Secondary 3 Earth and Space PDF

EARTH & SPACE The Dimensions of Space The Origin of Life 1  Objectives 3 To understand the process of the formation of Earth To understand the conditions required for the emergence of life Assignment: Pg. 152-153 2  F...

EARTH & SPACE The Dimensions of Space The Origin of Life 1  Objectives 3 To understand the process of the formation of Earth To understand the conditions required for the emergence of life Assignment: Pg. 152-153 2  Formation of Earth – 4.6 bya Small particles of rock, dust and gas slowly come together under the effects of their own gravity, in a process called accretion. After millions of years, planet Earth takes shape. 3  Formation of Earth – 4.2 bya The pressure at Earth’s core is so intense that rocks melt and mix together. Gases escape. The planet’s surface cools and forms a crust of solid rock. 4  Formation of Earth – 3.5 mya The oceans and atmosphere develop. The atmosphere is made up of volcanic gases that trigger rains, filling the oceans. Rocky surfaces not submerged under water create the first continents. It is at this point that life is thought to have emerged. 5  Formation of Earth – Today Earth’s interior is still extremely hot. It is made up of a core covered by a mantle of partially melted rock. Earth’s crust, a solid layer of rock, floats on the upper part of the mantle. 6  Collisions with Celestial Bodies It is believed that countless celestial bodies bombarded Earth during the first few million years of existence. One of the impacts may have formed the Moon. 7  Conditions Essential For Emergence of Life Conditions essential for the emergence of life: conditions that made it possible for the synthesis of the first organic molecules and their development into living cells. 1. Presence of essential chemical elements 2. Presence of an energy source 3. Presence of liquid water 4. Presence of a very long time 8  1. Essential Chemical Elements Complex organic molecules (AKA living things) are mainly made up of 4 elements: Carbon (C) Oxygen (O) Hydrogen (H) Nitrogen (N) Other elements such as sulphur (S) can also be found in these organic molecules It is believed the Earth’s early atmosphere was mostly composed of water vapour (H2O), carbon dioxide (CO2) as well as low amounts of methane (CH4), Sulphur dioxide (SO2) and ammonia gas (NH3). 9  2. Energy Source The synthesis (making) of complex molecules from simple molecules demand a lot of energy; hence a powerful energy source is essential for life to begin. Possible energy sources at the beginning of life: Ultraviolet rays from the Sun Electrical discharges caused by lightning Heat released from volcanic eruptions and hot springs 10  3. Liquid Water For life to develop, the planet must have a large reserve of liquid water. Water is essential to the reactions leading to the appearance of the first molecules that in turn lead to the emergence of life forms. Humans can only survive up to 3 days without any intake of water. Life is believed to first appeared in a kind of “primitive broth”. Water is also believed to have protected the first living organisms from the harsh climatic conditions found on dry land. 11  4. Very Long Time The organizing of complex molecules into living cells was generally considered a rather random occurrence; hence the probability of getting the right mix was very low to start with. Scientists estimated the right mix was less than 1 in 1,000,000,000 at the beginning The more time passed, the greater the number of molecular bonds formed and the greater the probability of producing living cells. The first unicellular organism formed was likely cyanobacteria. 12  Emergence of Life Complex Liquid First Chemical Simple Chemical Energy organic water + Bonding living elements molecules reactions molecules time cells 13 Habitable Zone (now) 14  Signs of Life Elsewhere Astrobiologist: a scientist who looks for signs of life within and beyond the solar system. Current research areas in particular: 1. Mars 2. Europa (one of Jupiter’s moons) 3. Titan (one of Saturn’s moons) 15 Titan Titan is the only moon in the whole solar system that has a dense atmosphere composed of nitrogen, like the atmosphere of Earth. In its freezing temperature, many chemical compounds that preceded the appearance of life have been preserved. 16  SETI Institute SETI Institute: Search for Extra- Terrestrial Intelligence institute Uses a number of radio telescopes to decode signs of ET intelligence by analyzing millions of signals from outer space. Over 3 million people in the world have participated in sorting these signals by connecting to the SETI project with their computers. 