Chapter 25: History of Life

Question 1

Chp 25

Macroevolution?

Answer 1

• broad pattern of evolution above species level
• fossil records show macroevolutionary changes: emergence of terrestrial vertebrates, impact of mass extinctions, etc..

Question 2

Chp 25

How did chemical & physical processes on early Earth produce very simple cells?

Answer 2

1. abiotic synthesis of small organic molecules
2. joining of small molecules into macromolecules
3. packaging of molecules into protocells
4. origin of slef-replicating molecules

Question 3

Chp 25

Synthesis of organic compounds on early earth

Answer 3

• Hydrothermal vents: area on the seafloor where hot eater & minerals gush into the ocean; a place where organic compounds could have been produced
• Alkaline vents: release water with high pH and warm water; more suitable for formation of stable organic compounds
• Meterotes; another possible source of organic molecules

Question 4

Chp 25

Abiotic synthesis of macromolecules

Answer 4

• Small organic molecules can polymerize when they are concentrade on hot sand/clay/rock
• ex: adding montmorillonite (soft mineral clay) greatly increase rate of vesicle formaiton (whcih cause simple growth, metabolism, etc…)

Question 5

Chp 25

Self-replicating RNA

Answer 5

• rna plays a huge role in protein synthesis
• rna molecules, ribosomes, can catalyze many different reactions
• natural selection and coppying errors have contributed to rna being able to self replicate

Question 6

Chp 25

Fossil records document history of life

Answer 6

• sedimentary rocks: layers called strata are the richest source of fossils
• fossil records are biased based on species existing for a long time, abundancy, and having hard parts (shells & skeletons)
• radiometric dating: relative ages of fossils can be inferred
• a radioactive parent isotope decays to a daughter isotope
• half life: time required for half the parent isotope to decay
• longer half lives help date older fossils

Question 7

Chp 25

The origin of new group of organisms

Answer 7

• mammals belong to tetrapods
• unique mammalian features can be traced in the fossil record

Question 8

Chp 25

What is the geologic record devided into?

Answer 8

• Hadean, Archaean, Proterozoic, & Phanoerozoic eons
• phanoerozoic is dvided into: paleozoic, mesozoic, & cenozoic
• Hadean: origin of solar system & earth
• Archaean: prokaryotes develop
• Proterozoic: atmospheric oxygen, single & multicellular eukaryotes
• Phanoerozoic: animals, colonizations of land, humans, present

Question 9

Chp 25

1st single celled organism

Answer 9

stromatolites: oldest nown fossils

Question 10

Chp 25

Photosynthesis & the oxygen revolution

Answer 10

• oxygen was produced by oxygenic photosynthesis
• oxygen revolution caused the extinction of many prokaryotic groups
• some groups adapted and others using cellular respiration to harvest energy

Question 11

Chp 25

1st eukaryotes

Answer 11

• endosymbiosis: when a prokaryotic cell engulfed a small cell that would evolve into mitochondrion; how eukaryotes originated
• endosymbiont: a cell that lives within a host cell
• serial endosymbiosis: says that mitochondria evolved before plastids (chloroplasts & relevant organelles) through a sequence of endosymbiotic events

Question 12

Chp 25

Origin of multicellularity

Answer 12

• evolution of eukaryotic cells -> greater range of unicellular forms
• second wave of diversification: algae, plants, fungi, and animals develop

Question 13

Chp 25

Cambiran explosion

Answer 13

• refers to sudden appearance of fossils resembling modern animal phyla in cambrian period
• provides first evidence of predator-prey interactions
• new defense adaptaions appeared

Question 14

Chp 25

Plate tectonics

Answer 14

• theory that says that earth’s crust is composed of plates floating on earth’s mantle
• continental drift: movements in mantle that cause plates to move over time
• these plates moving can collide to form mountains or cause eartthquakes

Question 15

Chp 25

Consequences of continental drift

Answer 15

• Pangea formation effect were: deepening of ocean basins, reduction in shallow-water habitat, colder/drier climate inland
• contiental drift caused organisms to adapt as climate changes occured

Question 16

Chp 25

Mass Extinctions

Answer 16

• extinction can be caused by biotic/abiotic environment
• mass ectinciton: increased rate of extinction

Question 17

Chp 25

Two of the big five mass extinction events

Answer 17

• Permian extinction: caused extinction of about 96% marine animal species b/c of volcanism, global warming, ocean acidfication, etc…
• Cretaceous extinction: half of marine species, families of terrestrial plants/animals, all of dinosaurs went extinct

Question 18

Chp 25

Consequences of Mass Extinctions

Answer 18

• diversity takes long to recover
• can change types of organisms found in ecological communities
• eliminate lineages with advantageous (novel) features

Question 19

Chp 25

Adaptive radiations

Answer 19

• def: rapid evolution of diverisly adapted species from a common ancestor
• may follow mass extinction, evolution of novel characteristics, colonization of new regions
• ex: extinction of dinosaurs opened ecological niches and expansion of mammals in diversity & size

Question 20

Chp 25

Changes in Rate & Timing

Answer 20

• Heterochrony: evolutionary change in rate/timing of developmental events
• can have a significant impact on body shape
• paedomorphosis: rate of reproductive development accelrates compared to somatic development

Question 21

Chp 25

Changes in spatial pattern

Answer 21

• homeotic genes: determine basic features and their placement/position
• ex: Hox genes - provide positional info during animal embryonic development