Biology Lecture Notes

Biology Lecture Notes - Lecture Notes Biology 152-Spring...

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Lecture Notes Biology 152-Spring Sem. plants have: a thallus (body) stipe (stem) blades (leaves) Alternation of Generations: multicellular sporophytes (2N) to produce spores and multicellular gametophytes (N) to produce gametes. Some are heteromorphic, others are isomorphic protists that use pseudopods Foraminifera-forams marine, usually w/ symbiotic algae have porous shells (tests) fossils! Radiolarians-fused, silica based tests [radiolana] Amoebas: gymnamoebas entamoebas slime molds Cellular-multicellular Many cooperating cells; haploid except zygote Relatives of Land Plants: Rhodophyta red algae no flagella Chlorphyta:
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green algae closest ancestors to plants also found in lichens (symbiotic w/ fungi) chlamydomona, volvox, ulva Plant Diversity closest relatives: charophyceans (achlorophyta) rosette cellulose-synthesizing complexes peroxisome-enzyme containing organelles formation of a phragmoplast during cell division flagellated sperm DNA use of sporopollenin to prevent zygote drying Unique Characteristics of Plants apical meristems: local regions of cell division at tips of roots and shoots multicellular dependant embryos-retained in maternal tissues allowing for transfer of nutrients through placental cells=embryophytes Alternation of Generations gametophytes and sporophytes that are both multicellular walled spores produced in sporangia that are covered in sporopollenin multicellular gametangia archegonia-female gametophyte antherida-male gametophyte Adaptations for life on land: water conservations: cuticle on epidermis, stomates for O 2 and CO 2 exchange water transport: xylem and phloem (vascular tissue) secondary compounds
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Evolution of seed plants: reduction of gametophyte female gametophyte remains in mega-sporangia of Sporophyte protection, nutrients male gametophyte dispersed in pollen seeds-multicellular embryo, food + protective coat similar to spores heterosporous sporophytes megasporangium megaspores microsporangium-microspores-male gametophytes (pollen) surrounded y integument (Sporophyte tissue) ovule = integument, megasporangium, megaspore if fertilized, develops into seed pollen-male gametophytes Why have a seed? allows to withstand harsh environments seed dispersal 2 Clades: gymnosperms angiosperms Gymnosperms: no ovaries-use cones evolved 250 mya only 750 species in 4 phyla: gingophyta-ginkos cycadophyta-cycads gnetophyta-ephedra
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coniferophyta-conifers, cone-bearers pines, furs, spruces, yews, cedars, cypress, redwood, sequoia… usually evergreen needle-like leaves to withstand harsh conditions Life Cycle of a Pine: sporophyte dominant
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This note was uploaded on 04/07/2008 for the course BIOL 152 taught by Professor Schnurr/vawter during the Spring '08 term at Wells.

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Biology Lecture Notes - Lecture Notes Biology 152-Spring...

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