Origin of Life on Earth
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Questions and Answers

Which of the following factors influence the fossil record bias?

  • Plants with non-photosynthetic properties
  • Presence of soft-bodied organisms
  • Species that lived in isolated environments
  • Species that were abundant and widespread (correct)

    • Stromatolites are composed of diatoms and sediment.

    False

    What is the process by which autotrophs produce organic molecules from carbon dioxide?

    photosynthesis

    The oldest known fossils are __________-year-old stromatolites.

    <p>3.5 billion</p> Signup and view all the answers

    What significant impact did photosynthetic bacteria have on Earth's atmosphere?

    <p>They generated oxygen through photosynthesis.</p> Signup and view all the answers

    Match the following terms with their descriptions:

    <p>Phototrophs = Organisms that obtain energy from sunlight Chemoautotrophs = Organisms that obtain energy from chemical reactions Cyanobacteria = Photosynthetic bacteria that produce oxygen Stromatolites = Rock-like structures formed by cyanobacteria</p> Signup and view all the answers

    What was a key characteristic of the early Earth's atmosphere?

    <p>Thick with water vapor and nitrogen</p> Signup and view all the answers

    The oxygen revolution refers to the increase of oxygen in the atmosphere due to the activities of heterotrophs.

    <p>False</p> Signup and view all the answers

    Prokaryotes dominated Earth’s environment from __________ to __________ billion years ago.

    <p>3.5, 2.0</p> Signup and view all the answers

    The Oparin-Haldane hypothesis suggests that oxygen was present in the early atmosphere necessary for the formation of organic compounds.

    <p>False</p> Signup and view all the answers

    Who conducted the famous experiment in 1953 that supported the Oparin-Haldane hypothesis?

    <p>Stanley Miller and Harold Urey</p> Signup and view all the answers

    The abbreviation for the gases present in the early Earth's atmosphere includes water vapor, nitrogen and its oxides, carbon dioxide, methane, ammonia, ______, and hydrogen sulfide.

    <p>hydrogen</p> Signup and view all the answers

    Match the following scientists to their contributions regarding the origin of life:

    <p>A.I. Oparin = Primordial soup hypothesis J.B.S. Haldane = Organic molecules in early oceans Stanley Miller = Experiment simulating early Earth conditions Harold Urey = Worked with Miller on the same experiment</p> Signup and view all the answers

    What provided the energy for the formation of organic molecules in early Earth according to the hypothesis?

    <p>Volcanism and thunderstorms</p> Signup and view all the answers

    Name one of the four requirements necessary for the creation of organic chemicals from simple molecules.

    <p>No free oxygen, source of energy, chemical building blocks, lots of time</p> Signup and view all the answers

    The Miller-Urey experiment resulted in the discovery of amino acids, which are used to make proteins.

    <p>True</p> Signup and view all the answers

    What key property of protocells allows them to maintain a different chemical environment from their surroundings?

    <p>Homeostasis</p> Signup and view all the answers

    The first genetic material is believed to have been DNA.

    <p>False</p> Signup and view all the answers

    What process involves the joining of monomers to form polymers?

    <p>Polymer synthesis</p> Signup and view all the answers

    Meteorites are posited to have transported __________ to Earth.

    <p>organic molecules</p> Signup and view all the answers

    Match the following components with their respective roles or characteristics:

    <p>Amino Acids = Building blocks of proteins Nucleotides = Building blocks of RNA/DNA Protocells = Early cellular structures Hot Sand = Catalyst for polymer synthesis</p> Signup and view all the answers

    Which of the following best describes liposomes?

    <p>Membrane-like structures surrounding abiotically produced molecules</p> Signup and view all the answers

    Laboratory simulations of early-Earth conditions have failed to produce organic polymers.

    <p>False</p> Signup and view all the answers

    What type of environment do protocells maintain that is crucial for their function?

    <p>Internal chemical environment</p> Signup and view all the answers

    What is a major role of RNA in biological systems?

    <p>It can store information in its nucleotide sequence and catalyze reactions.</p> Signup and view all the answers

    Ribozymes are capable of making copies of DNA.

