Bio Exam 3
Spores vs. Seeds
"A spore consists of a single cell and contains no preformed embryonic parts. In contrast, a seed typically has hundreds or thousands of cells, forming an embryo and a specialized tissue that stores food: the endosperm. All this is enclosed in a usually tough, multicellular outer wall: the seed coat. Moreover, spores and seeds differ in what they give rise to. A fern spore gives rise to the prothallus of the gametophyte generation; a seed, to the baby plant of the new sporophyte generation."
heterospory
"Advanced" feature All gymnosperms All angiosperms Leads to the SEED And POLLEN
Defining Algae
- Kingdom Protista - Pigment types (chlorophyll a, b, c, and phycobili pigments) - Cell Covering: cellulose, silica, naked, calcium
Cool Plant Caluerpa taxifolia
- invasive, killer algae - grows with vigor, resists cold water - aquarium clones (cutting algae and distributing it) - finds it way into the Mediterranean sea - eliminates other plants and fish (highly toxic) - creates new equilibrium (dense, uniform carpet) a system was designed to kill this prohibited algae with chlorine
Ginkgo (Ginkgoales)
1 species Unknown in wild, previously widespread Swimming sperm and fleshy seed coat
Double Fertilization Process
1. Pollen tube grows through stigma 2. Germ cell in pollen grain divides and releases 2 sperm cells (n) 3. Tube grows through embryo sac (female gametophyte) 4a. one sperm cell fuses with the egg, producing the 2n zygote 4b. the other sperm fuses with 2 polar bodies at the center of the sac, producing the 3n endosperm tissue Embryo feeds off endosperms, develops inside embryo sac surrounded by a protective seed coat
Characters Linking Gnetales to Angiosperms
1. flower-like reproductive parts 2. vessels in secondary wood (xylem) 3. reduced female gametophyte 4. leaves with netted venation (gnetum) 5. sugar-rich pollination droplet 6. double fertilization
Red Algae (Rhodophyceae) Fossil Record
1.5-2 billion years ago about 5,500 species mostly marine (seaweeds)
Cycad (Cycadales)
130 species old world tropics monophyletic All with coralloid roots Symbiosis with Nostoc (cyanobacteria) Converts N Nodules Occupy poor habitats swimming sperm two families: cycadaceae and zamiaceae
Defining Gymnosperms
15 families 75-80 genera 820 species All woody (trees, shrubs, lianas) Dominant vegetation colder & arctic regions Tallest, most massive, longest-lived* Reproduction slow
Alage
2 Domains: Eukaryotes and Bacteria Kingdom: Protists (except for cyanobacteria) and were mostly unicellular things (very simple)
Bryophyte sporophyte
3 parts: capsule, stalk, and basal foot spores produced in capsule
Conifers
600 species in 7 families Most important gymnosperms Pine, spruce, fir, cedar, etc. Complex seed cones 300 mya - Carboniferous
Gnetophytes
90 species, 3 genera Xylem vessels Double fertilization Transition to angiosperms?
monophyletic group
A group of species that includes an ancestral species and all of its descendants fern allies are NOT a monophyletic, but ferns are
Anthophyte Hypotheis
Angipsperms and Gnetophytes are the only extant members of a clade called "Anthophytes" Gnetales are a sister group to Angiosperms and this precursors to flowering plants
Cool Fern Azolla
Aquatic
Cool Plant Pinus longaeva
Bristlecone Pine longest living tree 4,000+ years old
Pteridosperms
Carboniferous seed ferns May not really be ferns "Primordial seed plants"
Hornworts
Cool symbiosis Nostoc Colonies Cyanobacterium converts nitrogen gas into ammonium Hornwort secretes mucilage with carbohydrate
Where did Angiosperms come from?
Darwin's "Abominable Mystery" Flowering plants: early Cretaceous (130-120 MYA) No fossils showing the Gymnosperm-Angiosperm transition Answer hinges largely on the ID of a sister group among extinct and extant plants. Hypotheses: 1. "Anthophyte" Hypothesis 2. "Gnephine" Hypothesis
Seed
Develops from an ovule. Ovule = integumented megasporangium
Ferns and Fern Allies
Devonian Period (400-350 mya) First Vascular plants First tetrapods First terrestrial anthropods later: first seed plants
Fern Morphology
Dominant generation: independent sporophyte Body consists of three organs: Underground rhizome (stem) Adventitious roots Fronds (leaves)
Monilophytes
Eusporangiate, Leptosporangiate, Horsetails, and Whisk ferns actual ferns
Gymnosperms
Extant seed plants produce seeds and pollen but no flowers or fruit seed is NOT enclosed in a fruit
Economic Importance of Algae
Food Bioremediation Vitamin Supplements Environmental Indicators Biotechnical Applications (biofuels)
Phaeophyceae (Brown Algae)
Fossil Record - 490 mya 1,500 species mostly marine, few fresh water live attached to surfaces can be over 50 meters long
fern morphology
Free-living gametophyte Also called a prothallus Produces sperm and eggs Sporophyte starts attached
Bryophyte Reproduction
Gametophytes produce gametes in specialized structures Called GAMETANGIA Eggs produced in ARCHEGONIA Eggs remain in structure Sperm produced in ANTHERIDIA Sperm released into water Sperm finds the egg zygote forms remains in archegonium develop into: Embryo (sporophyte remains dependent)
Green Plants
Green Algae, Bryophytes, Lycophytes, Monilophytes, Gymnosperms, Angiosperms all have chlorophyll b and store starch monophyletic
Gymnosperm domination
Gymnosperms could thrive even when warm, moist conditions shifted. Gymnosperms became dominant and remained so until about 65 mya Mass extinction, followed by radiation of angiosperms
What trees did dinosaurs eat?
