Nova origins how life began worksheet

  Nova Origins How Life Began worksheet  

  1. signs of life   

✔ Planet Earth formed a cloud of space rock, dust, and gas.  millions of years it was a mass of hot molten rock with a poisonous atmosphere. But eventually, its crust cooled to the point where water could form vast oceans.

✔ The shallow fringes of these oceans were probably where life began, about  3.8 billion years ago, in a series of chemical reactions that assembled the first living cells.

  a. Early Earth   

✔ For  500 million years, Earth was a giant furnace of searingly hot rock, constantly bombarded by asteroids and meteorites.

✔ As each lump of space rock crashed into the planet, its energy was converted into more heat. But these impacts also delivered chemical elements that were to be vital ingredients of life.

  b. Chemical Cauldron   

✔ As the planet cooled, huge volcanoes filled the air with toxic gases. But they also erupted vast quantities of water Vapour that cooled and fell as rain filled the oceans.

✔ Lightning may have then triggered chemical reactions in the water, forming complex molecules that were able to make copies of themselves- the basis of life.

  c. First cells  

✔ The chemical processes that were essential to life needed to occur in a protected place, This was provided by a substance that could form tiny, tough-walled bubbles

✔ These were the first living cells – microscopic packages of life-giving chemicals that become bacteria, the simplest surviving life forms.

  d. Energy from light  

✔ Life needs energy. The first cells used chemical energy. but about 3.5 billion years ago cells called cyanobacteria started.

✔ They used it to make food from water and carbon dioxide, releasing vital oxygen. Similar cyanobacteria created these stromatolites (responsible for the oxygenation of the atmosphere)  on the coast of Western Australia.

  e. Deep heat  

✔ It is likely that the first living cells developed in warm, coastal pools of salty water. However, life may have begun in the deep ocean, around hot volcanic vents and the gust of energy-rich chemicals from the ocean floor.

✔ Simple organisms that still live in these vents are probably very like the earliest living cells.

  2. How life began?  

✔ Billion years ago, a chance combination of chemicals somewhere on Earth’s surface created a substance that could soak up the energy and reproduce itself – the first living organism.

✔ This was the beginning of the amazing story of life on Earth.

  a. Variety of life  

✔ As soon as the thing is slightly different from its parents. If the difference helps it to survive, it is likely to pass on the advantages to its own young.

✔ This is the basis of evolution. Many years later, it may lead to a change that is large enough for the result to be called a different species.

  b. Evolution  

✔ Every living thing is slightly different from its parents. If the difference helps it to survive, it is likely to pass on the advantages to its own young, This is the basis of evolution.

✔ Many years later, it may lead to a change this large enough for the results to be called a different species

  c. Natural selection  

✔ The main mechanism of evolution is called natural selection. Life in the natural world is a competition, with losers or winners.

✔Those that survive and breed happen to have a combination

  d. Mass extinctions  

✔ Since life began there have been five mass extinctions catastrophic events that killed off a large proportion of life on Earth. After each extinction life was recovered slowly and new types of animals. plants and other living things appeared.

✔ These extinctions were caused by natural forces, but evidence suggests that we are in the early stage of the sixth mass extinction caused by human activity.

  Here are some mass extinctions  

1. ORDOVICIAN (440 MYA)

✔ This extinction destroys 60 (%) Percent of the species living in the oceans. At the time, there was little if any life on land.

2. DEVONIAN (358 MYA)

✔ More than three-quarters of the species living in the Devonian Period were wiped out. life in shallow seas was most badly affected.

3. PERMIAN ( 250 MYA)

✔ At the end of the Permian, life suffered a global catastrophe that almost destroyed life altogether, Very few species survived.

4. TRIASSIC (200 MYA)

✔ The first period of the dinosaur era the Mesozoic ended with an extinction that killed off most of the dinosaur competitors

5. CRETACEOUS (66 MYA)

✔ The mass extinction that destroyed the giant dinosaurs at the end of the Cretaceous Period was Possibly caused by an asteroid impact In the past 500 million years more than 90 (%) Percent of all life on Earth has vanished.

  Timeline of life  

✔ Life has existed on planet Earth for 3.8 billion years. Over that time it has evolved into a dazzling diversity of forms from microscopic bacteria to giant dinosaurs.

✔ for most of the earth’s long history, the only living thing was single-celled microbes that lived in the oceans but around 600 million years ago the first multicellular animals appeared.

