Molecular Structures and Biomolecules Quiz
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Questions and Answers

Are enzyme-catalyzed reactions always decompositions?

  • No, they only work under acidic conditions.
  • Yes, all enzymes function only in decomposition.
  • No, they can also synthesize larger molecules. (correct)
  • Yes, they only break down molecules.

    • What effect does cold temperature have on enzyme activity?

  • It slows down the reaction rate. (correct)
  • It speeds up the reaction rate.
  • It denatures the enzymes.
  • It has no effect; enzymes are unaffected by temperature changes.

    • How does heat affect enzyme activity?

  • It slows down enzyme reactions significantly.
  • It maintains the same reaction rate as at lower temperatures.
  • It denatures the enzymes and can increase the reaction rate. (correct)
  • It has no noticeable impact on the enzymes.

    • What impact does a change in pH have on enzyme activity?

    <p>It disrupts hydrogen bonds and can denature the enzyme.</p> Signup and view all the answers

    What kind of biomolecule are enzymes categorized as?

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

    What does it mean for enzymes to be specific?

    <p>They only work with a specific substrate and reaction.</p> Signup and view all the answers

    What is the monomer of an enzyme?

    <p>Amino acid.</p> Signup and view all the answers

    Which statement about the lab enzyme used is correct?

    <p>It is specific to its substrate and does not act on other substances.</p> Signup and view all the answers

    What is the primary role of a biological buffering system when the pH of an environment becomes too acidic?

    <p>It stabilizes the pH by neutralizing excess acids.</p> Signup and view all the answers

    Which of the following best describes how carbon's bonding capability relates to its valence electrons?

    <p>Carbon can make four bonds due to having four valence electrons.</p> Signup and view all the answers

    Which characteristic defines a polar molecule?

    <p>It has unequal sharing of electrons, resulting in partial charges.</p> Signup and view all the answers

    What defines a nonpolar molecule?

    <p>It has equal sharing of electrons among its atoms.</p> Signup and view all the answers

    Which of the following types of molecules would be classified as hydrophilic?

    <p>Ionic compounds</p> Signup and view all the answers

    Which type of molecules is typically hydrophobic?

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

    What is the primary function of nucleic acids in biological systems?

    <p>Transmission of genetic information</p> Signup and view all the answers

    Which type of reaction involves the breaking down of molecules using water?

    <p>Hydrolysis reaction</p> Signup and view all the answers

    What role do lipids primarily serve in organisms?

    <p>Energy storage</p> Signup and view all the answers

    How do unsaturated fats differ from saturated fats?

    <p>Unsaturated fats have double bonds in their tails.</p> Signup and view all the answers

    What constitutes the R-group of an amino acid?

    <p>It is a variable side chain that determines the amino acid's properties.</p> Signup and view all the answers

    What describes the secondary structure of proteins?

    <p>The formation of alpha-helices and beta-pleated sheets.</p> Signup and view all the answers

    What is the primary function of enzymes in biochemical reactions?

    <p>To catalyze reactions and speed up their progress.</p> Signup and view all the answers

    What distinguishes competitive inhibitors from noncompetitive inhibitors?

    <p>Only competitive inhibitors can be displaced by substrate.</p> Signup and view all the answers

    How does the lock-and-key mechanism differ from the induced-fit mechanism of enzyme action?

    <p>Induced-fit allows for adjustments in enzyme shape upon substrate binding.</p> Signup and view all the answers

    What best explains the reusability of enzymes?

    <p>Enzymes can be used multiple times because they are not changed by the reaction.</p> Signup and view all the answers

    How many molecules are represented in the molecular formula $2C_2H_4O_2$?

    <p>2</p> Signup and view all the answers

    How many atoms of hydrogen are represented in the molecular formula $2C_2H_4O_2$?

    <p>8</p> Signup and view all the answers

    What is the primary characteristic of an ionic compound?

    <p>It is formed by the transfer of electrons.</p> Signup and view all the answers

    What is the definition of a covalent compound?

