Download Chapters 16-19: Diversity of Life 1. Taxonomic Classification The Classification of Organisms

Chapters 16-19:
Diversity of Life
1. Taxonomic Classification
2. Viruses and Prokaryotes
3. Protists and Fungi
4. Plants
5. Animals
1. Taxonomic Classification
The Classification of Organisms
There 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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The Taxonomic Hierarchy
Each level of the hierarchy is referred to as
a taxa:
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Humans
eukarya
animal
chordates
mammals
primates
hominids
Homo
sapiens
The Major “Taxa”
The 3 Domains: Bacteria
Archaea
Eukarya
4 Kingdoms Protists, Fungi, Plants & Animals
of Eukarya:
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
Viruses are Small, Simple, Non-living
Consist 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
bacteria
euk. cell
viruses
Viruses come in Immense Variety
Differ in:
• size & shape
• genetic
material
• DNA, RNA,
double or
single strand
• mode of
infection
• host
specificity
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AIDS Virus Infection
The AIDS virus is a retrovirus:
must convert RNA to DNA
Types of Prokaryotes
Prokaryotes = 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
Prokaryotes come in 3 Basic Shapes
spherical
(coccus)
rod-shaped (bacillus)
corkscrew-shaped
(spirillum)
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3. Protists and Fungi
Types of Protists
Protists = most single-celled eukaryotic
organisms
• some can form multicellular aggregates
• 2 basic types of protist:
1) Protozoa (“first animals”)
• heterotrophs (ingest food)
• amoebae, paramecia,
zooplankton, trypanosomes
• many are parasites
• e.g., trypanosomes,
plasmodium (causes malaria)
trypanosomes
2) Algae (“photosynthetic protists”)
• phytoplankton (dinoflagellates,
diatoms, volvox)
• “seaweeds”
diatoms
seaweed (kelp)
volvox
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The Fungi
Types of Fungi
include:
• molds
• yeast
• mushrooms
Key Characteristics of Fungi
Fungi 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
4. Plants
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What constitutes a Plant?
Plants are multicellular, photosynthetic,
and share characteristic modes of reproduction
Major plant
phyla, classes
The Bryophytes
Liverworts
Mosses
Key features:
• lack true leaves, roots,
stems
• no internal vasculature
• rely mainly on diffusion
• limits their size
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 Plants
Horsetails
Ferns
• most primitive
vascular plant
Gymnosperms
pine
All “cone-bearing” plants:
• conifers (pines, firs, etc…),
cycads, gingko
cycad
• seeds
produced
in cones
juniper
(not flowers)
gingko
Angiosperms
All flowering plants:
• produce seeds* in flowers (via fertilization of gametes)
• disperse seeds via fruits
*seeds are plant embryos + nutrients within a seed coat
• most dominant type of plant
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5. Animals
Invertebrates
Vertebrates
Characteristics of Animals
All members of the Animal Kingdom:
• are multicellular
• consist of eukaryotic cells w/o cell walls
• are heterotrophs
• consume food derived from other organisms
• feed by “ingesting” food
• unlike fungi which “absorb” food externally
Most members of the Animal Kingdom:
• have a symmetrical body plan
• radial or bilateral symmetry
• have distinct tissues, organs
• reproduce sexually
Radial vs Bilateral Symmetry
Radial Symmetry
• symmetrical halves “no matter how you slice it”
Bilateral
Symmetry
• only one
plane of
symmetry
symmetry as viewed from the dorsal (back)
or ventral (belly) sides
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Vertebrate vs Invertebrate
Vertebrate 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”
Invertebrates
Major Invertebrate Phyla
“Lower” Invertebrates “Higher” Invertebrates
Porifera
• all sponges
Cnidarians
• anemones, coral, jellyfish
Platyhelminthes
• all “flatworms”
Nematodes
• all “roundworms”
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”)
The Cnidarians
Anemones, jellyfish,
corals…
• have radial symmetry
• are sessile, or freefloating
• only 2 embryonic
germ layers
• endoderm
(inner layer)
• ectoderm
(outer layer)
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
Trichinella
• small in size, frequently
parasitic
• important decomposers
fresh water nematode
“heartworms”
Annelids (Segmented Worms)
Earthworms, leeches, sandworms…
• repetitive
body segments
• closed circulatory system*
• digestive tract
with 2 openings
(mouth, anus)*
The Mollusks
Grouped into 3 main classes:
GASTROPODS (snails & slugs)
BIVALVES (clams, scallops, oysters)
CEPHALOPODS (squid, octopus, cuttlefish)
snail
scallop
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octopus
squid
Cephalopods:
• most advanced
mollusks
• unusually high
intelligence
nautilus
The Arthropods
3 main classes of Arthropod:
INSECTS
• estimated
9 million
species!
ARACHNIDS
• spiders, ticks
scorpions,
mites
CRUSTACEANS
• crabs, shrimp
lobsters,
barnacles
Characteristic Arthropod Features
Have an exoskeleton (external skeleton)
• must “molt” for growth to occur
Many undergo metamorphosis
• e.g., moths, butterflies
Segmented
bodies
Open circulatory systems
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The Echinoderms
Starfish, sea urchins,
sea cucumbers…
• calcium carbonate
endoskeleton
• radial symmetry (adult)
• larvae are bilateral
Vertebrates
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
Reptiles
• “jawless” fishes
Chondrichthyes
• cartilagenous fishes
Osteoichthyes
• bony fishes
• lizards, snakes, turtles…
Birds (Aves)
• chickens, eagles…
Mammals
• humans, cats, dogs…
Amphibians
• frogs, salamanders…
Agnatha
Jawless fishes:
• hagfish
• lamprey
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?)
Amphibians
• need water to reproduce
• breathe through skin &
lungs*
• 1st vertebrates to leave
the water
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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Birds (Aves)
• thought to have evolved from reptiles
• wings & feathers*
• first homeothermic organisms*
• maintain constant body temperature (warm-blooded)
• amniotic egg
Mammals
• most have placenta*
• young develop internally
• mammary glands*
• nourish young with milk
• homeothermic
• hair*
Key Terms for Chapters 16-19
• taxa, domain, kingdom, phylum…
• bacteria, archaea, eukarya, fungi, protists
• bacillus, coccus, spirillum
• protozoa, algae
• bilateral vs radial symmetry, vertebrate vs invertebrate
• sessile vs motile, exoskeleton vs endoskeleton
• notochord, amniotic egg, homeothermic
Relevant Review Questions:
ch. 16 – 3, 6; ch. 17 – 3, 5, 9
ch. 18 – 1, 3-5, 7-15; ch. 19 – 3
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