17  Objectives 4 To know the Laws of Evolution To be introduced to the Geological Time Scale To be aware of the extinctions that have occurred To discover the origins of our species Assignment: Pg. 154-158 18 What if Earth ever existed for only 24 hours? Video: https://youtu.be/jtNs5k2K HXU 19  Geological Time Scale Geological time scale: a scale that divides the history of the Earth into eras and each era is divided into periods Based on significant events such as the appearance or extinction of species (living organisms) 20 Geological Time Scale 21 Precambrian Era (Rodinia) First continent, Rodinia was formed about 900-1100 million years ago 22  Precambrian Era (4600 mya) Includes 88% of the Earth’s history, spanning over 4 billion years. Earth (as we know it) and life itself formed during this era. Fossils from this time are rarely discovered because most living organisms had soft bodies. 23  Precambrian Era (4600 mya) First era of geological time Began with the formation of the solar system including Earth Beginning of oxygen accumulation in the atmosphere 24 Precambrian Era (4600 mya) First signs of life Appearance of first bacteria Appearance of first protists (unicellular organisms) Ended with the appearance of soft-bodied invertebrates such as Ediacaran fauna (significant stage in the development of life because these animals had various specialised cells) 25 Paleozoic Era (543-246 mya) Lasted almost 300 million years Divided into 6 periods (Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian) 26 Paleozoic Era (543-246 mya) Life flourished and diversified because of hot climates and shallow oceans Appearance of hard-bodied invertebrates (animals without backbones) Appearance of trilobites, marine arthropods that swam or crawled Ended with the mass extinction --- 90% of marine species and 70% of terrestrial species 27  Paleozoic Era (Gondwana) At the beginning of the Cambrian Period (542-488 Ma), two continents (Laurentia & Siberia) split from Rodinia About 540 million years ago, Baltica detached too The remaining Rodinia is now called Gondwana 28  Paleozoic Era (Cambrian Period, 543-511 mya) Multiplication of aquatic invertebrate species Appearance of invertebrates with hard shells First animal with a vertebral column appeared: Pikaia (small animal about 5cm and resembled an eel) The ancestor of reptiles, dinosaurs, birds and mammals, including humans 29  Paleozoic Era (Ordovician Period, 510-440 mya) Presence of numerous marine alage species Appearance of first marine vertebrates (cartilaginous fishes) & nautiluses appeared 30  Paleozoic Era (Ordovician Period, 510-440 mya) Colonization of dry land by plant life: Such as mosses, mushrooms and lichens appeared Colonization of dry land by animals Towards the end of the period, there was the first major extinction due to extreme cold 31 Paleozoic Era (Silurian Period, 439-410 mya) Multiplication of terrestrial plant species 32  Paleozoic Era (Devonian Period, 409-364 mya) Multiplication of fish species Appearance of first amphibians and insects Arthropods (mites, scorpions, centipedes) were the first to colonise the continents First primitive terrestrial plants diversified Some were as tall as trees Did not reproduce flowers or seeds Reproduced through spores Second massive extinction towards the end 33  Paleozoic Era (Carboniferous Period, 363-289 mya) Continental drift continued and a single continent, Pangea was formed Rodinia 34 Paleozoic Era (Carboniferous Period, 363-289 mya) Presence of vast humid forests Appearance of first conifers Their fossilised remains are our coal beds today Appearance of first reptiles: turtles, snakes, lizards and iguanas appeared Multiplication of amphibian species 35  Paleozoic Era (Permian Period, 290-246 mya) Climate of Pangea varied drastically with temperatures ranging between 0oC and 40oC Multiplication of reptile species Multiplication of insect species Third mass extinction but largest in the Earth’s history 36 Mesozoic Era (245-66 mya) Divided into 3 periods: Triassic, Jurassic and Cretaceous AKA the Age of the Dinosaurs Climate was warmer and less extreme than during the Paleozoic era ~10oC higher than today Ended with the mass extinction of the dinosaurs 37  Mesozoic Era (Triassic Period, 245-207 mya) Multiplication of first conifers Appearance of first dinosaurs and mammals Reptiles dominated this era, with dinosaurs roaming the continents, the waters and the skies One of the largest animals ever lived: Brachiosaurus Most impressive