Biology 1401 Chapter 6 Energy And Metabolism
Questions and Answers
- 1.
Oxidation and reduction reactions are chemical processes that result in a gain or loss in
- A.
Atoms.
- B.
Neutrons.
- C.
Electrons.
- D.
Molecules.
- E.
Protons.
Correct Answer
C. Electrons.Explanation
Oxidation and reduction reactions involve the transfer of electrons between atoms or molecules. In an oxidation reaction, a substance loses electrons, while in a reduction reaction, a substance gains electrons. Therefore, the correct answer is electrons, as these reactions result in a gain or loss of electrons.Rate this question:
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- 2.
Reactions that occur spontaneously and release free energy are called _____ reactions.
- A.
Activation
- B.
Exergonic
- C.
Catabolistic
- D.
Thermodynamic
- E.
Endergonic
Correct Answer
B. ExergonicExplanation
Exergonic reactions are reactions that occur spontaneously and release free energy. These reactions are characterized by a negative change in Gibbs free energy, indicating that the products have lower energy than the reactants. In exergonic reactions, the energy released is available to do work in the cell or be used for other processes. This is in contrast to endergonic reactions, which require an input of energy to proceed. Therefore, the correct answer is exergonic.Rate this question:
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- 3.
A chemical reaction in which the products contain less energy than the ____ will tend to proceed spontaneously.
- A.
Reactants
- B.
Enzymes
- C.
Coenzymes
- D.
Substrates
- E.
Cofactors
Correct Answer
A. ReactantsExplanation
In a chemical reaction, the reactants are the starting materials that undergo a transformation to form products. The statement suggests that if the products have less energy than the reactants, the reaction will tend to occur spontaneously. This is because a spontaneous reaction is one that releases energy, and if the products have less energy, it means that energy is being released during the reaction. Therefore, the reactants are the correct answer as they are the substances that are transformed in the reaction.Rate this question:
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- 4.
Protein catalysts that speed up the various metabolic biological reactions in an organism are called.
- A.
Substrates.
- B.
Cofactors.
- C.
Reactants.
- D.
Products.
- E.
Enzymes.
Correct Answer
E. Enzymes.Explanation
Enzymes are protein catalysts that accelerate the rate of metabolic reactions in living organisms. They do so by lowering the activation energy required for a reaction to occur, thereby increasing the speed at which it takes place. Enzymes are specific to particular reactions and are not consumed or permanently altered during the process. They play a crucial role in various biological processes, such as digestion, respiration, and DNA replication. Therefore, enzymes are the correct answer to this question.Rate this question:
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- 5.
Enzymes have specific ____ with which they interact.
- A.
Products
- B.
Substrates
- C.
Reactants
- D.
Atoms
- E.
End-products
Correct Answer
B. SubstratesExplanation
Enzymes have specific substrates with which they interact. Substrates are the molecules that enzymes bind to and act upon during a chemical reaction. Enzymes have a specific shape and active site that allows them to bind to their specific substrates, facilitating the conversion of reactants into products. The interaction between enzymes and substrates is highly specific, as each enzyme can only bind to and catalyze a particular substrate or group of substrates. This specificity ensures that enzymes are able to carry out their specific functions in the body efficiently.Rate this question:
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- 6.
The specificity of an enzyme is due to its active site. The active site is shpaed so that only a certain
- A.
Substrate molecule can fit into it.
- B.
Product molecule can fit into it.
- C.
Reactant molecule can fit into it.
- D.
Cofactor molecule can fit into it.
- E.
Histone molecule can fit into it.
Correct Answer
A. Substrate molecule can fit into it.Explanation
The specificity of an enzyme is determined by its active site, which is specifically shaped to accommodate a particular substrate molecule. The active site has a unique structure that allows only the substrate molecule to fit into it, facilitating the enzymatic reaction. This specificity ensures that the enzyme only catalyzes the desired reaction with the specific substrate, while excluding other molecules such as products, reactants, cofactors, or histones from binding to the active site.Rate this question:
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- 7.
The organic non-protein components that aid in enzyme functioning are called
- A.
