Biology Chapter: Cells and Organisms
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Biology Chapter: Cells and Organisms

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Questions and Answers

At what temperature do thermophiles typically grow best?

  • 80°C - 110°C
  • 40°C - 50°C
  • 15°C - 25°C
  • 50°C - 60°C (correct)

    • Which of the following statements about Archaea is correct?

  • They lack cell walls.
  • They include some extremophiles. (correct)
  • They have well-defined nuclei.
  • They are universally larger than bacteria.

    • Which is NOT a characteristic of the kingdom Fungi?

  • Cell walls made of chitin
  • Non-motile
  • Decomposers
  • Photosynthetic (correct)

    • What type of reproduction is primarily associated with Plantae?

    <p>Sexual reproduction only</p> Signup and view all the answers

    Which group does NOT fall under the classification of Plantae?

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

    Which type of organism is known for its ability to thrive in acidic environments?

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

    What is a distinguishing feature of Protista?

    <p>They are not fungi, animals, or plants.</p> Signup and view all the answers

    Why are fungi considered important in ecosystems?

    <p>They are the best decomposers.</p> Signup and view all the answers

    What is the function of enzymes in biochemical reactions?

    <p>They speed up metabolic processes without changing themselves.</p> Signup and view all the answers

    What can cause proteins to become denatured and non-functional?

    <p>Inconsistent temperature or pH levels</p> Signup and view all the answers

    Which component is NOT part of a nucleotide?

    <p>Amino acid</p> Signup and view all the answers

    Which type of cell contains a cell wall made of cellulose?

    <p>Plant cells</p> Signup and view all the answers

    Which nucleotides are components of RNA?

    <p>A, G, C, U</p> Signup and view all the answers

    What is the primary role of adenosine triphosphate (ATP) in cells?

    <p>To carry energy</p> Signup and view all the answers

    What is the structure of DNA?

    <p>Double-stranded helix</p> Signup and view all the answers

    What type of bonds connect the nitrogenous bases in DNA?

    <p>Hydrogen bonds</p> Signup and view all the answers

    What is the primary role of cells in living organisms?

    <p>Cells are the basic units of structure and function.</p> Signup and view all the answers

    How can one differentiate between an organ and a tissue?

    <p>By its ability to perform multiple functions.</p> Signup and view all the answers

    Which of these is NOT considered a basic building block of life?

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

    What distinguishes cells from one another?

    <p>Their size, shape, structure, and function.</p> Signup and view all the answers

    What is an example of a tissue?

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

    What represents the smallest common denominator of life?

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

    Which of the following is an organ?

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

    What is a key distinction between active and passive transport in cells?

    <p>Active transport requires energy; passive transport does not.</p> Signup and view all the answers

    What type of organisms are classified as Animalia?

    <p>Multicellular, heterotrophic eukaryotes capable of mobility at some life stage</p> Signup and view all the answers

    Which of the following elements constitute 96.5% of all atoms in an organism?

    <p>Carbon, hydrogen, oxygen, nitrogen</p> Signup and view all the answers

    What type of bond is formed by the unequal sharing of electrons?

    <p>Polar covalent bond</p> Signup and view all the answers

    What defines a prokaryotic cell?

    <p>Unicellular and lacks a nucleus</p> Signup and view all the answers

    Which statement is true about ionic bonds?

    <p>They involve the gain and loss of electrons</p> Signup and view all the answers

    Which of the following best defines multicellular organisms?

    <p>Organisms made of multiple cells working together</p> Signup and view all the answers

    What type of interaction is a hydrogen bond?

    <p>An attraction between a hydrogen atom and an electronegative atom</p> Signup and view all the answers

    Which of the following is NOT true regarding eukaryotic cells?

    <p>They lack a defined nucleus</p> Signup and view all the answers

    What is the primary role of microtubules in the context of motor protein movement?

    <p>Facilitate the movement of molecular motors like kinesins and dyneins</p> Signup and view all the answers

    Which of the following functions is NOT associated with lysosomes?

    <p>Synthesizing cholesterol</p> Signup and view all the answers

    Which statement about intermediate filaments is accurate?

    <p>They provide structural support and resist mechanical stress.</p> Signup and view all the answers

    How does Taxol (paclitaxel) affect microtubules?

    <p>It prevents tubulin subunits from dissociating, stabilizing microtubules.</p> Signup and view all the answers

    Which of the following statements about peroxisomes is true?

    <p>They digest fatty acids and participate in cholesterol synthesis.</p> Signup and view all the answers

    What is the function of colchicine in relation to microtubules?

