Chpt 12: The History of Life

1. Chpt12: The History of Life

2. Warm-Up • Which of these structures are the best evidence of an evolutionary relationship? • bat wing and bee wing • bat lower jaw and whale lower jaw • whale flipper and bee wing • bat wing and whale flipper

3. Objectives • Students will be able to describe the ways that fossils can form. • Students will be able to recognize the role of index fossils in determining the ages of rocks. • Students will be able to recognize the role microbes played in the shaping of life on Earth. • Students will be able to summarize the theory of Endosymbiosis. • Students will be able to relate increased biodiversity to sexual reproduction. • Students will be able to examine the evolutionary relationships between humans and other primates. • Students will be able to recognize the names and relative ages of extinct hominids. • Students will be able to summarize the events and forces that shaped human evolution.

4. Chpt12 Sec 12.1: The Fossil Record • Key Concept • Fossils are a record of life that existed in the past.

5. Chpt12 Sec 12.1: The Fossil Record • Fossils can form in several ways • Permineralization: • Occurs when minerals are carried by water and deposited around a hard structure • Natural Casts: • Form when flowing water removes all of the original bone or tissue, leaving just an impression in sediment

6. Chpt 12 Sec 12.1: The Fossil Record • Fossils can form in several ways • Trace fossils: • Record the activity of an organism • Amber-preserved fossils: • Organisms that become trapped in tree resin that hardens into amber after the tree gets buried underground • Preserved remains: • Entire organisms become encased in material such as ice or volcanic ash or immersed in bogs

7. Chpt12 Sec 12.1: The Fossil Record • Fossils can form in several ways • Explain why some organisms are not fossilized • Propose a reason for why so few complete fossils are discovered.

8. Chpt12 Sec 12.1: The Fossil Record • Fossils can form in several ways • Explain why some organisms are not fossilized • Some organisms cannot withstand the extreme pressures of the rock. • Some organisms do not have the appropriate structural integrity • Propose a reason for why so few complete fossils are discovered. • Natural disasters • Decomposition occurs

9. Chpt12 Sec 12.2: The Geologic Time Scale • Key Concept • The geologic time scale divides Earth’s history based on major past events

10. Chpt12 Sec 12.2: The Geologic Time Scale • Index fossils are another tool to determine the age of rock layers. • Identify one way that scientist can determine how old rocks are.

11. Chpt12 Sec 12.2: The Geologic Time Scale • Index fossils are another tool to determine the age of rock layers. • Identify one way that scientist can determine how old rocks are. • They can look at the composition of minerals present in the rock material • They can look at the strata where the rock is located

12. Chpt12 Sec 12.2: The Geologic Time Scale • Index fossils are another tool to determine the age of rock layers. • Index fossils are fossils of organisms that existed only during specific spans of time over large geographic areas. • The shorter the life span of a species, the more precisely the different strata can be correlated • An example of a index fossil is a Fusulinid ---------------------------

13. Chpt12 Sec 12.2: The Geologic Time Scale • The geologic time scale organizes the Earth’s history • Geologic time scale: a representation of the history of the Earth. It organizes Earth’s history by major changes or events that have occurred, using evidence from the fossil and geologic records.

14. 60 Seconds

15. Chpt12 Sec 12.3: The Origin of life • Key Concept • The origin of life on Earth remains a puzzle

16. Chpt12 Sec 12.3: The Origin of life • Think back…. Recall what a hypothesis is…

17. Chpt12 Sec 12.3: The Origin of life • A hypothesis is a proposed explanation or answer to a scientific question. It is stated as an if then statement.

18. Chpt12 Sec 12.3: The Origin of life • Several sets of hypotheses propose how life began on Earth • Organic molecule hypothesis • Miller-Urey experiment • 1953 Stanley Miller and Harold Urey designed an experiment to test a 1920s hypothesis • Scientists had proposed that an input of energy from lightening led to the formation of organic molecules from inorganic molecules present in the atmosphere of early Earth • The four gases thought to be present in the atmosphere were methane, ammonia, hydrogen, and water vapor

19. Chpt12 Sec 12.3: The Origin of life • Several sets of hypotheses propose how life began on Earth • Organic Molecule Hypotheses • Meteorite hypothesis • A meteorite fell near Murchison Australia in 1969 showing… • Organic molecules can be found in space • From this meteorite more than 90 amino acids have been found • How many of the numerous amino acids identified from the meteorite can be found on Earth?

