Enzymes and Their Investigations
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Questions and Answers

What are enzymes?

Catalysts that speed up the rate of a chemical reaction without being changed or used up in the reaction.

Which of the following best describes enzyme specificity?

  • Enzymes are specific to one particular substrate. (correct)
  • Enzymes do not participate in reactions.
  • Enzymes are non-specific catalysts.
  • Enzymes can act on multiple substrates.

    • What happens when starch solution is mixed with amylase?

    The amylase breaks down the starch in the solution.

    Enzymes are made in non-living cells.

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

    What is the lock and key model related to?

    <p>Enzyme activity and specificity.</p> Signup and view all the answers

    If we did not produce digestive enzymes, it would take around _ weeks to digest one meal.

    <p>2-3</p> Signup and view all the answers

    What is recorded during the enzyme investigations?

    <p>The time taken for the reaction to be completed.</p> Signup and view all the answers

    What happens when the iodine solution remains orange-brown during the pH experiment?

    <p>The reaction is complete.</p> Signup and view all the answers

    What is the primary function of enzymes in living organisms?

    <p>To act as catalysts in chemical reactions</p> Signup and view all the answers

    Enzymes are unchanged after a chemical reaction.

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

    What model describes the specificity of enzyme action?

    <p>Lock and key model</p> Signup and view all the answers

    Enzymes are __________ made in living cells.

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

    How quickly do enzymes allow for the digestion of a meal compared to without enzymes?

    <p>Around 4 hours</p> Signup and view all the answers

    All enzymes work on multiple substrates.

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

    What would happen if we did not produce digestive enzymes?

    <p>It would take around 2-3 weeks to digest one meal.</p> Signup and view all the answers

    Match the type of reaction with its description:

    <p>Decomposition = Breaks down molecules into smaller units Synthesis = Combines smaller units into larger compounds Hydrolysis = Breaks down molecules using water Condensation = Joins molecules by removing water</p> Signup and view all the answers

    What indicates that starch has been digested during the pH experiment with amylase?

    <p>The iodine solution remains orange-brown</p> Signup and view all the answers

    Amylase activity increases as the pH moves away from its optimal level.

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

    What should be done every 10 seconds after mixing the starch solution with amylase and buffer?

    <p>Place a drop of mixture on the iodine solution.</p> Signup and view all the answers

    The enzyme amylase works best at a specific ______.

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

    Match the terms with their descriptions:

    <p>Amylase = Enzyme that breaks down starch Buffer solution = Maintains pH stability Iodine test = Indicator for starch presence Denaturation = Loss of enzyme activity due to structural change</p> Signup and view all the answers

    What is the consequence of a low temperature on enzyme activity?

    <p>Molecules have low kinetic energy</p> Signup and view all the answers

    The experiment should only be conducted at a single pH value to obtain reliable results.

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

    What is checked by observing the color change of the iodine solution?

    <p>The completion of starch digestion by amylase.</p> Signup and view all the answers

    What is the optimum temperature for enzyme activity in the human body?

    <p>37⁰C</p> Signup and view all the answers

    Denaturation of enzymes is a reversible process.

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

    What happens to enzymes when exposed to temperatures beyond their optimum?

    <p>They denature.</p> Signup and view all the answers

    Increasing temperature from 0⁰C to the optimum __________ enzyme activity.

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

    Why do low temperatures not denature enzymes?

    <p>They do not affect enzyme shape.</p> Signup and view all the answers

    Match the following terms related to enzymes with their definitions:

    <p>Optimum temperature = Ideal temperature for enzyme activity Denaturation = Loss of enzyme shape and function Active site = Region where substrate binds Substrate = Molecule upon which an enzyme acts</p> Signup and view all the answers

    Increasing molecular movements decreases the rate of reaction in enzymes.

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

    What happens to the active site of an enzyme when it is denatured?

    <p>It loses its shape.</p> Signup and view all the answers

    What is the primary factor that determines enzyme specificity?

    <p>The shape of the enzyme's active site</p> Signup and view all the answers

    The lock and key hypothesis illustrates how enzymes can fit multiple substrates.

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

    What happens to the enzyme after the reaction has occurred?

    <p>The enzyme is unchanged and can catalyze further reactions.</p> Signup and view all the answers

    The formation of an enzyme-substrate complex occurs when the substrate fits into the enzyme's ______.

    <p>active site</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Enzyme = A protein that catalyzes biochemical reactions Substrate = The molecule upon which an enzyme acts Active site = The region of the enzyme that binds to the substrate Enzyme-substrate complex = The temporary complex formed when an enzyme binds to its substrate</p> Signup and view all the answers

    In the enzyme action process, what happens immediately after an enzyme and substrate collide?

