Earth's Timeline and Emergence of Life PDF

Lesson 3.1 Earth's Timeline and Emergence of Life General Biology [1/2] 2 Science, Technology, Engineering, and Mathematics  So far, Earth is the only planet known to support life. The mere presence of life forms on Earth sets it aside from the other known planets...

Lesson 3.1 Earth's Timeline and Emergence of Life General Biology [1/2] 2 Science, Technology, Engineering, and Mathematics  So far, Earth is the only planet known to support life. The mere presence of life forms on Earth sets it aside from the other known planets in the universe. 2 Scientists started to formulate a series of theories regarding the emergence of life forms on the planet and relate it to the physical changes on Earth’s environment. 3 How do primitive life forms emerge? 4  Learning Competency At the end of the lesson, you should be able to do the following: Describe general features of the history of life on Earth, including generally accepted dates and sequence of the geologic time scale and characteristics of major groups of organisms present during these time periods (STEM_BIO11/12-IIIc-g-8). 5  Learning Objectives At the end of the lesson, you should be able to do the following: Describe Earth’s geologic time scale. Identify theories on the emergence of life on Earth. Enumerate early life forms present during the primitive Earth. 6  Earth’s Geologic Time Scale Earth has been around for billions of years and the way that scientists make an estimate is through the geologic time scale. This refers to a system of dating the history of Earth in a chronological manner using geological data. 7  Earth’s Geologic Time Scale The geologic time scale reflects the entire geological history of our planet. The geologic time scale is divided into eons, eras, periods, and epochs. 8 What are the major events in each part of the geologic timescale? 9  Earth’s Geologic Time Scale Eon Era Period Epoch Phanerozoic Eon (542 MYA) Precambrian Eon (4 BYA) means ‘visible life’ that was represents the period between constructed through rock units the birth of the planet and the that bear abundant fossils. appearance of life forms. 10  Earth’s Geologic Time Scale Eon Era Period Epoch Phanerozoic Eon (542 MYA) Precambri an Eon (4 BYA) Proterozoic Archean Hadean 11  Earth’s Geologic Time Scale Eon Era Period Epoch Phanerozoic Eon (542 MYA) Precambri an Eon (4 BYA) Proterozo ic Archean Hadean 12  Earth’s Geologic Time Scale Eon Era Period Epoch Phanerozoic Eon (542 MYA) Precambria n Eon (4 Paleozoic BYA) Cenozoic Mesozoic era Proterozo era era is also known ic is also known is also known as the ‘age as the ‘age as the ‘age of Archean of mammals of reptiles’ invertebrates Hadean ’ 13  Earth’s Geologic Time Scale Eon Era Period Epoch Phanerozoic Eon (542 Cenozoic MYA) era Precambria n Eon (4 Mesozoic BYA) era Quaternary Tertiary Proterozo ic Period Period human mammals Archean Plaeozoic evolution diversity era Hadean 14  Earth’s Geologic Time Scale Eon Era Period Epoch Phanerozoic Cretaceous Period Eon (542 Cenozoic extinction of dinosaurs, MYA) era first primates, first Precambria flowering plants n Eon (4 Mesozoic Jurassic Period BYA) first birds, dinosaurs era Proterozo diversity ic Archean Plaeozoic Triassic Period era first mammals, first Hadean dinosaurs 15  Earth’s Geologic Time Scale Eon Era Period Epoch Phanerozoic Permian Eon (542 Cenozoic MYA) era Carboniferous Precambria n Eon (4 Mesozoic Devonian BYA) era Proterozo ic Silurian Archean Paleozoic Ordovician era Hadean Cambrian 16  Earth’s Geologic Time Scale Eon Era Period Epoch Phanerozoic Eon (542 Cenozoic MYA) era Epochs are the shortest Precambria subdivision unit in the n Eon (4 Earth’s geologic time scale Mesozoic BYA) that is characterized by the era Proterozo changes in life forms and ic may vary from continent to Archean Plaeozoic continent. era Hadean 17 Which time period is the most important for the emergence of diverse life forms on Earth? 18 Tips To recall the geologic periods from oldest to most recent, just remember the mnemonics “Can Old Senators Demand Copious Power Than Junior Congressmen? Tough Question!” The first letter of each word represents the first letter of each period in order. 