Chapter 19. History of Life on Earth

Transcription

1 Chapter 19 History of Life on Earth Adapted from Holt Biology 2008

2 Chapter 19 Section 3: Evolution of Life Key Vocabulary Terms Adapted from Holt Biology 2008

3 Cyanobacteria Photosynthetic prokaryotes Adapted from Holt Biology 2008

4 Endosymbiosis A mutually beneficial relationship in which one organism lives within another

5 Content Objectives I will be able to identify: The major evolutionary developments that occurred during Precambrian time? The dominant organisms that evolved during the Paleozoic Era? The dominant organisms that evolved during the Mesozoic and the Cenozoic Era? Adapted from Holt Biology 2008

6 Chapter 19 Section 3: Evolution of Life Notes Adapted from Holt Biology 2008 Adapted from Holt Biology 2008

7 Chapter 19 Section 3: Evolution of Life Precambrian Time Adapted from Holt Biology 2008 Adapted from Holt Biology 2008

8 Precambrian Time Precambrian time spanned between about 4.5 billion and 542 million years ago.

9 Precambrian Time Single-celled prokaryotes and later, eukaryotes, evolved and flourished in Precambrian time.

10 Precambrian Time The evolution of multicellular organisms set the stage for the evolution of modern organisms.

11 YOUR TURN Active Reading Section 3 Evolution of Life Adapted from Holt Biology 2008

12 Evolution of Life The oldest fossils (3.5 billion years old) are cyanobacteria. Adapted from Holt Biology 2008

13 Formation of Oxygen Scientists think that about 2.5 billion years ago, cyanobacteria began adding oxygen to Earth s atmosphere.

14 Formation of Oxygen As ancient cyanobacteria carried out photosynthesis, they released oxygen gas into Earth s oceans.

15 Formation of Oxygen This oxygen eventually escaped into the air.

16 Formation of Oxygen Helped to form oxygen gas as a product of photosynthesis. Adapted from Holt Biology 2008

17 Formation of Oxygen The accumulation of atmospheric oxygen allowed organisms to live on land.

18 Formation of Oxygen As oxygen reached Earth s upper atmosphere, the sun s rays caused some of the oxygen gas (O 2 ) to chemically react and form molecules of ozone (O 3 ).

19 Formation of Oxygen Ozone (O 3 ) helped to block harmful UV rays. Adapted from Holt Biology 2008

20 Formation of Oxygen Organisms on the very early Earth could not survive on land because ultraviolet radiation damaged their DNA.

21 Formation of Oxygen After millions of years, enough ozone had accumulated to make land a safe place for organisms to live.

22 Eukaryotic Life Later in Precambrian time, the first eukaryotes appeared.

23 Origin of Energy-Producing Organelles Mitochondria and chloroplasts likely originated as described by the endosymbiotic theory proposed by Lynn Margulis.

24 Origin of Energy-Producing Organelles Endosymbiotic theory proposes that larger bacteria engulfed smaller bacteria, which then began to live inside larger cells.

25 Origin of Energy-Producing Organelles Endosymbiosis is a mutually beneficial relationship in which one organism lives within another.

26 Eukaryotic Life According to this theory, mitochondria are the descendants of symbiotic, aerobic (oxygen-requiring) bacteria.

27 Eukaryotic Life Chloroplasts are thought to be the descendants of symbiotic, photosynthetic bacteria.

28 Size and Structure Mitochondria are the same size as most bacteria. Chloroplasts are the same size as some cyanobacteria.

29 Eukaryotic Life They also contain their own DNA, which is similar to that of prokaryotes.

30 Genetic Material Both chloroplasts and mitochondria contain genes that are different from those found in the nucleus of the host cell. These genes are closely related to bacterial genes.

31 Ribosomes Mitochondrial and chloroplast ribosomes are similar in size and structure to bacterial ribosomes.

32 Reproduction Like bacteria, chloroplasts and mitochondria reproduce by simple fission. This replication takes place independently of the cell cycle in the host cell.

