chapters 28 30
TRANSCRIPT
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Chapters 28-30: Diversity of Life
1. Taxonomic Classification
2. Viruses and Prokaryotes
3. Protists and Fungi
4. Plants
5. Animals
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1. Taxonomic Classification
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The Classification of OrganismsThere are ~1.5 million known species on
our planet.• total # or species on earth estimated to be
anywhere from 7 to 100 million
To study so many organisms and their evolutionary relationships requires:
• standard nomenclature• same name used worldwide for a given organism
• hierarchy, system of classification• allows organization by “relatedness”
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By classifying organisms into groups(“taxa”), it help us to answer such questions as:•Is a snake more closely related to a worm or a lizard?•Is a mushroom more related to a plant or a mold?
All organisms are separated into 4 major groups (Kingdoms), which are further sub-divided into smaller and smaller groupings
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The Taxonomic HierarchyEach level of the hierarchy is referred to as
a taxa:
Domain
Kingdom
PhylumClass
Order
Family
Genus
Species
Humans
eukarya
animal
chordates
mammals
primates
hominids
Homo
sapiensKing Philip Can Only Find Green Socks
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Each organisms is named using both its genus and species.A species is defined as a group of organisms that interbreed with one another to produce fertile offspring.
beetle: Agra katewinsletaelichen: Caloplaca obamaeWasp: Polemistus chewbacca
Example: horse: Equus caballus donkey: Equus asinus
Same genus, different species. Their offspring, the mule, is sterile.
worm: Craniella abracadabra
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The Major “Taxa”
The 3 Domains:
4 Kingdomsof Eukarya:
Bacteria Archaea Eukarya
Protists, Fungi, Plants & Animals
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Bacteria:• “common” prokaryotes
Archaea (or archaebacteria):
• “unusual” prokaryotes or “extremophiles”• thrive in harsh environments (acid, high salt, boiling…)
Eukarya:• all organisms made of eukaryotic cells
Protists: single-celled eukaryotes
Fungi: multicellular; absorb food
Plants: multicellular; photosynthesize
Animals: multicellular; ingest food
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2. Viruses and Prokaryotes
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euk. cellbacteria viruses
Viruses are Small, Simple, Non-livingConsist of genetic material (DNA or RNA) inside a protein coat (may have a membrane envelope).
• no metabolic capabilities
• reproduce only within a host
• frequently “lyse” or kill host cell
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Viruses come in Immense Variety
Differ in:
• size & shape
• genetic material
• mode of infection
• host specificity
• DNA, RNA, double or single strand
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AIDS Virus Infection
The AIDS virus is a retrovirus:must convert RNA to DNA
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Types of ProkaryotesProkaryotes = single-celled organisms
lacking nuclei and other organelles
Bacteria• live in every conceivable environment
• immense variety of metabolism, physiology
• play many essential biological roles• nitrogen fixation (all plants depend on it!)
• decomposition (essential for recycling of nutrients)
• digestion (gut flora in humans, cattle,…)
Archaea• thrive in very extreme environments
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Prokaryotes come in 3 Basic Shapes
spherical(coccus)
rod-shaped (bacillus)
corkscrew-shaped(spirillum)
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Extreme Habitats
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3. Protists and Fungi
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Types of ProtistsProtists = most single-celled eukaryotic
organisms
• some can form multicellular aggregates
• e.g., trypanosomes, plasmodium (causes malaria)
1) Protozoa (“first animals”)
• heterotrophs (ingest food)
• amoebae, paramecia, zooplankton, trypanosomes
• many are parasites
• 2 basic types of protist:
trypanosomes
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zygote
sporozoite
gametocytes
Sexual phasein mosquito
femalegamete
malegamete
foodcanal
salivarygland
1. In the gut of a female Anopheles mosquito, gametes fuse, and the zygote undergoes many divisions to produce sporozoites, which migrate to her salivary gland.
2. When the mosquito bites a human, the sporozoites pass from the mosquito salivary glands into the bloodstream and then the liver of the host.
livercell
3. Asexual spores (merozoites) produced in liver cells enter the bloodstream and then the red blood cells. A sexual phase
in humans
5. Merozoites and toxins pour into the bloodstream when the red blood cells rupture, causing chills and fever.
4. When the red blood cells rupture, merozoites invade and reproduce asexually inside new red blood cells.
6. Some merozoites become gametocytes, which enter the blood- stream. If taken up by a mosquito, they become gametes.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
MALARIA
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2) Algae (“photosynthetic protists”)
• phytoplankton
• “seaweeds”
(dinoflagellates,diatoms, volvox)
volvoxseaweed (kelp)
diatoms
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The Fungi
Types of Fungiinclude:
• molds
• yeast
• mushrooms
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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
fertilization
zygospore
meiosisSexual
Asexual
sporangium
mycelium
+ strain
– strain
© Runk/Schoenberger/Grant Heilman Photography
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Key Characteristics of FungiFungi digest organic material externally (they don’t ingest food like animals do):
• secrete digestive enzymes, absorb food
• some are detritus feeders (consume dead matter) some are parasites (prey on living)
• decomposition of dead organic matter is extremely important for ecosystems (recycles nutrients)
Fungal cells have cell walls (made of chitin)
Can reproduce sexually or asexually
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4. Plants
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What constitutes a Plant?