20. Chpt12 Sec 12.3: The Origin of life • Several sets of hypotheses propose how life began on Earth • Early cell structure hypothesis • Iron-sulfide bubble hypothesis • Iron-sulfide rising from the ocean floor combined with cooler waters of the ocean tend to form chimney structures • Biological molecules combined with the compartments of these “chimneys” 4 billion years ago • The walls of these structures acted as the first cell membranes

21. Chpt12 Sec 12.3: The Origin of life • Several sets of hypotheses propose how life began on Earth • Early cell structure hypothesis • Lipid membrane hypothesis • Lipid molecules spontaneously for membrane enclosed spheres called liposomes • Liposomes could form around organic molecules • Give rise to the first true cells

22. Chpt12 Sec 12.3: The Origin of life • Several sets of hypotheses propose how life began on Earth • RNA as early genetic material • RNA, rather than DNA, was the genetic material that stored information in living things on early Earth • Ribozymes are RNA molecules that can catalyze specific chemical reactions • Where can ribosomes be found within the cell? • Unlike DNA, RNA can replicate itself without enzymes • Short chains of RNA will form inorganic materials in a test tube • What process could be responsible for the shift from RNA to DNA

23. Chpt12 Sec 12.4: Early Single-Celled Organisms • Key Concept • Single-celled organisms existed 3.8 billion years ago

24. Chpt12 Sec 12.4: Early Single-Celled Organisms • Microbes have changed the physical and chemical composition of Earth • Single-celled organisms changed the Earth’s surface by depositing minerals • Name some minerals you have previously learned about • Single-celled organisms changed the atmosphere by giving off oxygen as a byproduct of photosynthesis • Before photosynthesis evolved bacteria would have to be anaerobic

25. Chpt12 Sec 12.4: Early Single-Celled Organisms • Microbes have changed the physical and chemical composition of Earth • The earliest prokaryotic single-celled organism is called the cyanobacteria • Bacteria that can carry out photosynthesis • Single-celled prokaryotic organism with no membrane bound organelles • Stromatolites are domed, rocky structures made of cyanobacteria and sediment

26. Chpt12 Sec 12.4: Early Single-Celled Organisms • Eukaryotic cells may have evolved through endosymbiosis • Eukaryotic organisms evolved by 1.5 billion years ago • Identify what a eukaryotic cell has that a prokaryotic cell does not. • Endosymbiosis: a relationship in which one organism lives inside the body of another. Bothe will benefit from this relationship. • Name the two organelles that are said to be examples of endosymbiosis.

27. Chpt 12 Sec 12.4: Early Single-Celled Organisms

28. Chpt12 Sec 12.4: Early Single-Celled Organisms • The evolution of sexual reproduction led to increased diversity • Recall what a-sexual reproduction is. • Define sexual reproduction.

29. Chpt12 Sec 12.4: Early Single-Celled Organisms • The evolution of sexual reproduction led to increased diversity • Recall what a-sexual reproduction is. • A single parent produces offspring that are genetically similar to itself • Can produce many offspring quickly. • Define sexual reproduction. • Needs two parents • Both parents give genes to their offspring • Sexual reproduction allows new combinations of genes to come together • Sexual reproduction creates more genetic variation

30. Chpt12 Sec 12.6: Primate Evolution • Key Concept • Humans appeared late in Earth’s history

31. Chpt12 Sec 12.6: Primate Evolution • Humans share a common ancestor with other primates • The qualities that make an organism a primate are • Flexible hands and feet • Forward looking eyes • Enlarged brains • Arms that can rotate in a circle • Have thumbs

32. Chpt12 Sec 12.6: Primate Evolution • Humans share a common ancestor with other primates • Prosimians: oldest living primate group • Nocturnal animals • Anthropoids: humanlike primates • Old World Monkeys • New World Monkeys • Hominoids • Lesser apes • Greater apes • AND…

33. Chpt12 Sec12.6: Primate Evolution • Humans share a common ancestor with other primates • Hominoids: • Hominids • Walk upright • Have long lower limbs • Thumbs that oppose • Large brains • Includes all of the species in the human lineage

34. Chpt12 Sec 12.6: Primate Evolution • Humans share a common ancestor with other primates • Animals that can walk upright are called bipedal

35. Chpt12 Sec 12.6: Primate Evolution • There are many fossils of extinct hominids

36. Chpt 12 Sec 12.6: Primate Evolution

37. Chpt12 Sec 12.6: Primate Evolution • Modern Humans arose about 100,000 years ago • The first appearance of Homo sapiens, dates to roughly 100,000 years ago in what is now Ethiopia. • Tools are a marker of human evolution. • Genes controlling the size and complexity of the human brain evolved faster than analogous genes in nonhuman primates.

38. Reflection • Describe the ways that fossils can form. • Recognize the role of index fossils in determining the age of rocks • Summarize the theory of endosymbiosis • Recognize the names of extinct hominids.