19 Tips The periods in geological time scale from oldest to most recent are Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian, Triassic, Jurassic, Cretaceous, Tertiary, Quaternary. 20 How do you think scientists tried to explain their early ideas regarding the origin of life on Earth? 21  Theories on the Origin of Life on Earth spontaneous generation theory Theories regarding the origin primordial soup theory of life on Earth theory of panspermia 22  Theories on the Origin of Life on Earth Spontaneous Generation The experiment of Needham 23  Theories on the Origin of Life on Earth Spontaneous Generation Pasteur’s experiment disproved spontaneous generation. 24  Theories on the Origin of Life on Earth Theory of Panspermia The theory of panspermia (exogenesis) suggests that building blocks of life came from Origin of life on Earth according to another planet. the panspermia theory 25  Theories on the Origin of Life on Earth Primordial Soup Theory Suggests that life started in a primordial soup of organic molecules. It tries to explain how catalysts for nonliving things became living 26  Early Evidence of Life on Earth One of the earliest known evidence of life on Earth includes the stromatolite fossils collected from various samples of metasedimentary rocks in western Greenland and Stromatolite fossils on were aged 3.7 billion the rock near the shore 27  Early Evidence of Life on Earth In 2015, fossils of the microbial mat (primitive microbial colony) that may represent potential biotic life dated 4.1 billion-year-old were collected in Western Australia. Microbial colony-forming mats or biofilms 28 Will modern-day organisms emerge if speciation during the Cambrian period did not occur? 29  Check Your Understanding Write the word true if the given statement is correct and false if otherwise. 1. Abiogenesis states that living organisms originate from preexisting living organisms. 2. First life forms are believed to have emerged 3.7 billion years ago. 3. The spontaneous generation theory is still considered as a valid theory even today. 30  Check Your Understanding Complete the table below by providing the important events that happened during the given time period. Period Events Paleozoic Era (ancient life) Cambrian Ordovician Silurian Devonian Carboniferous Permian 31  Check Your Understanding Complete the table below by providing the important events that happened during the given time period. Period Events Mesozoic Era (middle life) Triassic Jurassic Cretaceous Cenozoic Era (recent life) Tertiary Quaternary 32  Let’s Sum It Up! The geologic time scale is divided into eons, eras, periods, and epochs. Early theories regarding the origin of life on Earth started during the 16th century in Europe. These theories include the spontaneous generation theory, primordial soup theory, and theory of 33  Let’s Sum It Up! The primordial soup theory suggests that life started in a primordial soup of organic molecules. It tries to explain how catalysts for nonliving things became living cells from chemical compounds abundant on early Earth. 34  Let’s Sum It Up! The theory of spontaneous generation states the idea that life comes from lifeless or nonliving material through a mysterious process. The theory of panspermia states that the building blocks of life come from outside Earth. 35  Let’s Sum It Up! Present-day organisms share common ancestors that evolved through time. First life forms are believed to have emerged 3.7 billion years ago. 36  Let’s Sum It Up! The geologic time scale of Earth 37 Challenge Yourself How did the development of photosynthetic organisms lead to the alteration of Earth’s atmosphere? 38 Photo Credit Slide 23.: Panspermie by Silver Spoon Sokpop is licensed under CC BY-SA 3.0 via Wikimedia Commons. 39 Bibliography Johnson, G.B., and Raven, P.H. 2001. Biology: Principles & Explorations. Austin: Holt, Rinehart, and Winston. Klug, W.S., Spencer, C.A., and Cummings, M.R. 2016. Concepts of Genetics. Boston: Pearson. Mader, S.S. 2014. Concepts of Biology. New York: McGraw-Hill Education. Rakesh Kumar Rastogi. 2007. Concepts of Biology XII. New Delhi: Rastogi Publications. Reece, J.B. and Campbell, N.A. 2011. Campbell Biology. Boston: Benjamin Cummings/Pearson. Shri Hemant Roy. 2005.Comprehensive MCQs in Biology.New Delhi: Golden Bells. 40