Biology Quiz: Cell Structure and Function
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Questions and Answers

What role do histones play in relation to genetic material?

  • They are primarily responsible for lipid metabolism.
  • They assist in the transmission and expression of genetic material. (correct)
  • They solely facilitate protein synthesis.
  • They form complexes with proteins only.
  • Which statement accurately describes the function of cholesterol in the body?

  • It primarily aids in carbohydrate metabolism.
  • Cholesterol serves solely as a structural component of cell membranes.
  • It acts exclusively as a storage form of energy.
  • Cholesterol is a raw material for the synthesis of steroid hormones. (correct)
  • How do membrane proteins contribute to cell membrane physiology?

  • They can serve multiple roles including transport, support, and signaling. (correct)
  • They are primarily involved in energy production.
  • They exclusively act as enzymes in metabolic reactions.
  • They only provide structural support to the membrane.
  • What is the primary purpose of carbohydrates like glycogen in the body?

    <p>They provide a quick source of energy through stored glucose.</p> Signup and view all the answers

    What are the primary characteristics of the cell membrane's lipid bilayer?

    <p>It exhibits flexibility and selective permeability to water.</p> Signup and view all the answers

    Which function of carbohydrates is crucial for maintaining tissue function?

    <p>Interlaces with glycocalyx of adjacent cells</p> Signup and view all the answers

    What is NOT a function of the cell membrane?

    <p>Providing nutrients to cells</p> Signup and view all the answers

    Which of the following describes facilitated diffusion?

    <p>It uses membrane-bound carrier systems.</p> Signup and view all the answers

    Which factor does NOT affect the rate of simple diffusion?

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

    What is the primary reason why water is considered a universal solvent in protoplasm?

    <p>It can dissolve electrolytes and biological substances.</p> Signup and view all the answers

    Which of the following correctly describes the role of electrolytes in protoplasm?

    <p>They serve as buffers and contribute to osmotic potential.</p> Signup and view all the answers

    Which mechanism require energy to move substances across the cell membrane?

    <p>Active transport</p> Signup and view all the answers

    What characterizes globular proteins found in protoplasm?

    <p>They undergo secondary and tertiary folding.</p> Signup and view all the answers

    What is a direct consequence of the selectively permeable nature of cell membranes?

    <p>Generation and transmission of nerve impulses</p> Signup and view all the answers

    Which component of protoplasm is specifically enclosed by the nuclear membrane?

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

    Which of the following processes is characterized by movement from high concentration to low concentration without energy?

    <p>Simple diffusion</p> Signup and view all the answers

    Why is the latent heat of vaporization of water important for the body?

    <p>It serves as a cooling mechanism.</p> Signup and view all the answers

    What is the main role of lipids in cell membranes?

    <p>Regulate water flow in and out of cells</p> Signup and view all the answers

    Which statement about cell theory is accurate?

    <p>The activities of organisms derive from interactions of their cells.</p> Signup and view all the answers

    What is the role of structural proteins in protoplasm?

    <p>They provide the cytoskeleton framework and contractile functions.</p> Signup and view all the answers

    What occurs during the process of cell division according to cell theory?

    <p>New cells arise from existing cells.</p> Signup and view all the answers

    What characterizes osmosis in biological systems?

    <p>It is the net diffusion of water across a semi-permeable membrane.</p> Signup and view all the answers

    Which statement about active transport is incorrect?

    <p>It does not require metabolic energy.</p> Signup and view all the answers

    The osmotic pressure of a solution is primarily dependent on what factor?

    <p>The number of osmotically active particles in the solution.</p> Signup and view all the answers

    Which process forces fluids through a membrane due to hydrostatic pressure differences?

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

    What is the main function of the Na-K pump present in all body cells?

    <p>To maintain ion concentration differences across the cell membrane.</p> Signup and view all the answers

    What distinguishes primary active transport from secondary active transport?

    <p>Primary active transport relies on ion gradients created by secondary transport.</p> Signup and view all the answers

    What is the physiological significance of solvent drag?

    <p>It has little physiological application.</p> Signup and view all the answers

    Which feature is not characteristic of facilitated diffusion?

    <p>It moves substances against their concentration gradient.</p> Signup and view all the answers

    What is the primary role of the pump in body cells?

    <p>It maintains the resting membrane potential.</p> Signup and view all the answers

    Which property is NOT attributed to the protein carrier complex?

    <p>Receptor for Ca2+ at the cytoplasmic surface.</p> Signup and view all the answers

    In secondary active transport, what primarily drives the movement of other substances with Na+?

    <p>The concentration gradient established by primary active transport.</p> Signup and view all the answers

    What distinguishes counter transport from co-transport in the context of sodium transport?

    <p>Counter transport involves substances moving in opposite directions while co-transport involves the same direction.</p> Signup and view all the answers

    What process describes the formation of vesicles that transport substances into the cell?

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

    Which of the following statements about phagocytosis is accurate?

