Biology: Cells and Cell Theory
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Questions and Answers

Considering the limitations imposed by diffusion, what is the most likely adaptation observed in cells to maintain efficient nutrient uptake and waste removal?

  • Decreasing the surface area to volume ratio.
  • Maintaining a small cell size and increasing the surface area to volume ratio. (correct)
  • Increasing cell volume to maximize internal reactions.
  • Developing specialized organelles to slow down diffusion rates.

    • A scientist discovers a new unicellular organism. Which observation would violate a core tenet of the cell theory?

  • The organism contains DNA and ribosomes.
  • The organism can adapt to different environmental conditions.
  • The organism is able to reproduce asexually.
  • The organism's cells arise spontaneously from non-cellular material. (correct)

    • Why is the cell considered the basic unit of life?

  • Because it is the smallest structure visible with a light microscope.
  • Because it contains all the necessary organelles for complex processes like photosynthesis.
  • Because it can be easily isolated and studied in a laboratory setting.
  • Because it is the fundamental unit of structure, function, and organization in living organisms. (correct)

    • Why is the surface area to volume ratio important for cell function?

    <p>It affects the efficiency of nutrient and waste exchange with the environment. (C)</p> Signup and view all the answers

    Which of the following statements accurately reflects the relationship between cell structure and function?

    <p>Cell structure is closely related to its function, with structural adaptations enabling specific tasks. (A)</p> Signup and view all the answers

    Which of the following best describes the primary role of mitochondria in eukaryotic cells?

    <p>Generating ATP through cellular respiration. (A)</p> Signup and view all the answers

    A plant cell is placed in a hypotonic solution. Which structure primarily prevents the cell from bursting?

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

    What is the main purpose of the large central vacuole in plant cells?

    <p>To store nutrients and degrade waste products (B)</p> Signup and view all the answers

    In which specific part of the chloroplast does the Calvin cycle take place?

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

    What is the most accurate description of thylakoids?

    <p>Flattened sacs where photon energy capture occurs (A)</p> Signup and view all the answers

    How do chloroplasts contribute to the function of plant cells?

    <p>By converting light energy into chemical energy via photosynthesis. (B)</p> Signup and view all the answers

    Animal cells do not have:

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

    What is the name of the theory that explains how mitochondria and cholorplasts came to be?

    <p>The Theory of Endosymbiosis (C)</p> Signup and view all the answers

    What is the primary difference between plasmodesmata in plant cells and gap junctions in animal cells regarding cell communication?

    <p>Plasmodesmata create a continuous cytoplasm between cells, whereas gap junctions form channels that open and close to regulate communication. (A)</p> Signup and view all the answers

    Which observation provides the strongest evidence supporting the endosymbiotic theory for the origin of mitochondria and chloroplasts?

    <p>Mitochondria and chloroplasts contain their own circular DNA and replicate independently via a process similar to binary fission. (B)</p> Signup and view all the answers

    In the context of endosymbiosis, what is the most accurate description of the 'host' cell's role?

    <p>It engulfs another cell, creating a mutually beneficial relationship where the engulfed cell performs specific functions. (A)</p> Signup and view all the answers

    If a cell were unable to form gap junctions, which of the following processes would most likely be directly affected?

    <p>The coordinated contraction of muscle cells in animal tissues. (D)</p> Signup and view all the answers

    Which of the following supports how mitochondria are derived from aerobic bacteria?

    <p>Mitochondria contain ribosomes. (A)</p> Signup and view all the answers

    Which of the following characteristics is unique to eukaryotic cells and not found in prokaryotic cells?

    <p>The presence of a nucleus containing DNA. (D)</p> Signup and view all the answers

    A researcher discovers a new single-celled organism. After examining its cellular structure, they observe that the cell lacks membrane-bound organelles. To which domain does this organism likely belong?

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

    Which cellular structure is primarily responsible for modifying and sorting proteins for secretion or use within the cell?

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

    What is the primary function of the nucleolus within the eukaryotic nucleus?

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

    A cell requires a large amount of energy to perform its functions. Which organelle would likely be found in abundance within this cell?

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

    If a cell were unable to produce functional ribosomes, which of the following processes would be most directly affected?

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

    If a plant cell were unable to produce a functional central vacuole, which of the following processes would be most directly affected?

    <p>Water uptake and turgor pressure (A)</p> Signup and view all the answers

    Which of the following best describes the function of the smooth endoplasmic reticulum (ER)?

    <p>Lipid synthesis and detoxification (A)</p> Signup and view all the answers

    What is the role of transport vesicles in the endomembrane system?

    <p>To transport molecules between different parts of the system. (A)</p> Signup and view all the answers

    A researcher observes a cell actively breaking down and recycling damaged organelles. Which of the following organelles is most likely involved in this process?

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

    Which of the following pairs of structures are directly involved in protein synthesis?

    <p>Ribosomes and rough endoplasmic reticulum (D)</p> Signup and view all the answers

    How might long-term use of one drug increase resistance to a different drug that has never been taken?

