The History of Life:

Question 1

One group of O2 generating bacterias, the __________, formed rock-like structures called __________, which are abundantly preserved in the fossil record.

Answer 1

• Cyanobacteria

- Stromatolites

Question 2

T/F: When O2 first appeared in the atmosphere, it was poisonous to most of the anaerobic prokaryotes that inhibited Earth at the time.

Answer 2

TRUE

Question 3

Aerobic metabolism:

Answer 3

proceeds more rapidly, and harvests energy more efficiently, than anaerobic metabolism.

Question 4

Further increases in atmospheric O2 concentrations in the late _______ enabled several groups of multicellular organisms to evolve.

Answer 4

Precambrian

Question 5

The high concentrations of atmospheric O2 allowed the evolution of what?

Answer 5

giant flying insects and amphibians that could not survive in today’s atmosphere

Question 6

The drying of the lowland swamps at the end of the _______ rapidly decreased the O2 concentration.

Answer 6

Permian

Question 7

Biologists refer to the assemblage of all organisms of all kinds living at a particular time or place as a __________.

Answer 7

Biota

Question 8

All of the plants living at a particular time or place are called its ______________; all of these animals are its ____________.

Answer 8

Flora………Fauna

Question 9

Geologist divided earth’s history into eras and periods based on what ?

Answer 9

On their distinct fossil assemblages.

Question 10

Multicellular life was largely or completely aquatic during the ___________.

Answer 10

Cambrian

Question 11

What are evolutionary radiations?

Answer 11

Periods of such rapid diversification.

Question 12

Why was there a Mass extinction toward the end of the Permian (about 250 MYA)?

Answer 12

Massive volcanic eruptions sent out debris which blocked sunlight and cooled the climate, resulting in the largest glaciers in Earths history.
Atmospheric Oxygen dropped by half, so animals couldn’t survive. Thus killing off about 96 percent of all multicellular species.

Question 13

During the Jurassic period, Pangaea became fully divided into two large continents:

Answer 13

Laurasia (which drifted northward) and Gondwana (drifted Southward)

Question 14

When did Laurasia and Gondwana begin to break apart into the continents we know today?

Answer 14

By the early Cretaceous (145-65 MYA)

Question 15

We are living in the ______ period.

Answer 15

The Quaternary

Question 16

What are the principles of stratigraphy:

Answer 16

• Fossils of similar organisms are found in widely separated places on Earth
• Certain fossils are always found in younger strata, and certain other fossils are always found in older strata
• Organisms found in younger strata are more similar to modern organisms than are those found in older strata

Question 17

What happens in the Half-life?

Answer 17

• Half of the atoms in a radioisotope decay to become a different, stable (nonradioactive) isotope.
• We use this to date fossils

Question 18

Radiometric dating:

Answer 18

• uses radioisotopes of carbon to date fossils

- Can date fossils that are less than 60,000 years old.

Question 19

The history of life is divided into ________, which in return are subdivided into __________.

Answer 19

Eras…….Periods

Question 20

What is continental Drift?

Answer 20

The movement of the lithospheric plates and the continents they carry

Question 21

Why is continental Drift caused?

Answer 21

It is caused by convection currents in the magma, which move the plates and the continents that lie on top of them.

Question 22

The position and sizes of the continents influence:

Answer 22

• Oceanic circulation Patterns
• Global Climates
• Sea levels (influenced directly by plate tectonics)

Question 23

T/F: Most mass extinctions of marine organisms have coincided with low sea levels.

Answer 23

True

Question 24

How have volcanoes occasionally changed the history of life?

Answer 24

The collision of the continents 275 MYA, (during the Permian Period) formed a single land mass, causing a multitude of massive volcanic eruptions. Emissions from these eruptions blocked alot of sunlight,, creating the advance of glaciers and causing a drop in seal level.
-(responsible for playing part in our greatest mass extinction)

Question 25

A meteorite caused/contributed to a mass extinction when? And How do we know this to be true?

Answer 25

• Occurred at the end of the Cretaceous Period (about 65 MYA)
• There’s high concentration of Iridium found in rocks deposited during the Cretaceous
• Scientists discover a circular crater, 180 km in diameter, buried beneath the Yucatan Peninsula of Mexico.

Question 26

What are the prevailing hypotheses about the cause of the mass extinction event (65 MYA)?

Answer 26

-Possibilities of Mass Extinction at the end of the Cretaceous:
1- Primary Explanation——> Crater hitting Earth
2- Climate cools during late Cretaceous due to Continental drift.
3- Spike in Volcanic activity (in India)

Question 27

The fossil record indicates that after Earth’s major mass extinction events, there is a great increase in biodiversity. Explain why an increase in biodiversity occurs after these mass extinctions:

Answer 27

-There’s an increase in biodiversity because of those organisms which survived (maybe a predator was killed off).

Question 28

The beginning of the Cambrian Period is marked in the fossil record by the “Cambrian Explosion.” What is meant by the “Cambrian Explosion?”

Answer 28

• *(Occurring about 542 MYA)
• Rapid increase of multicellular organisms
• Lots and lots of animals and multicellular organisms fossils have been found here
• It began before the Cambrian and the “explosion” took millions of years.
• Multicellular life was largely or completely aquatic during this time (Cambrian)–If there was life on land, it probably was restricted to micro-organisms.