land animal: Tyrannosaurus rex 4th mass extinction with over 50% of fishes, sponges and corals disappeared 38  Mesozoic (Jurassic Period, 206-145 mya) Multiplication of dinosaur species Appearance of first birds Stable climate, favourable to the development of marine and land fauna Towards the end of this period, Pangea started to break up 39  Mesozoic (Cretaceous Period, 144 - 66 mya) Pangea divided into continents, which eventually drifted to their current locations Separation between South America and Africa was completed India moved northwards 40 Mesozoic Era (Cretaceous Period, 144 - 66 mya) Continental drift triggered major climate changes Sea level was 200m higher than it is today Flowering plants multiplied and bees flourished Mammals remained small in size 5th massive extinction occurred Meteorite impact in northern Yucatan, Mexico 41 Cenozoic Era (65 mya to Today) The Cenozoic, our present era, has lasted 65 million years. It is during this era that most of the species of birds, mammals and flowering plants we know today appeared. AKA The Age of the Mammals Our species, Homo sapiens, arrived very late in this era, about 200,000 years ago. 42 Cenozoic Era (Tertiary Period, Paleogene, Eocene epoch) 43  Cenozoic Era (Tertiary Period, Paleogene, 65 – 23 mya) 65 – 50 m.y.a: climate was hotter than today 50 – 23 m.y.a: Long cooling period and major drought Antarctica covered with ice Coniferous forests thrived in temperature zones Flora and fauna developed during this time are characteristic of the plants and animals we know today 44 Cenozoic Era (Tertiary Period, Neogene, 23 – 1.8 mya) Characterised by the proliferation of graminaceous plants, on which large herbivores (plant-eaters) fed Graminaceous: a large family of plants that includes wheat, rice, bamboo and sugar cane Appearance of first primates, chimpanzee and human ancestors. 45  Cenozoic Era (Quaternary Period, 1.8 mya – today) Period in which we live at present Appearance of first human beings Ice ages (the last one ended 10,000 years ago) 46  Cenozoic Era (Quaternary Period, 1.8 mya – today) On several occasions, polar ice covered a large part of the Northern Hemisphere Affected the development of different species Woolly rhinoceros and mammoth: cold periods Hippopotamus and elephants: warm periods 47  Earth’s Mass Extinctions The extinction of a species is the disappearance of all individuals belonging to that species. It is caused by the inability of the individuals to adapt to change(s) in their environment or due to human activities. 48 Earth’s Mass Extinctions 49  Mass Extinction #3: Permian Period Occurred about 245 million years ago, marking the transition from the Paleozoic to the Mesozoic era. More than 90% of marine life and 70% of land- dwelling species became extinct. 50  Mass Extinction #3: Permian Period Continental drift caused major rifts in the Earth’s crust, leading to the most intense volcanic eruptions. Enormous amounts of CO2 ejected à triggered global warming à disappearance of a large number species unable to adapt Recent discovery of a crater (from a meteorite impact) at the bottom of Antarctic Ocean, dating back 250 million years ago and coinciding with the end of the Permian period, could also explained the mass extinction. 51  Mass Extinction #5: Cretaceous Period Occurred some 65 million years ago Not as significant as the Permian mass extinction Disappearance of 50% of marine species and many plants and animals, including the dinosaurs. 52  Mass Extinction #5: Cretaceous Period Most accepted hypothesis for the cause of this mass extinction is a huge impact from an asteroid Impact released an enormous amount of dust into the atmosphere à blocked out the Sun à causing climate to cool à a severe reduction of photosynthesis à fatal consequences for many species 53  Recent Extinctions ~11,000 years ago, several animals disappeared from around the world Mostly large mammals such as mammoth, sabre-toothed tiger, giant beaver, short-face skunk Even more recently, others like dodo bird and passenger pigeon Causes: hunting, fire, the spread of diseases by humans and environmental changes 54 Mass Extinction #6: Now? 55 Mass Extinction #6: Now? 56  Laws of Evolution Evolution: a slow process that brings about changes in living organisms that may create new species Occurs randomly and selectively Genes mutate randomly, causing changes in an individual These changes are then screened by natural selection. 57  Natural Selection Natural Selection: a process that occurs naturally within a species. It results in the reproduction of organisms with traits that allow them to survive better in their environment. 