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UNO - BIOL 1450 - Class Notes - Week 5

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UNO - BIOL 1450 - Class Notes - Week 5

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background image BIOLOGY II CHAPTER 2
Concept 2.1: Plant Protists
Protozoan Locomotion 
 Pseudopodia: o  Moveable extension of the cytoplasm  Flagella: o  Large, filamentous “tail” that propels the cell  Cilia: o  Series of small, filamentous “hairs” that beat in coordination to  create a current  Rhizaria  Foraminifera: Shells composed of calcium carbonate that have holes in 
them; Pseudopodia extend through the holes for swimming and feeding
 Radiolaria: delicate internal skeletons made of silicon; Pseudopodia 
extend out from shell
 Archaeplastida  Red Algae o  Form of seaweed
o  Phycoerythrin (pigment)
o  Tropical, marine
o  Used in many foods
 Green Algae o  Evolutionary precursors to the land plants  Unikonta        Ecological Relationships of Protozoa o Symbioses and Photosynthesis Concept 2.1: Plant Diversity I (How Plants Colonized the Land)
Timeline of Colonization
1.2 bya coatings of cyanobacteria  500 mya small primitive land plants, fungi 370 mya tall plants, primitive forests Evolution of Land Plants Derived from Charophytes: o Share these characters: Rossette-shaped cellulose-synthesizing complexes  Peroxisome enzymes Flagellated sperm structure Sperm from land plants are similar in structure to 
Phragmoplast formation Derived Plant Characteristics Alteration of Generations  o Sporophyte and Gametophyte
background image Walled Spores from Sporangia o Haploid cells (spores) protected by hard coating Multicellular Gametangia o Gamete producing structures are multicellular  Apical Meristems o Points where growth occurs Nonvascular Plants Liverworts  Hornworts Moss Seedless Vascular Plants Diversification during Devonian and Carboniferous (400-500 mya) Branched sporophyte allows more complex forms Competition for space and light led to increased height Evolution of Major Characters Transport Tissue: o Xylem and Phloem
o Strengthened by lignin
o Allowed transport of water and nutrients efficiently
o Provided strength to allow vertical growth 
o Competition for sunlight pushed height increase
Roots: o Lignified
o Earlies fossils with roots are 400 mya
o Similar in structure to stems
o Likely evolved form lower stems
The Seedless Vascular Plants Lycophyta: Club Mosses, Spike Mosses, Quilworts Pterophyta: Ferns, Horsetails, and Whisk Ferns Concept 2.3: Plant Diversity II (The Conifers)
Origins of Seed Plants
First evidence 360 mya Seed: o Embryo 
o Nutritional products 
o Protective coat
Other characters: o Reduced gametophyte generation 
o Heterospory
o Pollen
Heterospory All non-seed plants have homospory o Single size spore gives rise to male/female gametophyte Evolved different shaped spored
background image o Megaspores (egg)
o Microspores (sperm)
Advantage of Seeds Early spores: o Small, wind dispersed
o Tolerable of poor conditions
o Single celled- no food source 
Seeds:  o Multicellular 
o Large seed coat
o Supply of food
Gymnosperm Evolution First fossil evidence 380 mya o Archaeopteris First seed bearing plants o 360 mya
o all are extinct
Earliest true gymnosperms o 305 mya
o Lived with Lycopods
o Permian dried and favored conifers
With the evolution of angiosperms, gymnosperms were pushed to harsher
o Most gymnosperms found in northern latitudes
o Many gymnosperms went extinct after angiosperm evolution
Extant Gymnosperm Groups: o Cycadophyta: Tough ferns 2 nd  largest group of gymnosperms  Palm like leaves and large cones in center o Ginkgophyta: 1tree
o Gnetophyta: Looks like flowering plant but with cones
3 surviving genera: Gnetum Ephedra Welwitschia o Coniferophyta Largest gymnosperm group 600 spp of conifers Most are large trees and evergreen Needles as leaves Concept 2.4: Plant Diversity III (The Angiosperms)
Angiosperm Characteristics
 Grouped into a single taxa o  Anthophyta
background image o  Most diverse plant group 
o  250,000 spp
o  90% of living plant spp
 Major Adaptations: o  Flowers 
o  Fruits
Angiosperm Evolution  Originated at least 140 mya Dominated by mid Cretaceous (100 mya) New fossils from China (125 mya) o Archaefructus
o Anthers and closed carpels
o No petals or sepals- primitive form
o No wood
o Possibly aquatic
Molecular and Morphologic Evidence:  o Gymnosperms and angiosperms diverged (305 mya)
o Possible angiosperm ancestor
Bennettitales Ancient plant with flower-like strucutes Basal Angiosperms: o Amborellaceae
o Water Lillies (nymphaeacea)
o Star Anise (Austrobaileyales)
Monocots Magnoliids Eudicots Late Triassic (220 mya): o Continent of Pangea becoming arid
o Mass plant extinction event
Also many early dinosaurs o Numbers of wet adapted plants (ferns) decreases
o Numbers of drought tolerant species (gymnosperms) increases
o Slow increase in new Angiosperms
Also increase in insect pollinators Cretaceous (150 mya): o Massive radiation of flowering plants
o Increase in flower structures and slower diversity
o Co-evolution of insects, massive radiation
o Andiosperms replace ferns and cycads as dominant plant
Cretaceous-Tertiary (65 mya) o Large canopy forming angiosperm trees replace conifers as  dominant tree o Conifers pushed to extreme environments 

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School: University of Nebraska at Omaha
Department: Biology
Course: Biology II
Professor: Timothy Dickson
Term: Fall 2016
Tags: Biology
Name: Biology II; Weeks 3-5
Description: These notes cover all of chapter 2
Uploaded: 02/16/2018
13 Pages 46 Views 36 Unlocks
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