Chapter 17 History of Life.

Chapter 17 History of Life

17-1 I. The Fossil Record scientists who collect and study fossils
17-1 I. The Fossil Record scientists who collect and study fossils A. Paleontologists- B. Fossil record- 1. Info. from past; about structure of organisms, what they ate, what ate them (predator), in what environment they lived, and the order in which they lived. 2. Provides evidence about the history of life on Earth.

3. Shows how different groups of organisms, including species, have changed over time.
4. Is incomplete, so provides limited info. about history of life on Earth 5. Over 99% of all species that lived on Earth have died out. 6. Most fossils form in sedimentary rock. a. Sedimentary rock forms when particles of sand, silt, and clay are compressed together b. Fossil Formation: Conditions must be conducive to fossils forming.

II. Methods of Dating Fossils
A. Relative dating- 1. the age determined by comparing placement of fossils in other layers of rock 2. Rock layers form in order by age—the oldest on the bottom, with more recent layers on top. Page 419

3. Index fossil - a species that is recognizable and that existed for a short period but had a wide geographic range a. Used to compare the relative ages of fossils B. Absolute Dating 1. Radioactive dating is the use of half-lives to determine the age of a sample. a. half-life = length of time required for half of the radioactive atoms in a sample to decay. b. Calculated by the age of a sample based on the amount of remaining radioactive isotopes it contains.

2. Carbon-14 Dating = most common forms of fossil dating.
a. begins to decay when an organism dies. b. Carbon-12 is not radioactive and does not decay c. By comparing the amounts of carbon-14 and carbon-12 in a fossil, researchers can determine when the organism lived.

III. Geologic Time Scale
A. Paleontologists use the geologic time scale to represent evolutionary time. B. Basic divisions are eras and periods. C. Eras are subdivided into periods D. Geologists divide the time between Precambrian time and the present into three eras: Paleozoic Era Mesozoic Era Cenozoic Era

Clock Model of Earth’s History
Page 422 First humans Radiation of mammals First prokaryotes First land plants First multicellular organisms Cenozoic Era Mesozoic Era Paleozoic Era Precambrian Time First eukaryotes Accumulation of atmospheric oxygen

IV. Formation of Early Earth
17-2 IV. Formation of Early Earth A. 4 billion years ago, Earth cooled and solid rocks formed on its surface. B. Millions of years later, volcanic activity shook Earth’s crust. C. 3.8 billion years ago, Earth’s surface cooled for water to remain a liquid  oceans covered much of the surface. D. Earth's early atmosphere -NO free OXYGEN- may have had hydrogen cyanide, carbon dioxide, carbon monoxide, nitrogen, hydrogen sulfide, and water.

Spark simulating lightning storms ADD TO NOTES: Mixture of gases simulating atmosphere of early Earth ’s- Miller and Urey tried to simulate atmosphere on early Earth in a lab setting. Condensation chamber 2. Experiment- suggested that organic compounds needed for life could have arisen from simpler inorganic compounds present on early Earth. Water vapor Cold water cools chamber, causing droplets to form. Result: Liquid -amino acids and other organic compounds produced

Add to notes: Honors ONLY
3. From simple, organic molecules to cells? How? a. Proteinoid Microspheres- structurally like cells, but missing genetic material to pass on traits Like cells: they have selectively permeable membrane; simple ways of storing and releasing energy; globular in shape; BUT MISSING GENETIC MATERIAL b. RNA may have been the first genetic material eventually leading to DNA as genetic material

V. The First Cells? A. Evidence suggests - cells similar to modern bacteria were common mill. years after Earth had water . VI. Microfossils (microscopic fossils) A. unicellular prokaryotic organisms resembled modern bacteria. B. have been found in rocks over 3.5 billion years old C. must have evolved without oxygen if primitive Earth had no free oxygen. D. About 2.2 bya, photosynthetic bacteria began to release oxygen into the oceans, then the atmosphere.

VIII. Origin of Eukaryotic Cells
VII. Significance of Oxygen on Earth A. Oxygen (photosynthesis) in the atmosphere meant life forms could grow larger and even become multicellular. VIII. Origin of Eukaryotic Cells A. Endosymbiotic Theory  eukaryotic cells with organelles arose from living communities of prokaryotic organisms.

Endosymbiotic Theory Page 427 Plants and plantlike protists
Primitive Photosynthetic Eukaryote The endosymbiotic theory proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms. Ancient prokaryotes may have entered primitive eukaryotic cells and remained there as organelles. Animals, fungi, and non-plantlike protists Ancient Anaerobic Prokaryote Primitive Aerobic Eukaryote

ADD TO NOTES: Theory of Endosymbiosis
1. Proposed that chloroplasts and mitochondria arose from invading prokaryotes that enter larger cells. 2. Would than be able to use oxygen for ATP  mitochondria Mitochondrion Ancient Anaerobic Prokaryote Primitive Aerobic Eukaryote

Endosymbiotic Theory Prokaryotes that carried out photosynthesis evolved into chloroplasts. Chloroplast Photosynthetic bacteria The endosymbiotic theory proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms. Ancient prokaryotes may have entered primitive eukaryotic cells and remained there as organelles. Primitive Photosynthetic Eukaryote