Major plant phyla, classes
Plants are multicellular, photosynthetic,and share characteristic modes of reproduction
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The Bryophytes
Liverworts
Key features:
Mosses
• lack true leaves, roots, stems
• no internal vasculature
• rely mainly on diffusion
• limits their size
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– Can live on bare rock, fences, cracks of sidewalks• Selective advantage to being small and simple
– Help convert rocks to soil
– Peat moss• Used as fuel
• Holds water
• Used in gardens to improve soil
Adaptations and Uses of Nonvascular Plants
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The Tracheophytes
Tracheophytes are the vascular plants:
• contain vessels to transport material internally
There are 3 basic types of vascular plant:
• seedless vascular plants (e.g., ferns, horsetails)
• gymnosperms (all “cone-bearing” plants)
• angiosperms (all flowering plants)
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Seedless Vascular PlantsHorsetails Ferns
• most primitive vascular plant
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Seedless Vascular Plants
• Vascular tissue – Xylem conducts water and minerals– Phloem transports organic nutrients
• Have true roots, stems, and leaves• Seedless vascular plants produce windblown
spores (not seeds)
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Seed PlantsGymnosperms and Angiosperms
– Most plentiful plants in the biosphere today
– Seeds contain a sporophyte embryo and
stored food within a protective coat
• Allows an embryo to survive during long
periods of dormancy
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Gymnosperms
• conifers (pines, firs, etc…), cycads, gingko
• seeds produced in cones (not flowers)
All “cone-bearing” plants:
pine
cycad
gingko
juniper
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Conifers– Pine, spruce, fir, cedar, hemlock, redwood,
and cypress– Adapted to cold, dry weather– Needlelike leaves conserve water with thick
cuticle and recessed stomata– Dominant sporophyte produces pollen cones
and seed cones– Wood is used in construction and for making
paper
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AngiospermsAll flowering plants: • most dominant type of plant
*seeds are plant embryos + nutrients within a seed coat
• produce seeds* in flowers (via fertilization of gametes) • disperse seeds via fruits
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Flower Diversity
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Seed Plants• Life cycle
– Sexual reproduction in flowering plants is dependent on the flower
• Produces both pollen and seeds
– Pollination can be by wind or pollinator• Bees, wasps, flies, butterflies, moths, beetles, and even
bats• Many flowers are adapted to attract quite specific
pollinators
– Fruits• Final product of a flower• Aids in the dispersal of seeds
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5. Animals
Invertebrates
Vertebrates
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Characteristics of AnimalsAll members of the Animal Kingdom:
• consume food derived from other organisms
• feed by “ingesting” food• unlike fungi which “absorb” food externally
• consist of eukaryotic cells w/o cell walls
• are heterotrophs
• are multicellular
Most members of the Animal Kingdom:• have a symmetrical body plan
• radial or bilateral symmetry
• have distinct tissues, organs• reproduce sexually
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Animal Diversity
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Radial vs Bilateral SymmetryRadial Symmetry
• symmetrical halves “no matter how you slice it”
Bilateral Symmetry• only one plane of symmetry
bilateral symmetry
anterior
posterior
dorsal
ventral
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Vertebrate vs InvertebrateVertebrate animals
• have a backbone or “vertebral” column
• less than 3% of known animal species
Invertebrate animals• NO backbone or “vertebral” column
• > 97% of known animal species
• any “non-vertebrate” animal
The vertebrate/invertebrate distinction is somewhat “old school”
They more or less constitute “sub-kingdoms”
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Invertebrates
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Major Invertebrate Phyla“Lower” Invertebrates
Porifera• all sponges
Cnidarians• anemones, coral, jellyfish
Platyhelminthes• all “flatworms”
Nematodes• all “roundworms”
“Higher” Invertebrates
Annelids• all “segmented worms”
Mollusks• snails, clams, squids
Arthropods• insects, spiders, crabs
Echinoderms• starfish, sea urchins
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The Porifera (Sponges)
The simplest, most primitive animal phylum• lack distinct tissues or organs• some reproduce asexually (no union of sperm & egg)• don’t necessarily display bodily symmetry• are sessile (i.e., fixed in placed, “non-motile”)
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Simple Sponge AnatomyFilter feeder
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
b. Sponge organization
c.
d.
