Characteristics of Living Things and Cells
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Questions and Answers

Who was the first scientist to observe living cells in pond water?

  • Theodor Schwann
  • Antonie Von Leeuwenhoek (correct)
  • Matthias Schleiden
  • Robert Hooke

    • What is one key characteristic of eukaryotic cells compared to prokaryotic cells?

  • They lack a membrane-bound nucleus.
  • They have a genome made of RNA.
  • They can perform photosynthesis.
  • They contain membrane-bound organelles. (correct)

    • According to cell theory, which of the following statements is correct?

  • New cells arise without any pre-existing cells.
  • Cells can originate spontaneously from non-living matter.
  • All living organisms are composed of multiple cells.
  • Cells are the basic unit of structure in all living things. (correct)

    • What is a significant difference in the size range of animal cells compared to plant cells?

    <p>Plant cells are typically larger, ranging from 10 to 100 µm.</p> Signup and view all the answers

    What term describes organisms made up of a single cell?

    <p>Unicellular organisms</p> Signup and view all the answers

    Which of the following accurately describes prokaryotic cells?

    <p>They include organisms like bacteria and archaea.</p> Signup and view all the answers

    What are the building blocks of life responsible for all life processes?

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

    Which statement best describes the nucleus of prokaryotic cells?

    <p>It is absent in prokaryotic cells.</p> Signup and view all the answers

    Which statement accurately describes prokaryotic cells?

    <p>They lack a nucleus but have a nucleoid region for genetic material.</p> Signup and view all the answers

    What distinguishes eukaryotic cells from prokaryotic cells?

    <p>Eukaryotic cells have a complex structure with a defined nucleus.</p> Signup and view all the answers

    Which component is involved in the locomotion of prokaryotic cells?

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

    What is the primary function of the plasma membrane in eukaryotic cells?

    <p>To regulate entry and exit of substances.</p> Signup and view all the answers

    Which of the following lists all organelles found in eukaryotic cells?

    <p>Nucleus, Golgi bodies, lysosomes, mitochondria.</p> Signup and view all the answers

    Which characteristic is true about the genetic material of eukaryotic cells?

    <p>It is made up of multiple linear chromosomes within a nucleus.</p> Signup and view all the answers

    How do prokaryotic cells reproduce?

    <p>By binary fission.</p> Signup and view all the answers

    Which structure is absent in animal cells but present in plant cells?

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

    What is the primary function of the Rough Endoplasmic Reticulum?

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

    Which structure is referred to as the 'powerhouse of the cell'?

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

    What is the main role of lysosomes in the cell?

    <p>Digesting biomolecules</p> Signup and view all the answers

    How many types of plastids are mentioned, and what is one of their functions?

    <p>Three types; pigment storage</p> Signup and view all the answers

    The nuclear envelope is composed of how many layers, and what are they permeable to?

    <p>Two layers; ions, molecules, and RNA</p> Signup and view all the answers

    What distinguishes Smooth Endoplasmic Reticulum from Rough Endoplasmic Reticulum?

    <p>Presence of ribosomes</p> Signup and view all the answers

    What is the primary function of cytoplasm in a cell?

    <p>Housing organelles and metabolic activities</p> Signup and view all the answers

    Ribosomes are primarily composed of which two components?

    <p>Proteins and ribonucleic acids</p> Signup and view all the answers

    What primary function do lysosomes perform within eukaryotic cells?

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

    Which organelle is primarily referred to as the 'Powerhouse of the Cell' due to its role in energy production?

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

    What is the main role of the nucleus within a eukaryotic cell?

    <p>Genetic information containment and cell regulation</p> Signup and view all the answers

    What types of plastids are responsible for the green pigmentation in plants?

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

    What is the primary function of ribosomes in a cell?

    <p>Synthesis of proteins</p> Signup and view all the answers

    What is the role of centrosomes within animal cells?

    <p>Microtubule organization and cell division</p> Signup and view all the answers

    Which organelle is responsible for providing structure and rigidity to plant cells?

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

    What type of plastid is responsible for storage of starch, proteins, and fats?

