AP Biology Chapter 25 Notes

The History of Life on Earth

What you need to know…

•  The ______of the Earth and when prokaryotic and eukaryotic life emerged.

•  Characteristics of the ______planet and its atmosphere.

•  How ______and ______tested the Oparin-Haldane hypothesis and what they learned.

•  Methods used to ______fossils and rocks.

•  Evidence for ______.

•  How continental drift can explain the current ______of species.

Concept 25.1: Conditions on early Earth made the origin of life possible

·  Chemical and physical processes on early Earth may have produced very simple cells through a sequence of 4 stages:

1.  Small ______molecules were synthesized

2.  Joining of these small molecules into ______(proteins, carbs, etc)

3.  Packaging of molecules into “______” (membrane-containing droplets, whose internal chemistry differed from that of the external environment)

4.  Origin of ______-replicating molecules

·  A. I. Oparin and J. B. S. Haldane – hypothesized that the ______atmosphere, thick with water vapor, nitrogen, carbon dioxide, methane, ammonia, hydrogen, and hydrogen sulfide, with energy from lightening and UV radiation could have formed organic compounds

·  Stanley Miller and Harold Urey conducted lab experiments to test this ______and produced a variety of amino acids

·  ______ are aggregates of abiotically produced molecules surrounded by a membrane or membrane-like structure

·  The first genetic material was probably self-replicating RNA, not DNA

o  RNA molecules called ______ have been found to catalyze many different reactions

o  For example, ribozymes can make complementary copies of short stretches of their own sequence or other short pieces of ______

Concept 25.2: The fossil record documents the history of life

•  The fossil record is biased in favor of species that

–  ______for a long time

–  Were ______and ______

–  Had ______parts

•  The absolute ages of fossils can be determined by ______dating

•  Each isotope has a known ______, the time required for half the parent isotope to decay

Concept 25.3: Key events in life’s history include the origins of single-celled and multicelled organisms and the colonization of land

•  The ______record is divided into the Archaean, the Proterozoic, and the Phanerozoic eons

•  The oldest known fossils are ______, rock-like structures composed of many layers of bacteria and sediment

•  This “oxygen revolution” from 2.7 to 2.2 billion years ago

–  Posed a ______for life

–  Provided opportunity to ______energy from light

–  Allowed organisms to exploit ______ecosystems

•  The hypothesis of ______ proposes that mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes living within larger host cells

–  An ______ is a cell that lives within a host cell

–  Key evidence supporting an endosymbiotic origin of mitochondria and plastids:

•  Similarities in inner ______structures and functions

•  ______is similar in these organelles and some prokaryotes

•  These organelles ______and ______their own DNA

•  Their ______are more similar to prokaryotic than eukaryotic ribosomes

•  ______began to colonize land about 500 million years ago

•  ______likely colonized land together by 420 million years ago

•  ______are the most widespread and diverse land animals

•  ______evolved from lobe-finned fishes around 365 million years ago

Concept 25.4: The rise and fall of dominant groups reflect continental drift, mass extinctions, and adaptive radiations

•  Earth’s continents move slowly over the underlying hot mantle through the process of ______

–  Oceanic and continental plates can collide, separate, or slide past each other

–  Interactions between plates cause the formation of mountains and islands, and earthquakes

•  Formation of the supercontinent ______ about 250 million years ago had many effects

–  A ______in shallow water habitat

–  A ______and ______climate inland

–  Changes in ______as continents moved toward and away from the poles

–  Changes in ______circulation patterns leading to global cooling

•  The break-up of Pangaea lead to ______speciation

•  The current distribution of ______reflects the movement of continental drift

•  At times, the rate of ______has increased dramatically and caused a ______(loss of large numbers of species in short periods of time)

–  By removing large numbers of species, ecological communities can be drastically altered losing evolutionary ______forever

•  Mass extinction can pave the way for ______ (periods of evolutionary change where groups of organisms form many new species whose adaptations allow them to fill different ecological niches)

–  EX. Galapagoas finch species

Concept 25.5: Major changes in body form can result from changes in the sequences and regulation of developmental genes

·  “______” – a filed of study in which evolutionary biology and developmental biology converge

·  Illuminating how slight ______divergences can be magnified into major morphological differences between species

·  Sometimes, structures that originally played one role gradually acquire a different one – ______

·  EX. Feathers of modern birds were co-opted for flight after functioning in some other capacity such as thermoregulation

·  ______ is an evolutionary change in the rate or timing of developmental events

·  The contrasting shapes of human and chimpanzee skulls are the result of small changes in relative growth rates

·  In ______, the rate of reproductive development accelerates compared with somatic development

·  ______genes determine such basic features as where wings and legs will develop on a bird or how a flower’s parts are arranged

·  Ex. Hox Genes

·  Hox genes are a class of homeotic genes that provide ______information during development

·  If Hox genes are expressed in the wrong location, body parts can be produced in the wrong location

You should now be able to…

  1. Define radiometric ______, serial ______, Pangaea, snowball Earth, ______, ______, and ______
  2. Describe the contributions made by Oparin, Haldane, Miller, and Urey toward understanding the ______of organic molecules
  3. Explain why RNA, not DNA, was likely the ______genetic material
  4. Describe and suggest evidence for the ______events in the history of life on Earth from Earth’s origin to 2 billion years ago
  5. Briefly describe the Cambrian explosion
  6. Explain how continental drift ______to Australia’s unique flora and fauna
  7. Describe the ______extinctions that ended the Permian and Cretaceous periods
  8. Explain the function of ______ genes