Cell Composition and Organic Molecules Quiz
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Questions and Answers

Which type of protein is responsible for speeding up biological reactions?

  • Functional proteins (correct)
  • Regulatory proteins
  • Transport proteins
  • Structural proteins

    • What is the role of hemoglobin in the body?

  • To produce antibodies
  • To transport oxygen (correct)
  • To regulate metabolic processes
  • To provide structural support

    • Which reagent is used to test for proteins in a sample?

  • Benedict's solution
  • Biuret reagent (correct)
  • Phenolphthalein
  • Iodine solution

    • What is a characteristic of structural proteins?

    <p>They provide support and shape to cells and tissues.</p> Signup and view all the answers

    Insulin is an example of which type of protein?

    <p>Regulatory protein</p> Signup and view all the answers

    What color change indicates a positive result for starch in the iodine test?

    <p>From brown to deep purple or black</p> Signup and view all the answers

    Which of the following chemicals is NOT a component of Benedict's reagent?

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

    What initial color is Benedict's reagent before it is heated?

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

    What is the role of iodine reagent in the iodine test?

    <p>To detect the presence of starch</p> Signup and view all the answers

    How should the samples be observed after adding iodine reagent to determine the presence of starch?

    <p>By noting the color change</p> Signup and view all the answers

    What role does water play in cellular function?

    <p>It serves as a universal solvent and is involved in chemical reactions.</p> Signup and view all the answers

    Which statement accurately describes dehydration reactions?

    <p>They occur when two monomers are joined, releasing a water molecule.</p> Signup and view all the answers

    What distinguishes proteins from carbohydrates?

    <p>Proteins are composed of amino acids; carbohydrates are polymers of sugars.</p> Signup and view all the answers

    Which of the following elements is NOT a common component of amino acids?

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

    Which groups of ions are mentioned as less than 1% of cell mass but are still vital for cellular functions?

    <p>Cations like Na+ and K+; Anions like Cl- and HCO3-.</p> Signup and view all the answers

    What color change is observed in the Benedict test when testing a very high concentration of glucose?

    <p>Orange Red</p> Signup and view all the answers

    Which of the following statements regarding the Benedict test is false?

    <p>Water will change color when tested.</p> Signup and view all the answers

    What is the purpose of heating the test tubes in the Benedict test?

    <p>To facilitate color development.</p> Signup and view all the answers

    In the Benedict test, which color indicates a moderate concentration of glucose?

    <p>Yellow Orange</p> Signup and view all the answers

    What chemical change is expected after adding Benedict reagent to starch?

    <p>No change occurs</p> Signup and view all the answers

    Which tube will likely demonstrate the first visible color change in the Benedict test?

    <p>Tube 2 (Glucose)</p> Signup and view all the answers

    Comparing the colors produced by different glucose concentrations, which sequence is correct from lowest to highest concentration?

    <p>Green, Yellow, Orange, Orange Red</p> Signup and view all the answers

    How many drops of Benedict reagent are added to each test tube?

    <p>5 drops</p> Signup and view all the answers

    What indicates the presence of protein when using the Biuret reagent?

    <p>The solution changes to purple</p> Signup and view all the answers

    Which of the following is a disaccharide formed by the combination of glucose and galactose?

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

    Which type of carbohydrate is formed by long chains of glucose units?

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

    What color is iodine solution when it is not in the presence of starch?

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

    What is the primary storage form of glucose in plants?

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

    What is a key process that occurs when monosaccharides link to form disaccharides?

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

    Which of the following correctly pairs a monosaccharide with its type?

    <p>Glucose - Monosaccharide</p> Signup and view all the answers

    What is the role of Biuret reagent in the protein detection test?

    <p>To indicate protein presence by color change</p> Signup and view all the answers

    Study Notes

    Cell Composition

    • Cells are composed of water (70%), inorganic ions, and organic molecules.
    • Water is the most abundant component serving as a universal solvent and playing a crucial role in chemical reactions.
    • Inorganic ions, present in small quantities (<1% of cell mass), are vital for various cellular functions and metabolism.
    • Organic molecules are macromolecules essential for biological processes that sustain life.

    Organic Molecules

    • The four main types of organic molecules are:
      • Proteins: Polymers created by joining amino acids through peptide bonds.
      • Carbohydrates: Polymers of sugars like glucose, fructose, and galactose.
      • Lipids: Fats, oils, and waxes primarily composed of carbon and hydrogen.
      • Nucleic Acids: Polymers made of nucleotides that carry genetic information (DNA and RNA).

    Dehydration and Hydrolysis

    • Dehydration is a chemical reaction that joins two monomers to form a polymer by releasing a water molecule.
    • Hydrolysis is the opposite of dehydration, where a polymer is broken down into monomers by adding a water molecule.

    Proteins

    • Proteins are polymers of 20 distinct amino acids, each with a specific side chain that contributes to their structure and function.
    • Proteins are essential for a wide range of cellular functions.
    • Functional Proteins: These proteins perform specialized tasks like:
      • Antibodies: Combating disease-causing pathogens as part of the immune response.
      • Enzymes: Catalyzing biological reactions (e.g., amylase, lipase, pepsin).
    • Transport Proteins: These proteins facilitate the movement of substances within the cell and body:
      • Hemoglobin : Transporting oxygen throughout the body.
      • Albumin: Transporting fatty acids in the blood.
    • Regulatory Proteins: These proteins control cellular metabolism, such as:
      • Insulin: Regulating blood glucose levels.
    • Structural Proteins: These proteins provide support and structure to cells and organisms:
      • Keratin: Found in hair and nails.
      • Myosin: Found in muscle tissue.

    Testing for Proteins

    • Biuret test:
      • Uses a blue reagent containing copper sulfate (CuSO4) and sodium hydroxide (NaOH).
      • Produces a purple color in the presence of proteins.

    Carbohydrates

    • Carbohydrates include simple sugars (monosaccharides) and complex sugars (polysaccharides).
    • Monosaccharides:
      • Glucose, fructose, and galactose are essential cellular nutrients.
    • Disaccharides: Form when two monosaccharides join through a glycosidic bond.
      • Maltose: Glucose + Glucose
      • Lactose: Galactose + Glucose
      • Sucrose: Fructose + Glucose
    • Polysaccharides: Formed by linking chains of glucose units.
      • Starch: Plants store glucose as starch.
      • Glycogen: Animals store glucose as glycogen.
      • Cellulose: The primary component of plant cell walls.

    Testing for Starch or Glycogen

    • Iodine Test:
      • Uses a brown iodine solution.
      • Turns a deep purple to black in the presence of starch.

    Testing for Glucose

    • Benedict test:
      • Uses a blue Benedict reagent containing sodium carbonate (Na2CO3), sodium citrate, and copper(II) sulfate (CuSO4).
      • The color change after heating a solution containing glucose depends on the glucose concentration:
        • Green: Very low concentration.
        • Yellow: Low concentration.
        • Yellow-Orange: Moderate concentration.
        • Orange: High concentration.
        • Orange-Red: Very high concentration.
        • Blue (No change): No glucose present.
        • Benedict reagent also does not react with starch.

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