Introduction to Unicellular Organisms
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Questions and Answers

What do protists, archaea, and bacteria make up together?

  • Only unicellular organisms
  • All living things on Earth
  • A small percentage of living things on Earth
  • Most of the living things on Earth (correct)

    • What is a common ancestor?

  • A single ancestor that all living things come from (correct)
  • A type of eukaryote
  • A type of archaea
  • A type of prokaryote

    • What is the main difference between eukaryotes and prokaryotes?

  • The number of cells they have
  • The type of environment they live in
  • The type of food they eat
  • The presence or absence of a nucleus (correct)

    • What does the name 'archaea' suggest?

    <p>That they are very old</p> Signup and view all the answers

    What type of environment did archaea likely live in when they first appeared on Earth?

    <p>An extreme environment with little oxygen and harsh temperatures</p> Signup and view all the answers

    What is a characteristic of thermophiles?

    <p>They like extreme temperatures</p> Signup and view all the answers

    What do methanogens produce?

    <p>Methane gas</p> Signup and view all the answers

    Why are archaea considered extremophiles?

    <p>Because they like extreme environments</p> Signup and view all the answers

    What is the main difference between a nucleoid and a nucleus?

    <p>A nucleoid is not membrane-bound</p> Signup and view all the answers

    What is the shape of bacterial chromosomes?

    <p>Circular, double-stranded DNA</p> Signup and view all the answers

    What is the function of plasmids in bacteria?

    <p>They provide genetic advantages to bacteria</p> Signup and view all the answers

    What is the purpose of inclusion bodies in bacteria?

    <p>To store nutrients</p> Signup and view all the answers

    Why do bacteria need to store nutrients in inclusion bodies?

    <p>Because they have no membrane-bound organelles</p> Signup and view all the answers

    What is the purpose of chemotaxis in bacteria?

    <p>Both A and B</p> Signup and view all the answers

    What is the main difference between prokaryotes and eukaryotes?

    <p>Prokaryotes have no membrane-bound organelles, while eukaryotes do</p> Signup and view all the answers

    What is the function of flagella in bacteria?

    <p>To move towards nutrients</p> Signup and view all the answers

    What is a characteristic that distinguishes archaea from bacteria and protists?

    <p>Cell walls and cell membranes</p> Signup and view all the answers

    What is the term used to describe protists that are related to plants?

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

    What is the primary environment in which protists are found?

    <p>Moist or aquatic environments</p> Signup and view all the answers

    What is the term used to describe the movement of bacteria towards or away from chemicals?

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

    What is the outermost structure of a bacterium that can be washed off?

    <p>Slime layer</p> Signup and view all the answers

    What is the protein that makes up the prokaryotic flagella?

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

    What are the small, yellow projections found on the surface of some bacteria?

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

    Where can bacteria be found?

    <p>All around us and even inside of us</p> Signup and view all the answers

    What is the term used to describe the structure that surrounds the cell wall of a bacterium?

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

    What is the primary function of flagella in bacteria?

    <p>To move towards nutrients</p> Signup and view all the answers

    Study Notes

    Unicellular Organisms

    • Unicellular organisms, including protists, archaea, and bacteria, make up most of the living things on Earth.
    • All living things come from a common ancestor.

    Eukaryotes and Prokaryotes

    • The main evolutionary difference is between the kingdoms of eukaryotes and prokaryotes.
    • Eukaryotes have a nucleus, whereas prokaryotes do not (meaning they came before the nucleus).

    Archaea

    • Archaea are the oldest organisms, and their name sounds like "archaic", meaning really old.
    • They were the first to appear on Earth and are used to extreme environments, such as high temperatures, weird weather conditions, and little oxygen.
    • They are extremophiles, meaning they like extreme environments.
    • There are three types of archaea:
      • Thermophiles (like extreme temperatures)
      • Halophiles (like extremely salty environments)
      • Methanogens (make methane gas)
    • Archaea have different cell walls and cell membranes than bacteria or protists.

    Protista

    • Protista is a "grab bag" for unicellular organisms, including some multicellular ones.
    • Protists are eukaryotes that are not plants, fungi, or animals.
    • They mostly live in moist or aquatic environments.
    • Protists can be categorized into:
      • Photosynthesizing protists (related to plants, called Algae)
      • Non-photosynthesizing protists (related to fungi and animals, with subgroups like Protozoa, including amoebas, and fungal-like, including slime molds)
    • Protists have evolved unique ways of getting nutrients, such as photosynthesis, and unique movement structures, like cilia, flagella, and amoeba-like movements.

    Bacteria

    • Bacteria can be found in diverse environments, including all around us and inside of us.
    • Because of this, they can both help and hurt us.
    • Bacteria have a general structure, including:
      • Capsule (or slime layer)
      • Cell wall
      • Plasma membrane
      • Prokaryotic flagella (made of protein flagellin, used for movement and chemotaxis)
      • Fimbriae (or pili, small yellow projections)
    • Inside the cell, bacteria have:
      • Cytoplasm
      • Ribosomes
      • No nucleus, but a nucleoid area for the chromosome
      • Chromosome is not membrane-bound and is circular, double-stranded DNA
      • Some bacteria have plasmids (extra pieces of DNA)
      • Inclusion bodies (store nutrients for the bacteria)
    • Prokaryotes have no membrane-bound organelles, so they need to get their nutrients straight from the environment and store them in inclusion bodies.

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    Description

    Learn about the different types of unicellular organisms, including protists, archaea, and bacteria, and their evolutionary differences.

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