Biology Quarter 3 Exam

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The Fossil Record provides evidence about…

the history of life on Earth.

What does the fossil record also show?

How different groups of organisms, including species, have changed over time

1st step of fossil formation

An  organism dies and is buried with layers of sediment

2nd step of fossil formation

Layers of sediment begin to compress making sedimentary rock. Chemical activity turns the organism’s remains into rock.

3rd step of fossil formation

After thousands of years, the  sea level changes, bringing layers of rock closer to the surface.

4th step of fossil formation

Erosion allows the organism’s remains to be exposed.

Radioactive Dating

One method a paleontologist may use to estimate the age of fossils

Index Fossils

Another method a paleontologist may use to estimate the age of a fossil and get the absolute age of the fossil.

Fossils

Evidence of an organism that lived long ago that is preserved in Earth’s rocks

Paleontologists estimate that about 99% of species are…

…extinct from life’s origins.e extinct from life’s origins.

Climate and Ancient Geography

Things that can be determined from fossils

Trace Fossils

Any indirect evidence left by an organism. Includes footprints, burrows, and fossilized feces.

Molds (in Fossils)

Are impressions of an organism.

Cast Fossils

Molds filled with sediment

Replacement Fossils

The original material of an organism is replaced with mineral crystals that can leave detailed replicas of hard or soft parts.

Petrified or Permineralized Fossils

Empty pore spaces are filled in by minerals such as petrified wood.

Amber

Preserved tree sap traps entire organism. The sap hardens into this and preserves the trapped organism.

Original Material

Mummification or freezing preserves original organisms

Stratum

Older fossils are found in the bottom, newer fossils are found in the top.

Relative Dating can determine…

Age of fossil with respect to another rock or fossil (that is, older or younger)

Relative Dating is performed by…

Comparing depth of a fossil’s source stratum to the position of a reference fossil or rock (index fossils)

Relative Dating Drawbacks

Imprecision and limitations of age data

Radioactive Dating can determine…

Age of a fossil in years

Radioactive Dating is performed by…

Determining the relative amounts of a radioactive isotope and nonradioactive isotope in a specimen

Radioactive Dating Drawbacks

Difficulty of laboratory methods

Half-life

The length of time required for half of the radioactive atoms in a sample to decay

In radioactive dating, scientists calculate the age of a sample based on…

The amount of remaining radioactive isotopes it contains

What has been learned from fossils

• Several episodes of mass extinction that fall between time divisions

• The geologic time scale begins with the formation of Earth about 4.6 billion years ago or 460 mya.

Mass Extinction

An event that occurs when many organisms disappear from the fossil record almost at once

The Geological Time Scale shows the whole history of the earth chopped up into…

Eons, Eras, Periods, and Major Organisms

The numbers at the boundaries between the periods in the Geological Time Scale tell us…

How long ago that boundary happened in millions of years

In the Geological Time scale the most recent periods are at the ___ of the time scale while the older are near the ______.

Top, Bottom

TRUE OR FALSE: In the very early days of earth there was life

FALSE, there was none at all

You can find _________ fossils in _________ stages of Earth’s history

Different

Life first appeared on earth as a very simple form known as…

Bacteria

For most of the time during the Precambrian Period, Bacteria and other ______-______ organisms were the only life on Earth

single-celled

The first multi-celled organisms appeared at the ___ of the ___________ period.

end, Precambrian

The first animals had ____ bodies and looked _______ like the animals alive today.

soft, nothing

The first animals looked more like ______ than animals.

Plants

In the ___________ Era, animals with shells were seen more in the fossil record.

Palaeozoic

The first back-boned animals formed during the ___________ ___

Palaeozoic Era

We are descendants of…

Back boned animals

At the end of the _______ period in the Palaeozoic Era, 251 million years ago there was a mass extinction and __% of life on Earth was wiped out.

Permian, 83

The Mesozoic Era is also called…

The Age of Reptiles

Why was the Mesozoic Era called “The Age of Reptiles”

Because reptiles dominated both the land and sea

The Mesozoic is split into 3 periods…

Triassic, Jurassic, and Cretaceous

The time when dinosaurs walked the Earth was…

The Mesozoic Era

_______ survived the Cretaceous extinction

Mammals

The Cenozoic Era is divided into 2 periods…

Tertiary and Quaternary

In the Tertiary Period, animals started to ____.

Grow

We are living in the _________ period

Quaternary

Why is the Quaternary Period important?

It covers the evolution of humanity

Why are each periods on the Geological Time Scale important?

Each host significant evolutionary changes to species diversity and extinction.

The moon was created when…

A planet the size of mars named “Thea” crashed into the Earth and the bits and pieces left by Thea formed it.

