Agenda 2/7/11 • Chem Warmup • AP Exam grade changes • Finish Protista slides • Look at pond water while I check Ch. 29 notes • Protista animations and practice we’ll do on Wed. in computer lab Homework – Incorporate Ch. 30 by Wed., and 31 by Fri., 32&33 by next Mon., 34 by next Wed. Test next Friday!!!!
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Agenda 2/7/11 Chem Warmup AP Exam grade changes Finish Protista slides Look at pond water while I check Ch. 29 notes Protista animations and practice we’ll.
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Agenda 2/7/11
• Chem Warmup• AP Exam grade changes• Finish Protista slides• Look at pond water while I check Ch. 29 notes• Protista animations and practice we’ll do on Wed. in
computer lab
Homework – Incorporate Ch. 30 by Wed., and 31 by Fri.,32&33 by next Mon., 34 by next Wed.Test next Friday!!!!
Protista – making sense of it!! This is a paraphyletic kingdom
• Different ways of thinking about them:1) Based on nutrition:
plant-like (photosynthetic) = algae 2) Based on phylogeny (how your packet is organized): Using similarities in cell structure, SSU-rRNA, life cycles, and
cytoskeletal proteinsSTILL VERY MUCH A WORK IN PROGRESS
• The kingdom Protista formed a paraphyletic group, with some members more closely related to animals, plants, or fungi than to other protists.
• Systematists have split the former kingdom Protista into as many as 20 separate kingdoms.
• Still,“protist” is used as an informal term for this great diversity of eukaryotic kingdoms.
• The conventional model of relationships among the three domains place the archaea as more closely related to eukaryotes than they are to prokaryotes.– Similarities include proteins
involved in transcription and translation.
– This model places the host cell in the endosymbiotic origin of eukaryotes as resembling an early archaean.
Why grouped this way? Be sure you addressed this in your notes?
Not so important to memorize as it is to see why classified as they are.
Match the Protist with it’s description and identify it’s taxons/clades as applicable1) Blooms cause red tides2) Causes potato blight3) Causes an STD4) Has a red eyespot5) Kelp6) Moves with pseudopodia7) Sushi wraps8) 2 part glass-like silica walls9) Causes malaria10) Causes “hiker’s diarrhea”11) Closest relatives of land
plants12) Causes sleeping sickness13) Algae with yellow and
brown pigments14) Convergent evolution to
fungi15) Has micro and macronuclei
A) Slime moldB) DiatomsC) Oomycetes (water molds,etc.)D) Red algaeE) Brown algaeF) Golden algaeG) DinoflagellatesH) EuglenaI) Ciliate like ParameciumJ) Trypanosoma sp.K) Trichomonas vaginalisL) Giardia intestinalisM) PlasmodiumN) AmoebaO) Green algae
Which 3 of these have seaweed members?
Agenda 2/8/11
• Everyone see pond critters? What kinds?• Go over matching Protista activity• Start How Plants Colonized Land – to Vascular
Plants
Homework – Incorporate Ch. 30 by Wed., and 31 by Fri.,
32&33 by next Mon., 34 by next Wed.
Test next Friday!!!!
Plants move onto land
• Advantages increased sunlight unfiltered by water, more carbon dioxide in the atmosphere than in water, soils rich in nutrients, and fewer predators/pathogens at first.
• Challenges lack of water, dessication, and a lack of structural support against gravity
• Changed Earth for the rest of us – oxygen, food
• There are four main groups of land plants: bryophytes, pteridophytes, gymnosperms, and angiosperms.
• The most common bryophytes are mosses.
• The pteridophytes include ferns.• The gymnosperms include pines and
other conifers.• The angiosperms are the flowering plants.
Evolutionary adaptations to terrestrial living characterize the four main groups of land plants
1) Both possess rosette cellulose-synthesizing complexes (vs. linear in other algae) that synthesize the cellulose microfibrils of the cell wall.