58  Tiktaalik roseæ 375-million-year old fossil found in Nunavut Assumed to be the first species of fish to climb on land Operculum, a large bone that covers the gills of bony fish is absent à the animal likely used its lungs more often than its gills to breathe. Fins show a crude outline of fingers 59 From Water to Land 60  The Walking Shark Video: https://youtu.be/ndbw7SQMCcQ 61 Evolution of Elephants 62  The Origin of Our Species Humans and all species of monkeys have a common ancestor and are part of the same group: the order of Primates. This makes us cousins to monkeys instead of being descended from monkeys. The human lineage separated from the great apes several million years ago. Due to lack of evidence, the evolution of the human species is not well understood by scientists. 63 The Extended Family Tree 64 The Human Family Tree 65 Evolution of Humans 66 Australopithecus afarensis An almost complete skeleton of a child from the Australopithecus afarensis species was discovered in 2000 in Dikika, Ethiopia. 3.3 million years old 67  Paranthropus robustus Paranthropus is also called Australopithecus robustus. Members of this genus were bigger and taller than the Australopithecus. With robust skulls and teeth, certain species of Paranthropus lived at the same time as some species of the genus Homo. 68 Homo neanderthalensis Homo neanderthalensis or Neanderthal man, shared the territories of Europe, Middle East, Asia and Africa with our species (Homo sapiens) but disappeared some 30,000 years ago. Neanderthals are recognisably human but have distinctive facial features and a stocky build that were evolutionary adaptations to cold, dry environments. Neanderthals were generally shorter and had more robust skeletons and muscular bodies than modern humans. 69 Homo floresiensis 70  Homo sapiens Our species, Homo sapiens, is the only surviving member of the human lineage. We appeared around 195,000 years ago. We develop at a slower rate than monkeys in order to allow time for the development of higher functions. 71  Homo sapiens Human traits that have appeared through evolution and help distinguish our species from other animal species include: Bipedalism Finer hair Large complex brain 72 Bipedalism Bipedalism: the ability to move around on two feet Bipedalism freed up our hands, allowing them to be put to various uses, such as making clothes and tools 73  Finer Hair Our hair is finer than that of other mammals and covers less. Partial nudity (hairless on some parts of the body) was advantageous for humans because of the need to keep cool during the day in the scorching heat of the African savanna. Human body also contains more sweat glands than that of any other species. 74  Large Complex Brain Our brain is large and complex, making it possible for us to have superior mental capabilities compared to other animals. The brain enabled us to become very inventive: To meet a variety of wants and needs To communicate using complex languages Some scientists also believe the major development of our brain occurred to: Improve our socialization skills Help us find better ways of gathering food and protect us from predators 75 Other Animals Known to Use Tools Video: https://youtu.be/_b8HXYNaov8 76 Recap: History of Life on Earth Video: https://youtu.be/H2 _6cqa2cP4 77  Objectives 5 To learn the different types of fossils To understand how we tell the age of the fossils Assignment: Pg. 159-162. 78  Fossils Fossils: any remains or trace of an organism that has been preserved for a very long time in Earth’s crust, including skeletons, shells, leaves, eggshells, footprints, etc., found in sediments and sedimentary rocks 79  Fossilization Fossilization: the long process of transforming a living organism into a fossil Fossils are often discovered in sedimentary rocks underwater by the accumulation of solid particles (sand, silt, clay) called sediments. 80  Why the Interest in Fossils? Why are people interested in fossils? People are interested because fossils provide information about various life forms that have existed in the Earth’s history and about environmental changes and help us reconstruct the history of life. Experts in the study and research of fossils are called paleontologists. 