    <p>By increasing the amount of smooth ER, leading to faster detoxification of various substances. (D)</p> Signup and view all the answers

    How does mRNA get from the nucleus to the Ribosome?

    <p>The mRNA exits through nuclear pores. (C)</p> Signup and view all the answers

    A certain toxin inhibits the function of the cytoskeleton. What cellular process would be most immediately disrupted?

    <p>Cell movement and transport of materials within the cell (A)</p> Signup and view all the answers

    If a cell is specialized for detoxification, which organelle would likely be more abundant compared to other cells?

    <p>Smooth endoplasmic reticulum (C)</p> Signup and view all the answers

    Within the endomembrane system, what is the direct relationship between the rough ER and the golgi apparatus?

    <p>The rough ER modifies and folds new proteins, and then ships them via vesicles to the golgi apparatus for further modification and sorting. (D)</p> Signup and view all the answers

    A plant cell is placed in a hypertonic solution. Which structure primarily prevents the cell membrane from collapsing?

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

    How do cells with the same DNA become so different?

    <p>Differentiation occurs because certain genes are turned on or off in different cell types. (C)</p> Signup and view all the answers

    Prolonged exposure to certain drugs can lead to an increase in smooth endoplasmic reticulum (ER). How does this affect drug tolerance?

    <p>It increases drug tolerance, requiring higher doses to achieve the same effect. (C)</p> Signup and view all the answers

    How might drug tolerance, developed through increased smooth ER, impact the effectiveness of antibiotics in drug addicts?

    <p>Antibiotics would be less effective, requiring higher doses to combat infections. (B)</p> Signup and view all the answers

    What is the primary role of the Golgi complex in processing proteins and lipids received from the endoplasmic reticulum?

    <p>Modifying, sorting, and packaging proteins and lipids for transport (B)</p> Signup and view all the answers

    During protein processing in the Golgi complex, what types of modifications can occur to the side chains of proteins?

    <p>Sugars may be trimmed, and phosphate groups may be added (C)</p> Signup and view all the answers

    Which of the following is NOT a primary function of the cytoskeleton?

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

    How do the three main types of cytoskeleton elements differ in terms of size?

    <p>Microtubules are the largest, followed by intermediate filaments and then microfilaments. (C)</p> Signup and view all the answers

    What is the primary function of microfilaments within a cell?

    <p>Changes in cell shape (A)</p> Signup and view all the answers

    What is the main role of intermediate filaments in the cytoskeleton?

    <p>Maintenance of cell shape (A)</p> Signup and view all the answers

    Lysosomes contain enzymes that operate at a low pH. Why is this acidic environment important for their function?

    <p>It is required for the optimal activity of the digestive enzymes. (D)</p> Signup and view all the answers

    What happens to the raw materials generated by the breakdown of biomolecules within lysosomes?

    <p>They are returned to the cytoplasm for reuse. (C)</p> Signup and view all the answers

    Flashcards

    Cell

    The basic unit of life, which makes up all living organisms.

    Cell Theory

    A fundamental principle of biology stating that all living organisms are made of cells, cells are the basic unit of structure and function, and all cells arise from pre-existing cells.

    Diffusion

    The process by which molecules spread from areas of high concentration to areas of low concentration.

    Surface Area/Volume Ratio

    A ratio that determines how well a cell can exchange materials with its environment, influencing cell size and function.

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    Pre-existing Cells

    The concept that all cells stem from already existing cells, as stated in the cell theory.

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    Prokaryote

    A cell with no nucleus and circular DNA.

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    Eukaryote

    A cell with a true nucleus and linear DNA.

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    Difference in DNA Shape

    Prokaryotic DNA is circular; Eukaryotic DNA is linear.

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    Cell Size

    Prokaryotic cells are smaller than eukaryotic cells.

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    Cell Complexity

    Prokaryotic cells are simpler; eukaryotic cells are complex with organelles.

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    Ribosomes

    Sites of protein synthesis found in both prokaryotic and eukaryotic cells.

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    Nucleus Function

    Control center of the cell, storing hereditary information and directing activities.

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    Endomembrane System

    Network that modifies, produces, and transports molecules in eukaryotic cells.

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    Smooth Endoplasmic Reticulum

    Site for lipid synthesis and detoxification in eukaryotic cells.

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    Rough Endoplasmic Reticulum

    Site for protein synthesis, studded with ribosomes in eukaryotic cells.

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    Endosymbiosis

    A relationship where one species lives inside another species.

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    Endosymbiosis Theory

    Theory explaining the origin of chloroplasts and mitochondria from symbiotic bacteria.

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    Chloroplasts

    Organelles that originated from photosynthetic bacteria through endosymbiosis.

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    Mitochondria

    Organelles derived from aerobic bacteria and are responsible for energy production.

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    Cell-to-Cell Communication

    Process where cells use structures to exchange signals and molecules.