Reactants.
- B.
Cofactors.
- C.
Coenzymes.
- D.
Substrates.
- E.
Products.
Correct Answer
C. Coenzymes.Explanation
Coenzymes are the organic non-protein components that aid in enzyme functioning. They are essential for the catalytic activity of enzymes and often act as carriers of specific functional groups or electrons during enzymatic reactions. Unlike cofactors, which can be either organic or inorganic, coenzymes are specifically organic molecules. Substrates, on the other hand, are the molecules upon which enzymes act to catalyze a reaction, while reactants are the substances that undergo a chemical reaction. Products are the substances formed as a result of a chemical reaction.Rate this question:
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- 8.
The inorganic non-protein components that participate in enzyme catalysis are known as
- A.
Coenzymes.
- B.
Cofactors.
- C.
End-products.
- D.
Substrates.
- E.
Reactants.
Correct Answer
B. Cofactors.Explanation
Coenzymes are small organic molecules that assist enzymes in carrying out their catalytic functions. However, the question specifically asks for inorganic non-protein components, which excludes coenzymes. Cofactors, on the other hand, are inorganic molecules or metal ions that are necessary for the proper functioning of certain enzymes. Therefore, cofactors are the correct answer in this case.Rate this question:
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- 9.
The chief energy currency of all cells is a molecule called
- A.
Cyclic AMP.
- B.
NADH.
- C.
FADH.
- D.
ATP.
- E.
ADP.
Correct Answer
D. ATP.Explanation
ATP (adenosine triphosphate) is the chief energy currency of all cells. It is a molecule that stores and releases energy for cellular processes. When ATP is broken down into ADP (adenosine diphosphate) and inorganic phosphate, energy is released and can be used by the cell. This energy is required for various cellular activities, such as muscle contraction, active transport, and synthesis of macromolecules. Therefore, ATP is the correct answer as it is directly involved in providing energy for cellular functions.Rate this question:
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- 10.
The chemistry of living systems representing all chemical reactions is called
- A.
Catabolism.
- B.
Anabolism.
- C.
Metabolism.
- D.
Enzymology.
- E.
Thermodynamics.
Correct Answer
C. Metabolism.Explanation
Metabolism refers to all the chemical reactions that occur within living organisms, including catabolic and anabolic reactions. Catabolism involves breaking down complex molecules into simpler ones, while anabolism involves building complex molecules from simpler ones. Therefore, metabolism encompasses both catabolism and anabolism, making it the correct answer. Enzymology is the study of enzymes, and thermodynamics is the study of energy transformation, which are not comprehensive terms for all chemical reactions in living systems.Rate this question:
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- 11.
A calorie is the commonly used unit of chemical energy. It is also the unit of
- A.
Light.
- B.
Magnetism.
- C.
Sound.
- D.
Heat.
- E.
Radioactivity.
Correct Answer
D. Heat.Explanation
A calorie is commonly used to measure chemical energy, which is released in the form of heat during chemical reactions. It is not used to measure light, magnetism, sound, or radioactivity. Therefore, the correct answer is heat.Rate this question:
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- 12.
When an atom or molecule gains one or more electrons, it is said to be
- A.
Energized.
- B.
Oxidized.
- C.
Polarized.
- D.
Activated.
- E.
Reduced.
Correct Answer
E. Reduced.Explanation
When an atom or molecule gains one or more electrons, it undergoes reduction. Reduction is a chemical process in which the atom or molecule gains electrons and decreases its oxidation state. This leads to a decrease in the positive charge or an increase in the negative charge of the atom or molecule. Therefore, the correct answer is reduced.Rate this question:
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- 13.
Life's ultimate source of energy is derived from
- A.
The sun.
- B.
Plants.
- C.
Water.
- D.
Air.
- E.
Cells.
Correct Answer
A. The sun.Explanation
The sun is the ultimate source of energy for life on Earth. Through the process of photosynthesis, plants convert sunlight into chemical energy, which is then passed on to other organisms in the food chain. This energy is essential for the growth, development, and functioning of all living organisms. Water, air, and cells are important components of life, but they do not serve as the ultimate source of energy.Rate this question:
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- 14.
