Bio 101 origin of life

• Earth provides hints on the variety of life that inhibits it
• Microorganisms are assumed to have been the first life forms on Earth, existing for billions years before the emergence of plants and animals
• Mammals, birds and flowers have evolved over 130-200 million years ago
• Humans have been on this planet for the past 2.3 million years
• Biology


  The science that examined life
• Early Earth Conditions


  • Frequent volcanic eruptions which released gases such as carbodioxide (CO2) and sulphur oxide (SO2) and water vapor into the atmosphere
  • Bombarded by meteorites, asteroids and comets, which delivered organic molecules, water, and other compounds to the surface
  • Atmosphere rich in gases like hydrogen (H2), Helium (He), methane(CH4) , ammonia (NH3) , and carbon dioxide, but lacked oxygen
• Primitive life forms


  Simple, single-celled organisms that resembled modern bacteria and archaea, known as prokaryotes
• Theories on the Origin of Life

  • Idea of Special Creation
  • Theory of Abiogenesis (spontaneous generation)
  • Theory of Biogenesis
  • Theory of Chemical Evolution
  • Cosmozoic Theory (Theory of Panspermia)
  • Theory of Catastrophism
• Idea of Special Creation

  • God, the All-Powerful, created all the many forms of life that exist today on planet Earth
• Theory of Abiogenesis (spontaneous generation)


  • Living things were naturally created from non-living things such as simple organic compounds
  • Origin of insects, frogs, toads, maggots, tapeworms and micro-organisms from non-living materials
• Theory of Biogenesis


  • Living things come from living things, as theorized by Francesco Redi and Louis Pasteur
• Theory of Chemical Evolution


  • Life emerged in water on primitive earth from chemicals, around 4.2 billion years ago
  • Proposed by A.I. Oparin and J.B.S. Haldane
• Cosmozoic Theory (Theory of Panspermia)


  • Life came from outer space in the form of spores which grew and evolved into different organisms
  • Proposed by Richter, Arrhenius and others, but lacks evidence and was discarded
• Theory of Catastrophism


  • God has created life on earth in several ways, each of which was preceded by a disaster brought on by a geological disturbance
  • Supported by French scientists Georges Cuvier and Orbigny
• Influence of Living Things on the Chemistry of the Earth

  • Photosynthesis
  • Carbon Cycle
  • Nitrogen Cycle
  • Oxygen Production
  • Weathering and Erosion
  • Biomineralization
  • Pollution and Waste
• Photosynthesis


  Plants, algae, and some bacteria use sunlight to convert carbon dioxide and water into glucose and oxygen
• Carbon Cycle


  1. Carbon dioxide (CO2) is taken up by photosynthetic organisms, such as plants and phytoplankton, during photosynthesis, converting it into organic carbon compounds

  2. Carbon is then transferred through the food chain as organisms consume and respire, releasing CO2 back into the atmosphere
• Nitrogen Cycle


  1. Nitrogen fixation by certain bacteria converts atmospheric nitrogen gas into ammonia

  2. Nitrification converts ammonia into nitrate, which can be taken up by plants or returned to the atmosphere through denitrification

  3. Decomposition of organic matter releases nitrogen back into the soil
• Plants and some microorganisms produce oxygen as a byproduct of photosynthesis, essential for the survival of most living organisms
• Living organisms, especially plants, play a role in weathering and erosion processes, contributing to the cycling of minerals and nutrients in the Earth's crust
• Some organisms, such as corals and mollusks, extract minerals from their environment to build shells and skeletons, which can become part of sedimentary rocks and influence the chemistry of the Earth's crust
• Human activities, such as burning fossil fuels and deforestation, release large amounts of carbon dioxide into the atmosphere, contributing to climate change
• Pollution from agricultural runoff and industrial waste can have detrimental effects on the environment
• Life


  The condition that distinguishes organisms from inanimate objects, characterized by various properties and processes that enable growth, reproduction, response to stimuli, and adaptation to the environment
• Fundamental Characteristics of Life

  • Organization
  • Metabolism
  • Homeostasis
  • Growth and Development
  • Reproduction
  • Response to Stimuli (Responsiveness)
  • Evolutionary Adaptation
• Organization


  Living organisms exhibit a high degree of organization, with hierarchical levels of complexity ranging from atoms and molecules to cells, tissues, organs, and organ systems
• Metabolism


  The sum of all chemical reactions occurring within an organism, including processes involved in energy production, nutrient utilization, and waste elimination
• Homeostasis


  The ability of an organism to regulate and maintain constant internal conditions such as temperature, pH, and nutrient levels within narrow ranges
• Growth and Development


  Growth is an increase in size, mass, or complexity over time, and development is a process of maturation and differentiation that leads to the emergence of specialized structures and functions
• Reproduction


  The process by which organisms produce offspring, ensuring the continuity of life from one generation to the next, including fission and fusion
• Response to Stimuli (Responsiveness)


  Living organisms respond to physical, chemical, and biological cues from their environment
• Evolutionary Adaptation


  All living organisms exhibit a "fit" to their environment, and adaptations enhance an individual's ability to survive and reproduce, but are not constant and change with the environment
• Forms of Energy


  • Kinetic energy
  • Potential energy
  • Light energy
  • Sound energy
  • Heat energy
  • Electrical energy
  • Chemical energy
• Fuels


  Energy-rich carbon substances that release energy when burned in air (oxygen), including coal, petrol, kerosene, and food
• Energy Requirements of Biological Activities

  • Muscular Activities
  • Active Transport
  • Production of heat
  • Metabolic processes
• Energy is used up for muscular activities, active transport, production of heat, and metabolic processes
• Forms of energy


  • Light energy
  • Sound energy
  • Heat energy
  • Electrical energy
  • Chemical energy
• Energy-rich carbon substances


  Fuels (e.g. coal, petrol, kerosene)
• Food


  Energy-rich carbon substance, the fuel of living things
• Energy requirements of biological activities

  • Muscular activities
  • Active transport
  • Production of heat
  • Metabolic processes
  • Growth