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Lecture

Bio Lecture One.docx

25 Pages
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Department
Biology
Course Code
BIOL 1011
Professor
Mark Johnson

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Bio Lecture One 1/8/2013 9:19:00 AM Plants and the Colonization of Land  Plants create substances, hashish, aspirin, morphine etc. as a secondary substance to protect itself from predators.  Plants are important they create basis for life.  Many organism do different things for its environment  1. Energy- food  2. Energy- fossil fuels  3. Clothing  4. Drugs, medicine  5. Ecosystem functioning  6. Biodiversity  Plants split from red algae 1500 million years ago  Multicellular eukaryotes 1500 million years ago  Photosynthesis invented by prokaryotes, cyanobacteria, creating a oxygen increase  Takes 1 billion years for atmospheric oxygen to begin, it was first absorbed by oceans etc.  Colonization of Land 500 million years ago  Oxygen started to build up in atmosphere which was fatal to some anaerobic plants.  Splits leads to 2 branches  Plants don’t use pure sugar to store energy, sugar would uncontrollably absorb water  Features shared by all plants o 1)  Starch  Amylose- Glucose Moluecules glu-glu-glu  Amylopectin- Glucose Molecules different formation of glu’s  Chlorophyll b  An accessory pigment  Absorbs different wavelengths. Broadens the spectrum of light that can be absorbed by the plant. (More than just chlorophyll a  Cellulose  Made of polysaccharides  Thylakoid characteristics  “Pancake stacks” membranes o 2) Charophytes are the closest relatives of land plants, they have a common ancestor  Cell plate & phragmoplast  Makes cell plate in middle of cell. It is connected to a set of microtubules (phragmoplasts) which pull it apart  Plasmodesmata  Extensions of cell membrane through pores in the cell wall that allow fluid to move between cells  Sperm structure  Peroxisome enzymes  Enzymes are “special”  Rose-shaped cellulose synthesizing complexes o 3) Land plants  Cuticle  Waxy covering, adaption from being in water to being on land. Cuticle helps minimize loss of moisture  Sporopollenin  Allows cells to avoid attack from bacteria, fungi, drying out  Multicellular, jacketed sex organs, gametangia  Organs, they make gametes  Jacketed, sterile cells which do not divide  Antheridium- male form  Archegonium- female form  Embryophyte Condition  Offspring stays on “mom” the plant that produced the egg for some period of time. Egg is fertilized and is raised by the plant which it was fertilized on.  Alternation of generations  Alternation of a multicellular haploid phase and a multicellular diploid phase Bio Lecture Two 1/8/2013 9:19:00 AM Major Groups of Land Plants & Their Reproduction  Bryophyta (mosses)  Pyerophyta (ferns)  Coniferophyta (Conifers)  Anthophyta (Flowering plants) Chlamydomonas  A single-cell green alga without alternation of generations  Single cell organism acts as a gamete  + and –  Fertilization happens when nuclei combined to produce zygote  4 produced. 2+ and 2-  No multicellular diploid phase, therefore no alternation of generation  How did alt of gen. originate: o Zygote delays meiosis; instead it divides and grows, result: multicellular diploid  Multicellular diploid= sporophyte  Haploid= gametophyte  Animals reproduce: o Adult, undergoes meiosis, meiosis creates sperm or egg, sperm and egg will come together (fertilization), creates zygote, which develops back into adult.  Land Plants reproduce: o Meiosis produces spores, spore is a single cell that can develop further without uniting with another cell, spores germinate (open up) then turn into haploid generation (gametophyte), creates sperm and egg by mitosis from gametophyte, zygote is made, which develops into a larger organism (sporophyte), process repeats o Homospory:  1 kind of spore is made from meiosis o Heterospory  2 sizes of spore from meiosis  10 phyla of land plants o Four major, as mentioned above, mosses, ferns, conifers, flowering plants o Mosses  15000 species  low growing  somewhat confined to damp land environment  need sperm to swim  nonvascular tissue (no veins)  