Transcript SBI2.1beginningsoflife

DIVERSITY OF
LIVING THINGS
Where did we come from?
The Beginnings of Life
• Earth is ~ 4.567 billion years old
• Think of the earth’s history as one 24h period
(each second = 53 000 yrs)
• Universe began 2 days ago (14 billion y.a.)
• First signs of life at 3 am: “replicator” (4 billion y.a.)
• First prokaryotic cell at 5:20 am (common ancestor)
(survived in CO2 and water)
• 8 am – Organisms began to use light as an energy
source – photosynthesis (oxygen was produced
and was toxic!)
• Oxygen and UV combine to create the ozone
layer…the atmosphere was formed!
Early days on planet Earth
The Beginnings of Life
• 2 pm – Bacteria and
Archaea, and eukaryotes
combine
• Small organelles like
mitochondria and
chloroplasts fuse into larger
cells.
• 6:15 pm – plant, animal,
fungi lines begin to form
• 7:15 pm – Multicellular
plants and water animals
form
• 10:12 pm - (340 million ya)
the evolution of the amniotic
egg allowed eggs to be laid
on land.
The super-continent Pangaea
The Beginnings of Life
• 2 seconds before
midnight–
Homo sapiens arise
HOW MANY ORGANISMS?
• 287,655 plants,
including:
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15,000 mosses,
13,025 ferns,
980 gymnosperms,
199,350 dicotyledons,
59,300 monocotyledons;
• 74,000-120,000 fungi;
• 10,000 lichens;
HOW MANY ORGANISMS?
• 1,550,000 animals,
including:
– 1,490,200 invertebrates:
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1,250,000 insects,
70,000 molluscs,
40,000 crustaceans,
130,200 others;
– 58,808 vertebrates:
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29,300 fish,
5,743 amphibians,
8,240 reptiles,
9,934 birds,
5,416 mammals.
BIODIVERSITY
The Amazon – An example of
Biodiversity
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1 million insect species.
Tens of thousands of plants.
2000 birds and mammals.
To date, at least 40,000 plant
species, 3,000 fish, 1,294 birds,
427 mammals, 427 amphibians,
and 378 reptiles have been
classified.
Scientists have described between
96,660 and 128,843 invertebrate
species in Brazil alone.
1km2 may contain over 75,000
types of trees.
1km2 can contain about 90,790
tons of living plants.
Largest collection of living plants
and animal species in the world.
One in five birds live in the
Amazonian rainforests
The Amazon – Under Seige
• 1/5 has been
destroyed
• Between 1991 and
2000 an area twice
the size of Portugal
has disappeared.
• 52 000 square km
are disappearing
per year…mostly
for cattle farms.
Under siege (cont)
• It is estimated that
we are losing
140 000 species a
year!
MORE NUMBERS…
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Organism Number
Estimated number yet to be Discovered
Viruses 5,000
500,000
Bacteria 4,000
400,000-30 million
Fungi 70,000
1.5 million
Protozoans 40,000
100,000-200,000
Algae 40,000
200,000-10 million
Flowering plants 250,000
300,000-500,000
Roundworms 15,000
500,000-1 million
Mollusks 70,000
200,000
Crustaceans 40,000
150,000
Spiders and mites75,000
750,000-10 million
Insects 950,000
8-10 million
Vertebrates 45,000
50,000
HOW DO BIOLOGISTS KEEP TRACK
OF ALL THESE ORGANISMS?
CLASSIFYING LIVING THINGS
Linnean System of Classification
• Groups organisms according to their
structural similarities - TAXONOMY
• Binomial nomenclature…
– The first part of any scientific name is called the
genus. A genus may be used alone. First letter
capitalized. (Written in italics.)
– The second part is called the species and is
never used alone. (Written in italics.)
– Eg. Canis lupis
– Escherichia coli (E. coli)
TAXA
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Kingdom Organisms less similar (broad category)
Phylum
Class
Order
Family
Genus
Species Organisms very similar (narrow category)
• Each level called a taxon (plural ‘taxa’)
• “King Philip Could Order Four Good Salads”
(a mnemonic)
Kingdom Archaebacteria
• Prokaryotic
• heterotrophs
• Bacteria in extreme
conditions (eg.
volcanoes)
Kingdom Eubacteria
• lack nuclei
(prokaryotic)
• Heterotrophs or
autotrophs
• Can reproduce
asexually
• Bacteria found
everywhere (eg E.
coli)
Kingdom Protista
• some terrestrial, some
aquatic
• Some have
chloroplasts
• Most single-celled.
• Some autotrophs,
some heterotrophs,
some both
• reproduce sexually and
asexually
• e.g. Amoeba,
Paramecium
Kingdom Fungi
• Like plants but unable
to carry out
photosynthesis
• Heterotrophs
• Most are multicellular
• Have cell walls but not
made of cellulose
• Reproduce sexually
and asexually
• Most are terrestrial
• e.g. Yeasts, moulds,
mushrooms
Kingdom Plantae
• Cell walls contain
cellulose
• Multi-cellular
• Autotrophs
• Most reproduce
sexually and
asexually
• Have chloroplasts
• e.g. Mosses, ferns,
seed plants
Kingdom Animalia
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No cell walls
Multicellular
Heterotrophs
Most reproduce sexually
Both terrestrial and
aquatic
• Includes invertebrates (no
backbone) and
vertebrates (have
backbone)
• e.g. Clam, fish, turtle, cat,
human
HOMEWORK
• Page 376, Q #1-5
Dichotomous Classification Keys
Choose your own adventure!
• Helps place organisms
into appropriate
groups.
• Each key includes two
choices for each
characteristic.
• No two keys are the
same.
• WARNING…Do not
classify based on the
behavior of the
organisms…just their
structure!
A Classification Tree of the Six Kingdoms:
All Living Organisms
Prokaryotic?
YES
NO
Live in harsh
environment?
YES
Archaebacteria
Eukaryotic cells: Are they multi-cellular?
NO
NO
Protista
YES
Eubacteria
Cell Wall?
YES
NO
Animalia
Wall of Cellulose?
YES
NO
Plantae
Fungi
YOU TRY IT!!
• Make a classification tree using 10
items!