Geological and Biological History of the Earth

Question 1

How old is the earth?

Answer 1

4.568 billion years old

Question 2

Describe the conditions of early earth.

Answer 2

formed by the primordial solar disk; dust and gas orbit the sun due to its gravitational force; lots of volcanoes and collisions from asteroids

Question 3

Describe how oceans formed.

Answer 3

earth cools over millions of years → elements form minerals → minerals form rocks → rocks release water vapor → vapor condenses into rainwater → fills basins to form oceans

Question 4

Describe how and when the moon was formed.

Answer 4

3.8 billion years ago; small planet collided with earth and dislodged the material that formed the moon

Question 5

What are the two requirements for the origin of life, and what phenomena allowed them to be met on early earth?

Answer 5

formed by volcanic emissions
1. elements necessary to form organic molecules (C, H, O, N)
2. energy sources to drive chemical reactions (lightning, UV radiation, hot igneous rocks)

Question 6

List the potential signs of life on ancient earth. Where were they found?

Answer 6

found mostly in Australia
1. carbon isotopes preserved within mineral structure of zircon matches those of living organisms
2. ancient bacterial structures found in sedimentary rocks
3. stromatolites indicate presence of cyanobacteria → oxygen released as a byproduct of photosynthesis → oxygen enters oceans → rust bands are formed bc of high levels of dissolved iron → all iron is eventually oxidized → oxygen is released into the atmosphere → increase in oxygen levels for evolution of life forms

Question 7

What are the differences between prokaryotes and eukaryotes?

Answer 7

prokaryotes are the first life forms on earth, do not have DNA contained in nuclear membrane, no organelles, not capable of sexual reproduction, small, and unicellular

Question 8

What is the endosymbiotic theory?

Answer 8

the evolution of eukaryotes likely occurred as a result of endosymbiosis between multiple prokaryotes; consumed prokaryotes likely became the mitochondrion and chloroplast because both organelles have their own DNA

Question 9

What are the advantages of multicellularity?

Answer 9

1. larger size
2. longer life span (replacement of cells is possible)
3. specialization (organ systems, etc. enable the possibility of sexual reproduction)

Question 10

During what period did multicellular life occur?

Answer 10

Ediacaran

Question 11

Describe Cambrian radiation.

Answer 11

a short interval in which nearly all readily fossilizable animal phyla first appeared in the fossil record; development of shells and skeletons; thought to be caused by an increase in atmospheric oxygen as well as the development of mouthparts in predators, meaning prey developed adaptation to help survive and reproduce

Question 12

Describe the transition of life from aquatic to terrestrial.

Answer 12

2.6 Ga: prokaryotes first colonized terrestrial environments → invertebrates → plants → fungi → vertebrates → tetrapods → synapsids → mammals → mammals diversify after dinosaurs went extinct → 300 Ka: oldest human fossil

Question 13

Describe the scenarios for incomplete fossil records.

Answer 13

1. gradualism - slow, gradual morphological changes over time
2. punctuated equilibria - periods of stasis punctuated by brief periods of rapid change; associated with speciation events

Question 14

Define extinction, background extinction, mass extinction, extinction selectivity, and the lilliput effect.

Answer 14

extinction - process of a lineage no longer having any living members
background extinction - the normal rate of extinction for taxa or biota
mass extinction - an event that causes a statistically significant increase above background extinction rates
extinction selectivity - some organisms are more likely to go extinct during extinction events due to some aspect of their ecology or lifestyle (i.e. triolbites with benthic larvae were more likely to survive than planktonic larvae during the ordovician extinction)
lilliput effect - before extinction events, animals are typically very large, and after the extinction, animals are typically very small

Question 15

Describe the 6 major mass extinction events in order, including major casualties and potential causes.

Answer 15

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1. ordovician - marine invertebrates (i.e. trilobites); the movement of supercontinent Gondwana caused sea levels to rise and fall repeatedly, destroying habitats
2. late devonian - marine invertebrates and placoderms (i.e. dunkleosteus); diversity of plant life on land changed the environment
3. permian-triassic - marine species and terrestrial vertebrates; gradual change in climate followed by a sudden catastrophe (i.e. volcanic eruption or asteroid impact)
4. triassic-jurassic - pseudosuchians (modern-day crocodiles and extinct relatives); climate change, asteroid impact, or volcanic activity
5. cretaceous-paleogene - non-avian dinosaurs, marine reptiles, early mammals, amphibians, birds, reptiles, insects; K-Pg boundary contains a high level of iridium, which suggests asteroid impact
6. holocene - amphibians (i.e. chytrid fungus killing golden toads due to warmer temperatures); humans contributing to climate change and introduction of invasive species