Supplemental Instruction 2/20/2018 BIOL 211 Exam 3 review Supplemental Instruction 2/20/2018

Origin of Land Plants ANSWER: Match these events with their appropriate times… Cyanobacteria Land plants First small plants Lifeless terrestrial environment 1st 3 billion years 500 MYA 1.2 BYA 370 MYA ANSWER: 1st 3 billion yrs: lifeless terrestrial environment 1.2 BYA: cyanobacteria 500 MYA: first small plants 370 MYA: land plants

Origin of Land Plants Land plants are related to protists. Alteration of generations is exhibited in which group? Brown algae Red algae Green algae A: Brown algae

3 main characteristics shared between most plants and protists: 1. Multicellular, photosynthetic autotrophs 2. Cellulose cell walls 3. Chloroplasts with chlorophylls a and b So.. We know plants began as aquatic algae.. Why move to a terrestrial environment? 1. More exposure to sunlight 2. Atmosphere with abundant CO2 3. Few herbivores and pathogens (at first) 4. Minerals in soil What specific type of green algae is believed to be the closest relative to land plants? Charophyceans

Characteristics separating plants from Charophyceans Apical meristems - plant’s stem cells that differentiate into various tissues Alteration of generations - gametophyte (n) produce gametes by mitosis; sporophyte (2n) produce spores (n) by meiosis Walled spores produced in sporangia - plant sporophyte has a multicellular sporangium that produces spores Multicellular gametangia - plants produce gametes within gametangia – F:archegonia M: antheridia; egg is fertilized in archegonia Multicellular, dependent embryos - plant embryos develop from zygotes that are retained in the tissues of female; female provides embryo with nutrients

Plants have a cuticle to prevent water loss while charophyceans (green algae) do not. How are plants grouped? By their vascular and reproductive structures. Groups include: Nonvascular – bryophytes Seedless vascular – ferns Gymnosperms (vascular, naked seeds) – conifers Angiosperms (vascular, covered seeds) – flowers

Nonvascular Bryophytes Phylums: Anthocerophyta (hornworts) Hepatophyta (liverworts) Bryophyta (mosses) Life cycle includes alteration of generations (like all plants) Gametophyte is the dominant stage - reduced sporophyte *require water for reproduction – sperm must have water to swim to egg in the archegonia – sperm are flagellated

Seedless Vascular Plants Life cycle with dominant sporophyte Vascular tissues – xylem and phloem Roots and leaves Two phyla: Lycophyta (lycopods, club mosses) Pterophyta (ferns, whisk ferns, horsetails) Sporangia produce spores on the sporophyte plant *Gametophyte reduced in ferns – trend in plant evolution

5 Characteristics of all seed plants Production of seeds Reduced gametophyte Heterospory – 2 types of spores Ovules Pollen What is a seed? Formed after fertilization of an egg by a sperm; the embryo.

Gymnosperms 4 phyla: Cycadophyta - palm trees Ginkgophyta - only one species: Ginkgo biloba Gnetophyta - not sure what these are Coniferophyta – conifers (pines, firs, cypress, cedars) “evergreen” Which of the following are amongst the oldest and largest organisms on earth? Palm trees Ginkgo Conifers C. Conifers

Angiosperms Monocots vs dicots – 1 cotyledon vs 2 Characteristics: Flowers, fruits, double fertilization Flowers increase success of pollination Fruits cover seeds to aid in dispersal Double fertilization – formation of zygote and endosperm Seed = mature ovule Fruit = mature ovary Both angiosperms and gymnosperms have ovules but gymnosperms are exposed to environment

Double fertilization Only occurs in angiosperms One sperm nucleus + egg = zygote (2n) One sperm nucleus + 2 polar bodies = endosperm (3n)

Parts of a Flower

Fungi The world’s largest organism - Fungi are not plants Eukaryotic heterotrophs that obtain food by absorption. Share a common ancestor with animals. Decomposers, parasites, or mutualistic symbionts. Unicellular or multicellular Composed of filaments (hyphae) – hyphae make up mycelium – hyphae can be divided by septa Cell walls are made of chitin Feeding network of fungus - mycelium Fruiting body produces spores Can reproduce either asexually or sexually – when hyphae meet it is called plasmogamy