Reactions that do not proceed spontaneously because they require energy from an outside source are called
- A.
Exergonic.
- B.
Xerogonic.
- C.
Metabolic.
- D.
Endergonic.
- E.
Endocytic.
Correct Answer
D. Endergonic.Explanation
Reactions that do not proceed spontaneously because they require energy from an outside source are called endergonic. Endergonic reactions involve the absorption of energy, usually in the form of ATP, to drive the reaction forward. This energy input is necessary to overcome the activation energy barrier and facilitate the formation of products. In contrast, exergonic reactions release energy and proceed spontaneously without requiring an external energy source. The terms xerogonic, metabolic, and endocytic are not applicable to this context.Rate this question:
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- 15.
Molecules that act as catalysts in biological systems are
- A.
ATP.
- B.
Cofactors.
- C.
Coenzymes.
- D.
Enzymes.
- E.
Genes.
Correct Answer
D. Enzymes.Explanation
Enzymes are molecules that act as catalysts in biological systems. They speed up chemical reactions by lowering the activation energy required for the reaction to occur. Enzymes are typically proteins that bind to specific substrates and facilitate the conversion of these substrates into products. They are essential for various biological processes, such as metabolism, digestion, and DNA replication. ATP, cofactors, and coenzymes are also involved in biological reactions, but they do not directly act as catalysts like enzymes do. Genes, on the other hand, contain the instructions for producing proteins, including enzymes, but they are not catalysts themselves.Rate this question:
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- 16.
Enzymes catalyze chemical reactions by lowering the
- A.
Entropy.
- B.
Free energy.
- C.
Activation energy.
- D.
Enthalpy.
- E.
Calories.
Correct Answer
C. Activation energy.Explanation
Enzymes catalyze chemical reactions by lowering the activation energy. Activation energy is the energy required to start a chemical reaction. Enzymes act as catalysts by providing an alternative pathway for the reaction with a lower activation energy, allowing the reaction to occur more easily and quickly. This lowers the energy barrier for the reaction, making it more favorable and efficient.Rate this question:
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- 17.
In an enzyme catalyzed reaction the reactant is called the
- A.
Ribozyme.
- B.
Catalyst.
- C.
Substrate.
- D.
End-product.
- E.
Activator.
Correct Answer
C. Substrate.Explanation
In an enzyme catalyzed reaction, the reactant is called the substrate. Enzymes are biological catalysts that speed up chemical reactions by binding to the substrate and facilitating its conversion into the desired product. The substrate is the specific molecule that the enzyme acts upon and undergoes a chemical change during the reaction. Therefore, the correct answer is substrate.Rate this question:
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- 18.
When the substrate is bound to the enzyme, the shape of the enzyme may change slightly, leading to
- A.
A better induced fit.
- B.
A great range of possible catalytic activities.
- C.
A greater supply of activation energy.
- D.
More permanent binding through intimate total contact.
- E.
More possible products of the reaction.
Correct Answer
A. A better induced fit.Explanation
When the substrate is bound to the enzyme, the shape of the enzyme may change slightly, which allows for a better induced fit. This means that the enzyme can more effectively bind to the substrate and form the enzyme-substrate complex. This improved fit enhances the catalytic activity of the enzyme, increasing its efficiency in converting the substrate into products.Rate this question:
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- 19.
Enzymes are very specific in their choices of substrates because each different enzyme has an active site that
- A.
Depends on unusual amino acids not common in proteins.
- B.
Has a certain unique amino acid to fit each substrate.
- C.
Is shaped to fit a certain substrate molecule.
- D.
Is lined with glycolipids and glycoproteins.
- E.
Passes electrons from one part of the substrate to another.