2) Both have peroxisomes with enzymes that help minimize loss of organic products due to photorespiration.
3) Structure of their sperm closely related
4) Produce cell plate in cell division alike,
includes the formation of a phragmoplast, an alignment of cytoskeletal elements and vesicles
5) Similarity between nuclear and chloroplast genes
Charophyceans are the green algae most closely related to land plants
• Several characteristics separate the four land plant groups from their closest algal relatives, including:– apical meristems (localized regions of cell
division at the tips of shoots and roots)– multicellular embryos dependent on the
parent plant– alternation of generations– sporangia that produce walled spores– gametangia that produce gametes
Several terrestrial adaptations distinguish land plants from charophycean algae
• In terrestrial habitats, the resources that a photosynthetic organism requires are found in two different places.– Light and carbon dioxide are mainly
aboveground.– Water and mineral resources are found mainly
in the soil.
• Therefore, plants show varying degrees of structural specialization for subterranean and aerial organs - roots and shoots in most plants.
• Multicellular plant embryos develop from zygotes that are retained within tissues of the female parent.
• The parent provides nutrients, such as sugars and amino acids, to the embryo.
• This distinction is the basis for a term for all land plants, embryophytes.
Fig. 29.4
• All land plants show alternation of generations in which two multicellular body forms alternate.– This life cycle also occurs in various algae.– However, alternation of generation does not
occur in the charophyceans, the algae most closely related to land plants.
•spore is a reproductive cell that can develop into a new organism without fusing with another cell.
• Unlike the life cycles of other sexually producing organisms, alternation of generations in land plants (and some algae) results in both haploid and diploid stages that exist as multicellular bodies.– For example, humans do not have alternation
of generations because the only haploid stage in the life cycle is the gamete, which is single-celled.
• Most land plants have additional terrestrial adaptations including:– adaptations for acquiring, transporting, and
conserving water, (water-proof cuticle, stomata that open and close, xylem and phloem)
– adaptations for reducing the harmful effect of UV radiation (Flavonoids absorb harmful UV radiation),
– adaptations for repelling terrestrial herbivores and resisting pathogens (secondary compounds such as alkaloids, terpenes, tannins, and phenolics with bitter tastes, strong odors, or toxic effects that help defend land plants against herbivorous animals or microbial attack.)
• The advanced charophyceans Chara and Coleochaeta are haploid organisms.– They lack a multicellular sporophyte, but the zygotes
are retained and nourished on the parent.
• The zygote of a charophyceans undergoes meiosis to produce haploid spores, while the zygote of a land plants undergoes mitosis to produce a multicellular sporophyte.– The sporophyte then produces haploid spores by
meiosis.
Alternation of generations in plants may have originated by delayed meiosis
• A reasonable hypotheses for the origin of sporophytes is a mutation that delayed meiosis until one or more mitotic divisions of the zygote had occurred.– This multicellular, diploid sporophyte would have
more cells available for meiosis, increasing the number of spores produced per zygote.
• Many charophycean algae inhabit shallow waters at the edges of ponds and lakes where they experience occasional drying.– A layer of sporopollenin prevents exposed
charophycean zygotes from drying out until they are in water again.
– This chemical adaptation may have been the precursor to the tough spore walls that are so important to the survival of terrestrial plants.
Adaptations to shallow water preadapted plants for living on land
• The diversity of modern plants demonstrates the problems and opportunities facing organisms that began living on land.
• Because the plant kingdom is monophyletic, the differences in life cycles among land plants can be interpreted as special reproductive adaptations as the various plant phyla diversified from the first plants.
• Bryophytes were probably Earth’s only plants for the first 100 million years that terrestrial communities existed.– Then vegetation began to take on a taller
• Modern vascular plants (pteridophytes, gymnosperms, and angiosperms) have food transport tissues (phloem) and water conducting tissues (xylem) with lignified cells.
• In vascular plants the branched sporophyte is dominant and is independent of the parent gametophyte.
