and southwestern US, but found on most continents 1. shrubby, stems resemble horsetails (jointed, with tiny scale-like leaves at each node) 2. some species monoecious, some dioecious 3. drug ephedrine |
| monoecious | male and female parts on same plant |
| Phylum Anthophyta | flowering plants also known as angiosperms ovules enclosed within carpel about 250,000 known living species (dominant photosynthetic organisms on land) predominant source of human food most widespread and diverse plant phylum |
| Eudicot | • most have embryos have two cotyledons (seed leaves) • leaves have netlike veins • flower part typically in multiples of 4 or 5 • pollen grains mostly with 3 or more apertures • endosperm mostly used up in mature eudicot seeds |
| Monocot | • embryos have one cotyledon • leaves have essentially parallel veins • flower part typically in multiples of 3 • endosperm typically present in mature monocot seeds |
| Laurasia | North America, Europe, Asia |
| Gondwanaland | angiosperms first appeared in Gondwanaland, in what was likely a drier interior region |
| advantages of flowering plants | 1. transfer of pollen over great distances promotes outcrossing 2. efficient seed dispersal via fruit 3. endosperm gives seedlings a fast start 4. leaves appropriate for fast growth in hot, dry environment |
| Calyx | sepals; usually green, leaf-like, and protect immature flower |
| Corolla | petals; usually colorful, attract pollinators; together with calyx called perianth |
| Androecium | stamens; male reproductive structures |
| Stamens | • filament + anther microspores produced within anther, shed as pollen |
| Gynoecium | female reproductive structure • center location is most protected • formed from leaf-like structure with ovules along margin • edges fold inwards around ovules, forming carpels |
| Ovary | –swollen base with 1 to hundreds of ovules; develops into fruit |
| Stigma | tip; sticky and/or feathery to catch pollen |
| Style | usually present; separates stigma from ovary |
| Nectaries | may be present at base of pistil; secrete sugar, amino acids, and other compounds to attract pollinators |
| Angiosperm Life Cycle: female gametophyte STEPS 1 and 2 | 1. single diploid megaspore mother cell in ovule undergoes meiosis while flower develops 2. of 4 haploid megaspores produced, usually 3 break down |
| Angiosperm Life Cycle: female gametophyte STEPS 3 and 4 | 3. remaining megaspore expands and replicates and divides until there are 8 haploid nuclei in two groups of 4 4. one nuclei from each group migrates toward center; these are polar nuclei |
| Angiosperm Life Cycle: female gametophyte STEPS 5 and 6 | 5. polar nuclei usually fuse to make a diploid nucleus, but may remain separate – in either case, they wind up in a single cell 6. cell walls form around other nuclei, creating the 7-celled, 8-nucleate embryo sac or megagametophyte (female gametophyte) |
| Angiosperm Life Cycle: female gametophyte STEPS 7 and 8 | 7. meanwhile, two layers (integuments) of ovule develop into seed coat with micropyle (small opening) 8. in the megagametophyte, one of the cells closest to the micropyle becomes the egg; the other two there are synergids |
| Angiosperm Life Cycle: Male gametophyte STEPS 1 and 2 | 1. anthers with patches of tissue that become chambers lined with nutritive cells 2. each patch has many diploid microspore mother cells |
| Angiosperm Life Cycle: Male gametophyte STEPS 3 and 4 | 3.microspore mother cell undergoes meiosis, making 4 haploid microspores that typically remain grouped in a tetrad 4.each microspore nucleus replicates and divides once (mitosis) without cytokinesis (binucleate microspore) |
| Angiosperm Life Cycle: Male gametophyte STEPS 5 and 6 | 5.usually, tetrad breaks up 6. 2-layer wall develops around each binucleate microspore, called a pollen grain • outer wall – sculptured, often has chemicals that react with an appropriate stigma to stimulate pollen tube formation |
| apertures in outer wall | – where pollen tube may grow out; eudicots – usually 3; monocots – usually 1 |
