Biology Chapter 8: Cells
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Biology Chapter 8: Cells

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Questions and Answers

What is the primary structural and functional unit of all living organisms?

  • Atom
  • Tissue
  • Cell (correct)
  • Organ

    • Who was the first person to see and describe a live cell?

  • Robert Brown
  • Theodore Schwann
  • Matthias Schleiden
  • Anton Von Leeuwenhoek (correct)

    • Which scientist proposed that all plants are composed of different kinds of cells?

  • Matthias Schleiden (correct)
  • Theodore Schwann
  • Robert Hooke
  • Louis Pasteur

    • What was discovered by Robert Brown that is crucial for understanding cell structure?

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

    What did Theodore Schwann conclude about animal cells based on his studies?

    <p>They have a thin outer layer.</p> Signup and view all the answers

    What distinguishes unicellular organisms from multicellular organisms?

    <p>The number of cells</p> Signup and view all the answers

    What role did the invention of the microscope play in the study of cells?

    <p>It revealed structural details of cells.</p> Signup and view all the answers

    According to the cell theory, what characteristic is unique to plant cells?

    <p>Presence of a cell wall</p> Signup and view all the answers

    What is a key characteristic of ribosomes?

    <p>They are non-membrane bound organelles.</p> Signup and view all the answers

    Which of the following is true about centrosomes?

    <p>They help in cell division.</p> Signup and view all the answers

    Which of the following statements about cell size is correct?

    <p>Human red blood cells are approximately 7.0 um in diameter.</p> Signup and view all the answers

    What is the primary shape classification of bacteria?

    <p>Bacillus, coccus, vibrio, and spirillum.</p> Signup and view all the answers

    What determines the shape of a cell?

    <p>The function the cell performs.</p> Signup and view all the answers

    Which type of cells are typically smaller and multiply more rapidly?

    <p>Prokaryotic cells.</p> Signup and view all the answers

    What is the largest isolated single cell?

    <p>Egg of an ostrich.</p> Signup and view all the answers

    Which of the following cell shapes is NOT mentioned in the content?

    <p>Pyramidal.</p> Signup and view all the answers

    What does the modern cell theory state about the origin of cells?

    <p>New cells are formed from other cells through division.</p> Signup and view all the answers

    Which statement correctly differentiates between prokaryotic and eukaryotic cells?

    <p>Eukaryotic cells contain a membrane-bound nucleus; prokaryotic cells do not.</p> Signup and view all the answers

    What type of cells contain organelles such as mitochondria and lysosomes?

    <p>Only eukaryotic cells.</p> Signup and view all the answers

    What is the primary component filling the volume of both prokaryotic and eukaryotic cells?

    <p>Cytoplasm.</p> Signup and view all the answers

    Who contributed to the final formulation of the cell theory by explaining cell division?

    <p>Rudolf Virchow.</p> Signup and view all the answers

    In which type of cell is DNA contained within a membrane-bound structure?

    <p>Only eukaryotic cells.</p> Signup and view all the answers

    What structural feature distinguishes an onion cell from a human cheek cell?

    <p>Presence of a cell wall.</p> Signup and view all the answers

    What did Schwann contribute to the cell theory?

    <p>He proposed that all living organisms are composed of cells.</p> Signup and view all the answers

    What is the primary structural characteristic of prokaryotic cells?

    <p>No well-defined nucleus</p> Signup and view all the answers

    Which of the following statements about plasmids is true?

    <p>Plasmids are circular DNA found outside the genomic DNA.</p> Signup and view all the answers

    In prokaryotic cells, the cytoplasm is described as what?

    <p>A fluid matrix filling the cell</p> Signup and view all the answers

    What is absent in prokaryotic cells compared to eukaryotic cells?

    <p>Nuclear membrane</p> Signup and view all the answers

    What size range is typical for prokaryotic cells?

    <p>1-2 um</p> Signup and view all the answers

    Which of the following characteristics is typical of prokaryotic cells?

    <p>Simplicity in structure</p> Signup and view all the answers

    What purpose do plasmids serve in prokaryotic cells?

    <p>They confer unique traits such as antibiotic resistance.</p> Signup and view all the answers

    What is a notable exception regarding the presence of cell walls in prokaryotes?

    <p>Mycoplasma are prokaryotes without a cell wall.</p> Signup and view all the answers

    What is the mesosome primarily involved in?

    <p>Cell wall formation and DNA replication</p> Signup and view all the answers

    Which layer of the bacterial cell envelope is responsible for shape and structural support?

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

    How do bacteria generally fall into two categories based on their cell envelope?

    <p>Gram positive and Gram negative based on staining properties</p> Signup and view all the answers

    What distinguishes the glycocalyx in different bacterial species?