Question 29

What are the geological consequences of the movement of the continental plates? What have been the biological consequences of the movement of the continental plates?

Answer 29

• In response to plate tectonic processes such as continental drift and volcanic activity
• Movement of plates have brought continents together at times and apart at other times.
• Some of these dramatic changes in Earth’s physical parameters resulted in mass extinctions

Question 30

In the geological time scale, what events determine the end of one era and the beginning of another?

Answer 30

the Geological time scale has Era’s which are broken down into periods, the end of an Era, shows a mass extinction occurred.

Question 31

What is the principle behind radiometric dating of fossils?

Answer 31

It uses radioisotopes to determine an absolute date (since carbon 14 decays over time)
-We can also use Half-life for these radioisotopes

Question 32

What is the accuracy rate of radiometric dating technique?

Answer 32

• C-14 dating is accurate for young fossils, however with older fossils, us of other radioisotopes will be needed
• It has an accuracy of (plus or minus)+- 10%

Question 33

Why is fossilization rare?

Answer 33

• It’s because whatever is being fossilized has to die, being covered by sediments, and it also has to escape destruction by heat, pressure, and erosion.
• this is why the fossil record is incomplete.

Question 34

what are the Characteristics of organisms (species) that have left the best fossils?

Answer 34

• They existed for a long time
• They were abundant
• they had large geographic ranges
• They had hard parts (such as shells and skeletons)

Question 35

Who proposed the concept of continental drift? and in what decade?

Answer 35

German Meteorologist, Alfred Wegner in 1912

Question 36

In what decade had scientists collected enough evidence to confirm that continental rift was a real phenomenon?

Answer 36

• In the 1960’s, evidence from geology, paleontology, and biology confirmed Wegner’s idea on continental drift
• By 1960’s physical evidence and increased understanding of plate tectonics.

Question 37

What mass extinctions occurred around 250 MYA (at the time Pangaea was believed to have existed)? Explain the role of climate change in this mass extinction event.

Answer 37

• Extinction of 96% of Earth’s species
• Oxygen levels drop rapidly (from 30% to 15%)
• (the Permian Extinction: which involved considerable loss of insect diversity!)

Question 38

What mass extinctions occurred 65 MYA? Explain the role of climate change in this mass extinction?

Answer 38

• “The Cretaceous Extinctions”, mass extinction event, including the loss of the dinosaurs (most of them)
• Caused by the Iridium that was sent out, after a giant asteroid known as the “Chicxulub Crater”
• Modern continents were beginning to take shape
• The climate cools due to continental drift and spike in volcanic activity (In India)

Question 39

Explain how the stratification of sedimentary rock can be used as a relative time scale for age of the fossils imbedded within it:

Answer 39

Because over time the sediments get covered, what is found on top, is relatively new, vice versa

Question 40

Paleozoic Era:

Answer 40

• meaning “ancient animal”
• sudden diversity of animals
• Establishment of terrestrial animals/plants
• –[Then mass extinction occurs]

Question 41

Mesozoic Era:

Answer 41

• meaning “middle animal”
• The age of reptiles
• Mammals angiosperms
• –[Mass extinction/Dino’s died off]

Question 42

Cenozoic Era:

Answer 42

• meaning “recent animal”

- mammals, birds which remain now, angiosperm

Question 43

Pangaea:

Answer 43

All land masses together about 250 MYA

Question 44

Around 250 MYA (Paleozoic era)

Answer 44

• Species evolving in isolation now together
• loss of coastlines (90% marine lie died)
• Ocean basins deeper, drainage of shallow coastal areas
• Mass extinction

Question 45

The Permian Extinctions:

Answer 45

• 90% of marine species extinct
• terrestrial species impacted heavily
• change of ocean currents—-> cool, dry, interior

Question 46

Laurasia and Gondwana:

Answer 46

• Starts about 180 MYA in Mesozoic Era
• Split into Northern and Southern land masses
• Species evolving in isolation again (allopatric isolation)

Question 47

Modern continents begin to take shape:

Answer 47

Starting about 65 MYA

Question 48

Crash of the Indian Plate into Eurasia Plate:

Answer 48

• Starts about 10 MYA

- forms the Himalayas

Question 49

What is Bio-geography?

Answer 49

The distribution of organisms on the planet

Question 50

Formation of Earth:

Answer 50

About 4.6 BYA

Question 51

First oceans:

Answer 51

About 3.8 BYA

Question 52

Origin of Life:

Answer 52

About 3.5 BYA

Question 53

Origin of Photosynthesis:

Answer 53

About 2.8 BYA

Question 54

First Eukaryotic Cells:

Answer 54

About 1.5 BYA

Question 55

About 542 MYA:

Answer 55

-Rapid increase of multicellular organisms aka “the Cambrian explosion”

Question 56

About 420 MYA:

Answer 56

-first vascular plants and terrestrial anthropods evolve (bugs/insects)

Question 57

About 65 MYA:

Answer 57

• “The Cretaceous Extinctions”
• Mass extinction event: loss of the dinos
• Chicxulub Crater hit and sent Iridium out

-@ the end of the Cretaceous-Tertiary (K/T boundary)

Question 58

At the end of the Cretaceous we go to the Tertiary were:

Answer 58

• There are flowering plants that are dominant on land
• Rapid radiation of mammels
• Increase in biodiversity