Chemical Reactions and Enzymes Quiz
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Questions and Answers

What are the initial substances in a chemical reaction called?

  • Enzymes
  • Reactants (correct)
  • Catalysts
  • Products

In a chemical reaction, atoms are created and destroyed to form new substances.

False (B)

What does a chemical equation model?

what happens in a chemical reaction

Chemical reactions change substances by breaking chemical ______ and forming new ones.

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

Match the following terms with the correct description:

<p>Reactants = Initial substances in a chemical reaction Products = Substances formed by a chemical reaction Chemical Bonds = Forces holding atoms together Chemical Equation = Model of what happens in a chemical reaction</p> Signup and view all the answers

What are the products of the chemical reaction when hydrogen peroxide breaks down?

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

The properties of the products are the same as the properties of the reactants in a chemical reaction.

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

What is the physical evidence that hydrogen peroxide is undergoing a chemical reaction?

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

What occurs at the equilibrium point in a reversible chemical reaction?

<p>Reactants and products are present, and the reaction proceeds in both directions at equal rates. (D)</p> Signup and view all the answers

A reversible reaction will eventually stop if left long enough.

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

What is bond energy?

<p>The amount of energy needed to break a specific chemical bond.</p> Signup and view all the answers

The amount of energy needed to start a chemical reaction is called the ______ energy.

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

Match the following concepts with their descriptions:

<p>Equilibrium = State where forward and reverse reaction rates are equal Activation energy = Energy needed to start a chemical reaction Bond energy = Energy required to break a specific chemical bond Reversible reaction = A chemical reaction that can proceed in both directions</p> Signup and view all the answers

What happens if some of the products of a reversible reaction are removed?

<p>The reaction proceeds in the direction required to restore the reactants and products to equilibrium. (B)</p> Signup and view all the answers

All chemical reactions release more energy than they absorb.

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

Explain the relationship between activation energy and the start of a chemical reaction.

<p>Activation energy is the minimum amount of energy that reactants must absorb to start a chemical reaction.</p> Signup and view all the answers

In the reaction 2H₂O₂ → 2H₂O + O₂, what happens to the atoms?

<p>The atoms are rearranged and bonded differently. (B)</p> Signup and view all the answers

In an irreversible chemical reaction, the reactants are never fully consumed.

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

What does the double arrow (⇌) indicate in a chemical reaction?

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

In the blood, carbon dioxide reacts with water to form ______.

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

In the reaction 2H₂O₂ → 2H₂O + O₂, which of the following is a product?

<p>Hâ‚‚O (C)</p> Signup and view all the answers

Match the following reaction types with their description:

<p>Irreversible Reaction = Proceeds in one direction until a reactant is completely consumed Reversible Reaction = Proceeds to an equilibrium point and in two directions</p> Signup and view all the answers

Matter is not conserved during chemical reactions.

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

What does the reaction in Figure 13 (2H₂O₂ → 2H₂O + O₂) illustrate about matter?

<p>Matter is conserved, even though molecules change. (D)</p> Signup and view all the answers

What is the name of the model where the enzyme's structure is not seen as fixed?

<p>Induced-fit model (D)</p> Signup and view all the answers

Enzymes function at their best in a wide temperature range.

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

What two molecules make up maltose?

<p>glucose molecules</p> Signup and view all the answers

Substrates fit into the ______ sites of enzymes.

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

Match the following terms with their description:

<p>Substrate = Molecule that the enzyme acts on Active Site = Region on an enzyme where substrate binds Enzyme = Catalyst that speeds up chemical reactions Induced Fit = The change in shape of the enzyme when a substrate binds</p> Signup and view all the answers

What can affect the shape and function of a protein enzyme?

<p>Both changes in temperature and pH (C)</p> Signup and view all the answers

The 'lock and key' model shows enzymes as static structures.

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

What is one way bonds in substrates are weakened?

<p>bending of enzyme</p> Signup and view all the answers

What happens to an enzyme when it denatures?

<p>It begins to unravel and unfold. (C)</p> Signup and view all the answers

All enzymes function optimally at a neutral pH.

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

Besides temperature, what other factor can cause an enzyme to denature?

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

The bonds that are affected by changes in temperature or pH in enzymes are called __________ bonds.

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

Match the enzyme with its optimal environment:

<p>Enzymes in the stomach = Acidic conditions Enzymes in the small intestine = Slightly basic conditions Many enzymes in cells = Nearly neutral pH</p> Signup and view all the answers

Why might a very high fever be dangerous for humans, according to the information?