81 Formation of Fossils 82  Types of Fossils Fossils are categorized according to the way they are formed. Sometimes, fossils are of mixed types, meaning that one part of the fossil is formed one way and the other part, another way. There are four common ways to form fossils; hence there are four types of fossils: 1. Petrified fossils 2. Cast fossils/ mould fossils 3. Body fossils 4. Trace fossils 83  Petrified Fossils Petrified fossils: the remains of organisms that harden during fossilization, becoming as hard as rock. Petrified fossils are made when minerals fill in all of the organism’s organic matter, hardening the tissues and preserving the remains. The hard tissue that make up bones, teeth, shells or tree trunks is most likely to become petrified fossils as the soft tissue either gets eaten up or gets decomposed quickly when an organism dies. Remains of organisms that petrify in this way usually conserve their original form. 84  Formation of Petrified Fossils Water is full of dissolved minerals. It seeps through the many layers of sediments to reach the remains of a dead organism à When the water evaporates, only the hardened mineral is left behind à Overtime, these mineral deposits completely replaced the remains of the dead organism, forming an image of the hard tissue (bones, shells, etc.) out of solid rock. 85 Formation of Petrified Fossils 86  Cast Fossils Cast Fossil: An impression (filled in with minerals), in sedimentary rocks as a result of the rocks taking the shape of the organism’s remains which later decomposed. 87  Mould Fossils Mould Fossil: An impression (empty; not filled in with minerals), in sedimentary rocks as a result of the rocks taking the shape of the organism’s remains which later decomposed. 88  Body Fossils Body fossil: A fossil where an entire body of an organism, including the soft tissue, is fossilized because the organism was trapped in matter that prevents the formation of microorganisms. Mammoths, bison and prehistoric humans frozen in ice became fossilized in their original condition. Many insects and small animals were also trapped in a substance called amber. Amber: solidified result of a resin produced by certain prehistoric plants 89  Body Fossils A young woolly mammoth which could be as old as 10,000 years old A 100-million-year-old insect trapped in amber is thought to have been able to secrete a chemical repellant and rotate its head 180 degrees 90  Trace Fossils Trace fossils: traces left in soft soil by an organism that lived a long time ago and have fossilized over the years 91  “Living Fossils” Some modern species do not resemble their ancestors, others barely evolved in millions of years and they are known as living fossils Video: https://www.youtube.com/watch?v=1w3dOTHbqOE Horseshoe crab The goblin shark 92 Review: Formation of Sedimentary Rocks 93 Fossil Dating Fossil dating is carried out using various methods. 1. Stratigraphic layers and relative dating 2. Absolute dating 94 Relative Dating Relative dating: a technique to determine an approximate age of rocks by examining their location in the arrangement of the layers (superpositioned layers) 95 Relative Dating Principles Relative dating is based on the following principles: Law of Original Continuity: All sedimentary rocks contained a single stratigraphic layer formed at the same time period. Law of Superposition: The deeper a stratigraphic layer is in the ground, the older it is. 96  Stratigraphy A stratigraphy layer: a layer that is made up of sedimentary deposits with the same characteristics (colour, particle size, type of rock etc.) 97  Absolute Dating Absolute dating: a technique used to determine the absolute age of fossils in years 98  Absolute Dating: Tree Ring Tree ring: age of a tree can be found by counting the total number of rings. 99  Absolute Dating: Radiometric Dating Radiometric dating: calculating the absolute age of rocks and fossils that contain radioactive isotopes, such as uranium (U) and carbon-14 (C-14). 100 Common Radioactive Isotopes & Radioactive Decay 101 Half-Life Half-life: the time taken to reduce a specific amount to half its initial value 102  Carbon-14 Dating In an organism’s lifetime, it absorbs a small amount of carbon-14, a radioactive type of carbon. After the organism dies, the carbon-14 present in the remains slowly disintegrates, at a regular rate, into non-radioactive carbon. By measuring the proportion of carbon-14 contained in a fossil, scientists can pinpoint the approximate age of the fossil in years. Carbon-14 dating is used on very young organic fossils, that is, under the age of 60,000 years old. Older fossils: other radioactive elements, such as uranium, are used. 103 Carbon-14 Dating 104  Carbon-14 Dating Process Interactive Procedure: https://www.sciencelearn.org.nz/image_maps/37-c-14-carbon-dating- process 105