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

    Study Notes

    Characteristics of Living Things

    • All living things share common characteristics, including growth, reproduction, response to stimuli, metabolism, homeostasis, and cellular organization.

    Definition of a Cell

    • A cell is the smallest and basic unit of life, responsible for all life processes.
    • Cells serve as the structural, functional, and biological units of all living beings and can replicate independently, earning them the title "building blocks of life."

    Discovery of Cells

    • Robert Hooke discovered cells in 1665 using a compound light microscope, describing them as small boxes.
    • Antonie van Leeuwenhoek observed the first living cells in pond water in 1674 and identified structures in those cells in 1678.
    • In 1833, Robert Brown discovered the nucleus in plant cells while studying orchid cells.
    • In 1838, Matthias Schleiden and Theodor Schwann formulated the cell theory based on their microscopic observations of plants and animals.

    Size and Shape of Cells

    • Animal cells typically range from 10 to 30 micrometers (µm) in size, whereas plant cells can measure between 10 and 100 µm.
    • Animal cells are generally round and irregularly shaped, while plant cells have a fixed rectangular or box-like structure.

    Cell Theory

    • Proposed by Theodor Schwann and Matthias Schleiden in 1838.
    • Three main points of cell theory:
      • Cells are the basic structural unit of all living things.
      • All living organisms are composed of cells.
      • New cells arise from pre-existing cells.

    Types of Cells

    • Based on Nucleus Organization:
      • Prokaryotic Cells: Simple, single-celled organisms without a true nucleus.
      • Eukaryotic Cells: More complex, containing a nucleus enclosed by a membrane.
    • Based on Cell Count:
      • Unicellular Cells: Composed of a single cell.
      • Multicellular Cells: Consisting of multiple cells.

    Prokaryotic Cells

    • Characterized by the absence of a nuclear membrane, mitochondria, Golgi bodies, chloroplasts, and lysosomes.
    • Genetic material is located on a single chromosome without histone proteins.
    • Bacteria and Archaea are included in prokaryotes, with cyanobacteria being photosynthetic members.

    Prokaryotic Cell Structure

    • Capsule: Protective outer covering in bacterial cells.
    • Cell Wall: Provides shape and structure.
    • Cytoplasm: Gel-like substance containing enzymes and organelles.
    • Cell Membrane: Regulates entry and exit of substances.
    • Pili: Hair-like structures for attachment.
    • Flagella: Whiplike structures aiding in locomotion.
    • Ribosomes: Sites for protein synthesis.
    • Plasmids: Circular DNA structures independent of chromosomal DNA.
    • Nucleoid Region: Contains genetic material.

    Eukaryotic Cells

    • Possess a true nucleus enclosed within a nuclear membrane, enabling complex cellular functions.
    • Includes protozoa, fungi, plants, and animals.

    Eukaryotic Cell Structure

    • Plasma Membrane: Separates the cell from the environment and contains embedded proteins for substance exchange.
    • Cell Wall: Rigid protective layer in plant cells (absent in animal cells).
    • Endoplasmic Reticulum (ER):
      • Rough ER: Studded with ribosomes for protein synthesis.
      • Smooth ER: Lacks ribosomes, involved in lipid production.
    • Nucleus: Houses DNA and proteins and oversees cell activities.
    • Golgi Apparatus: Packaging and transport of proteins and lipids.
    • Mitochondria: Energy production sites, known as the "powerhouse of the cell."
    • Lysosomes: Contain digestive enzymes, referred to as "suicidal bags."
    • Plastids: Found in plant cells; includes chloroplasts for photosynthesis, chromoplasts for color, and leucoplasts for storage.
    • Centrosomes: Organize microtubules for cell division, found only in animal cells.
    • Ribosomes: Can float freely or be embedded in the ER, essential for protein synthesis.
    • Vacuoles: Fluid-filled organelles aiding in storage and waste management.

    Summary

    • Cells are fundamental to life, and understanding their structure and function is crucial in biology. Living organisms exhibit a range of cell types, with distinct characteristics that facilitate their various life processes.

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