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 (B)

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. (B)</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 (D)</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 (B)</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 (B)</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 (B)</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 (A)</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 (D)</p> Signup and view all the answers

The first genetic material is believed to have been DNA.

<p>False (B)</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 (A)</p> Signup and view all the answers

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

<p>False (B)</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. (D)</p> Signup and view all the answers

Ribozymes are capable of making copies of DNA.

<p>False (B)</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 (A)</p> Signup and view all the answers

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

<p>False (B)</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 (C)</p> Signup and view all the answers

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

<p>False (B)</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 (B)</p> Signup and view all the answers

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

<p>False (B)</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. (B)</p> Signup and view all the answers

All eukaryotic cells contain chloroplasts.

<p>False (B)</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. (A)</p> Signup and view all the answers

Chloroplasts and mitochondria share similarities with modern bacteria.

<p>True (A)</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. (A)</p> Signup and view all the answers

Flashcards

Abiogenesis

The idea that life arose from non-living matter on early Earth through a series of chemical reactions.

Miller-Urey Experiment

An experiment that simulated the conditions of early Earth and produced organic molecules from inorganic matter.

Deep Sea Vents

Hydrothermal vents that release heat and chemicals from the Earth's interior into the ocean. They are often associated with the origins of life.

Polymers

Large molecules made up of repeating smaller units called monomers.

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Polymerization

The process of joining monomers together to form polymers.

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Protocells

Simple, self-organizing structures surrounded by a membrane that exhibit some properties of life, such as self-replication and metabolism. They are thought to be precursors to cells.

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RNA World Hypothesis

A type of nucleic acid that is thought to have been the first genetic material on Earth. It can act as both a genetic code and a catalyst for chemical reactions.

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Origin of Life

The process by which life arose from non-living matter on early Earth.

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Early Earth's Atmosphere

The early Earth's atmosphere was primarily composed of gases such as water vapor, nitrogen, carbon dioxide, methane, ammonia, hydrogen, and hydrogen sulfide.

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Reducing Atmosphere

A reducing atmosphere, unlike an oxidizing one, lacks free oxygen. This lack of oxygen promotes the addition of electrons (reduction) to molecules, allowing the formation of organic compounds from simpler ones.

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Oparin-Haldane Hypothesis

A hypothesis stating that organic molecules could have formed on early Earth from simple inorganic molecules in a reducing atmosphere, with energy provided by lightning and UV radiation.

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Primordial Soup

The hypothetical scenario where life's building blocks formed in a primeval 'soup' of organic molecules within the oceans of early Earth.

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Abiotic Synthesis of Monomers

The process where simple organic molecules, like amino acids, sugars, lipids, and nucleotide bases, are formed abiotically (without living organisms) from inorganic materials.

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Organic Synthesis

The formation of organic molecules from simpler inorganic molecules, like amino acids from simpler compounds.

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Chemical Evolution

The early Earth's environment provided the necessary conditions for the chemical processes leading to the origin of life.

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Ribozymes

RNA molecules can act as enzymes, catalyzing reactions like making copies of themselves.

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Abiotic synthesis

The process of creating complex molecules (polymers) from smaller ones (monomers).

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Autotrophs

Organisms that obtain their energy by converting inorganic carbon (CO2) into an organic carbon source (like glucose).

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Photoautotrophs

Autotrophs that use light as their energy source, like plants and cyanobacteria.

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Chemoautotrophs

Autotrophs that obtain energy by converting inorganic molecules, like sulfur compounds, into usable energy.

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Sedimentary Strata

The layers of sedimentary rock that record the history of life on Earth.

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Fossil Record

The study of fossils and their distribution in the rock layers, providing evidence for the evolution of life.

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Incomplete Fossil Record

The fossil record is not complete due to various factors, such as organisms not being preserved properly.

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Fossil Record Bias

The fossil record is biased towards organisms that were abundant, widespread, and had hard parts (bones, shells).

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Stromatolites

Rock-like structures formed by layers of cyanobacteria and sediment, the oldest known fossils.

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Heterotrophs

Organisms that obtain energy by consuming other organisms.

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Photosynthesis

The process by which organisms use sunlight to convert CO2 and water into sugar and oxygen.

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Oxygen Revolution

The event where oxygen, produced by photosynthetic bacteria, began to accumulate in the atmosphere.

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Macromolecule Formation

The joining of small organic molecules into larger macromolecules like proteins and nucleic acids.

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Self-Replicating Molecules

Molecules capable of self-replication, leading to the inheritance of genetic information.

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Hadean Eon

The geological eon characterized by the early Earth's intense heat and violent conditions.

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Earth's Formation

The formation of Earth from a vast dust and gas cloud surrounding the young Sun.

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Early Earth's Geologic Activity

A period of intense geological activity on early Earth, marked by high volcanism and collisions with other celestial bodies.

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Ozone Formation

A process where oxygen interacts with ultraviolet (UV) light, forming a protective layer called ozone in the upper atmosphere.

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Aerobic Organisms

Organisms that require oxygen to survive and thrive.

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Eukaryotic Cell Evolution

The development of a nucleus and internal membrane system within cells, forming the basis for complex life.

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Endosymbiont Theory

The idea that mitochondria and chloroplasts originated as independent prokaryotic cells that were engulfed by larger cells, forming a beneficial partnership.

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Symbiosis

A relationship where two different species live in close association, often benefiting from each other.

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Organelles

Small, self-contained structures within cells that perform specialized functions.

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Mitochondria

The organelle responsible for cellular respiration, converting nutrients into energy.

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Chloroplasts

The organelle responsible for photosynthesis, converting sunlight into energy.

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Plasma Membrane Infolding

The process of infolding the outer membrane of a cell to create internal compartments and structures.

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Endoplasmic Reticulum (ER)

A network of membranes within a cell that helps in protein production and processing.

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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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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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