Lecture 1: History of Life on Earth

Question 1

What are the subdivisions of “time” in the geologic record?

Answer 1

Eons > Eras > Periods > Epochs

Question 2

Formation of Earth

Answer 2

Occur 4.6 bya (billion years ago)

Question 3

Prokaryotes came first

Answer 3

3.6 bya

Question 4

Conditions of early Earth
- How did the first living cells appear?

Answer 4

Hypothesis: chemical and physical processes could have produced simple cells

Question 5

Conditions of early Earth
- What type of hypothesis deals with Synthesis of Organic Compounds of Early Earth?

Answer 5

Oparin- Haldane Hypothesis (1920)
- Earth’s early atmosphere was likely a reducing environment where organic compounds could have formed simpler molecules

Question 6

How many stages had the hypothesis and what each represented?

Answer 6

4 stages

1) the abiotic synthesis of small organic molecules
2) joining of small molecules into macromolecules
3) packaging of macromolecules into protocells
4) origin of self-replicating molecules that eventually made inheritance possible

Question 7

Conditions of Early Earth
- Who tested this hypothesis of Synthesis of Organic Compounds?

Answer 7

Miller & Urey’s Experiment (1953)
- AA found in modern organisms
- other organic compounds

Question 8

How do we date fossils?

Answer 8

Measure half-life of radioactive isotopes

Question 9

Archaean Eon

Answer 9

• First single-celled organisms
• sole inhabitants for more than 1.5 billion years
• oxygen levels increase
• Anaerobic

Question 10

The oxygen revolution changed Earth’s environment dramatically. The presence of free oxygen in the oceans and atmosphere likely led to what?

Answer 10

Aerobic Respiration

Question 11

Proterozoic Eon

Answer 11

First Eukaryotic Cells ~1.8 bya

Question 12

Endosymbiont Theory

Answer 12

Mitochondria and plastids were formerly small prokaryotes that began living within larger cells

Question 13

What is Endosymbiont?

Answer 13

a cell that lives within another cell (host cell)

Question 14

Evidence that supported the Endosymbiont Theory

Answer 14

Evidence supporting the endosymbiotic origin of mitochondria and plastids

• inner membrane have enzymes and transport systems homologous to those in living prokaryotes
• Own DNA (Circular DNA)
• Replication similar to some prokaryotes
• Machinery for protein synthesis
• Ribosomes are more similar to prokaryotic ribosomes

Question 15

Origin of Multicellularity

Answer 15

• Colonial Hypothesis (more leaning towards)
• Syncytial Hypothesis

Question 16

What is Colonial Hypothesis?

Answer 16

Stick together, dependent, result to two radial ancestors

Question 17

What is Syncytial Hypothesis?

Answer 17

only creates radial animals

Question 18

Paleozoic Era

Answer 18

Colonization of land (~ 500 mya)

Question 19

What did the Colonization of Land do the adaptations of the environment?

Answer 19

• They facilitated reproduction on land
• Minimized desiccation
• Requires eggs that don’t dry out

Question 20

What animals had the Colonization of Land (Paleozoic Era)?

Answer 20

• Arthropods among first animals to colonize land
• Followed by tetrapods the evolved from lobe-finned fishes

Tetrapods= 4 foot

= Acanthostega- first to recognize limbs
= Tiktaalik- fish similar to tetrapods

Question 21

Mesozoic Era

Answer 21

Age of Reptiles
“ Age of the Dinosaurs”

Question 22

What plants had in the Mesozoic Era?

Answer 22

Cone-bearing plants dominant

Question 23

Cenozoic Era

Answer 23

Age of Mammals

Question 24

Mesozoic Era, Triassic Period

Answer 24

• Cone-bearing plants (gymnosperms) dominate landscape
• dinosaurs evolve and radiate
• origin of mammals

Question 25

Mesozoic Era, Jurassic Period

Answer 25

- Gymnosperms continue to dominate plants - dinosaurs abundant and diverse

Question 26

Mesozoic Era, Cretaceous Period

Answer 26

- Flowering plants (angiosperms) appear and diversity - many groups of organisms. including most dinosaurs, become extinct at end of period

Question 27

Continental Drift

Answer 27

Movements in the mantle cause the plates to move over time

Question 28

Rise and Fall of Flora and Fauna What is related to speciation and extinction rates?