| Pollination | – transfer of pollen to a stigma 1. usually between flowers of separate plants 2. agents include wind, water, gravity, mammals, birds, insects 3. various reward systems for animal agents (pollen, nectar, etc.) |
| Self-pollination | 1.small, inconspicuous flowers 2.shed pollen directly onto stigma 3. good when pollinators aren’t around (Artic, mountains) 4.if you are well-adapted, might as well produce clones 5.disadvantage of genetic load of bad mutations |
| Fertilization | 1. pollen grain cytoplasm absorbs substances from stigma 2. bulge forms through an aperture in pollen grain; becomes pollen tube |
| Pollen tube | follows chemical gradient through style to micropyle • chemicals diffuse from embryo sac • micropyle usually reached within a few days (up to a year in some species) |
| Pollen Grain | grain has two nuclei; one, the generative nucleus, lags behind |
| Generative Nucleus | undergoes mitosis to make two non-flagellated sperm; this may occur in pollen grain or in pollen tube (male gametophyte now mature) |
| Double Fertilization | essentially unique to angiosperms • one sperm unites with egg, forming zygote • other sperm unites with polar nuclei, forming 3N primary endosperm • primary endosperm rapidly undergoes many cycles of mitosis, forming endosperm |
| Endosperm | provides nutrients for embryo; in many seeds, it is gone by the time the seed is mature |
| Seeds consist of | 2N embryo, 3N endosperm, and 2N seed coat (seed coat from parent female tissue) |
| Embryo | quickly forms all systems, then growth arrested (dormancy) – mature seed about 10% water, very low metabolic activity |
| seed coat | tough, relatively impermeable 1. protection from predators, pathogens 2. protection from desiccation, harsh conditions (crucial on land) 3. may allow seed to last hundreds of years |
| Germination | breaking dormancy = resuming metabolic activity, growing out of seed coat; occurs after water penetrates seed coat to embryo, bringing oxygen |
| Fruits | mature ovaries |
| Fleshy Fruits | pomes (apples), drupes (peaches), true berries (blueberries, peppers), hesperidiums (oranges), pepos (melons, gourds), aggregate fruits (strawberries, raspberries), multiple fruits (pineapple, fig) |
| Dry Fruits | – follicles (milkweed, magnolia), legumes (peas, beans), siliques and silicles (mustards), capsules (irises, lilies, orchids), caryopses (grasses), nuts (chestnuts, hazelnuts, acorns), achenes (sunflowers), samaras (maples, elms, ashes), |
| Stolons | runners – long slender stems that grow along soil (ex.: strawberry |
| Rhizomes | underground stems – common in grasses; bulbs and tubers are rhizomes specialized for storage (ex.: potato) |
| Suckers | – roots produce sprouts that grow into new plants (ex.: apple, raspberry, banana) |
| Adventitious Leaves | – numerous plantlets develop from tissue in notches along leaves |
| Apomixes | embryos in seeds may be produced asexually |
| First Flowers | 1. numerous spirally arranged sepals, petals, stamens, and carpels 2. petals and sepals similar in color and form 3. all parts free (not fused) |
| Complete Flower | calyx + corolla + androecium + gynoecium |
| Incomplete | one or more whorls absent |
| Perfect | has both androecium and gynoecium |
| Imperfect | missing either androecium or gynoecium |
| Connation | fusing within a whorl |
| Adnation | fusing between whorls (for example, sepals and petals fused together) |
| Radial Symmetry | anscestral type, example buttercups |
| Bilateral Symmetry | derived type, examples: snapdragons, orchids |
| Wind Pollination | 1. copious amounts of pollen 2. most pollen travels no more than 100 m 3. flowers small, greenish, odorless 4. corollas reduced or absent 5. male and female parts often well-separated on plant to reduce chance of self-pollination |
| Animal Pollination | some cycads and gnetophytes also have this, so symplesiomorphic trait |
| Bee Pollination | •find by odor •orient by shape/color/texture •blue or yellow flowers •many have stripes or lines of dots • flower only open when bees are active • pollen collecting apparatus specific for particular plant |
| Other Insect Pollination | moths, butterflies, flies, beetles |
