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plant devo
lecture 14
| Question | Answer |
|---|---|
| what freed plants from dependence on water for sexual reproduction | evolution of pollen |
| compare conifers and cycads | conifers don't have flagella on sperm and have simple pollen cones..cycads have flagella and pinnate leaves |
| gnetophytes | compound pollen cones |
| types of gymnopserms | conifers, cycads, gnetophytes, ginkos |
| types of angiospersms | eudicots, monocots, magnolias |
| stamens | male sex organs bearing microsporangia (anther and filament) |
| carpels | female sex organs bearing megasporangia (stigma, style, ovary) |
| describe the steps on the male side for angiosperms up to pollination | mature sporophyte (2n) in anther -> meiosis -> microspore ->mitosis - pollen grain (male gametophyte) pollination |
| escribe steps on female side in angiosperms up to pollination | ovule in ovary -> meiosis -> megaspore -> mitosis -> embryo sac (female gametophyte) |
| what happens in an angiosperm post fertilization | zygote is 2n (other cells form nutritive tissue in seed) -> fruit develops from ovary wall containing seed -> seed disperses and there is a developing sporophyte |
| how does the female gametophyte form in angiosperms | ovule is diploid megaspore mother cell...divides meiosis to form haploid megaspore. 3x mitosis -> 7x cytokinesis. Left with primary endopserm cell, antipodal cells, polar nuclei, and synergid cell |
| describe formation of male gametophyte in angiosperms | anther stores pollen sacs surround by tapetum. microsporocyte leaves pollen sac and divides by meiosis and eventually reaches a four cells tage...four microspores. divide by mitosis to form a pollen grain (male gametophyte) forms pollen grain |
| how does the pollen grain move? | direct contact (self-fertilization) or pollination |
| what is the equivalent of mate selection in plants | pollen selection |
| how do you know if a species is self-incompatible | the stigma rejects the pollen from its own plowers. |
| benefits of having self-incompatible species | promotes variation; limits inbreeding |
| which gene is reponsible for selection | S gene. in haploid pollen grain - one S gene..recipient stigma is diploid and has two S genes |
| what happens when a pollen grain lands upon a stimga of a compatible pistil | it germinates to form a pollen tube |
| one the pollen tube form...what happens? | the pollen tube digetst its way thorugh spongy tissue of style or grows downward |
| what is required for rapid growh of pollen tube | calcium 2+ ions..taken up at growing tip of the tube as well as cell adhesion proteins |
| what directs downward pollen tube growth | signals form ovule |
| double fertilization | pollen tube discharges two sperm into embryo sac. one sperm fertilizes the egg the other sperm combines with the polar nuclei, giving rise to the food-storing sperm..unique to angiosperms |
| how does the embryo develop in the seed | zygote divides asymmetrically, each cell has a different fate |
| what is established by asymmetric division of embryo in seed | polarity and longitudinal axis |
| what does apical cell form | embryo proper |
| what does basal cell form | suspensor |
| what happens when suspensor ceases to elongate | meristems established in embryos |
| in eudicots what happens when the cotyledons form | globular embryos progress to hear stage embryos |
| what happens as cotyledons elongate? | internal tissue starts to differentiate |
| what is between the hypocotyl and cotyledons | shoot apex, root apex is at the other end. each contain apical meristem |
| role of endosperm and cotyledon | accumulate storage products to sustain embryo growth and development |
| what accumulates in endosperm | starch, lipids, proteins |
| what happens at late stage embryo development | seed loses water and enters dormancy |
| what is necessary step for germination | imbibition of water |
| radicle | first organ to emerge from germinating seed |
| whathappens in eudicots in germination | hook forms in hypocotyl and growth pushes hook above ground |
| what happens in monocot germination | coleoptile pushes upward through soil and into air. shoot then grows up through tube of coleoptile |
| what is the role of the fruit | develops from ovary; protects enclosed seeds and aids in dispersal of seeds by wind or animals |
Created by:
nkjohnston1424
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