• The first vascular plants, pteridophytes, were seedless.
• Vascular plants built on the tissue-producing meristems, gametangia, embryos and sporophytes, stomata, cuticles, and sproropollenin-walled spores that they inherited from mosslike ancestors.
Additional terrestrial adaptations evolved as vascular plants
• The seedless vascular plants, the pteridophytes consists of two modern phyla:– phylum Lycophyta - lycophytes– phylum Pterophyta - ferns, whisk ferns, and
horsetails• These phyla probably
evolved from different ancestors among the early vascular plants.
• Most pteridophytes have true roots with lignified vascular tissue.
• These roots appear to have evolved from the lowermost, subterranean portions of stems of ancient vascular plants.– It is still uncertain if the roots of seed plants
arose independently or are homologous to pteridophyte roots.
Pteridophytes provide clues to the evolution of roots and leaves
• From the early vascular plants to the modern vascular plants, the sporophyte generation is the larger and more complex plant.– For example, the leafy fern plants that you are
familiar with are sporophytes.– The gametophytes are tiny plants that grow
on or just below the soil surface.– This reduction in the size of the gametophytes
is even more extreme in seed plants.
A sporophyte-dominant life cycle evolved in seedless vascular plants
• A heterosporous sporophyte produces two kinds of spores.– Megaspores develop into females
gametophytes.– Microspores develop into male
gametophytes.
• Regardless of origin, the flagellated sperm cells of ferns, other seedless vascular plants, and even some seed plants must swim in a film of water to reach eggs.
• Roots develop from horizontal rhizomes that extend along the ground.
• Upright green stems, the major site of photosynthesis, also produce tiny leaves or branches at joints.– Horsetail stems have a large air canal to allow
movement of oxygen into the rhizomes and roots, which are often in low-oxygen soils.
• Reproductive stems produce cones at their tips.– These cones consist of clusters of
sporophylls.• Sporophylls produce sporangia with haploid
• Ferns first appeared in the Devonian and have radiated extensively until there are over 12,000 species today. – Ferns are most diverse in the tropics but are
also found in temperate forests and even arid habitats.
• Ferns often have horizontal rhizomes from which grow large megaphyllous leaves with an extensively branched vascular system.– Fern leaves or fronds
• Ferns produce clusters of sporangia, called sori, on the back of green leaves (sporophylls) or on special, non-green leaves. http://www.youtube.com/watch?v=5hGQcmM6njY– Sori can be arranged in various patterns that are useful
in fern identification.– Most fern sporangia have springlike devices that
catapult spores several meters from the parent plant.– Spores can be carried great distances by the wind.
• While coal formed during several geologic periods, the most extensive beds of coal were deposited during the Carboniferous period, when most of the continents were flooded by shallow swamps.
• Dead plants did not completely decay in the stagnant waters, but accumulated as peat.
• The swamps and their organic matter were later covered by marine sediments.
• Heat and pressure gradually converted peat to coal, a “fossil fuel”.
• All seed plants are heterosporous, producing two different types of sporangia that produce two types of spores.– Megasporangia produce megaspores, which
give rise to female (egg-containing) gametophytes.• Microsporangia produce microspores, which give
rise to male (sperm-containing) gametophytes.
• In contrast to heterosporous seedless vascular plants, the megaspores and the female gametophytes of seed plants are retained by the parent sporophyte.
• The conifers, phylum Coniferophyta, is the largest gymnosperm phylum.– The term conifer comes from the reproductive
structure, the cone, which is a cluster of scalelike sporophylls.
– Although there are only about 550 species of conifers, a few species dominate vast forested regions in the Northern Hemisphere where the growing season is short.
• All angiosperms are placed in a single phylum, the phylum Anthophyta.
• As late as the 1990s, most plant taxonomists divided the angiosperms into two main classes, the monocots and the dicots.– Most monocots have leaves with parallel veins,
one cotyledon in the seed, and flowering parts in multiples of 3’s. Cotyledon=seed leaf
– Most dicots have netlike venation, 2 cotyledons in the seed, and flowering parts in multiples of 4’s and 5’s.