    <p>False</p> Signup and view all the answers

    What term describes organisms that convert CO2 into an organic carbon source?

    <p>Autotrophs</p> Signup and view all the answers

    Protocells are formed from ______ and can enclose RNA.

    <p>membrane vesicles</p> Signup and view all the answers

    Which type of autotroph uses light as an energy source?

    <p>Photoautotrophs</p> Signup and view all the answers

    The fossil record shows a consistent and unchanging variety of organisms over time.

    <p>False</p> Signup and view all the answers

    Match the following types of organisms with their energy sources:

    <p>Photoautotrophs = Light energy Chemoautotrophs = Inorganic molecules Heterotrophs = Organic compounds Autotrophs = Carbon dioxide</p> Signup and view all the answers

    The deeper one goes into sedimentary ______, the older the organisms are.

    <p>strata</p> Signup and view all the answers

    What is the estimated age of the oldest known fossils of microorganisms?

    <p>3.5 billion years</p> Signup and view all the answers

    The exact method by which life on Earth began is fully understood.

    <p>False</p> Signup and view all the answers

    Name the four main stages hypothesized for the origin of life.

    <ol> <li>Abiotic synthesis of small organic molecules 2. Joining of small molecules into macromolecules 3. Packing into protocells 4. Origin of self-replicating molecules</li> </ol> Signup and view all the answers

    The geological eon following the Hadean is known as the ______.

    <p>Archean</p> Signup and view all the answers

    Match the following components of the origin of life with their correct descriptions:

    <p>Abiotic synthesis = Formation of simple organic molecules Macromolecules = Joining of small organic molecules Protocells = Droplets with membranes that maintain internal chemistry Self-replicating molecules = Molecules capable of inheritance</p> Signup and view all the answers

    Which of the following best describes the conditions of Earth during the Hadean eon?

    <p>Extreme heat and high volcanism</p> Signup and view all the answers

    Life forms on early Earth existed in conditions similar to those experienced today.

    <p>False</p> Signup and view all the answers

    How did scientists hypothesize that simple cells were formed on early Earth?

    <p>Through a sequence of abiotic synthesis, joining of molecules, packing into protocells, and origin of self-replicating molecules.</p> Signup and view all the answers

    What was the significance of the increase in oxygen levels on early Earth?

    <p>It allowed for the evolution of aerobic organisms.</p> Signup and view all the answers

    All eukaryotic cells contain chloroplasts.

    <p>False</p> Signup and view all the answers

    What is the primary function of mitochondria in eukaryotic cells?

    <p>Cellular respiration</p> Signup and view all the answers

    Eukaryotic cells are believed to have originated from __________ and genetic exchanges between prokaryotes.

    <p>symbioses</p> Signup and view all the answers

    Match the following organelles with their characteristics:

    <p>Mitochondria = Site of cellular respiration Chloroplasts = Site of photosynthesis Nucleus = Contains genetic material Endoplasmic Reticulum = Involved in protein synthesis</p> Signup and view all the answers

    What event allowed for the stabilization of the relationship between the host cell and engulfed bacteria?

    <p>The engulfed bacteria produced more ATP for the host cell.</p> Signup and view all the answers

    Chloroplasts and mitochondria share similarities with modern bacteria.

    <p>True</p> Signup and view all the answers

    When did eukaryotic life begin, according to scientific evidence?

    <p>2.1 billion years ago</p> Signup and view all the answers

    The layer of __________ helped to protect Earth from harmful UV radiation.

    <p>ozone</p> Signup and view all the answers

    Which of the following is NOT a piece of evidence supporting the Endosymbiont Theory?

    <p>Mitochondria are involved in photosynthesis.</p> Signup and view all the answers

    Study Notes

    History of Life on Earth

    • Life on Earth, evident in fossils, dates back 3.5 billion years.
    • The precise moment and method of the first living cell's origin remain unknown.
    • Scientific hypotheses on the origin of life are based on observed data and experiments from chemistry, geology, physics, and biology.