sponge wall
pore
spicule
amoebocyte
collar cell (choanocyte)
nucleuscollar
flagellum
amoebocyte
osculum
H2O inthroughpores
H2O out
centralcavity
epidermalcell
a. Yellow tube spoge,Aplysina fistularis
a: © Andrew J. Martinez/Photo Researchers, Inc
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The CnidariansAnemones, jellyfish,corals…• have radial symmetry
• are sessile, or free- floatingAll aquatic• only 2 embryonic germ layers
• endoderm (inner layer)
• ectoderm (outer layer)
Mouth and
anus
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Cnidarian DiversityCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
b. Sea anemone, Corynactis c. Cup coral, Tubastrea
e. Jellyfish, Aureliad. Portuguese man-of-war, Physalia
b: © Azure Computer & Photo Services/Animals Animals; c: © Ron & Valerie Taylor/Bruce Coleman, Inc.; d: © Runk/Schoenberger/Grant Heilman Photography; e: © © Amos Nachoum/Corbis
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The Platyhelminthes (Flatworms)
• bilateral symmetry
• have internal organs
• lack respiratory, circulatory systems
• many are parasites
“Planaria”“Tapeworms”
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The Nematodes (Roundworms)• estimated 500,000 different species
• small in size, frequently parasitic
• important decomposers
fresh water nematode
Trichinella
“heartworms”
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What some roundworms can do to you– Trichinosis
• Caused by Trichinella spiralis• Humans contract the worm by eating undercooked
pork• Larvae migrate out of intestines and form painful
cysts in the muscles
– Elephantiasis• Caused by a filarial worm • Migrates into lymphatic vessels and prevents
lymph drainage• Swelling of limbs occurs
– Pinworms and hookworms• Roundworm parasites which cause problems in
children
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Annelids (Segmented Worms)Earthworms, leeches, sandworms…
• repetitive body segments
• closed circula- tory system*
• digestive tract with 2 openings (mouth, anus)*
• Gas exchange is across the body wall
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The MollusksGrouped into 3 main classes:
GASTROPODS (snails & slugs)
BIVALVES (clams, scallops, oysters)
CEPHALOPODS (squid, octopus, cuttlefish)
snail scallop
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octopus squid
nautilus
Cephalopods:• most advanced mollusks
• unusually high intelligence
http://www.youtube.com/watch?v=jN99Kx_ghC8http://www.youtube.com/watch?v=p9A-oxUMAy8
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The Arthropods3 main classes of Arthropod: INSECTS
• estimated 9 million species!
ARACHNIDS• spiders, ticks scorpions, mites
CRUSTACEANS• crabs, shrimp lobsters, barnacles
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Characteristic Arthropod FeaturesHave an exoskeleton (external skeleton)
• must “molt” for growth to occur
Segmented bodies
Open circula- tory systems
• e.g., moths, butterfliesMany undergo metamorphosis
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The Echinoderms
Starfish, sea urchins,sea cucumbers…• calcium carbonate endoskeleton
• radial symmetry (adult)• larvae are bilateral
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Vertebrates
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The Phylum Chordata
Main characteristics of the Chordates:• have a notochord
• usu. gives rise to the backbone during development
• have a hollow nerve cord• becomes brain & spinal cord during development
• pharyngeal “gill slits”• may disappear during development
• have a tail• may disappear during development
***All vertebrates are chordates but not all chordates are vertebrates***
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Major Chordate Classes
Agnatha• “jawless” fishes
Chondrichthyes• cartilagenous fishes
Osteoichthyes• bony fishes
Amphibians• frogs, salamanders…
Reptiles• lizards, snakes, turtles…
Birds (Aves)• chickens, eagles…
Mammals• humans, cats, dogs…
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Agnatha
Jawless fishes:
• hagfish
• lamprey
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Chondrichthyes
Sharks, rays and skates• skeleton made of cartilage* (no bone)• have jaws*
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Osteoichthyes
All bony fishes (have true bone*)• most diverse class of vertebrates
• have scales* • air bladder* (precursor to lungs?)
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Amphibians
• need water to reproduce
• breathe through skin &lungs*
• 1st vertebrates to leavethe water
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Reptiles
• water-proof skin*
• first organisms to develop in an amniotic egg*• can develop away from water
• first true “land” vertebrates
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• A water-impermeable structure which contain a fluid and so the embryo to develop on land without danger of desiccation.
• It also contain a yolk to nourish the developing organism.
• Amniotic eggs protect the developing organism, as well as aid in gas and energy exchange.
What is an amniotic egg?
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YOLK: sacs that contains the nutrients
CHORION: encloses all the other sacs
ALLANTOIS: sac that stores the metabolic wastes
AMNION: A fluid-filled sac that provides an aquatic environment to the developing embryo/
Amniotic egg structure
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Birds (Aves)
• thought to have evolved from reptiles
• wings & feathers*
• first homeothermic organisms*• maintain constant body temperature (warm-blooded)
• amniotic egg
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Mammals
• most have placenta*• young develop internally
• mammary glands*
• homeothermic
• hair*
• nourish young with milk