Correct Answer
C. Is shaped to fit a certain substrate molecule.Explanation
Enzymes are proteins that catalyze specific chemical reactions in the body. The active site of an enzyme is a region where the substrate molecule binds and undergoes a reaction. The shape of the active site is crucial for the enzyme-substrate interaction. It is complementary to the shape of the substrate molecule, allowing them to fit together like a lock and key. This specific shape ensures that only the correct substrate can bind to the enzyme, leading to efficient catalysis. Therefore, the statement "is shaped to fit a certain substrate molecule" explains why enzymes are very specific in their choices of substrates.Rate this question:
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- 20.
At the conclusion of an enzyme catalyzed reaction, the enzyme
- A.
Must be resynthesized from its amino acids.
- B.
Frees itself from the product and is ready to be reused.
- C.
Must be transported from outside of the cell.
- D.
Changes into an active form.
- E.
Closes up its active site and cannot bind to more substrate.
Correct Answer
B. Frees itself from the product and is ready to be reused.Explanation
After the completion of an enzyme-catalyzed reaction, the enzyme is able to free itself from the product and is prepared to be reused. Enzymes act as catalysts, facilitating chemical reactions without being consumed in the process. Therefore, once the reaction is complete, the enzyme can detach from the product and remain available for further reactions. This ability to be reused is a fundamental characteristic of enzymes, allowing them to participate in multiple reactions and increase the efficiency of biochemical processes.Rate this question:
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- 21.
The ability of an enzyme to catalyze a reaction is not affected by
- A.
Temperature.
- B.
PH.
- C.
Salt concentration.
- D.
Binding of specific regulatory molecules.
- E.
Excess cofactor.
Correct Answer
E. Excess cofactor.Explanation
Excess cofactor does not affect the ability of an enzyme to catalyze a reaction. Enzymes require cofactors, such as metal ions or coenzymes, to function properly. However, an excess of cofactor does not enhance the enzyme's catalytic activity beyond its optimal level. Temperature, pH, salt concentration, and binding of specific regulatory molecules can all have significant effects on enzyme activity.Rate this question:
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- 22.
The sites where molecules other than substrates bind in an enzyme to alter its activity are called _____ sites.
- A.
Catalytic
- B.
Allosteric
- C.
Metabolic
- D.
Amino acid
- E.
Activity
Correct Answer
B. AllostericExplanation
Allosteric sites are sites in an enzyme where molecules other than substrates bind, causing a change in the enzyme's activity. These molecules, known as allosteric regulators, can either enhance or inhibit the enzyme's activity. Unlike the active site where substrates bind, allosteric sites are located away from the active site and can modulate the enzyme's function by inducing a conformational change. This allows for the regulation of enzyme activity in response to changes in the cell's metabolic needs or external signals. Therefore, allosteric is the correct answer for this question.Rate this question:
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- 23.
One of the most important coenzymes that accepts electrons/hydrogens is
- A.
NAD+.
- B.
NADH.
- C.
ATP.
- D.
NADPH.
- E.
Ribozyme.
Correct Answer
A. NAD+.Explanation
NAD+ is a coenzyme that plays a crucial role in accepting and transferring electrons or hydrogens during cellular respiration. It acts as an oxidizing agent, accepting electrons from molecules such as glucose and transferring them to the electron transport chain. NAD+ is converted to NADH in this process, which then participates in ATP synthesis. NAD+ is essential for energy production in cells and is involved in various metabolic reactions. On the other hand, NADPH is primarily involved in anabolic reactions, such as fatty acid and nucleotide synthesis. Therefore, NAD+ is the correct answer as it is directly involved in accepting electrons/hydrogens.Rate this question:
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- 24.
ATP gives up energy when it is converted to
- A.
DNA.
- B.
NADP.
- C.
NADH.
- D.
ADP and phosphate.
- E.
RNA.
Correct Answer
D. ADP and phosphate.Explanation
ATP (adenosine triphosphate) is an energy molecule that stores and releases energy for cellular processes. When ATP is converted to ADP (adenosine diphosphate) and phosphate, energy is released. This conversion occurs during cellular activities such as muscle contraction, active transport, and synthesis of molecules. The released energy is used to drive various metabolic reactions in the cell. Therefore, ADP and phosphate is the correct answer as ATP gives up energy when it is converted to ADP and phosphate.Rate this question:
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- 25.
