Chapter 25 History of Life on Earth

Question 1

What are the 4 conditions of early Earth that made origin of life possible?

Answer 1

1. Abiotic synthesis of small organic molecules
2. Joining of these small molecules into macromolecules
3. Packaging of molecules into protocells
4. Origin of self-replicating molecules

Question 2

How long ago did Earth form? What gases were potentially found there?

Answer 2

• formed 4.6 billion years ago
• nitrogen, nitrogen oxide, carbon dioxide, ammonia, methane, and hydrogen could have all been found

Question 3

What is the abiotic synthesis of macromolecules?

Answer 3

When small organic molecules polymerize when concentrated on hot sand, clay, or rock

Question 4

What are protocells?

Answer 4

Cells that may have formed from fluid filled vesicles with a membrane-like structure

• could have been vesicles containing RNA capable of replication

Question 5

Why is it that RNA could have been the first genetic material?

Answer 5

B/c their molecules, ribozymes, have been found to catalyze many different reactions and can be replicated quicker/more stable

Question 6

What kind of species do fossils favor?

Answer 6

those that have:
- existed for a long time
- were abundant and widespread
- has hard parts

Question 7

Radiometric dating

Answer 7

Absolute age of fossils that’s determined by their measurement

Question 8

Isotope

Answer 8

Has a known half-life which is the time required for half of the parent isotope to decay

Question 9

What are tetrapods?

Answer 9

Mammals that belong to the group of animals

Question 10

What is the geologic record?

Answer 10

A record divided into:
- Hadean
- Archaean
- Proterozoic
- Phanerozoic

Question 11

What are the 3 eras of the Phanerozoic?

Answer 11

• Paleozoic
• Mesozoic
• Cenozoic

Question 12

What are stromatolites?

Answer 12

Oldest known fossils formed by the accumulation of sedimentary layers on bacterial mats

• dates back 3.5 billion years ago

Question 13

What is the oxygen revolution?

Answer 13

Oxygen accumulation and rusting of iron-riched terrestrial rocks that caused the extinction of many prokaryotic groups

• 2.7 to 2.3 BYA

Question 14

What is the endosymbiont theory?

Answer 14

Proposed that mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes living within larger host cells

Question 15

Endosymbiont

Answer 15

A cell that lives within a host cell

• cells ends up splitting in an animal or plant cell

Question 16

What is serial enodymbiosis?

Answer 16

Supposes that mitochondria evolved before plastids through a sequence of endosymbiotic events

Question 17

What is the cambrian explosion?

Answer 17

Refers to the sudden appearance of fossils resembling modern animal phyla in the cambrian period

• provides the first predator-prey interactions

Question 18

What are some key evidence of supporting endosymbiotic theory?

Answer 18

1. inner membrane are similar to plasma membranes of prokaryotes
2. Division and dna structures are similar in some organelles and prokaryotes
3. organelles transcribe and translates their own DNA
4. Ribosomes are more similar to prokaryotic than eukaryotic ribosomes

Question 19

What was the colonization process of earth?

Answer 19

1. Plants and fungi likely colonized land together
2. Tetrapods evolved from love-finned fishes
3. Human lineage evolved from tetrapods
4. We see the modern human arrive 195,000 years ago

Question 20

What is the theory of plate tectonics?

Answer 20

Earth’s crust is composed of plates floating on Earth’s mantle

Question 21

How does plate tectonics occur?

Answer 21

1. Plates move slowly through continental drift
2. Oceanic and continental plats collide, separate, and slide past each other which cause physical formations and earthquakes

Question 22

What were the effects of Pangaea?

Answer 22

• deepening of ocean basins
• reduction in shallow water habitat
• colder and drier climate on land

Question 23

Consequences of continental drift on organisms

Answer 23

• Causes a continent’s climate to change as it moves directions
• Separation of land masses can lead to allopatric speciation

Question 24

What is mass extinction?

Answer 24

Result of disruptive global environmental changes that causes species to dramatically die off

Question 25

How many mass extinctions has there been?

Answer 25

5 mass extinctions

Question 26

Permian Extinction

Answer 26

Defines the boundary b/w Paleozoic and Mesozoic era where 96% of marine animal species went extinct

Question 27

Cretaceous Extinction

Answer 27

Occurred 65.5 MYA. about 1/2 of all marine species, many terrestrial plants, and animals including dinosaurs went extinct

Question 28

What are some consequences of mass extinctions?

Answer 28

• can alter ecological communities and niches
• can change the type of organisms found in ecological communities

Question 29

Adaptive Radiation

Answer 29

Rapid evolution of diversly adapted species from a common ancestor

Question 30

When does adaptive radiation occur?

Answer 30

• after mass extinction
• colonization of new regions
• evolution of novel characteristics

Question 31

Homeotic Genes

Answer 31

Genes that determine basic features such as where the legs will develop

Question 32

Paedomorphosis

Answer 32

Rate of reproductive development that accelerates compared to somatic development

Question 33

Heterotrophy

Answer 33

Evolutionary changes in the rate of timing of developmental events

• has significant impact on body shape

Question 34

Regional Adaptive Radiation

Answer 34

Can occur when organisms colonize new environments with little competition

Question 35

How should evolutionary trends be looked at?

Answer 35

It should be analyzed in a broader context