* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 24 - S3 amazonaws com
Survey
Document related concepts
Ecology of Banksia wikipedia , lookup
History of botany wikipedia , lookup
Plant breeding wikipedia , lookup
Plant ecology wikipedia , lookup
Plant physiology wikipedia , lookup
Ornamental bulbous plant wikipedia , lookup
Plant morphology wikipedia , lookup
Plant evolutionary developmental biology wikipedia , lookup
Evolutionary history of plants wikipedia , lookup
Perovskia atriplicifolia wikipedia , lookup
Fertilisation wikipedia , lookup
Pollination wikipedia , lookup
Flowering plant wikipedia , lookup
Transcript
Chapter 23 Main Ideas: 1. Like all plants, the life cycles of mosses, ferns, and conifers include alternation of generations. 2. Flowers are the reproductive structures of anthophytes. 3. In anthophytes, seeds and fruits can develop from flowers after fertilization. I. Reproduction in Plants A. Asexual reproduction 1. vegetative reproductionnew plants grow from parts of an existing plant 2. most plants can reproduce w/vegetative reproduction B. Alternation of Generations 1. consists of a sporophyte stage & a gametophyte stage 2. all cells of a sporophyte are diploid 3. some cells can undergo meiosis to form haploid spores 4. some cells can undergo cell division to form haploid gametophytes 5. when a sperm fertilizes an egg, a diploid zygote is formed=sexual reproduction & it’s the 1st cell of the sporophyte stage 6. zygote can undergo cell division & form an embryo sporophyte 7. if it matures, the cycle begins againbasic pattern for most plants C. Life Cycle of Mosses 1. gametophyte stage is the dominant stage 2. haploid spore can germinate & form a protonemasmall green filament of cells that develop into gametophytes(male & female) 3. if a film of water is present motile sperm(from antheridium) travels/swims in a film of H2O to an egg(in archegonium) a.chemotaxis–>movement of a cell/organism in response to a particular chemical 4. fertilization occurs producing a diploid zygote 5. zygote divides forming a sporophytehas a stalk & a capsule 6. sporophyte remains attached to the gametophyteH2O & nutrients 7. cells i/s the capsule undergo meiosisproduce haploid spores 8. capsule ruptures releasing spores & if a spore germinates the cycle begins again. C. Life Cycle of Ferns 1. sporophyte stage is the dominant stage 2. remember that sori are on the underside of fronds & sori are clusters of sporangia 3. meiosis occurs in the sporangiahaploid spores 4. sporangia release the spores 5. spore germinates forming a prothallus–>heart-shaped gametophyte–>has both antheridium & archegonium 6. again the sperm must swim through a film of water to reach the egg 7. fertilization occurs producing a diploid zygotewhich develops into a sporophyte 8. initially sporophyte depends on the gametophyte for nutrients, but once the sporophyte produces fronds it can photosynthesize 9. prothallus will die & the sporophyte will produce a rhizome & then roots & fronds will develop 10. once sporangia appear on the fronds, the cycle can begin again D. Life Cycle of Conifers 1. conifers are heterosporous–>produce 2 types of spores that dev into male & female gametophytes 1. sporophyte stage is the dominant stage 2. most conifers have male & female cones on separate branches 3. female cones have 2 ovules at the base of ea scale of each cone w/I ea ovule meiosis of a cell prod 4 megaspores a. 3 megaspores disintegrate b. remaining megaspore undergoes mitosis & becomes the female gametophyte c. ea gametophyte consists of 2-6 archegonia d. ea. archegonia contains an egg 4. male cones also have sporangia that produce microspores a. microspores become pollen grainsmale gametophyte 5. pollinationtransfer of pollen grains from the male to the female cone a. pollen grains enter the female cone through the micropyle which is the opening in the ovule b. fertilization does not occur for at least 1 yrthe male & female gametophytes mature during this time c. as the gametes mature, the pollen grain releases a sperm nucleus through a pollen tube to the egg(fertilization) d. zygote forms & is dependent on the female gametophyte for nutrients II. Flowers A. Flower structure 1. petalscolorful structures at the top of a stem that can both attract pollinators & provide them w/a landing platform 2. flower stempeduncle 3. sepalsleaflike & encircle peduncle below the petals; protect the flower bud 4. stameni/s petals & is the male reproductive structure 5. antherat tip of stamen & produces pollen(sperm) 6. pistilattached to top of the peduncle & is the female reproductive structure a. 3 parts: the stigma, style, & ovary b. ovary is the bottom part of the pistil 7. if a flower has sepals, petals, stamens, & pistils=complete B. Pollination mechanisms 1. self pollination & cross pollination a. self pollinating plants can pollinate themselves/another flower on the same plant b. cross pollinated plants receive pollen from another plant 2. animal pollination a. when animals move from plant-plant they carry pollen from 1 plant to another b. plants have colors & scents that attract animals 3. wind pollination a. plants that lack showy flowers/fragrant scents are us. wind pollinated b. these plants prod. large amts of lightweight pollen C. Photoperiodism 1. the amount of light present effects both growth & flower production 2. photoperiodism–>the flowering response that’s influenced by the number of hrs of uninterrupted darkness a. the beginning of flower dev for ea plant species is a response to a range in the number of hrs of darkness=its critical period b. short-day plant-->flowers when exposed to a number of hrs of darkness that is greater than its critical period c. long-day plant-->flowers when the number of hrs of darkness is less than its critical period d. intermediate-day plant–>flowers as long as the number of hrs of darkness is neither too great/too few e. day-neutral plant-->flowers over a range in the number of hrs of darkness III. Flowering Plants A. Life cycle 1. anthophytes–>most diverse & widespread grp of plants a. unique b/c they have flowers b. dominant sporophyte generation 2. gametophyte development a. in anthophytes dev of male & female gametophytes begins in an undeveloped flower b. anthophytes are heterosporous–>pistil prod megaspores & the stamens prod microspores c. female gametophyte 1. a specialized cell i/s the ovule of the pistil’s ovary undergoes meiosis–>prod 4 megaspores 2. 3 of the 4 megaspores disintegrate 3. the nucleus of the functional megaspore undergoes mitosis 4. result=large cell w/8 nuclei 5. the nuclei migrate3 to ea end of the cell & 2 in the middle 6. polar nuclei-->2 nuclei in the center of the ovule 7. 1 of the 3 nuclei closest to the micropyle becomes the egg d. male gametophyte 1. forms in the anther as microspores are produced by meiosis in the pollen sac 2. each microspore goes through mitosis & a thick wall surrounds the nuclei-->immature male gametophyte(pollen grain) 3. within the male gametophyte are the tube nucleus & the generative nucleus 4. when the gamete is mature the anther will split open B. Results of Reproduction 1. embryo contained in a seed is the next sporophyte generation 2. seed development begins w/fertilization 3. endospermprovides nourishment for the embryo & is the result of cell divisions 4. the o/s layer of the ovule becomes the seed coatprotection 5. as seeds develop, ovary enlarges & becomes the fruit 6. seeds are fully formed at maturity, but still have to germinate 7. seeds will germinate only when conditions are favorable, some can wait long periods 8. dormancy-->period of inactivity/no growth in a seed 9. germination-->the process when the embryo in the seed starts to grow a. water & temperature play major roles in seed germination b. 1st part of the embryo to appear is called the radicle c. portion of the stem nearest seed-->hypocotyl