✔ This led to an evolutionary explosion of complex oceanic life forms during the Cambrian period and once the first simple plants had evolved life was able to colonize the continents as well as the oceans.

  Geological Time  

✔ The history of life is recorded by fossils preserved in rock layers older rocks lie beneath more recent ones so each layer represents a period.

✔ Scientists divide this vast period into eras and these are further divided into smaller times called periods This geological timescale is the basis of the timeline shown here measured millions of years ago (MYA).

  The Dinosaurs  

✔ For 165 million years life on Earth was dominated by the most spectacular animals that have ever existed the dinosaurs.

✔ The Mesozoic era was a high point in the history of life because it was the age of dinosaurs. These fantastic creatures included the biggest heaviest and most terrifying of all land animals.

✔ They evolved into an amazing variety of forms ranging from huge armoured leaf-eaters to nimble feathered hunters and gave rise to the birds that still flourish today.

  there were many types of dinosaurs during the Mesozoic era  

1. Ornithischians

✔ The word ornithischians means “bird-hipped”. It refers to the way that the pelvic bones of these dinosaurs resemble those of birds.

✔ The ornithischians also had beaks supported by special jawbones. but confusingly the birds themselves are small theropod dinosaurs part of the saurischian group.

2. Saurischians

✔ The Saurischian dinosaurs of the early Mesozoic era had pelvic bones that resembled those of lizards so the word saurischian means “lizard-hipped” but many of the later forms evolved bird-like pelvic bones which the birds were to inherit saurischian also had longer more flexible necks than the ornithischians.

3. Marginocephalians

✔ These consisted of ceratopsians like the pentaceratops with its huge horned neck frill and pachycephalosaurs with very strong armoured skulled.

4. Theropods

✔ Spinosaurus was one of the biggest theropods the groups that included all the powerful hunters they all walked on their hind legs and many had feathers.

5. Sauropodomorphs

✔ The sauropodomorphs included the biggest dinosaurs colossal animals such as Brachiosaurus.

✔ They were all plant eaters that supported their immense weight on four pillar-like legs resembling those of elephants they had very long necks which were often balanced by equally long tails.

6. Ornithopods

✔ One of the successful groups of dinosaurs the Ornithopods ranged from lightweight animals that ran on two legs to a heavyweight like this Muttaburrasaurus. They were all plant-eaters.

7. Thyreophorans

✔ The thyreophorans included the heavily armoured ankylosaurs and stegosaurs such as this spiny Kentrosaurus.

✔ Among them, Tyrannosaurus Rex the most powerful land predator that has ever existed was a giant theropod dinosaur a super-sized killer armed with massive jaws and teeth that could bite through solid bone.

✔ The Tyrannosaurus were the most deadly hunters of the entire 165 million-year Mesozoic era the age of dinosaurs. The biggest and most famous of them.

✔ Tyrannosaurus rex evolved near the end of the era a few million years before the global catastrophe that wiped out all the giant dinosaurs.

✔ It was specialized for killing inflicting huge bites that crippled its prey or caused it to die of shock. It would then rip its victim apart biting out great chunks of meat and swallowing them whole.

  Other Gaint animals living during the Mesozoic era  

1. Reptile neighbours

✔ The dinosaurs were not the only giant reptile living during the Mesozoic era. They shared their world with marine reptiles such as Mosasaurus and Pterodactylus.

✔ These animals were not dinosaurs although the pterosaurs were close relatives. Most were hunters and some marine reptiles had massively strong jaws. The pterosaurs were much more lightly built with small bodies and long efficient wings of stretched skin.

2. Mosasauryus

✔ At up to 15m(50 ft) long Mosasaurus was a powerful predator that lived at the end of the age of dinosaurs.

3. Pterodactylus

✔ Like all pterosaurs, Pterodactylus was a warm-blooded furry-bodied animal that probably flew as well as a bird.

  Catastrophe  

✔ The Mesozoic era ended 66 million years ago with a mass extinction event that eliminated all dinosaurs except the birds.

✔ It may have been caused by the impact of a giant asteroid in what is now Mexico. At the same time, huge volcanoes were erupting in India and the combination must have a catastrophic effect on the climate.

  Asteroid impacts  

✔ The asteroid that hit Mexico 66 million years ago was at least 10 km (6 miles) wide. The high-speed impact of such a huge rock would have filled the atmosphere with debris and dust blotting out the sun for many years.

✔  Scientists still do not know what killed off the big dinosaurs or how birds crocodiles and other animals managed to survive

After the dinosaur humans began, plants, fish and flowers evolved.