Under standard conditions, ATP can release for every molecule
- A.
Less than 1 cal of energy.
- B.
1 to 2 cal of energy.
- C.
7.3 Kcal of energy.
- D.
7.3 cal of energy.
- E.
Different amounts of energy depending on the cell.
Correct Answer
C. 7.3 Kcal of energy.Explanation
Under standard conditions, ATP can release 7.3 Kcal of energy for every molecule. ATP is the primary source of energy in cells and is used for various cellular processes. The energy released from ATP is used to drive chemical reactions and perform mechanical work in the cell. This energy is released when ATP is hydrolyzed to ADP and inorganic phosphate. The hydrolysis of ATP is an exergonic reaction, meaning it releases energy. The amount of energy released is approximately 7.3 Kcal per mole of ATP under standard conditions.Rate this question:
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- 26.
The regulation of simple biochemical pathways often involves the end-product binding to the allosteric site of the first enzyme in the sequence. This mode of regulation is called
- A.
Competitive inhibition.
- B.
Biochemical regulation.
- C.
Cellular control.
- D.
Product catalysis.
- E.
Feedback inhibition.
Correct Answer
E. Feedback inhibition.Explanation
In feedback inhibition, the end-product of a biochemical pathway binds to the allosteric site of the first enzyme in the sequence, inhibiting its activity. This mechanism allows the cell to regulate the production of the end-product and prevent an excessive accumulation. By binding to the allosteric site, the end-product acts as a negative feedback signal, effectively shutting down the pathway when its concentration reaches a certain threshold. This mode of regulation ensures that the cell maintains homeostasis and optimizes the use of resources.Rate this question:
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- 27.
In a chemical reaction in a living system, enzymes are used as catalysts. Which of the following statements about enzymes is incorrect?
- A.
Enzymes enter reactions and can be reused.
- B.
Enzymes speed up chemical reactions in living systems.
- C.
Enzymes reduce the energy of activation necessary for a chemical reaction to go forward.
- D.
Enzymes increase the energy of activation necessary for a chemical reaction to go forward.
- E.
Enzymes provide energy for chemical reactions.
Correct Answer
E. Enzymes provide energy for chemical reactions.Explanation
Enzymes do not provide energy for chemical reactions. Instead, they lower the energy of activation required for a chemical reaction to occur, which speeds up the reaction. Enzymes themselves are not consumed in the reaction and can be reused.Rate this question:
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- 28.
The First Law of Thermodynamics simply states that
- A.
Energy is constantly being created in the universe.
- B.
Disorder in the universe is continually increasing.energy can be created but not destroyed.
- C.
Energy can be created but not destroyed.
- D.
Energy cannot be created or destroyed, just changed from one to another.
- E.
Energy can be recycled through the universe.
Correct Answer
D. Energy cannot be created or destroyed, just changed from one to another.Explanation
The First Law of Thermodynamics, also known as the Law of Conservation of Energy, states that energy cannot be created or destroyed, only transformed from one form to another. This means that the total amount of energy in a closed system remains constant. Energy can change from potential to kinetic, from mechanical to thermal, or from one type to another, but the total energy within the system remains the same. This principle is fundamental in understanding the behavior and transformations of energy in various physical and chemical processes.Rate this question:
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- 29.
The Second Law of Thermodynamics simply states that
- A.
Energy can be recycled through the universe.
- B.
Energy cannot be created or destroyed, just changed from one form to another.
- C.
Disorder in the universe is continually increasing.
- D.
Energy is constantly being created in the universe.
- E.
Energy can be created but not destroyed.
Correct Answer
C. Disorder in the universe is continually increasing.Explanation
The Second Law of Thermodynamics states that disorder in the universe, also known as entropy, is continually increasing. This means that systems tend to move towards a state of greater randomness and disorder over time. While energy can be converted from one form to another, it cannot be recycled indefinitely or created or destroyed. The increase in entropy is a fundamental principle that governs the behavior of energy and systems in the universe.Rate this question:
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