Topic 9

Question 1

What are the features an entity needs to have in order to be considered alive?

Answer 1

1. Organization
2. Metabolism
3. Response to stimuli
4. Homeostasis
5. Adaptation
6. Reproduction

Question 2

What is organization as a feature that an entity needs to have to be considered alive?

Answer 2

Structurally composed of one or more cells (multicellular)

• basic units of life

Question 3

What is metabolism as a feature that an entity needs to have to be considered alive?

Answer 3

A system of management of energy and materials via chemical reactions

Question 4

What is response to stimuli as a feature that an entity needs to have to be considered alive?

Answer 4

Response to stimuli via changes in growth, alteration of chemical reactions, or movement

Question 5

What is homeostasis as a feature that an entity needs to have to be considered alive?

Answer 5

maintenance of some internal chemical and/or thermal consistency, relative to variation outside of the organism

Question 6

What is adaptation as a feature that an entity needs to have to be considered alive?

Answer 6

the ability to change over time in response to the environment.

Question 7

What is reproduction as a feature that an entity needs to have to be considered alive?

Answer 7

the ability to produce new individual organisms

Question 8

What are viruses?

Answer 8

Viruses are infectious parasitic entities that span the boundary between living and non-living.

• The origins of viruses are unclear because they do not form fossils

Question 9

Why is it debated whether viruses are alive or not?

Answer 9

• Viruses have nucleic acids (DNA or RNA) that can replicate, mutate, and respond to natural selection
• But, viruses lack metabolism and homeostasis, and cannot reproduce outside of a host cell

Question 10

What are the three eons that geologic record is divided into?

Answer 10

Archaean, Proterozoic, and Phanerozoic

Question 11

When was the Phanerozoic eon? What three eras make up the Phanerozoic eon?

Answer 11

• includes the last half billion years and encompasses multicellular eukaryotic life.
• The three eras are Paleozoic, Mesozoic, and Cenozoic.
• Major boundaries between geological divisions correspond to mass extinction events in the fossil

Question 12

What are fossils? What can fossils tell us?

Answer 12

Fossils are preserved remains/evidence of organisms that lived in the past.

• Fossils are associated with sedimentary rock (formed by accumulation of mud, silt, or sand. Layers are called strata).
• Fossils are used to calibrate phylogenies, record extinct species, and link evolutionary events with geological and environmental changes on Earth.

Question 13

What is the fossil record?

Answer 13

The fossil record provides direct evidence of evolutionary history.

It is also biased and incomplete.

• Fossilization requires burial in sediment, but sediments accumulate episodically and not continually. Therefore only the hard parts organisms are typically fossilized.

Question 14

The probability of an organism becoming fossilized increases if:

Answer 14

1. the organism existed for a long time.
2. The organism was abundant and widespread
3. Hard rather than soft-bodied
4. Aquatic rather than terrestrial
5. Inshore marine rather than offshore marine
6. Decomposing organisms were absent

Question 15

What is a cast?

Answer 15

A type of fossil record where minerals fill space in sediment where the organism decays after having been buried.

• Leaves an imprint on what it once was.

Question 16

What is a replacement (petrified) fossil?

Answer 16

A type of fossil record where the organism’s tissues are replaced by minerals. (like a sculpture)

Question 17

What is a trace fossil?

Answer 17

a type of fossil record where the fossil records evidence of behavior

• tracks, burrows, feces, etc.

Question 18

What is a preserved fossil?

Answer 18

A type of fossil record that retains the original organic matter

• carbon films, amber, tar or peat, frozen, etc.
• sub-fossils have a high percent of organic matter.

Question 19

What is relative dating?

Answer 19

• A way of determining the age of fossils, but does not indicate how long ago the fossil was created
• sedimentary strata reveal the relative ages of fossils

Question 20

What is absolute/radiometric dating?

Answer 20

• a way of determining the age of fossils
• radioactive decay of isotopes of various elements

Question 21

What does half-life mean in absolute/radiometric dating?

Answer 21

It is the time required for 50% of atoms in a given amount of isotope to decay

• other isotopes are suitable for rock and fossil specimens older than several thousand years

Question 22

What is plate tectonics theory?

Answer 22

Considers that Earth’s crust is composed of large plates that have been slowly moving since about 3.4 billion years ago.

• tectonic plates move slowly through the process of continental drift

Question 23

What is continental drift?

Answer 23

• causes tectonic lates to collide, separate, or slide past each other.
• interactions between plates cause the formation of mountains, islands, and earthquakes
• locations of continental land masses have changed over time

Question 24

What did continental drift cause during the Phanerozoic Eon?

Answer 24

The formation of the supercontinent Pangaea. This caused:

1. deepening of ocean basins
2. reduction in shallow water habitats
3. colder and drier climate inland

Question 25

What are the consequences of continental drift during the Phanerozoic Eon?