The earth filled with water after…

Meteors with small amounts of ice started to very slowly shower the Earth

3.9 Billion Years ago the first _______ ____ was born in the depths of the sea

organic life

The first islands were formed by

Volcanos on Earth erupting

The Snowball Earth

The period when ice completely covered the Earth

540 million years ago, after the Snowball Earth, ______ was found in the oceans and atmosphere

Oxygen

375 million years ago the _____ _____ got thicker and prevented the sun’s radiation from touching the Earth

Ozone Layer

Because of the thickened Ozone Layer, the perfect place for life on ____ was created.

Land

After the first creature steps on land, creatures grow stronger ____ to move more freely on land.

Limbs

All animals laid eggs in water except for lizards, who started to…

lay them on land, allowing animals to move further from the water and conquer more land

Meat-eater

A monkey like creature eventually evolves into humans

After meat-eaters got “pushed” off trees and became “grass monkeys” they needed to walk on their ___ ____ to survive starting the era of humans.

two legs

Earth originally had a very hot surface from…

colliding meteorites

Earth had a Vry hot planet core from…

radioactive materials 

Volcanoes spewing lava and gases helped to form…

the early atmosphere

The Earth’s Early atmosphere contained:

Hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen, sulfide and water

About 4.6 billion years ago, Earth might have cooled enough for…

the water in its atmosphere to condense

The condensing of Earth’s atmosphere might have led to…

millions of years of rain storms with lightning, enough rain to fill depressions that became Earth’s oceans.

Earth’s continents have moved during Earth’s history and are still moving today at a rate of about ___ centimeters per year.

six

Plate Tectonics

The theory for how the continents move

Miller-Urey experiment

Showed one possible way for inorganic molecules to form Organic Molecules.

Formation of microspheres led to

evolution of RNA and DNA

For free oxygen, first came Autotrophic prokaryotes that…

were anaerobic

After Autotrophic Prokaryotes that were anaerobic came the…

autotrophic prokaryotes similar to present day archaebacteria

After Autotrophic Prokaryotes that were similiar to present day archaebacteria came

Heterotrophic prokaryotes. 

2.8 billion years ago, after Heterotrophic Prokaryotes, photosynthetic bacteria began to…

pump oxygen into the oceans

Cyanobacteria

Photosynthetic Bacteria

After cyanobacteria began to pump oxygen into the oceans…

oxygen gas accumulated in the atmosphere.

The rise of oxygen in the atmosphere drove some life forms to extinction, while other life forms evolved…

new, more efficient metabolic pathways that used oxygen for respiration

Endosymbiotic Theory

Explains the origin of Eukaryotic Cells

What does the Endosymbiotic Theory say?

• Heterotrophic bacteria have plasmids (DNA loop) & simple ribosomes in their cytoplasm

• Mitochondria have circular DNA & bacteria-like ribosomes

• So…Eukaryotic cells may have engulfed prokaryotic cells & by mutualism created the “first mitochondria.”

Who proposed the endosymbiotic theory?

Lynn Margulis

How Eukaryotic Cells evolved

• Autotrophic bacteria are Cyanobacteria with chlorophyll

• So, Eukaryotic cells may have engulfed prokaryotic cyanobacteria & by mutualism created the “first chloroplast.”

Eukaryotes reproducing sexually enabled…

evolution to take place

Prokaryotes restricts ___________

Variability

Development of multicellular organisms for single celled organisms increased _________ greatly

Diversity

Evolution of Life 5-4 billion Years ago

Earth Formation; Life: too hot/chaotic ; Atmosphere: outgassing, H20 condenses

Evolution of Life 4-1 billion Years ago

Precambrian; Life; Warm seas, chemical evolution, 1st virus, 1st bacteria in beginning Later 1st multi-celled organisms, rapid diversification, invertebrates; Atmosphere: enrichment of O2 —> O2 increases —> present atmosphere

Evolution of Life 600-220 Million Years ago

Paleozoic; Life: Beginning invertebrates, end vertebrates ; Atmosphere: present atmosphere

Evolution of Life 220-20 Million Years ago

Mesozoic; Life: vertebrates beginning, end mammals ; Atmosphere: present atmosphere

Evolution of Life 20 Million Years Ago-Present

Cenozoic; Life: beginning mammals, end humans ; Atmosphere: beginning present atmosphere end pollution

Summary of Cenozoic Quartenary

Time (millions of years ago): 1.8-present ; Key events: Glaciations, mammals increased, humans

Summary of Cenozoic Tertiary

Time (millions of years ago): 65-1.8 ; Key events: Mammals diversified, grasses

Summary of Mesozoic Cretaceous

Time (millions of years ago): 145-65 ; Key events: Aquatic reptiles diversified, flowering plants, mass extinction

Summary of Mesozoic Jurassic

Time (millions of years ago): 208-145 ; Key events: Dinosaurs diversified, birds

Summary of Mesozoic Triassic

Time (millions of years ago): 245-208; Key events: Dinosaurs, small mammals, cone-bearing plants

Summary of Paleozoic Permian

Time (millions of years ago): 290-245 ; Key events: Reptiles diversified, seed plants, ferns mass extinction