    <p>Its thickness and composition</p> Signup and view all the answers

    What type of structure in prokaryotic cells resembles selectively permeable membranes found in eukaryotes?

    <p>Plasma membrane</p> Signup and view all the answers

    Which of the following accurately describes the role of the derived structures of mesosomes?

    <p>DNA replication and distribution</p> Signup and view all the answers

    What component of the cell envelope acts as a protective unit in bacteria?

    <p>All components together</p> Signup and view all the answers

    Which characteristic of the glycocalyx is notable among bacterial cells?

    <p>Varied in composition and thickness</p> Signup and view all the answers

    Which organelle is present in animal cells but absent in almost all plant cells?

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

    What is the primary function of ribosomes in both plant and animal cells?

    <p>Protein synthesis</p> Signup and view all the answers

    Which structure is responsible for packaging and transporting proteins in a cell?

    <p>Golgi apparatus</p> Signup and view all the answers

    What distinguishes plant cells from animal cells in terms of structure?

    <p>Absence of centrioles</p> Signup and view all the answers

    What is the function of the lysosome in a cell?

    <p>Digestion of waste materials</p> Signup and view all the answers

    Which component is part of the endomembrane system in cells?

    <p>All of the above</p> Signup and view all the answers

    What role does the nucleus play in a cell?

    <p>Control of cellular activities</p> Signup and view all the answers

    What is the role of the chloroplast in plant cells?

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

    What is the primary function of the smooth endoplasmic reticulum?

    <p>Lipid synthesis</p> Signup and view all the answers

    What defines a characteristic of the plasma membrane?

    <p>Selective permeability for substances</p> Signup and view all the answers

    Study Notes

    Chapter 8: Cell: The Unit of Life

    • What is a Cell?: Unicellular organisms exist independently and perform life functions. Cells are the fundamental structural and functional units of living organisms.
    • Cell Theory: All living organisms are composed of cells, and all cells arise from pre-existing cells.
    • Overview of Cells: Cells have a distinct outer boundary (cell wall in plant cells, membrane in animal cells). Inside is a dense membrane-bound structure called the nucleus, containing genetic material (DNA).
    • Prokaryotic Cells: These cells lack a membrane-bound nucleus and other membrane-bound organelles besides ribosomes. Example: Bacteria, blue-green algae, mycoplasma and PPLO. Characteristics include: cell wall (except in mycoplasma), cytoplasm, naked genetic material (circular DNA), plasmids (small circular DNA).
    • Eukaryotic Cells: These cells have a true nucleus (membrane-bound) and other membrane-bound organelles, like the endoplasmic reticulum, Golgi complex, lysosomes, mitochondria, microbodies, and vacuoles. Example: Protists, plants, animals, and fungi. Larger and more complex than prokaryotic cells.
    • Cell Shape and Size: Cells vary greatly in size (e.g., Mycoplasma is the smallest, ostrich eggs are largest), shape (e.g., disc-like, polygonal, columnar, thread-like), and activities depending on their role/function.

    8.1 What is a Cell?

    • Unicellular organisms perform all crucial life functions within a single cell.

    8.2 Cell Theory

    • All organisms are made of cells. All living cells come from pre-existing cells.

    8.3 Overview of Cells

    • Cells are fundamental building blocks. They have an outer membrane, and a nucleus containing DNA.

    8.4 Prokaryotic Cells

    • Prokaryotic cells are small and multiply quickly.
    • Lack membrane-bound organelles (except ribosomes).
    • Possess a complex cell envelope (glycocalyx, cell wall, plasma membrane).
    • May have flagella for movement.
    • Possess plasmids (small, extra-chromosomal DNA).

    8.5 Eukaryotic Cells

    • Eukaryotic cells have membrane-bound organelles.
    • Plant and animal cells have differences (e.g., plant cells have cell walls and plastids; animal cells have centrioles).
    • Cytoplasm is the main area for cellular activities.
    • Ribosomes are present in both prokaryotic and eukaryotic cells.

    8.5.1 Cell Membrane

    • Cell membranes are mainly composed of lipids and proteins organized into a bilayer with polar heads facing outwards.
    • Different membrane proteins exist.

    8.5.2 Cell Wall

    • Forms an outer covering for fungal and plant cells, providing mechanical support and protection.
    • Composed of different materials (e.g., cellulose in plants).
    • A middle lamella helps to hold cells together.

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    Cell: The Unit of Life PDF

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    Explore the fundamental unit of life in this quiz on Chapter 8: Cells. Learn about unicellular organisms, cell theory, and the differences between prokaryotic and eukaryotic cells. Test your knowledge on cell structures and functions in living organisms.

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