Gymnosperms dominant dinosaurs had modifications for eating pine cones dinosaurs are so big because the trees are so big and tough to eat, generating metabolic heat within the dinosaur (mesotherm)
Production of 2 forms of Spores
Heterospory MALE - Microspores tiny, produce male gametophytes with sperm FEMALE - Megaspores larger, produce female gametophytes with eggs
Fern allies
Historically recognized grouping: Lycopods, Quillworts, Spikemosses, Horsetails, Whisk ferns Fern-like but not "true ferns"
Gymnosperms ---> Angiosperms
Hypothesis A: - gnetohpyes are closest relatives to angiosperms Hypothesis B: - all gymnosperms are closest relative to angiosperms
Angiosperms
Most dominant plant group on Earth Prettiest plant group on Earth Most economically important plant group on Earth 89% of terrestrial plants are Flowering Plants
Mariculture
Nori farming/cultivation very complex life cycle Kathleen Drew Baker + Japanese farmers figure out life cycle and create an industry from it (global collaboration)
Cool Moss Sphagnum
Peat moss (wetland moss) decay resistant form peat bogs/peatlands covers 3% of the earth's surface more than 10,000 years old Tollund man found in 1950 is 2,000+ years old and is completely preserved by the peat moss explosive spore liberation
5 Types of Conifers
Pinaceae: temperate Araucariaceae: dinosaur looking, old tree Podocarpaceae: tropical Taxaceae: Arils (seed with outside fleshy coating) and Taxol: used in chemotherapy Cupressaceae: very long lived and large trees (sequoias)
Ecological Importance of Algae
Primary Producers (photosynthesis) starting point of food chain Global Cycling of Nutrients (C, N, O2) Basis of complex communities
Advantage of Heterospory
Retention and protection of gametophytes Sperm no longer sent out on their own to "swim for their life" No water needed Eggs protected, megagametophyte supported Allowed the evolution of the seed and pollen grain
Advantages of seeds
Seeds are "better" than spores for dispersal - Seeds can remain dormant. - "Wait" for better conditions.(Spores are short-lived) Seeds have seed coat (integument). Resist mechanical damage and pathogen attack. (Spore walls tough, but thinner) Seed coats can be modified for dispersal.Shaped like wings or fleshy.
Gymnosperm Reproduction
Seeds develop from ovules after egg cells within ovules are fertilized
Gymnosperm Seeds
Seeds exposed on surfaces of leaflike structures (sporophylls) aggregated into cones no ovaries so no fruits
Cool Fern Tree Fern
Spherical sori - Eusporangiate
Leptosporangiate ferns
Sporangia delicate - walls only one or a few cell layers thick, and areas where sporangial cells are modified for dehiscence
Eusporangiate ferns
Sporangia thick-walled, lack specialized zones of dehiscence Primitive like early vascular plants and Lycophytes
Cool Plant Liquidambar styraciflua
Sweetgum - spikey ball of seeds - resin can be chewed - star shaped leaves - bright red fall color
Algae Habitats
Ubiquitous (can live anywhere) Aquatic, terrestrial, snow can often from symbiotic relationships
Chlorophyta Growth Forms
Unicells filaments colonies thalli
Fern Life Cycle
Unit of dispersal = spores Produced by sporangia Sporangia clustered in sori singular = sorus) Usually small button-like dots on backs of fronds
three types of Gnetophytes
Welwitchia: monotypic Epherda Gnetum
Mosses
Widely distributed, esp. alpine, boreal, temperate, and tropical forests Able to live in very dry or very cold habitats Many can dry out entirely, then rehydrate
Pollination
Wind-blown pollen grains land on drops of fluid produced by the ovules on the ovulate scales (pollination droplet) when the water evaporates back into the micropyle (opening in ovule), the pollen grains go with it *follows movement of water* pollen grain germinates and produces a pollen tube for the sperm (mature gametophyte) to travel through ovule will develop into a seed integument (outer coating) will become the seed coat
Cool Plant Wollemia nobilis
Wollemi pines - found in a gorge in Australia in 1994 - previously only known from fossil record (rediscovered) - fewer than 100 in the wild - drops branches instead of leaves like other trees. branches are loosely connected to trunk which allows it to sustain drought and harsh conditions. - poorly adapted to Australia's dry climate
strobilus
a structure present on many land plant species consisting of sporangia-bearing structures densely aggregated along a stem. Strobili are often called cones, but many botanists restrict the use of the term cone to the woody seed strobili of conifers
Chlorophyta Cell Walls
absent cellulose or modifications
Cool Plant Heterosigma
actually moves around to avoid the plankton that eats it
Red Algae Habitats
attached to surfaces many are reef building calcium cell covering leads to habitat builders
Phaeophyceae Cell Walls
cellulose alginates
Red Algae Cell Walls
cellulose some with calcium carbonate
Red Algae Pigments
chlorophyll a phycobilins carotenoids (efficent light harvesting)
Chlorophyta Pigments
chlorophyll a & b carotenoids Food reserve: starch
Phaeophyceae (Brown Algae) Pigments
chlorophyll a and c fucoxanthins
sori
collection of sporangia (where spores are made) little spots on the backs of fern leaves
Fall color change in the USA vs Europe
color displays a tree's natural endurance in America and Asia, mountain ranges run north to south, allowing for easy migration of tree species when the ice sheets came from the poles. However, in Europe, the mountain ranges run east to west, forcing species to migrate OVER the ranges, which is much more difficult, resulting in lost species.