<p>It can cause enzymes to denature, disrupting vital functions. (D)</p> Signup and view all the answers

Enzymes in the stomach are resistant to denaturation by the stomach's acidic environment.

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

What common example of denaturation can be seen while cooking?

<p>cooking an egg</p> Signup and view all the answers

What happens to protein molecules in egg whites when they start cooking?

<p>They extend and form a network. (C)</p> Signup and view all the answers

Denatured proteins can always regain their normal function.

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

Explain how denaturation affects enzymes.

<p>Denaturation alters the shape of enzymes, preventing them from properly accepting substrate molecules, which affects their catalytic function.</p> Signup and view all the answers

The proteins in egg whites change from _____ to a gel-like substance when cooked.

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

Match the terms with their definitions:

<p>Denaturation = The process of protein structure alteration Enzyme = A protein that acts as a catalyst Catalyst = A substance that increases the rate of a chemical reaction Substrate = The molecule upon which an enzyme acts</p> Signup and view all the answers

Flashcards

What are reactants?

Substances that are changed during a chemical reaction. They are the starting materials.

What are products?

The substances formed by a chemical reaction. They are the end result of the reaction.

How do chemical reactions change substances?

Chemical reactions break and form bonds to change substances into different substances. This process rearranges atoms but doesn't create or destroy them.

What is a chemical equation?

A way to represent a chemical reaction, showing the reactants on the left side and the products on the right side. It also illustrates the conservation of matter.

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What is the principle of conservation of matter?

The principle that matter cannot be created or destroyed in chemical reactions. Atoms are simply rearranged.

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What is an enzyme?

A type of protein that speeds up chemical reactions without being consumed in the process.

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How do enzymes work?

Enzymes work by lowering the activation energy needed for a reaction to occur, making it easier and faster. They are specific to certain reactions.

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Why are chemical reactions important in living things?

Chemical reactions are crucial for life processes, such as breaking down food for energy, building new molecules, and maintaining life.

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Chemical Reaction

A chemical change where atoms are rearranged and bonds are broken and formed, resulting in new substances with different properties.

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Reactants

The substances that react with each other to form products in a chemical reaction.

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Products

The new substances that are formed in a chemical reaction.

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Conservation of Matter

The principle that states that matter cannot be created or destroyed in a chemical reaction, only transformed.

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Reversible Chemical Reaction

A chemical reaction that can proceed in both directions, reaching a state of balance where the rates of the forward and reverse reactions are equal.

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Chemical Equilibrium

The point in a reversible reaction where the rates of the forward and reverse reactions are equal, and the concentrations of reactants and products remain constant.

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Irreversible Chemical Reaction

A chemical reaction that proceeds in one direction only, until all reactants are consumed.

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Acid

A substance that can donate a proton (H+ ion) in a chemical reaction.

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Protein Denaturation

The process where proteins lose their original shape and function, often caused by heat, pH changes, or other environmental factors.

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Enzymes

A substance that speeds up a chemical reaction without being consumed in the process. They are usually proteins with a specific shape that fits the reacting molecules.

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Induced-fit model

The model where an enzyme changes shape slightly to better fit its substrate, like a lock bending around a key.

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Substrate

The molecule that an enzyme acts upon, like a key fitting into a lock.

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Active site

The specific region on an enzyme where the substrate binds, much like a key fits into a lock.

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Lock-and-key model

The model where the enzyme and substrate have complementary shapes, fitting together like a lock and key.

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Enzyme's 3D structure

The 3D structure formed by a protein due to interactions between its amino acids, critical for enzyme function.

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Factors affecting enzyme activity

Factors that can change an enzyme's shape and therefore its function, leading to decreased activity.

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Optimal temperature range for enzymes

The range of temperatures where an enzyme functions optimally, often around the organism's normal body temperature.

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Equilibrium

A point where the forward and reverse reaction rates are equal, resulting in no net change in concentrations of reactants and products.

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Reversible Reactions

Reactions that can proceed in both directions, involving the conversion of reactants to products and vice versa.

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Activation Energy

The minimum amount of energy that reactants must absorb to initiate a chemical reaction.

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Exothermic Reactions

Reactions that release more energy than they absorb, resulting in a net release of energy.

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Endothermic Reactions

Reactions that absorb more energy than they release, requiring energy input to proceed.

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Bond Energy

The amount of energy required to break a specific chemical bond.

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Le Chatelier's Principle

The principle that states a system will always shift to regain equilibrium if disturbed, by favoring the direction that relieves the stress.

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Homeostasis

The maintenance of a stable internal environment within a living organism.