Answer 25

1. Formation of Pangea (approx. 250 million years ago) 2. Continental drift strongly influenced Earth's biodiversity (changes to the environment as continents moved north or south) 3. The distribution of fossils reflects the geologic movement of continents.

Question 26

How many mass extinction events were there? What are the two most notable extinctions called?

Answer 26

5 mass extinction events - The two most notable mass extinctions were the Permian extinction and the Cretaceous extinction.

Question 27

What was the Permian mass extinction? What caused it?

Answer 27

This extinction defines the boundary between the Paleozoic and the Mesozoic eras (252 mya) - The earth's most severe extinction event. Approx. 60% of all biological families were wiped out. Very rapid - The best supported hypothesis for the cause of this extinction is catastrophic environmental change due to volcanic activity

Question 28

What was the Cretaceous mass extinction? What caused it?

Answer 28

This extinction defines the period between the Mesozoic and Cenozoic eras. About 20% of all families went extinct. - The cause was a massive meteorite impact from 66 mya. (we know this because of the presence of iridium in sedimentary rock. - dust clouds caused by the impact blocked sunlight, disturbing the global climate.

Question 29

What is the Holocene extinction?

Answer 29

The 6th, human-caused mass extinction that is currently ongoing. - The Holocene extinction is a result of human activity, driven by population growth and overconsumption of the earth's natural resources.

Question 30

What are some consequences of mass extinctions?

Answer 30

- The loss of biodiversity alters ecological communities and niches available to organisms - adaptive radiation

Question 31

What is adaptive radiation?

Answer 31

The rapid evolution of diversely adapted species from an ancestral species. - occurs when a change in the environment makes new ecological niches available - Mass extinction can lead to adaptive radiation.

Question 32

What can adaptive radiation be followed by?

Answer 32

1. Mass Extinctions 2. Evolution of novel characteristics 3. Colonization of new regions

Question 33

Adaptive radiations may follow: 1. Mass extinctions

Answer 33

By eliminating so many species, mass extinctions can pave the way for adaptive radiation. - e.x. the disappearance of dinosaurs (except birds) allowed for the expansion of mammals in diversity and size

Question 34

Adaptive radiations may follow: 2. Evolution of novel characteristics

Answer 34

The adaptive radiation of photosynthetic prokaryotes, land plants, insects, and tetrapods were enables by novel adaptations - e.x. adaptive radiation of birds following the evolution of powered flight.

Question 35

Adaptive radiations may follow: 3. Colonization of new regions

Answer 35

Adaptive radiation can occur when new organisms colonize new environments with little competition. - e.x. Hawaiian plants, textbook example

Question 36

When was earth formed?

Answer 36

About 4.6bya. - Earth's surface was inhospitable to life until about 3.8bya.

Question 37

How did life begin on earth?

Answer 37

Life likely originated through a set of chemical reactions that gave rise to the molecules of life. - the prevailing scientific hypothesis is that the transition from non-living to living entities was not a single event, but an evolutionary process of increasing complexity.

Question 38

What are the hypothesized sequence of stages of the chemical and physical processes that may have produced single cells on earth? (The origin of life)

Answer 38

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

Question 39

What are Prokaryotes? What are the two domains of prokaryotes?

Answer 39

- The oldest fossil evidence of life is of prokaryotes (3.5 - 3.7 bya). - Prokaryotes are: 1. Unicellular 2. DNA is not contained in the nucleus 3. Lack of membrane-bound organelles. - The two domains of prokaryotes are bacteria ad archaea.

Question 40

What are stromatolites?

Answer 40

The oldest known fossils - rocks formed by the accumulation of sedimentary layers on prokaryote mats - created by the layered prokaryote species in shallow marine environments

Question 41

What was the Great Oxygenation Event (GOE)? How did it start? (slide 42)

Answer 41

Earth's early oceans and atmosphere had almost no free oxygen, and oxygen began accumulating around 2.7 bya. - Oceanic photosynthetic prokaryotes (cyanobacteria) used the sun's energy to fix CO2, producing O2 as a byproduct. - initially, O2 produced by cyanobacteria reacted with iron dissolved in oceans. Banded iron formations formed from the precipitate. - All soluble iron eventually precipitated and O2 saturation in the oceans was reached. Atmospheric O2 began accumulating.

Question 42

Why did many prokaryotic groups go extinct during the Great Oxygenation Event?

Answer 42

Since early prokaryotes evolved in oxygen-free conditions, they used anaerobic metabolism. - O2 was toxic to anaerobic prokaryotes. - This marked the end of the Archean Eon

Question 43

Did all prokaryotes go extinct during the Great Oxygenation Event? How did they adapt?

Answer 43

No! - Some prokaryotic groups survived and retained anaerobic metabolism - Other prokaryotes evolved anaerobic respiration to adapt to oxygen rich oceans and atmosphere.