Four extant groups of Gymnosperms
conifers, cycads, gnetophytes, and ginkgo
Phaeophyceae Economic uses
directly consumed and used to dress wounds and treat burns Alginate is used in toothpaste, soaps, water/fire proofing, and treats acid reflux
Red Algae Economic Uses
directly consumed, agar agarose (dental impressions), carrageenan (thickening agent in foods), found to block transmittence of HIV and Herpes when used as lubricants
Bryophyte Gametophytes
dominant generation flattened (THALLOID) grow close upon the ground - absorption directly into photosynthetic tissue stemlike structures with thin, leaflike appendages usually only one cell thick close to the ground, anchored by rhizoids, long, tubular single cells (no tissues)
Vascular Plants
everything after Bryophytes Lycophytes, Monilophytes, Gymnosperms, Angiosperms
Land Plants
everything after Green Algae Bryophtyes, Lycophytes, Monilophytes, Gymnosperms, Angiosperms
Seed Plants
everything after Monilophytes Gymnosperms and Angiosperms
Lycopods
fern Two forms of reproduction: Sporophylls - normal Gemma - clones
dimorphic fronds
fertile and sterile stems bryophytes also do this
Chlorophyta (Green Algae)
fossil record: 1.5-2 BYA about 8,000 species marine, freshwater, and terrestrial attached to surfaces or planktonic
Seed Plants / Gymnosperms
heterospory produce seeds but not flowers or fruits pollen grains: male reproduction seeds exposed on surfaces of leaflike structures (sporophylls)
Photosynthetic Protist
historical term applied to organisms that contain chloroplasts and photosynthesize but are NOT plants
Fern life cycle
homospory then later heterospory
Bryophytes
hornworts, mosses, liverworts 500-400 million years ago Sporophyte dependent *Gametophyte dominant* no true leaves, direct absorption of water and minerals, and no lignified vascular tissue
Megasporangium
inside the ovule Megasporangium (2n, nucellus) produces megaspore (n). Megaspore grows into megagametophyte (n). Megagametophyte produces eggs all happens in one place and eggs are retained
Cool Plant Kelp
kelp forests are dominated by large photosynthetic protists their holdfasts are called "attachment structures" and are like roots, but DO NOT take up nutrients Bladders hold blades up in the water column
Lycophytes
lycopods, quillworts, and spikemosses fern allies
Conifer Reproduction
male gametophyte contained in pollen grain and female gametophyte are retained in leave where they are made
Chlorophyta Relationships
many form symbiotic relationships with other organisms (sea anemones, slugs, fungi, etc.)
Algae Growth Forms
micro and macroscopic single cells colonies of single cells filaments (cells lined up) multicellular blade
Lycophyets are the only land plants with
microphylls
Algae are very simple
no tissues, no complex structures, no vascular system
Cool Fern Iridescent fern
optical illusion: cells with very thin walls stacked to block intense sunlight photoprotection from sunlight
Cool Plant Fiddleheads
ostrich fern is the best direct consumption avoid bracken fern as it is carcinogenic
Cool Plant: Ginkgo
plant went extinct in the wild but was rediscovered in China at a Buddhist temple, where it was preserved for its medicinal purposes. Monotypic: one representative of the whole species Dioecy: male or female plant (not both) Anachronistic fruits entire lineage went extinct, but it is a very temperate plant
Microsporangium
pollen grain Microsporangium (2n) produces microspore (n). Microspore grows into microgametophyte (n). Microgametophyte produces sperm
Cool Plant Nori (Porphyra)
red algae cold water seaweed
Synapomorphy
shared derived characteristic
Chlorophyta Economic Uses
some direct consumption BIOFUELS
Sporangium
the place where spores are made
Red Algae Growth
unicellular, simple filaments, and complex filamentous aggregations
Ovule
where female gametophyte lives will contain the next generation (egg) after fertilization, the ovule becomes the seed with the 2n sporophyte (embryo) inside
Gnetophytes Hypothesis
widespread group in the Mesozoic period (250-65 mya) and are now mostly extinct long thought the sister group to the Angiosperms Hooker, 1863 "Gnetales are intermediate step between Gymnosperms and Angiosperms"