Chapter 25 The History Of Life On Earth

Front 1

Describe the four stages of the hypothesis for the orgin of life on earth by chemical evolution.

Back 1

1) the abiotic(nonliving) synthesis of small orangic molecules, such as amino acids and nucleotides.
2)the join of these small molecules into macromolecules including proteins and nucleic acids.
3) the packaging of these molecules into "protobionts" droplets with membranes that maintained an internal chemistry different from that of their surrounding.
4) the origin of self-replicating molecules that eventually made inheritance possible.

Front 2

Describe the evidence that suggests that RNA was the first genetic material. Explain the significance of the discovery of ribozymes.

Back 2

the first genetic material may have been short pieces of RNA capable of guiding polypeptide synthesis and self-replication. Early protobionts containing such RNA would have been more effective at using resources and would have increased in number through natural selection.

Front 3

Explain why the fossil record provides an incomplete chronicle of evolutionary change.

Back 3

Many organisms probably did not die in the right place at the right time. Fossil records favor species that existed for a long time, were abundent and wide spread in certain kinds of environment, and had hard shells.

Front 4

Explain how radiometric dating can be used to determine the absolute age of rock strata. Explain how magnetism can be used ti date rock strata.

Back 4

A radioactive "parent" isotope decays to a "daughter" isotope at a constant rate. The rate of decay is measured in half-life. Measurement of the magnetism of various rock layers indicate that earths north and south pole have revearsed repeatedly in the past.

Front 5

Describe the major events in earths history from its origin until 2 billion years ago. In particular, note when earth first formed, when life first evolved, and what forms of life excisted in each eon.

Back 5

Earth formed 4.6 bya. 3.5 bya first prokaryote. 2.1 bya first eukaryotes. All archaean and some proterozoic.

Front 6

6. Name the reactions that have produced O2 on Earth. Describe the accumulation of atmospheric O2 over time and the effects of this accumulation on living things.

Back 6

O2 produced during water-splitting step of photosynthesis. Disolved into water until it reached a high enough concentration to react with dissolved iron. Reacted with iron to precipitate iron oxide. O2 gased out into the air. Doomed many prokaryotic groups.

Front 7

7. Explain the endosymbiotic theory for the evolution of the eukaryotic cell. Describe the evidence that supports this theory.

Back 7

Protists that mitochondria and plastids were formenly small prokaryotes that began living within larger rcells. Gained entrence to the host cell as undigested pray or internal parasites. The inner membranes of both organelles have enzymes and transport systems that are homologus to those found in the pasma membrane of living prokaryotes.

Front 8

Briefly describe the Cambrian explosion.

Back 8

A relatively brief time in history when large, hard-bodied forms of animals with most of the major body plans know today appeared in the fossil record. 535-525 million years ago.

Front 9

10. Discuss, with a suitable example, how continental drift (plate tectonics) explains the current or former distribution of organisms.

Back 9

Ocean basins became deeper, which lowered the sea level and drained shallow costal seas. Tremendous impact on physical enviroment and climate, which drove some species to extinction and provided new opportunites for groups of organisms that survived the crisis.

Front 10

11. Describe the mass extinctions that ended the Permian and Cretaceous periods. “A sixth mass extinction may be currently underway.” Explain this statement.

Back 10

the permain mass extinction claimed 96% of marine animals. occured at time of major valcanoes. Cretaceaous mass extinction was caused by a comet.

Front 11

Define adaptive radiation.

Back 11

Periods of evolutionary change in which groups of organisms form many new species who adaptions allow them to find different ecological roles, or nitches, in their communities.

Front 12

Define evo-devo

Back 12

Evo Devo is the evolutionary developmental bilogy; a field of biology that compares developmental processes of different multicellular organisms to understand how these processes have evolved and how changes can modify existing organismal features or lead to new ones.

Front 13

Define heterochrony

Back 13

Evoluionary change in the timing or rate of an organisms development.

Front 14

Define paedomorphosis

Back 14

the reteintion in an adult organism of the juvenile features of its evolutionary ancestors.

Front 15

14. Explain the function of Hox genes. Describe, with a suitable example, how changes in the number, sequence, or expression of Hox genes can lead to major morphological differences between species.

Back 15

Hox genes promts cells to develope into structures appropriate for a particular location. A mutation of the single Hox complex and provided genetic material associaed with the origin of the first vertabrates.

Front 16

Define exaption and illustrate this concept with an example

Back 16

structures that evolve in one context but became co-opted for another function called a exaptations.

Front 17

Define Geological record

Back 17

The division of Earths history into time periods grouped into 3 Eons. Archean, proterozoic, and phaneroic, and further subdivided into eras, periods, and epochs.

Front 18

Define protobiont

Back 18

A collection of abiotically produced molecules surrounded by a membrane or membrane like strucutre.

Front 19

Ribozymes

Back 19

An RNA molecules that functions as an enzyme, catalyzing reactions during RNA splicing.

Front 20

Serial endosymbiosis

Back 20

A hypotheis for the origin of Eukaryotes consisting of a sequence of endosymbiotic events in which mitochondria were derived from small prokaryotes that had been engulfed by larger cells.

Front 21

Stromatolite

Back 21

Layered rock that results from the activites of prokaryotes that bind thin films of sediment together.