CR Biology B Module 3 Lesson 2
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Questions and Answers

What distinguishes a protist from a bacterium?

  • Protists cannot perform photosynthesis.
  • Protists lack a nucleus.
  • Protists are eukaryotic and contain a nucleus. (correct)
  • Protists are prokaryotic organisms.
  • What role did smaller prokaryotic cells play in the endosymbiotic theory?

  • They evolved into the nucleus of eukaryotic cells.
  • They acted as hosts for larger cells.
  • They became organelles of the host cells. (correct)
  • They provided structural support to bacteria.
  • Which of the following provides evidence for the endosymbiotic theory?

  • Mitochondria and chloroplasts contain DNA similar to bacterial DNA. (correct)
  • The shape of mitochondria is similar to that of animal cells.
  • Chloroplasts can only exist in plant cells.
  • Mitochondria and chloroplasts lack DNA.
  • What did larger prokaryotic cells gain from their symbiotic relationship with smaller cells?

    <p>They obtained energy and organic molecules.</p> Signup and view all the answers

    What specialized function did the aerobic bacteria have in the context of the endosymbiotic theory?

    <p>They were specialized for breaking down chemicals and releasing energy.</p> Signup and view all the answers

    Which statement about the origins of eukaryotic cells is accurate?

    <p>Eukaryotic cells are more complex and evolved from symbiotic relationships among prokaryotic cells.</p> Signup and view all the answers

    Which of the following is NOT a component of the evidence supporting the endosymbiotic theory?

    <p>Mitochondria are different in structure from prokaryotic cells.</p> Signup and view all the answers

    What is the significance of the endosymbiotic theory in relation to the evolution of eukaryotes?

    <p>It proposes a symbiotic origin of mitochondria and chloroplasts within eukaryotic cells.</p> Signup and view all the answers

    Why are protists considered important in the study of evolution?

    <p>They are the first eukaryotic organisms and likely the ancestors to all eukaryotes.</p> Signup and view all the answers

    What process is used for the production of new mitochondria and chloroplasts?

    <p>Binary fission</p> Signup and view all the answers

    Which of the following statements about protists is accurate?

    <p>Protists possess a nucleus and membrane-bound organelles.</p> Signup and view all the answers

    What distinguishes ingestive protists from absorptive protists?

    <p>Ingestive protists engulf food particles.</p> Signup and view all the answers

    What is a common characteristic of the motility of protists?

    <p>Pseudopods are temporary extensions of cytoplasm.</p> Signup and view all the answers

    What occurs during the complex life cycle of the protist Spirogyra?

    <p>Zygotes formed undergo meiosis to produce haploid cells.</p> Signup and view all the answers

    What is a characteristic habitat of most protists?

    <p>Aquatic environments</p> Signup and view all the answers

    How can protists obtain food?

    <p>By absorption or ingestion.</p> Signup and view all the answers

    What happens to spores produced by Spirogyra under stressful conditions?

    <p>They fuse to form a diploid zygote.</p> Signup and view all the answers

    What type of reproduction is most commonly observed in many protists?

    <p>Asexual and sexual reproduction.</p> Signup and view all the answers

    Which of the following best describes the endosymbiotic theory related to protists?

    <p>Protists originated from prokaryotic cells through symbiosis.</p> Signup and view all the answers

    Simple protists have a nucleus in their cells.

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

    Chloroplasts in eukaryotic cells evolved from endosymbionts that were anaerobic bacteria.

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

    The circular DNA found in mitochondria is similar to the DNA found in eukaryotic cell nuclei.

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

    According to the endosymbiotic theory, the first eukaryotic cells arose from a relationship between multiple prokaryotic cells.

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

    Mitochondria have their own plasma membranes that are different from bacterial membranes.

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

    New mitochondria and chloroplasts are produced through a process called binary fission.

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

    All protists are multicellular organisms.

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

    Spirogyra primarily reproduces through sexual reproduction.

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

    Ingestive protists engulf food particles using their cell membrane.

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

    Most protists are found in dry environments and do not require moisture to survive.

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

    Study Notes

    Differences between Bacteria and Simple Protists

    • Protists are eukaryotic organisms with a nucleus in each cell, unlike bacteria which are prokaryotic.
    • Simple protists such as Paramecium and amoeba share some similarities with bacteria.

    Evolution of Protists

    • Protists are considered the oldest eukaryotes and likely evolved from prokaryotic cells.
    • The endosymbiotic theory explains the evolution of eukaryotic cells as a result of mutualistic relationships between prokaryotic cells.

    Endosymbiotic Theory

    • The first eukaryotic cells emerged when smaller prokaryotic cells (endosymbionts) were engulfed by larger prokaryotic cells (hosts).
    • Endosymbionts received protection and nutrients, while host cells gained organic molecules and energy.
    • Over time, endosymbionts evolved into essential organelles:
      • Aerobic bacteria became mitochondria, providing energy.
      • Cyanobacteria evolved into chloroplasts, enabling photosynthesis.

