Chapter 14 The History of Life. Section 14.1 The Record of Life.

Chapter 14The History of Life

Section 14.1 The Record of Life

Early History of Earth

-The Earth is 4.1- 4.2 billion years old

-Life originated in Earth’s oceans

between 3.4 - 3.9 billion years ago

History in Rocks

Fossils—Clues to the

past

- A fossil

(化石 ) is evidence of an

organism that lived

long ago

Fossil formation （ P 371 ）- For fossils to form, organisms usually have to be

buried in mud, sand, or clay soon after they die.

- These particles are compressed over time and

harden into a type of rock called sedimentary rock

( 沉积岩 ).

History in Rocks

Trace fossil-

Foot prints, nests/dens, or fossilized feces (poop)

Tell scientists about the activities going on at that time

History in Rocks

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Mold-

Organism dies in soft mold and leaves an imprint of it’s body

History in Rocks

Cast-

Starts as a mold, but over time a mixture of water and minerals fill in the mold

Makes a 3D model of the organism

History in Rocks

Petrified/ Permineralized fossil-Minerals invade and replace organism’s parts as it dies

Makes very detailed skeletons

Body is turned to stone

History in Rocks

Amber-preserved fossil

-Organism lands on a tree and gets stuck in the tree sap

-Over time the sap changes to Amber stone

-Organism is often perfectly preserved

History in Rocks

Relative dating ( 相对定年法 )

-As layers of sediment rock build on top of each other, the fossils in the deepest layers of rock most be older than those above them.

-General age of fossil, cannot be exact

History in Rocks

Radiometric dating ( 放射性定年法 )

-Using radioactive isotopes to age fossils

-Carbon-14

-Potassium-40

-Chlorine-36

History in Rocks

The geologic time scale

- The Precambrian ( 前寒武纪 )

- The Paleozoic Era( 古生代 )

- The Mesozoic Era( 中生代 )

- The Cenozoic Era( 新生代 )

Each era( 代 ) is subdivided into periods( 纪 )

Geological Calendar:

All of Time in just 1 year!

Formation of the Earth is

00:00 on 1/1

A Trip Through Geologic Time

The Precambrian Era


4570 – 542 million year ago1)Life Begins2)Prokaryotes form3)Eukaryotes form4)Invertebrates appear -complex organisms with no backbones

Geological Calendar: 2/25- 11/18

Life during the Precambrian

Unicellular prokaryote appear

(4000- 3400 million years ago)



More complex eukaryotic organism

appeared (2500 – 2100 million years ago)



Multicellular eukaryotes, such as sponges and

jellyfishes, and invertebrates diversified and

filled the oceans (543 million years ago)


A Trip Through Geologic TimeThe Paleozoic Era:542-251 million years ago

-First Vertebrates

-First Fish

-First Land Plants

-First Amphibians

-First Reptiles

-First TreesGeological Calendar:

11/18- 12/12

Cambrian explosion ( 寒武纪大爆发，535 to 525 million years ago)

Dramatic increase in number of species


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Permian extinction (二叠纪大灭绝)“The Great Dying”

-End of the Paleozoic Era

96% of Marine species

70% of vertebrates

83% of Insect species

-Caused by climate

change

-Hotter temperatures

-volcano activity

-Ice Age

-Dust reflects sunlight

The Mesozoic Era:200-65 million years ago

-First dinosaurs

-First mammals

-First flowers

-First birds


12/12 – 12/26


Mesozoic Mass Extinction:Second largest extinction

Caused by an asteroid impact and increased volcanic activity

Known as the K-T Extinction

Continental Drift

（板块漂移）

Movement of tectonic plates

The Cenozoic Era:65 million years ago – Present day

-Domination of

mammals

-Evolution of

Humans

-Modern Society


12/26 – 12/31


Geological Time Line Homework:Create your own representation of the Geological Time

- Work in Groups of 2 or 3

- Must show the ratio used

- Must show all events listed on p.376

- Creative designs can get bonus points

- You will present your time line next class

- MiniLab 14.2 on p.376 will help you;

You do not have to follow MiniLab 14.2!!

SHARE the work!

Section 14.2 The Origin of Life

Spontaneous generation

The idea that nonliving material can produce life

Origins: The Early Ideas

Spontaneous generation is disproved by Francesco Redi:


• Maggots only grow on meat exposed to flies

• What about microbes?

• There are bacteria everywhere?! How they must appear from a life force in the air…

Louis Pasteur:


• French Scientist• One of the creators of Microbiology

and did experiments that supported Germ Theory

1) Germs cause disease2) Germs do not spontaneous

generate

• Biogenesis ( 生源论 )

• The idea that living organisms

come only from other living

organisms

Simple organic molecules formed

In the 1930s, a Russian scientist, Alexander

Oparin, hypothesized that life began in the

oceans that formed on early Earth.

Origins: The Modern Ideas

Simple organic molecules formedIn 1953, two American scientists, Stanley Miller and Harold Urey, tested Oparin’s hypothesis by simulating the conditions of early Earth in the laboratory.


The formation of protocells

A protocell( 原细胞 ) is a large, ordered

structure, enclosed by a membrane, that

carries out some life activities, such as growth

and division.


Archaebacteria:

Early Life Forms

• First forms of complex life; Can only survive in extreme environments

• Used abundant organic molecules for food

• Evolved to produce glucose through chemo-synthesis

Photosynthesizing prokaryotes


Death By Oxygen!


• Most species up to this point were anaerobic prokaryotes

• Creation of an oxygen rich atmosphere changed environment

• Dramatic shift in microbe evolution

The Endosymbiont theory( 内共生理论 )Eukaryotes evolved through a symbiotic relationship between ancient prokaryotes.


Experimental evidence shows:

- Chloroplasts/Mitochondria

contain DNA that is similar

to the DNA in prokaryotes


have their own ribosomes


reproduce independently


That’s all

Chapter 14 The History of Life. Section 14.1 The Record of Life.

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Transcript of Chapter 14 The History of Life. Section 14.1 The Record of Life.