    <p>An enzyme-substrate complex is formed</p> Signup and view all the answers

    Enzymes are changed during the reaction and cannot be reused.

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

    What is the role of the enzyme in a biochemical reaction?

    <p>To lower the activation energy and speed up the reaction.</p> Signup and view all the answers

    What is the optimum pH for most enzymes?

    <p>pH 7</p> Signup and view all the answers

    Enzymes can function properly in both acidic and alkaline conditions regardless of their optimum pH.

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

    What happens to an enzyme when the pH is moved too far away from its optimum level?

    <p>The enzyme denatures and activity stops.</p> Signup and view all the answers

    Enzymes produced in the stomach have an optimum pH of ______.

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

    Match the following enzymes with their typical environment:

    <p>Pepsin = Stomach (pH 2) Chymotrypsin = Duodenum (pH 8) Amylase = Saliva (pH 7) Lipase = Duodenum (pH 8)</p> Signup and view all the answers

    Study Notes

    Enzymes

    • Enzymes are biological catalysts that speed up chemical reactions without being used up.
    • Enzymes are proteins that are essential to all living organisms.
    • Enzymes maintain the speed of metabolic reactions, which are the chemical reactions that keep organisms alive.
    • Enzymes are specific to particular substrates, meaning they only break down or join together certain molecules.
    • The enzyme's shape complements the shape of the substrate, allowing them to bind together.

    Enzyme Investigations

    • Experiments can be conducted to investigate the effect of temperature and pH on enzyme activity.
    • Investigating Effect of Temperature on Amylase:
      • Starch solution is heated to a set temperature.
      • Amylase is added to the starch solution, and the time taken for the reaction to be completed is recorded.
      • The experiment is repeated at different temperatures.
      • The quicker the reaction is completed, the faster the enzyme is working.

    Enzyme Action & Specificity

    • Enzymes are specific to one particular substrate.
    • The enzyme's shape is complementary to the substrate (lock and key model).
    • The product of the reaction is made from the substrate and released.

    Enzymes & Temperature

    • Enzyme activity increases with temperature until it reaches its optimal temperature.
    • At the optimal temperature, the enzyme works fastest.
    • After the optimal temperature, enzyme activity decreases as the enzyme denatures, meaning it loses its shape.

    Enzymes & pH

    • Enzymes have an optimal pH at which they work best.
    • If the pH is too acidic or too alkaline, the enzyme may denature and lose its activity.

    Enzymes

    • Enzymes are biological catalysts, meaning they speed up reactions without being used up.
    • They are proteins, essential for maintaining all metabolic reactions in living organisms.
    • Enzymes are specific to a particular substrate, meaning they only work with certain molecules.
    • The active site of an enzyme has a specific shape that is complementary to its substrate.
    • This is known as the lock and key model.
    • The enzyme and substrate form an enzyme-substrate complex, where the reaction occurs.
    • The products are then released, leaving the enzyme unchanged and ready to catalyze further reactions.

    Investigating enzyme activity

    • Investigating the effect of temperature on enzyme activity involves measuring the rate of a reaction at different temperatures.
    • Investigating the effect of pH on enzyme activity involves measuring the rate of a reaction at different pH levels.

    Investigating the effect of temperature on enzyme activity

    • Enzyme activity increases from 0°C to the optimum temperature as molecules have more kinetic energy and collide more frequently.
    • Enzymes denature at high temperatures, losing their shape and becoming inactive.
    • Denaturation is irreversible.

    Investigating the effect of pH on enzyme activity

    • Enzymes have an optimum pH at which they function best.
    • Most enzymes have an optimum pH of 7, but some have different optima depending on their function.
    • Extreme pH levels can denature enzymes and stop their activity.

    Enzymes & Temperature (Extended)

    • Enzymes are proteins with a specific shape maintained by bonds.
    • This shape is crucial for the active site and allows the enzyme to interact with its specific substrate.
    • Enzymes function optimally at a specific temperature, typically 37°C in the human body.

    Enzymes & pH (Extended)

    • The optimum pH for most enzymes is 7, while some have lower (e.g., stomach enzymes) or higher (e.g., duodenum enzymes) optima.
    • Extreme pH levels can disrupt the bonds in an enzyme, altering its shape and making it inactive.
    • Denaturation is irreversible and results in a complete loss of function.

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    Cambridge CIE IGCSE Biology Enzymes PDF

    Description

    Explore the fascinating world of enzymes, biological catalysts vital for life. This quiz covers enzyme functionality, specificity, and experiments designed to investigate the effects of temperature and pH on enzyme activity. Test your understanding of how enzymes work and their roles in metabolic reactions.

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