    Origin of Life

    • Early Earth's conditions, including a reducing atmosphere, likely facilitated the synthesis of organic molecules.
    • The atmosphere of early Earth likely contained water vapor, nitrogen, nitrogen oxides, carbon dioxide, methane, ammonia, and hydrogen sulfide.
    • The absence of free oxygen promoted chemical reduction reactions.
    • Energy, such as lightning and UV radiation, could have driven the synthesis of organic monomers.

    Oparin-Haldane Hypothesis (Primordial Soup)

    • This 1920s hypothesis suggests that organic molecules formed in Earth's early oceans from inorganic compounds.
    • The hypothesis includes the following requirements:
      • No free oxygen
      • Abundant energy sources such as volcanism, lightning, and UV radiation
      • Chemical building blocks, like water, ions, and dissolved gases
      • Sufficient time (earth's lifespan of about 4.6 billion years)
    • The Miller-Urey experiment supported this hypothesis.

    Synthesis of Monomers (Small Organic Molecules)

    • Laboratory simulations using early Earth's conditions show the formation of amino acids, sugars, lipids, and nucleotide bases.
    • These monomers are essential for the creation of more complex organic molecules.

    Synthesis of Polymers (Joining Monomers)

    • Experimental simulations show the formation of organic polymers (larger molecules) from monomers.
    • The formation of polymers likely occurred through dripping monomers onto hot rock, sand, or clay.

    Formation of Protocells

    • Abiotically produced molecules grouped together forming membrane-like structures called protocells. These exhibited life-like properties:
      • Self Replication
      • Metabolism
      • Homeostasis (maintenance of internal chemical environment)
    • Protocells were precursors to the cell.

    Origin of Self-Replicating Molecules

    • RNA is the likely original genetic material.
    • Ribozymes (RNA enzymes) can catalyze reactions that copy RNA and make proteins.
    • RNA's single-stranded structure allows versatile shapes, aiding in the chemical reactions required for life.

    The Fossil Record

    • Sedimentary rock layers (strata) hold fossils, allowing observation of changes in organisms over time.
    • Older strata contain older fossils.
    • Fossils provide a partial record of evolution. The fossil record is incomplete due to several reasons:
      • Organisms may not always die in places and times that promote fossil preservation.
      • Abundant and widespread species with hard parts are more likely to be fossilized.

    Prokaryotes

    • Prokaryotes (bacteria and archaea) dominated from 3.5 to 2 billion years ago.
    • Autotrophs (organisms that create their own food) evolved by converting CO2 into organic compounds like glucose.
    • Photosynthetic bacteria (cyanobacteria) produced oxygen, enriching the atmosphere and leading to the "Oxygen Revolution"

    Photosynthetic Bacteria and Oxygen Revolution

    • Cyanobacteria started releasing oxygen (O2) as a byproduct of photosynthesis.
    • Oxygen saturated the oceans and atmosphere, changing its composition.
    • This oxygenation paved the way for more complex life forms.
    • The ozone layer formed, decreasing the UV radiation and making the land more hospitable.

    Eukaryotes

    • Eukaryotic cells evolved from symbiotic relationships between prokaryotic cells.
    • The endosymbiotic theory explains the origin of mitochondria and chloroplasts from engulfed prokaryotes.
    • The theory proposes a relationship where one cell engulfs the other, and both benefit. One organism provides protection and other essential nutrients.

    Evidence Supporting Endosymbiont Theory

    • Chloroplasts and mitochondria are approximately the size of bacteria.
    • Both have double membranes.
    • These organelles have their own DNA, resembling prokaryotic DNA.
    • They have their own cell structures to create their proteins.

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    Bio Lecture 5: History of Life on Earth PDF

    Description

    Explore the history and theories surrounding the origin of life on Earth, including the Oparin-Haldane Hypothesis. This quiz delves into the conditions of early Earth that facilitated the synthesis of organic molecules and the scientific hypotheses that explain life's beginnings. Test your knowledge on the milestones in our planet's biological history.

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