    <p>It typically involves the transport of large particles such as bacteria.</p> Signup and view all the answers

    During exocytosis, what happens to substances within the cell?

    <p>They are transported to the exterior of the cell.</p> Signup and view all the answers

    The role of ATP in the activities of calcium pumps is primarily for which function?

    <p>To provide energy for the active transport of calcium ions.</p> Signup and view all the answers

    Study Notes

    Cell Physiology

    • Cells are the basic functional units of living organisms
    • Cell theory postulates that all living organisms are made of cells, all cells are similar chemically but differ in specialization, and new cells arise from existing ones.
    • The body is composed of protoplasm, a fluid, with the protoplasm enclosed by a cell membrane divided into cells.
    • Nucleoplasm is the protoplasm within the nuclear membrane, while cytoplasm is the area between the nucleoplasm and the plasma membrane.

    Protoplasm Composition

    • Water constitutes 75-85% of protoplasm

      • Acts as a solvent for biological substances (e.g., universal solvent)
      • Dissolves electrolytes and keeps suspended particles in solution.
      • Plays a role in maintaining a stable body temperature (high heat capacity).
      • Acts as a substrate in various biochemical reactions (e.g., hydrolysis).
    • Electrolytes (cations and anions)

      • Include sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), phosphates, sulfates, bicarbonates, and chloride ions.
      • Contribute to osmotic potential, important in water retention.
      • Substrates in metabolic reactions.
      • Involved as cofactors/coenzymes in enzymatic reactions.
      • Act as buffers.
    • Proteins (20% of protoplasm)

      • Globular proteins (e.g., enzymes)
        • Undergo secondary and tertiary folding
      • Structural proteins (form filaments like in cytoskeletons, connective tissues)
        • Provide strength and support to cells
      • Play a role in genetic material transmission and protein synthesis (e.g., histones in nucleoplasm).
    • Lipids (2% of protoplasm)

      • Include phospholipids, cholesterol, and triglycerides.
      • Help in separating protoplasmic compartments (e.g., phospholipids in membranes).
      • Cholesterol is involved in steroid hormone synthesis.
      • Neutral fats are sources of energy
    • Carbohydrates

      • Energy sources (e.g., glycogen is stored in liver and muscles).
      • Have roles in cell structure and function.

    Cell Membrane Physiology

    • Cell membranes are lipid bilayers with hydrophobic tails facing inward and hydrophilic heads facing outward.

    • Cell membranes are flexible and largely impermeable to water.

    • Cell membranes are made up of proteins, lipids, and carbohydrates.

    • Membrane Protein Functions

      • Structural support for the lipid bilayer
      • Transport substances in/out of the cell (carriers)
      • Acting as receptors for hormones
      • Acting as pumps for ions against concentration gradients (requiring ATP)
      • Catalyzing membrane reactions (enzymes)
    • Carbohydrate functions in terms of cell membrane -Act as receptors -Stimulate immune properties of the cell -Create interfaces with glycocalyx of neighboring cells, forming tissues -Provide cell surface negativity to repel other negative particles.

    • Lipid functions in terms of cell membrane -Regulate the amount of water flowing in and out of the cell -Separate intracellular and extracellular fluids -Provide shape and support to protoplasm. -Recognize hormones and mediate their effects -Transport needed substances in and out of the cell

    • Cell membrane is the basis of nerve and muscle impulse transmission

    Membrane Transport

    • Passive transport mechanisms (do not require energy):
      • Simple diffusion: Movement of substances from high to low concentration, across lipid bilayers or water channels. Examples include oxygen, carbon dioxide, alcohol, steroids, and fatty acids.
      • Facilitated diffusion: Movement of substances across membranes with the help of carrier proteins. Examples include glucose, amino acids.
    • Substances moved can be coupled (e.g., Na+ with glucose).
      • Osmosis: Net diffusion of water across a selectively permeable membrane.
      • Filtration: Movement of fluid across a membrane due to pressure differences.
      • Solvent drag: Movement of solvents drawing along with them dissolved solutes.
    • Active transport mechanisms(requires energy):
      • Primary Active Transport: Energy from ATP is directly used to move substances against their concentration gradients. An example is the sodium-potassium pump (Na-K+ pump).
      • Secondary Active Transport: Energy stored in an ion concentration gradient is used to move another substance against its concentration gradient.
    • Two substances move in the same direction (cotransport) or move in opposite directions (countertransport).

    Cytosis (Bulk Transport)

    • Endocytosis: Uptake of particles into the cell:
      • Pinocytosis (cell drinking): Uptake of fluids
      • Phagocytosis (cell eating): Uptake of large particles
    • Exocytosis: Release of material from the cell.

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    Description

    This quiz covers essential concepts related to cell structure and function, including the role of histones, cholesterol, membrane proteins, carbohydrates, and the lipid bilayer. Test your understanding of these crucial biological topics and their significance in cellular physiology.

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