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    Chronic Exposure to Drugs

    Long-term use of drugs leading to physiological changes in the body.

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    Smooth Endoplasmic Reticulum (Smooth ER)

    A type of ER involved in lipid metabolism and drug detoxification.

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    Drug Tolerance

    A state where higher doses of a drug are needed to achieve the same effect.

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    Golgi Complex

    An organelle that processes, packages, and exports proteins and lipids from the ER.

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    Transport Vesicle

    A small membrane-bound sac that transports proteins from the ER to the Golgi complex.

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    Lysosomes

    Organelles that act as the cell's garbage disposal system, recycling materials.

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    Digestive Enzymes in Lysosomes

    Enzymes present in lysosomes that break down biomolecules at low pH.

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    Cytoskeleton

    A network of protein strands that provides support, shape, and movement to cells.

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    Microfilaments

    The smallest cytoskeletal elements that change cell shape and support movement.

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    Microtubules

    The largest cytoskeletal elements responsible for organelle movement and cell mobility.

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    Nucleus

    The site of most of the cell's DNA, located inside the nuclear envelope.

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    Central vacuole

    Stores nutrients, maintains cell pressure, and balances pH; found only in plant cells.

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    ATP

    Adenosine triphosphate, the main energy currency of cells used in various cellular processes.

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    Plant Cell Structures

    Unique components of plant cells: cell wall, chloroplasts, and central vacuole.

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    Vacuole

    Multipurpose storage sac in plant cells, typically 50-90% of cell volume, used for storage and waste degradation.

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    Stroma

    The fluid matrix within chloroplasts where the Calvin Cycle takes place.

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    Thylakoids

    Flattened sacs in chloroplasts that contain chlorophyll and are the sites of light-dependent reactions.

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    Study Notes

    Cells: The Basic Unit of Life

    • Cells are the fundamental units of life, all living organisms are composed of one or more cells.
    • Cell size is limited by the surface area-to-volume ratio. A smaller cell has more surface area relative to its volume, promoting efficient exchange of materials.

    Cell Theory

    • All living organisms are composed of one or more cells.
    • Cells are the basic unit of structure, function, and organization in all living organisms.
    • All cells come from pre-existing cells.

    Types of Cells

    • Prokaryotic cells lack a nucleus and other membrane-bound organelles. Their DNA is circular. They are typically smaller and older.

      • Examples include bacteria and archaea.

    • Eukaryotic cells have a nucleus and other membrane-bound organelles. Their DNA is linear They are typically larger and younger and often multicellular.

      • Examples include animal and plant cells.

    Prokaryotic Cells

    • Ribosomes are the site of protein synthesis in both prokaryotic and eukaryotic cells.
    • Prokaryotic DNA is circular.
    • Prokaryotic cells lack membrane-bound organelles, have a cell wall, plasma membrane, and a capsule.
    • Prokaryotic cells are generally smaller than eukaryotic cells.

    Eukaryotic Cells

    • Eukaryotic cells are generally larger than prokaryotic cells.
    • Eukaryotic cells have a nucleus and other membrane-bound organelles.

    Eukaryotic Cell Organelles

    • Nucleus: The control center of the cell, containing DNA, which directs cell activity.
    • Endomembrane system: A network of interconnected membranes involved in protein and lipid synthesis, modification, and transport.
    • Cytoplasm & Cytoskeleton: The region between the nucleus and the plasma membrane. The cytoskeleton provides structure and support, facilitates transport, and enables movement.
    • Lysosomes: Membrane-bound vesicles containing digestive enzymes. They break down waste products and foreign invaders and recycle raw materials.
    • Mitochondria: Organelles responsible for converting energy from food into ATP (adenosine triphosphate), which the cell uses to function.

    Eukaryotic Cell Organelles: Plant Cells

    • Chloroplasts: Sites of photosynthesis in plant cells. They convert light energy into chemical energy.
    • Vacuoles: Sacs filled with fluid, primarily storing nutrients and degrading waste products; prominent in plant cells. A large central vacuole is generally present in plant cells.
    • Cell walls: Rigid outer layers that provide structure and support and help regulate water intake and retention. Present only in plant cells.

    Endosymbiosis Theory

    • Mitochondria and chloroplasts are believed to have arisen from prokaryotic cells that were engulfed by other cells, living in a symbiotic relationship.
    • Evidence supporting this idea includes their similar size to prokaryotic cells and their own circular DNA

    Cell Communication

    • Plasmodesmata: Plant cells are connected by channels called plasmodesmata, that allow cytoplasm to be shared

    • Gap junctions: Animal cells have gap junctions, channels that directly connect the cytoplasm of neighboring cells, allowing for facilitated movement of molecules and signals between them.

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    This quiz covers essential concepts regarding cells, the basic unit of life. Explore topics including cell theory, types of cells (prokaryotic and eukaryotic), and the importance of cell size in function. Perfect for students learning about cellular biology.

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