33 Multicellularity Arose from colonial organisms that developed cell specialization and cell communication (632 mya) Adapted from Holt Biology 2008

34 Mass extinctions Open up ecological niches and happen before bursts of diversification Adapted from Holt Biology 2008

35 Think, Share, Write #1 Why is the evolution of colonial organisms an important step in evolution? Adapted from Holt Biology 2008

36 Think, Share, Write #1 Why is the evolution of colonial organisms an important step in evolution? Colonial organisms developed the first example of separate functions being performed by different parts in a larger unit. Adapted from Holt Biology 2008

37 Chapter 19 Section 2: The Age of Earth Paleozoic Era Adapted from Holt Biology 2008 Adapted from Holt Biology 2008

38 Paleozoic Era The Cambrian Period, the first period in the Paleozoic Era, was a time of great evolutionary expansion.

39 Paleozoic Era ( mya) Marine invertebrates diversified and marine vertebrates evolved. Adapted from Holt Biology 2008

40 Paleozoic Era A vertebrate is an animal with a backbone.

41 Paleozoic Era ( mya) Land plants evolved. Adapted from Holt Biology 2008

42 The first multicellular organisms to live on land may have been fungi living together with plants or algae. Paleozoic Era

43 Paleozoic Era Plants and fungi began living on the surface of the land about 475 million years ago.

44 Paleozoic Era Eventually, great forests covered much of Earth s landscape.

45 Paleozoic Era Some arthropods, and then some vertebrates, left the oceans to colonize land.

46 Paleozoic Era The first land vertebrates, amphibians, came out of the sea about 370 million years ago.

47 Paleozoic Era Reptiles evolved from amphibian ancestors about 340 million years ago.

48 Mass Extinctions The fossil record indicates that mass extinctions occurred both at the end of the Ordovician Period (440 million years ago) and at the end of the Devonian Period (365 million years ago).

49 Mass Extinctions These events eliminated about 70% of all the species on Earth.

50 The most devastating of all mass extinctions occurred at the end of the Permian Period, about 245 million years ago.

51 Mass Extinctions About 96% of all animal species living at the time became extinct.

52 Chapter 19 Section 2: The Age of Earth Mesozoic and Cenozoic Eras Adapted from Holt Biology 2008 Adapted from Holt Biology 2008

53 Mesozoic and Cenozoic Eras Many of the dominant life-forms on our planet diverged during the Mesozoic and Cenozoic Eras.

54 Mesozoic and Cenozoic Eras ( mya) Reptiles, dinosaurs, and birds dominated the Mesozoic era. Adapted from Holt Biology 2008

55 Mesozoic and Cenozoic Eras ( mya) Mammals dominated the Cenozoic era. Adapted from Holt Biology 2008

56 Mesozoic and Cenozoic Eras During the Mesozoic Era, dinosaurs and other reptiles evolved to be the dominant lifeforms.

57 Mesozoic and Cenozoic Eras Therapsids, which were reptilelike mammals, gave rise to modern mammals at about the same time that dinosaurs evolved, in the Triassic Period.

58 Mesozoic and Cenozoic Eras The Cenozoic Era is the current era.

59 Mesozoic and Cenozoic Eras During this era, mammals became the dominant lifeform.

60 Mesozoic and Cenozoic Eras Modern humans did not appear until the Quaternary Period.

61 Mass Extinction A mass extinction 65 million years ago included about two-thirds of all land species, including most of the dinosaurs.

62 Adapted from Holt Biology 2008

63 Mass Extinction Scientists think that this mass extinction was caused by a catastrophic event that had widespread effects.

64 Summary Prokaryotes and later, eukaryotes, evolved in the Precambrian. The evolution of multicellular life preceded the evolution of modern life-forms. Atmospheric oxygen allowed life to survive on land.

65 Summary During the Paleozoic Era, marine invertebrates diversified, and marine vertebrates evolved. Some arthropods, and then some vertebrates, colonized the land.

66 Summary Reptiles, dinosaurs, and birds were the dominant animals in the Mesozoic Era, and mammalian animals were dominant in the Cenozoic Era.