Answer 28

- Plate tectonics - Mass extinctions - Adaptive radiations

Question 29

what are the consequences of the Continental Drift?

Answer 29

- Changes in climate - Changes in coastal area vs. inner landmass area - Water levels change

Question 30

How many Mass Extinctions happend?

Answer 30

5

Question 31

What are the names of the Mass Extinctions?

Answer 31

- Ordovician- Silurian Mass Extinction - Late Devonian - The Permian Extinction - Triassic- Jurassic Mass Extinction - The Cretaceous Extinction

Question 32

What is the name of the mass extinction that was called the K-T Extinction?

Answer 32

the Cretaceous Extinction

Question 33

Era/Period of Ordovician-Silurian Mass Extinction

Answer 33

- Paleozoic Era, - Between Ordovician and Silurian Period

Question 34

Year of Ordovician- Silurian Mass Extinction

Answer 34

455-430 MYA

Question 35

Era/Period of Late Devonian

Answer 35

Paleozoic Era End of Devonian Period

Question 36

Year of Late Devonian

Answer 36

359 MYA

Question 37

Era/Period of The Permian Extinction

Answer 37

- Paleozoic Era - End of Permian Period

Question 38

Year of Permian Extinction

Answer 38

251 MYA

Question 39

Era/Period of Triassic-Jurassic Mass Extinction

Answer 39

Mesozoic Era Between Triassic and Jurassic Period

Question 40

Year of Triassic-Jurassic Mass Extinction

Answer 40

200 MYA

Question 41

Era/Period of Cretaceous Extinction

Answer 41

Mesozoic Era End of Cretaceous Period

Question 42

Year of Cretaceous Extinction

Answer 42

65 MYA

Question 43

Life forms affect during Ordovician-Silurian Mass Extin?

Answer 43

- Most life was aquatic - Trilobites and early mollusks drastically reduced in number

Question 44

Life forms affect during Late Devonian Mass Extin?

Answer 44

75% of all species dried out - life in shallow seas affected more than other life forms

Question 45

Life forms affect during The Permian Extinction?

Answer 45

"The Great Dying" - 96% of marine animal species drastically altered life in ocean - most extreme episode of volcanism

Question 46

How can volcanism affect life forms?

Answer 46

- Produced enough CO2 to warm global climate by 6 C - ocean become acidic

Question 47

Life forms affect during Triassic- Jurassic Mass Extinc?

Answer 47

-50% of all species became extinct - Marine reptiles - some large amphibians - reef-building creatures - large numbers of cephalopod mollusks - many species of plants survived

Question 48

Life forms affect during Cretaceous Extinc?

Answer 48

- gone more than half of all marine species - eliminate many families of terrestrial plants and animals - including all dinosaurs

Question 49

What type of events led to changes on Earth that may have influenced these extinction and subsequent adaptive radiation events?

Answer 49

- The Permian Extinc - Triassic-Jurassic Mass Extinc - Cretaceous Extinc

Question 50

What led to the asteroid evidence of the K-T Extinction?

Answer 50

- Discovery of Chicxulub Crater (same age as K-T boundary) - Finding tsunami deposits in the Brazos River Basin, Texas - Discovering gravitational field anomalies on the Yucatan peninsula, from surveys done for oil exploration - Identifying spherules and shocked quartz in Haiti - Finding that an isotope of plutonium is not in the K-T boundary layer

Question 51

What Period/Era/Epoch evolved in Humans?

Answer 51

Cenozoic Era Quaternary Period Holocene Epoch