    <p>It causes microtubules to disappear, particularly in inflammatory conditions.</p> Signup and view all the answers

    What characteristic distinguishes kinesins from dyneins?

    <p>Kinesins usually move toward the plus ends of microtubules.</p> Signup and view all the answers

    What type of diseases could be caused by defective intermediate filaments?

    <p>Inherited skin-blistering disorders due to keratin mutations.</p> Signup and view all the answers

    Study Notes

    Cells: The Basic Units of Life

    • Cells are the fundamental building blocks of all living organisms.
    • They are the smallest unit capable of independent life.
    • Cells can be distinguished by size, shape, structure, and function.

    Types of Organisms

    • Prokaryotic: Lack a nucleus, single-celled, small size, examples include Bacteria and Archaea.
    • Eukaryotic: Have a nucleus, can be single-celled or multicellular, larger in size, examples include Protista, Fungi, Plantae, and Animalia.

    The Chemical Components of Cells

    • Essential Elements: C, H, O, and N make up the majority of an organism's atoms.
    • Electrolytes: K, Na, Cl, Mg, P, Ca, Fe, and I are important for various cellular functions.
    • Covalent Bonds: Electrons are shared equally or unequally between atoms.
      • Non-polar: Electrons are shared equally (e.g., C-C, C-H bonds).
      • Polar: Electrons are shared unequally due to differences in electronegativity.
    • Ionic Bonds: Atoms gain or lose electrons, forming charged ions that attract each other.
    • Hydrogen Bonds: Weak interactions between a hydrogen atom and a highly electronegative atom (like oxygen or nitrogen).

    Essential Molecules

    • Proteins: Large, complex molecules made up of amino acids.
      • Functions: Regulation, structure, signaling, transport, catalysis, motor proteins.
      • Enzymes: Biological catalysts that speed up chemical reactions.
        • Specificity: Enzymes catalyze specific reactions.
        • Reversible reactions: Enzymes can facilitate both forward and reverse reactions.
        • Coenzymes: Some enzymes require a coenzyme or cofactor for activity.
        • Factors affecting enzyme activity: Temperature, pH, enzyme concentration, substrate concentration.
    • Nucleotides: Monomers of nucleic acids (DNA and RNA).
      • Components: Nitrogenous base, sugar, phosphate groups.
      • RNA: A, G, C, U, mostly single-stranded.
      • DNA: A, G, C, T, double-stranded helix.
    • ATP: Adenosine triphosphate is the primary energy carrier in cells.

    Eukaryotic Cell Structure

    • Cell Wall: Found in plants, fungi, and bacteria, provides protection, structure, and support.
      • Composed of: Cellulose (plants), chitin (fungi), peptidoglycan (bacteria).
    • Cell Membrane: Encloses the cell and regulates what enters and exits.
      • Composed of: Phospholipid bilayer with embedded proteins.
    • Cytoplasm: The gel-like substance within the cell that houses the organelles.
    • Nucleus: Contains the cell's genetic material (DNA).
    • Ribosomes: Sites of protein synthesis.
    • Endoplasmic Reticulum (ER): Network of membranes involved in protein synthesis and lipid metabolism.
      • Rough ER: Has ribosomes attached, involved in protein synthesis.
      • Smooth ER: Lacks ribosomes, involved in lipid synthesis and detoxification.
    • Golgi Apparatus: Processes and packages proteins and lipids for secretion or delivery to other organelles.
    • Lysosomes: Contain digestive enzymes that break down cellular waste products and ingested materials.
    • Peroxisomes: Small vesicles involved in fatty acid and alcohol metabolism, cholesterol synthesis, and amino acid digestion.
    • Mitochondria: Powerhouses of the cell, responsible for cellular respiration and energy production.
    • Chloroplasts: Found in plant cells, responsible for photosynthesis.
    • Vacuoles: Storage compartments for water, nutrients, and waste products.
    • Cilia and Flagella: Hair-like or whip-like structures for movement.
    • Cytoskeleton: Network of protein fibers that provides structural support and enables cell movement.
      • Microtubules: Hollow tubes made of tubulin, involved in cell shape, organelle movement, and cell division.
        • Functions: Mitotic spindle formation, cilia and flagella structure, viral movement.
      • Microfilaments: Solid rods made of actin, involved in muscle contraction, cell shape, and movement.
        • Functions: Muscle contraction, cytoplasmic streaming.
      • Intermediate Filaments: Resilient networks of protein fibers, providing structural support and resisting mechanical stress.
        • Functions: Structural support, resistance to mechanical stress.

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