Introduction to Viruses and Bacteria
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Questions and Answers

Which of the following best describes the primary function of bacteria in the environment?

  • To create new species by introducing genetic mutations.
  • To cause diseases and infections in humans and animals
  • To produce oxygen through photosynthesis.
  • To break down dead organic matter, making nutrients available for other organisms. (correct)

    • What distinguishes bacteria from other single-celled organisms like fungi and algae?

  • Their lack of a nucleus and other membrane-bound organelles. (correct)
  • Their ability to form colonies.
  • Their presence in diverse habitats.
  • Their ability to reproduce through binary fission.

    • Where is the genetic information of a bacterium located?

  • In ribosomes scattered throughout the cytoplasm.
  • In numerous chromosomes within the nucleus.
  • In a distinct nucleus with a membrane.
  • In a single loop of DNA within the cytoplasm. (correct)

    • What is the purpose of the slime layer or capsule surrounding some bacteria?

    <p>To protect the bacterium from its environment and host immune systems. (C)</p> Signup and view all the answers

    Which of these shapes is NOT a typical form found in bacteria?

    <p>Amoeba (D)</p> Signup and view all the answers

    What does the term "saprotroph" indicate about a bacterium's feeding habits?

    <p>It breaks down dead organic matter for nutrition. (C)</p> Signup and view all the answers

    Knowing that a bacterium is called a 'streptococcus' provides information about which characteristic?

    <p>Its shape and arrangement (D)</p> Signup and view all the answers

    Which of these statements is TRUE about bacteria?

    <p>Bacteria have been on Earth longer than any other living organism. (B)</p> Signup and view all the answers

    What is the primary function of a capsid in a virus?

    <p>To protect the viral genetic material (A)</p> Signup and view all the answers

    Why are viruses considered obligate internal parasites?

    <p>They can only reproduce inside a host cell. (B)</p> Signup and view all the answers

    What distinguishes a bacteriophage from a typical virus?

    <p>Bacteriophages infect bacteria rather than other forms of life. (B)</p> Signup and view all the answers

    Which of the following characteristics is NOT displayed by viruses?

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

    What does it mean for a virus to be classified as pathogenic?

    <p>It is capable of causing disease. (D)</p> Signup and view all the answers

    Besides the shapes of viruses described in the content, which of the following best describes how a regular virus looks like in terms of its components?

    <p>A protein capsid containing either DNA or RNA. (B)</p> Signup and view all the answers

    What happens to viruses when they are not inside a host?

    <p>They enter a dormant state. (A)</p> Signup and view all the answers

    Which of the following is a key characteristic of viruses that contributes to them being considered non-living?

    <p>Their non-cellular nature and lack of metabolic activity. (B)</p> Signup and view all the answers

    Flashcards

    Virus reproduction

    Viruses reproduce by converting host cell DNA or RNA into viral nucleic acids to create new viruses.

    Bacteria

    Bacteria are unicellular, prokaryotic organisms belonging to the kingdom Monera, existing over 3.5 billion years.

    Prokaryotic

    Organisms without a membrane-bound nucleus, like bacteria.

    Structure of bacteria

    Bacteria have a simple unicellular structure, lacking a nucleus, with DNA in the nucleoid region.

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    Cell wall

    Bacterial cells are surrounded by a cell wall made of polysaccharides, proteins, and lipids.

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    Shapes of bacteria

    Bacteria can be spherical (coccus), rod-shaped (bacillus), spiral (spirillum), or comma-shaped (vibrio).

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    Saprotrophs

    Most bacteria are saprotrophs, feeding on dead organic matter as decomposers.

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    Flagella

    Threadlike structures that help some bacteria move in liquid environments.

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    Viruses

    Viruses are acellular entities displaying non-living characteristics.

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    Structure of viruses

    Viruses contain either DNA or RNA, enclosed in a protein coat called a capsid.

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    Size of viruses

    Viruses range from 20 to 300 nm, making them very small.

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    Obligate internal parasites

    Viruses must infect a host cell to replicate and multiply.

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    Viruses vs Living Organisms

    Viruses cannot feed, respire, or reproduce independently.

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    Pathogenic viruses

    Viruses that cause diseases in hosts, such as HIV/AIDS and flu.

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    Bacteriophages

    Viruses that specifically infect and replicate within bacteria.

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    Dormant viruses

    Viruses without a host become inactive, similar to 'sleeping' until a host is found.

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    Study Notes

    Viruses

    • Viruses are not classified as one of the 5 kingdoms of living organisms
    • Viruses are non-living as they lack cellular structure
    • Ongoing debate regarding viral classification as living/non-living
    • Viruses are extremely small (20-300nm), requiring an electron microscope to view
    • Shapes include rod-shaped, spherical, and complex
    • Typical virus contains DNA or RNA (never both) enclosed within a protein coat (capsid)
    • Viruses are acellular, lacking cytoplasm and organelles
    • Viruses cannot feed, excrete, respire, or move independently
    • Viruses are obligate internal parasites, requiring a host for reproduction
    • Viruses infect host cells to reproduce, converting host genetic material into new viral particles
    • Examples of human viral diseases are HIV/AIDS, chickenpox, herpes, and influenza

    Bacteria

    • Bacteria are single-celled prokaryotic organisms, classified in the Kingdom Monera
    • Bacteria have been around for more than 3.5 billion years.
    • Structurally simple, lacking nucleus and membrane-bound organelles
    • DNA located in a region called nucleoid.
    • Surrounded by a cell wall composed of polysaccharides, proteins, and lipids.
    • Some bacteria have a slime layer or capsule for protection.
    • Plasma membrane lies directly below the cell wall
    • Cell movement can occur via flagella
    • Cell shapes include coccus (round), bacillus (rod-shaped), spirillum (spiral-shaped), and vibrio (comma-shaped)
    • Bacteria vary in how they obtain energy:
    • Saprotrophs feed on dead organic matter
    • Autotrophs produce their own food through photosynthesis or chemosynthesis
    • Heterotrophs cannot make their own food, obtaining energy from external sources. This includes parasitic bacteria (obtain nutrients from a living organism)
    • Mutualistic bacteria live symbiotically, benefiting both organisms in the relationship
    • Bacteria can respire with (aerobic) or without (anaerobic) oxygen.
    • Bacteria reproduce asexually by binary fission, dividing into two new cells.
    • Under adverse conditions, many bacteria form endospores for survival

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    Related Documents

    Module 1 Viruses and Bacteria PDF

    Description

    Explore the fascinating world of viruses and bacteria in this quiz. Understand their classifications, structures, and roles in living organisms. Discover the debates surrounding viruses and the essential characteristics that define bacteria.

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