BSC 116 Lecture 8
BSC 116 Lecture 8 BSC 116
Popular in Principles Biology II
Popular in Art
This 3 page Class Notes was uploaded by Paola Araque on Monday February 15, 2016. The Class Notes belongs to BSC 116 at University of Alabama - Tuscaloosa taught by Dr. Cherry in Spring 2016. Since its upload, it has received 28 views. For similar materials see Principles Biology II in Art at University of Alabama - Tuscaloosa.
Reviews for BSC 116 Lecture 8
Report this Material
What is Karma?
Karma is the currency of StudySoup.
Date Created: 02/15/16
Plant Interaction and Reproduction ● Soils: the source of plant nutrition ○ organic components: ■ humus: organic matter produced by decomposition ■ supports diverse communities of bacteria, fungi, protists, insects, other invertebrates, and plant roots ○ inorganic components: ■ negative soil particles ■ positively charged cations ■ negatively charged anions (susceptible to leaching) ■ 1. roots acidify the soil solution ■ 2. CO2 reacts with H20 ■ 3. Mineral cations are released, displaced by H+ ■ 4. roots absorb released cations ■ mineral cations enter soil solution by cation exchange ● Plants require essential nutrients ○ 17 essential nutrients required to complete the life cycle ○ 9 macronutrients needed in large amounts ○ Plant nutrition often involves mutualistic relationships with other organisms ● Partners: rhizobacteria & endophytes ○ rhizobacteria mutualistic bacteria in the rhizosphere ○ endophytes: bacteria or mycorrhizal fungi that live in or between root cells ○ plants provide carbohydrates ○ rhizobacteria and endophytes: ■ make nutrients more available ■ produce their own antibiotics ■ absorb toxic metals ■ secrete chemicals to stimulate growth ● Plants and Bacteria Work Together in the N Cycle: ○ bacteria help plants acquire nitrogen ■ plants cannot use N2 in the atmosphere ■ instead they use NH4+ and NO3 ■ nitrate and nitrogenous organic compounds are exported from the xylem to the shoot system ● Legumes and Rhizobium Have Special Symbiosis: ○ Rhizobium forms root nodules: swellings where nitrogen fixation occurs ○ Legumes (peas, beans, peanuts, alfalfa) ● Plant Fungi Partnerships: mycorrhizae ○ plant supplies carbohydrates ○ fungus aids in absorption of water and minerals ● Some Plants Gain Water in Other Ways ○ epiphytes:grow on other plants; absorb rainwater, etc ○ parasitic plantmany with roots that functihaustori (similar to arbuscular mycorrihzae) ○ carnivorous plantset nitrogen from animals ● Angiosperms haveflowersruits and seeds ○ Flowers: 4 rings of specialized leaves (sporophylls) ■ petal, sepal, (sterile) ■ carpel, stamen (fertile) ○ complete flowers have all 4 floral organs ○ incomplete flowers lack 1 or more of the organs ● DoubleFertilization: pollen ○ anthers have 4 microsporangia= pollen sacs ■ microsporocytes (2n) undergo meiosis= 4 microspores (n) ■ generative cell + tube cell+ sporollen grain ■ generative cell has two sperm ■ tube cell= pollen tube ● DoubleFertilization: embryo sac ○ ovaries have ovules with a megasporangium ■ megasporocyte (2n) undergoes meiosis= 4 megaspores (n) ■ nucleus of surviving megaspore divides 3x= 8 nuclei ○ female gametophyte= embryo sac ■ 3 cells at micropyle: egg and 2 synergids ■ 3 cells at the other end: antipodal cells ■ 2 polar nuclei without membranes in large central cell ● DoubleFrtilization: fertilization ○ pollen attaches to stigma ○ tube cell forms pollen tube that grows downward ○ generative cell produces 2 sperm ○ pollen tube penetrates micropyle ○ 1 sperm fertilizes egg= embryo (2n) ○ 1 sperm fuses with 2 polar nuclei in central cell= endosperm (3n) ● Angiosperm Life Cycle: see powerpoint ● Embryo Development: eudicots ○ endosperm develops before embryo: ■ (3n nucleus divides→multinucleate cell) ○ zygote develops into embryo: ○ basal cell→suspensor; anchored in parent ○ terminal cell→proembryo ○ two cotyledons (“seed leaves”) develop cotyledons ○ shoot and root apices develop shoot apex and root apex ● Mature Seeds Capable of Dormancy: ○ eudicots: 2 cotyledons ■ hypocotyl connects to radicle; epicotyl connects to embryonic shoot ■ some with thick cotyledons and no endosperm ■ some have thin cotyledons and more endosperm ○ monocots: 1 cotyledon (scutellum) ■ coleorhiza surrounds embryonic root ■ coleoptile surrounds embryonic shoot ● Seed Germination ○ imbibition: uptake of water ■ causes expansion, rupturing seed coat ■ enzymes digest and mobilize stored nutrients ○ eudicots: ■ radicle emerges first, hypocotyl once above soil, epicotyl expands 1st leaves ○ monocots: ■ coleoptile emerges and shoot grows through it ● Ovaries Become Fruits: simultaneous seed and fruit development triggered by double fertilization ○ simple fruits: from single (or multiple fused) carpels ○ aggregate fruits: from flowers with multiple, separate carpels ○ multiple fruits: from multiple flowers in an inflorescence; ovary walls fuse ○ accessory fruits: incorporates other floral parts besides the ovaries ● Asexual Reproduction: Vegetative Shoots ○ fragmentation: parent plant severed ○ adventitious shoots: e.g., aspen groves ○ apomixis: seeds produced by mitosis; no fertilization ○ Pros: Doesn’t require a partner No fragile seedling stage Pass along parent’s genetic info ○ Cons: Pass along parent’s genetic info Self‐fertilization ‐ Same cons Avoid by self incompatability or separating male and female flower parts ● Human Modification of Plants: ○ help plants out by: ■ providing pollinators for crops ■ inoculating with mycorrhizae ■ rotating crops to replenish nitrogen ○ modify plants by: ■ artificial selection: selective breeding ■ bioengineering (GMO) ○ possible downsides of biotechnology ■ human health ■ effects on nontarget organisms ■ transgene escape (hybridization)