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Enzyme Denaturation

The process of an enzyme losing its shape and function due to factors like extreme temperature or pH changes.

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How does denaturation affect enzyme function?

When an enzyme's shape is altered, usually due to heat or pH changes, it can no longer bind to its substrate and catalyze reactions efficiently.

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How does temperature affect enzyme denaturation?

Extreme temperatures, especially high temperatures, disrupt the weak bonds that hold an enzyme's structure together, leading to denaturation.

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Why is a high fever dangerous?

A very high fever changes the internal body temperature, causing enzymes to denature, disrupting metabolic processes vital for life.

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How does pH affect enzyme denaturation?

Enzymes work best within a specific pH range. Outside this range, their shape can be altered, leading to denaturation and reduced activity.

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What is the typical pH range for most enzymes in the body?

Many enzymes in the body operate within a narrow pH range, around neutral (pH 7), to function optimally.

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How do stomach enzymes resist denaturation in the acidic environment?

Stomach enzymes are adapted to work effectively in the acidic environment of the stomach, where they help break down food.

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Why are enzymes crucial for living organisms?

Enzymes are essential for vital processes like digestion, respiration, and DNA replication. Denaturation disrupts these reactions, affecting overall health.

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Are all enzymes equally sensitive to pH changes?

The pH requirements vary between enzymes. Stomach enzymes thrive in acidic conditions, while others, like those in the intestines, function best in slightly basic environments.

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Study Notes

Chemical Reactions and Enzymes

  • Chemical reactions rearrange atoms, breaking and forming chemical bonds.
  • Reactants are the starting substances, and products are the resulting ones.
  • Chemical reactions involve the rearrangement of atoms, producing substances with different properties.
  • Chemical equations show reactants on the left and products on the right.
  • Atoms are conserved in chemical reactions, not created or destroyed.

Energy and Matter

  • Chemical reactions involve energy changes.
  • The reactants absorb energy to break bonds and release energy as new bonds form.
  • The amount released/needed depends on the bond energy of reactants and products.
  • Activation energy is the energy needed to initiate a reaction.
  • An example shows hydrogen peroxide breaking down to water and oxygen.

Chemical Equilibrium

  • Some reactions proceed to equilibrium or completion, consuming all reactants.
  • Reversible reactions proceed in both directions, reaching an equilibrium point where both reactants and products are present.
  • Maintaining equilibrium involves continuing reactions in both directions at equal rates.
  • Adding or removing products or reactants can change the equilibrium point. example: Carbon dioxide reacting with water to form carbonic acid in blood.

Activation Energy

  • All chemical reactions need a certain amount of initial energy to start.
  • This initial energy is called activation energy.
  • Enzymes are biological catalysts that lower the activation energy of reactions without being consumed in the process.
  • Activation energy is represented by the peak of an energy graph relative to the energy levels of products and reactants.

Catalysts - Enzymes

  • Catalysts speed up reactions, and enzymes are biological catalysts.
  • Enzymes reduce the activation energy required for reactions, increasing the rate.
  • Reaction rates depend on concentrations of reactants, collisions with sufficient force, and correct orientation during collisions.
  • Enzymes are proteins with specific, three-dimensional structures (active sites) that bind to substrates, facilitating reactions.

Endothermic and Exothermic Reactions

  • Exothermic reactions release more energy than they absorb.
  • Endothermic reactions absorb more energy than they release.
  • The difference in energy is represented by the graph of the reaction.
  • Energy can be in the form of heat or light.
  • Endothermic reactions feel cold because they absorb heat from the surroundings.
  • Exothermic reactions feel warm because they release heat.

Enzyme Structure and Function

  • Enzymes have specific shapes that allow only specific reactants (substrates) to bind to the active site.
  • This is the "lock-and-key" model of enzyme action: specific substrate fits the active site.
  • The enzyme's shape can change slightly upon binding to increase the bond-breaking efficiency (induced-fit).
  • Enzyme function depends on their specific three-dimensional structure.
  • Changes in temperature or pH can alter the enzyme's structure and function, leading to denaturation (loss of activity).

Other Key Concepts

  • Chemical reactions are crucial for life processes, from digestion to respiration.
  • Catalysts and enzymes are important for regulating reaction rates in organisms.

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Chemical Reactions and Enzymes PDF

Description

Test your knowledge on chemical reactions, enzymes, and the principles of energy changes in chemical processes. This quiz also covers the concept of chemical equilibrium. Challenge yourself to understand how reactants and products interact in chemical equations.

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