    Evidence for the Endosymbiotic Theory

    • Mitochondria and chloroplasts have their own circular DNA, similar to bacterial DNA.
    • They possess double membranes that resemble bacterial membranes.
    • They replicate similarly to bacteria through binary fission.
    • The internal structure and biochemistry of chloroplasts are akin to cyanobacteria.

    Characteristics of Protists

    • All protists have a nucleus and membrane-bound organelles, including mitochondria and endoplasmic reticulum.
    • Most protists are single-celled; some are multicellular.
    • Nutrition varies among protists: they can ingest, absorb, or photosynthesize.

    Habitats of Protists

    • Primarily aquatic, found in damp environments like soil, marshes, lakes, and oceans.
    • Some protists are free-living; others engage in symbiotic relationships with hosts, including humans.

    Motility in Protists

    • Protists exhibit motility and utilize appendages for movement:
      • Flagella: whip-like structures; may be singular or multiple.
      • Cilia: shorter and more numerous than flagella.
      • Pseudopods: temporary, foot-like cytoplasmic extensions.

    Reproduction in Protists

    • Complex life cycles include both asexual and sexual reproduction.
    • Example: Spirogyra reproduces asexually through binary fission; can produce spores in harsh conditions for sexual reproduction.
    • Spores can fuse to form a diploid zygote, which undergoes meiosis to produce haploid cells.

    Nutritional Methods of Protists

    • Ingestive: Engulf food particles and digest them in food vacuoles.
    • Absorptive: Absorb nutrients directly through cell membranes; important as decomposers.
    • Photosynthetic: Utilize sunlight to create food; significant producers in aquatic ecosystems.

    Summary of Protists

    • Protists possess nuclear membranes and other organelles, primarily inhabit aquatic environments, and exhibit mobility.
    • They have complex reproductive strategies and diverse nutritional methods, playing vital ecological roles.

    Differences between Bacteria and Simple Protists

    • Protists are eukaryotic organisms with a nucleus in each cell, unlike bacteria which are prokaryotic.
    • Simple protists such as Paramecium and amoeba share some similarities with bacteria.

    Evolution of Protists

    • Protists are considered the oldest eukaryotes and likely evolved from prokaryotic cells.
    • The endosymbiotic theory explains the evolution of eukaryotic cells as a result of mutualistic relationships between prokaryotic cells.

    Endosymbiotic Theory

    • The first eukaryotic cells emerged when smaller prokaryotic cells (endosymbionts) were engulfed by larger prokaryotic cells (hosts).
    • Endosymbionts received protection and nutrients, while host cells gained organic molecules and energy.
    • Over time, endosymbionts evolved into essential organelles:
      • Aerobic bacteria became mitochondria, providing energy.
      • Cyanobacteria evolved into chloroplasts, enabling photosynthesis.

    Evidence for the Endosymbiotic Theory

    • Mitochondria and chloroplasts have their own circular DNA, similar to bacterial DNA.
    • They possess double membranes that resemble bacterial membranes.
    • They replicate similarly to bacteria through binary fission.
    • The internal structure and biochemistry of chloroplasts are akin to cyanobacteria.

    Characteristics of Protists

    • All protists have a nucleus and membrane-bound organelles, including mitochondria and endoplasmic reticulum.
    • Most protists are single-celled; some are multicellular.
    • Nutrition varies among protists: they can ingest, absorb, or photosynthesize.

    Habitats of Protists

    • Primarily aquatic, found in damp environments like soil, marshes, lakes, and oceans.
    • Some protists are free-living; others engage in symbiotic relationships with hosts, including humans.

    Motility in Protists

    • Protists exhibit motility and utilize appendages for movement:
      • Flagella: whip-like structures; may be singular or multiple.
      • Cilia: shorter and more numerous than flagella.
      • Pseudopods: temporary, foot-like cytoplasmic extensions.

    Reproduction in Protists

    • Complex life cycles include both asexual and sexual reproduction.
    • Example: Spirogyra reproduces asexually through binary fission; can produce spores in harsh conditions for sexual reproduction.
    • Spores can fuse to form a diploid zygote, which undergoes meiosis to produce haploid cells.

    Nutritional Methods of Protists

    • Ingestive: Engulf food particles and digest them in food vacuoles.
    • Absorptive: Absorb nutrients directly through cell membranes; important as decomposers.
    • Photosynthetic: Utilize sunlight to create food; significant producers in aquatic ecosystems.

    Summary of Protists

    • Protists possess nuclear membranes and other organelles, primarily inhabit aquatic environments, and exhibit mobility.
    • They have complex reproductive strategies and diverse nutritional methods, playing vital ecological roles.

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    Description

    Explore the fundamental differences between bacteria and protists, focusing on their cellular structures. This quiz delves into the endosymbiotic theory and how eukaryotic cells evolved from prokaryotic ancestors, highlighting the significance of mutualistic relationships. Evaluate your understanding of these essential biological concepts.

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