IX. Asexual Reproduction
A. Prokaryotes reproduce asexually by binary fission. B. Results of asexual reproduction: 1. Daughter cells are exact copies of the parent cell. 2. Restricts genetic variation to mutations in DNA. X. Sexual Reproduction and Multicellularity 1. Shuffles genes in each generation 2. Sexual reproduction results in: a. offspring that are never identical to the parents b. more “options” to increase chances of survival ADD:

17-4 Page 439 XI. Patterns of Evolution Macroevolution-
1. refers to large-scale evolutionary patterns and processes Page 439

B. Six Patterns of Macroevolution
1. extinction a. Disappearance of an entire species 2. adaptive radiation- form of divergent evolution-homologous structures a. process by which a single species or a small group of species evolves into several different forms that live in different ways b. Darwin's finches, more than a dozen species evolved from a single species c. The disappearance of dinosaurs resulted in the adaptive radiation of mammals

Adaptive Radiation in Mammals
Artiodactyls Cetaceans Tubulidentates Sirenians Proboscideans Hyracoids Perissodactyls This diagram shows part of the adaptive radiation of mammals, emphasizing current hypotheses about how a group of ancestral mammals diversified over millions of years into several related living orders. Note that the dotted lines and question marks in this diagram indicate a combination of gaps in the fossil record and uncertainties about the timing of evolutionary branching. Ancestral Mammals This diagram shows part of the adaptive radiation of mammals, emphasizing current hypotheses about how a group of ancestral mammals diversified over millions of years into several related living orders. Note that the dotted lines and question marks in this diagram indicate a combination of gaps in the fossil record and uncertainties about the timing of evolutionary branching.

3. convergent evolution- evidence = analogous structures
a. process by which unrelated organisms come to resemble one another is called convergent evolution b. resulted in sharks, fish, dolphins, whales, seals, and penguins c. Convergent Evolution Involves Analogous Structures 4. coevolution a. process by which 2 species evolve in response to changes in each other over time

5. Gradualism vs. Punctuated Equilibrium
a. Darwin felt that biological change was slow and steady with small changes over time = gradualism b. Punctuated equilibrium- pattern of evolution in which long stable periods are interrupted by rapid change Punctuated equilibrium

6. changes in developmental genes and body plans
a. Changes in genes for growth and differentiation (hox genes) during embryological development could produce changes in body shape and size b. Changes in expression of dev. Genes (hox genes) may explain how wing differences evolved.

17-1 Which of the following statements about fossils is NOT true?
A. Most fossils form in sedimentary rock. B. Fossils occur in a particular order. C. Only a small portion of fossils are from extinct organisms. D. Fossils can be used in relative dating of rock formations.

17-1 The fossil record consistently shows evidence that
A. all forms of life have existed in all geologic eras. B. living organisms have only been on Earth for a short time. C. living things have changed over time. D. ancient life-forms are much the same as forms found living today.

17-1 Index fossils assist paleontologists in dating rocks because they represent species that A. were widely distributed and existed for a very long time. B. existed in a single location for a short period of time. C. were widely distributed and existed for a short time. D. existed in a single location for a very long time.

17-1 Determining the age of a fossil by comparing its placement with fossils in other layers of rock is called A. carbon-14 dating. B. fossil-indexing. C. relative dating. D. absolute dating.

17-1 According to the geologic time scale, geologic time begins with
A. Precambrian Time. B. the Paleozoic Era. C. the Quaternary Period. D. the Cambrian Era.

17-2 Which of the following gases was probably NOT present in the early Earth’s atmosphere? A. hydrogen cyanide B. oxygen C. nitrogen D. carbon monoxide

17-2 Miller and Urey's experiment was a simulation of Earth's early
A. volcanic activity. B. formation. C. atmosphere. D. life.

17-2 Proteinoid microspheres are different from cells because microspheres A. have selectively permeable membranes. B. do not have DNA or RNA. C. have a simple means of storing and releasing energy. D. separate their internal environment from the external environment.

17-2 The hypothesis that RNA sequences appeared before DNA sequences
A. has some evidence in its favor but is still being tested. B. has been rejected since DNA is required to make RNA. C. has been proven since RNA has been made in laboratories. D. has been rejected because it is illogical.

17-2 As concentrations of oxygen rose in the ancient atmosphere of Earth, organisms began to evolve A. anaerobic pathways. B. plasma membranes. C. metabolic pathways that used oxygen. D. photosynthesis.

17-4 Darwin's species of finches were very similar but different in beak size and feeding habits. This is an example of A. convergent evolution. B. coevolution. C. adaptive radiation. D. stabilizing selection.

17-4 A slow steady change in a particular line of descent is called
A. coevolution. B. gradualism. C. punctuated equilibrium. D. convergent evolution.

17-4 Master control genes are called A. hox genes.
B. developmental genes. C. embryonic genes. D. regulatory genes.

17-4 Some evidence suggests that species do not change much over long periods of time and then undergo relatively short periods of rapid speciation. This kind of change is called A. coevolution. B. genetic equilibrium. C. adaptive radiation. D. punctuated equilibrium.

17-4 Fossil evidence shows that mass extinctions
A. ended the existence of many species in a short period of time. B. occurred mainly when the dinosaurs disappeared. C. require an asteroid strike to occur. D. caused convergent evolution among animals.