| Bird Pollination | • large amounts of nectar • red – bees can’t see red, less likely to feed on the copious nectar • usually odorless – birds have a poor sense of smell • often in long, thick tube |
| Mammal Pollination | (bats especially) – uncommon, but for some species is the only means of pollination; variety of appearances |
| Dioecious | separate sexes. Two different plants |
| Monoecious | two sexes on same plant |
| dichogamous | stamens and pistils reach maturity at different times |
| genetic self-incompatibility | pollen tube arrested or never germinates |
| Two Basic Parts of Vascular Plants | root system and shoot system |
| Three Basic Organs of Vascular Plants | roots, stems, leaves |
| Three Basic Tissues of Vascular Plants | dermal, ground, vascular |
| Root System | • penetrates the soil/substrate and anchors the plant • absorbs water and ions for plant to use |
| Shoot System | consists of stems, leaves, and structures that serve reproductive functions (cones, flowers, fruits, seeds, etc.) |
| Stems | serve as framework and support to position leaves |
| Leaves | primary location for photosynthesis |
| Meristem | 1.give rise to all other cells of plant 2. composed of small, unspecialized cells that divide continually •after division, one cell remains meristematic •other cell becomes part of plant body; may or may not go through more mitosis before differentiating |
| Apical meristem | responsible for primary growth. near tips of roots, shoots 2. lengthening of primary plant body results 3. produces “primary” tissues that are partially differentiated |
| ground meristem | –produces ground tissue |
| protoderm | – produces epidermis |
| procambium | – produces primary vascular tissue |
| Lateral Meristems | responsible for secondary growth. 2. expand girth of plant (thickening of plant body) 3. produces “secondary” tissues; allows thick, woody trunk in some plants |
| Cork Cambium | cork cells in bark of woody plants (outer bark) |
| Vascular Cambium | secondary vascular tissue • secondary phloem – closest to cork • secondary xylem – internal; main component of wood |
| Dermal Tissue or Epidermis | 1. protective outermost cells, cover all parts of primary plant body 2. usually only one cell thick 3. cells usually flattened 5. most lack chloroplasts 4. covered on outside by waxy cuticle layer that varies in thickness |
| Guard Cells | paired cells flanking a stoma •control opening of stoma •have chloroplasts •stoma openings allow passage of gases •stomata occur on leaf epidermis, occasionally on stems and fruit •stomata usually more numerous on underside of leaves |
| Trichomes | – hair like epidermal outgrowths • occur on stems, leaves and reproductive organs • give surface a “woolly” or “fuzzy” appearance • keep surface cool • reduce evaporation rate • help protect from predators/pathogens |
| Root Hairs | single cells found near root tips • tubular extensions of individual epidermal cells • intimate contact with soil/substrate • responsible for all absorption in herbaceous plants (water, minerals, nutrients) |
| ground tissue | primarily parenchyma cells |
| Parenchyma Cells | most abundant cells of primary tissues •least specialized cell type (other than meristem) •usually capable of further division •usually remain alive after maturity; some over 100 years old •function in storage, photosynthesis (chlorenchyma), secretion |
| Collenchyma | • living at maturity (usually long-lived) • flexible, often in strands, forming support for organs (bend without breaking) • elongated cells with unevenly thickened primary cell walls • example: celery “string" |
| Sclerenchyma | • thick, tough secondary walls • usually lack living protoplasts at maturity • secondary walls often lignified (contain lignin); sometimes primary cell walls are lignified |
| Lignin | highly branched polymer that reinforces structure • common in cells that have a supporting or mechanical function in body structure |
| Fibers | long, slender, usually grouped in strands example: strands of flax, woven to make linen |
| Sclereids | – variable in shape; often branched; single or in groups example: gritty “stone cells” of pears |
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