1. Systematists are identifying the angiosperm clades
• While evolutionary refinements of the vascular system contributed to the success of angiosperms, the reproductive adaptations associated with flowers and fruits contributed the most.
• The flower is an angiosperm structure specialized for reproduction.– In many species, insects and other animals transfer
pollen from one flower to female sex organs of another.– Some species that occur in dense populations, like
grasses, rely on the more random mechanism of wind pollination.
The flower is the defining reproductive adaptation of angiosperms
• Stamens, the male reproductive organs, are the sporophylls that produce microspores that will give rise to gametophytes.– A stamen consists of a stalk (the filament) and a
terminal sac (the anther) where pollen is produced.
• Carpals are female sporophylls that produce megaspores and their products, female gametophytes.– At the tip of the carpal is a sticky stigma that receives
pollen.– A style leads to the ovary at the base of the carpal.– Ovules and, later, seeds are protected within the ovary.
• All angiosperms are heterosporous, producing microspores that form male gametophytes and megaspores that form female gametophytes.– The immature male gametophytes are contained within
pollen grains and develop within the anthers of stamens.• Each pollen grain has two haploid cells.
– Ovules, which develop in the ovary, contain the female gametophyte, the embryo sac.• It consists of only a few cells, one of which is the egg.
The life cycle of an angiosperm is a highly refined version of the alternation of
• When the pollen tube reaches the micropyle, a pore in the integuments of the ovule, it discharges two sperm cells into the female gametophyte.
(7) In a process known as double fertilization, one sperm unites with the egg to form a diploid zygote and the other fuses with two nuclei in the large center cell of the female gametophyte.
(8) The zygote develops into a sporophyte embryo packaged with food and surrounded by a seed coat.– The embryo has a rudimentary root and one or two seed
leaves, the cotyledons.• Monocots have one seed leaf and dicots have two.
• The demand for space and natural resources resulting from the exploding human population is extinguishing plant species at an unprecedented rate.
• This is especially acute in the tropics where half the human population lives and where growth rates are highest.– Due primarily to the slash-and-burn clearing of forests
for agriculture, tropical forests may be completely eliminated within 25 years.
• We have derived many medical compounds from the unique secondary compounds of plants.
• More than 25% of prescription drugs are extracted from plants, and many more medicinal compounds were first discovered in plants and then synthesized artificially.
• The filamentous structure of the mycelium provides an extensive surface area that suits the absorptive nutrition of fungi.
• The fungal mycelium grows rapidly, adding as much as a kilometer of hyphae each day.
• The fungus concentrates its energy and resources on adding hyphal length and absorptive surface area.– While fungal mycelia are nonmotile, by swiftly
extending the tips of its hyphae it can extend into new territory.
• Many fungi form heterkaryotic mycelia after 2 hyphae fuse – nuclei can exchange chromosomes, compensate for mutations, etc.
• In many fungi with sexual life cycles, karyogamy, fusion of haploid nuclei contributed by two parents, occurs well after plasmogamy, cytoplasmic fusion by the two parents.– The delay may be hours, days, or even years.
• The defining feature of the Ascomycota is the production of sexual spores in saclike asci.– In many species, the spore-forming asci are collected
into macroscopic fruiting bodies, the ascocarp.• Examples of ascocarps include the edible parts of truffles and
morels.
• Ascomycetes reproduce asexually by producing enormous numbers of asexual spores, which are usually dispersed by the wind.– These naked spores, or conidia, develop in long
chains or clusters at the tips of specialized hyphae called conidiophores.
(1) The sexual phase of the ascomycete lifestyle begins when haploid mycelia of opposite mating types become intertwined and form an antheridium and ascogonium.
(2) Plasmogamy occurs via a cytoplasmic bridge and haploid nuclei migrate from the antheridium to the ascogonium, creating a heterokaryon.