    <p>A compound formed by sharing electrons between atoms.</p> Signup and view all the answers

    How many valence electrons does nitrogen (N) have?

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

    What type of bond is formed when sodium (Na) and fluorine (F) combine?

    <p>Ionic bond</p> Signup and view all the answers

    What does it mean for a compound to be polar covalently bonded?

    <p>It has a partial positive charge on one side and a partial negative charge on the other side.</p> Signup and view all the answers

    What is the relationship between the number of bonds nitrogen can make and its valence electrons?

    <p>The number of bonds nitrogen can make is equal to the number of unpaired electrons in its outer level.</p> Signup and view all the answers

    Why can water dissolve polar or ionic compounds, but not nonpolar compounds like fat?

    <p>Nonpolar compounds do not have charged regions that attract water molecules.</p> Signup and view all the answers

    What are the products of water ionization?

    <p>H+ and OH-</p> Signup and view all the answers

    What does it indicate when a solution is described as acidic?

    <p>It contains more hydrogen ions than hydroxide ions.</p> Signup and view all the answers

    What characterizes a basic solution?

    <p>It contains more hydroxide ions than hydrogen ions.</p> Signup and view all the answers

    What does a neutral solution signify in terms of ion concentration?

    <p>It has equal concentrations of H+ and OH-.</p> Signup and view all the answers

    What does the pH scale measure?

    <p>The concentration of hydrogen ions in a solution.</p> Signup and view all the answers

    Which assertion about hydrogen bonding and water is true?

    <p>Hydrogen bonds are weak attractions between water molecules.</p> Signup and view all the answers

    Which acid was commonly used in pH lab experiments to change the pH of materials?

    <p>Hydrochloric acid</p> Signup and view all the answers

    Study Notes

    Molecular Structures

    • Atomic Structure: Atoms consist of protons, neutrons, and electrons.
    • Valence Electrons: Outermost electrons that determine bonding capacity.
    • Ionic Compounds: Formed when atoms gain or lose electrons to become stable ions.
    • Covalent Compounds: Formed when atoms share electrons to become stable.
    • Polar Covalent Bonds: Unequal sharing of electrons creates a partial positive and negative charge.
    • Water's Properties: Water's polarity allows it to dissolve many polar and ionic substances. Hydrogen bonding creates unique properties.
    • pH Scale: Measures acidity and basicity of a solution.
    • Acids: Have a higher concentration of H+ ions.
    • Bases: Have a higher concentration of OH- ions.
    • Neutral: Equal concentration of H+ and OH- ions.
    • pH Regulation: Organisms maintain a relatively stable pH through buffers.

    Biomolecules

    • Organic Molecules: Contain carbon and hydrogen.
    • Polar Molecules: Unequal sharing of electrons creates a partial positive and negative charge.
    • Nonpolar Molecules: Equal sharing of electrons creates no charge.
    • Hydrophilic: Water-loving molecules, polar molecules.
    • Hydrophobic: Water-repelling molecules, nonpolar molecules.
    • Carbohydrates: Monosaccharides, used as energy source.
    • Lipids: Fatty acids, energy storage, insulation.
    • Proteins: Amino acids, enzymes, structural roles.
    • Nucleic Acids: Nucleotides, carry genetic information.

    Synthesis and Breakdown of Biomolecules

    • Condensation Reaction: Water is removed to bond molecules together.
    • Hydrolysis Reaction: Water is added to break down molecules.

    Enzymes

    • Enzyme Function: Biological catalysts that speed up chemical reactions.
    • Enzyme Structure: Proteins with specific 3D shapes that provide an active site.
    • Substrate Specificity: Enzymes bind to specific substrates.
    • Enzyme Inhibitors: Competitive inhibitors block the active site; non-competitive inhibitors change the enzyme's shape.
    • Temperature and pH: Affect enzyme activity; extreme conditions denature enzymes.

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    Description

    Test your understanding of molecular structures and biomolecules in this quiz. Explore concepts such as atomic structure, ionic and covalent compounds, and the properties of water. Additionally, delve into the role of acids, bases, and pH in biological systems.

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