No true leaves  Gametophyte dominant  Homosporous  Moss Life Cycle: o  Sporangium contains spores  Mosses are called nonvascular plants o Ferns  20000 species most tropical  Vascular tissue  Swimming sperm  Sporophyte dominant  Homosporous or Heterosporous (one female one male)  Fern Life Cycle:  Meiosis takes place in sporangium  Fertilized egg creates new sporophyte  Sorus contain sporangium, sporangium contain spores  5 divisions of seed plants o Gymnosperms  Cycadophyta  Ginkgophyta  Coniferophyta  Cone bearing  Reproductive organs in cones  Sporophyte dominant  Heterosporous  Microgametopyte  Megagametophyte (Makes egg & then nourishes the embryo)   Gnetophyta o Angiosperms  Anthophyta= flowering plants o Four Parts of a seed:  Seed coat  Spore wall  Embryo  Food supply Bio Lecture Three 1/8/2013 9:19:00 AM Flowering Plants; Structure and Growth of Land Plants  The ovule becomes the seed  Conifer gametophyte o Microgametophyte (male)= pollen o Megagametophyte (female)  Pollen moved by wind only Flowering Plants  250,000 speccies  Reproductive organs in flowers  Sporophyte dominant  Heterosporous  Microgametophyte  Megagametophyte 8 nuclei  Triploid (3n) endosperm Flower Structure:  4 Whorl (a group of leaves that come out from the same place on the stem) o Outer set of whorl contain sepal (to protect soft stuff inside and aid in photosynthesis) o Petal is a whorl o Stamen (male part) o Carpel (female part)  Two Main groups of flowering plants; Monocot & Eudicot  See lecture 3 for differences and characteristics  Angiosperm Life Cycle- double fertilization   SUMMARY IN LECTURE 3  Systems of Land Plants:  Roots and Shoots  Root system  taproot-only in eudicots  fibrous roots-most monocots  root hairs (show SEM)  often fungal associates  Shoot system  1) Stems  nodes alternate w/ internodes  axillary bud, in angle (armpit) betw. stem and leaf  usu. dormant. Can become nondormant (e.g., if stem cut above: apical dominance)  2) Leaves  grt variation (show slides)  but gen’ly: blade, petiole  Cell walls in all plants o Primary and Secondary o Primary are thin, secondary for support thick o Composed of Cellulose microfibrils o HemiCellulose (polysaccharide) o Pectin  Stick together  Middle lamella  Made of pectic substances Cell Types:  Epidermal, cuticular layer, cuticle, wax o Secrotory trichomes Bio Lecture Four 1/8/2013 9:19:00 AM Primary & Secondary Growth  Cell Types; continued o Epidermal:  Cuticle formed by the epidermal cells, outer most part is wax. Cuticle protects against water loss, pathogens (viruses, bacteria, fungi) and UV radiation (causing mutations)  Sometimes develop into special structures  Wax on Pitcher plants help them catch prey  Nectar made by epidermal cells o Parenchyma  Most found cell in plants  General function o Collenchyma  Support, especially in young growing tissue  Thick, uneven, primary walls  lignin o Sclerenchyma  Hard cells, for support and protection  2 walls  lignin  Unlike fibers, short and rounded o Tracheids &Vessel elements  Involved in the movement of water and minerals (xylem)  Long and thin  Cells are dead when they are mature  Structurally very strong secondary walls that have lignin  Vessel elements found only in flowering plants, traceids in both flowering plants and confiers  Programmed cell death so cell can become a tracheid o Sieve elements  Form the main part of phloem: sugar water Plant Growth  Primary Growth o Growth from the tips  Secondary Growth o Growth that occurs from primary growth o Growth outward, makes wood  Meristems: o Apical meristems (see slide 29 for pictures of COLEUS)  Root AM and shoot AM  Primary growth  Produce: Dermal, Vascular, ground, tissues  Makes 3 other meristems:  Protoderm, Procambium, Ground meristem o Lateral meristems  Vascular cambium & cork cambium  Secondary growth   Root hairs increase surface area  Young root cross section  Shoot Structure & development o Young stems o  Secondary Growth o Wood, occurs from 2 new meristems o Cork o New Meristem is called vasular cambium, it is produced inside each vasuclar bundle o Vascular cambium one cell thick and produces xylem(secondary, a
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