(3) The ascogonium produces dikaryotic hyphae that develop into an ascocarp.
(4) The tips of the ascocarp hyphae are partitioned into asci.
(5) Karyogamy occurs within these asci and the diploid nuclei divide by meiosis, (6) yielding four haploid nuclei.
(7) Each haploid nuclei divides once by mitosis to produce eight nuclei, often in a row, and cell walls develop around each nucleus to form ascospores.
(8) When mature, all the ascospores in an ascus are dispersed at once, often leading to a chain reaction of release, from other asci.
(9) Germinating ascospores give rise to new haploid mycelia.
(1) Two haploid mycelia of opposite mating type undergo plasmogamy, (2) creating a dikaryotic mycelium that ultimately crowds out the haploid parents.
(3) Environmental cues, such as rain or temperature change, induce the dikaryotic mycelium to form compact masses that develop into basidiocarps.– Cytoplasmic streaming from the mycelium swells the
hyphae, rapidly expanding them into an elaborate fruiting body, the basidiocarp (mushrooms in many species).
– The dikaryotic mycelia are long-lived, generally producing a new crop of basidiocarp each year.
(4) The surface of the basidiocarp’s gills are lined with terminal dikaryotic cells called basidia.
(5) Karyogamy produces diploid nuclei which then undergo meiosis, (6) each yielding four haploid nuclei.– Each basidium grows four appendages, and one haploid
nucleus enters each and develops into a basidiospore.
(7) When mature, the basidiospores are propelled slightly by electrostatic forces into the spaces between the gills and then dispersed by the wind.
(8) The basidiospores germinate in a suitable habitat and grow into a short-lived haploid mycelia.
• By concentration growth in the hyphae of mushrooms, a basidiomycete mycelium can erect basidiocarps in just a few hours.– A ring of mushrooms may appear overnight.– At the center of the ring are areas where the
mycelium has already consumed all the available nutrients.
– As the mycelium radiates out, it decomposes the organic matter in the soil and mushrooms from just behind this advancing edge.
• Four fungal forms: molds, yeasts, lichens, and mycorrhizae, have evolved morphological and ecological adaptations for specialized ways of life.– These have occurred independently among the
zygote fungi, sac fungi, and club fungi.
Molds, yeasts, lichens, and mycorrhizae are specialized lifestyles that evolved
• Yeasts are unicellular fungi that inhabit liquid or moist habitats, including plant sap and animal tissues.– Yeasts reproduce asexually by simple cell
division or budding off a parent cell.– Some yeast reproduce sexually, forming asci
(Ascomycota) or basidia (Basidiomycota), but others have no known sexual stage (imperfect fungi).
• While often mistaken for mosses or other simple plants when viewed at a distance, lichens are actually a symbiotic association of millions of photosynthetic microorganisms held in a mesh of fungal hyphae.
• The fungal component is commonly an ascomycete, but several basidiomycete lichens are known.
• The photosynthetic partners are usually unicellular or filamentous green algae or cyanobacteria.
• The merger of fungus and algae is so complete that they are actually given genus and species names, as though they were single organisms.– Over 25,000 species have been described.
• In most cases, each partner provides things the other could not obtain on its own.– For example, the alga provides the fungus with
food by “leaking” carbohydrate from their cells.– The cyanobacteria provide organic nitrogen
through nitrogen fixation.– The fungus provides a suitable physical
environment for growth, retaining water and minerals, allowing for gas exchange, protecting the algae from intense sunlight with pigments, and deterring consumers with toxic compounds.• The fungi also secrete acids, which aid in the uptake
• Lichens are important pioneers on newly cleared rock and soil surfaces, such as burned forests and volcanic flows.– The lichen acids penetrate the outer crystals of
rocks and help break down the rock.– This allows soil-trapping lichens to establish
and starts the process of succession.– Nitrogen-fixing lichens also add organic