Biology 1 - Metabolism Chapter 8 Quiz

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Questions and Answers

What is the relationship between the Gibbs free energy (ΔG) of a reaction and whether it is spontaneous?

A reaction is spontaneous if the ΔG is zero.

A reaction is spontaneous if the ΔG is negative. (correct)

A reaction is spontaneous if the ΔG is positive.

The Gibbs free energy is not related to whether a reaction is spontaneous.

What happens to the energy of the reactants in an exergonic reaction?

Energy is released into the surroundings. (correct)

The energy of the reactants remains unchanged.

The energy of the reactants increases.

Energy is absorbed from the surroundings.

Which of the following statements accurately describes the relationship between the Gibbs free energy (ΔG) and the spontaneity of a reaction?

A reaction with a negative ΔG is spontaneous. (correct)

A reaction with a positive ΔG is spontaneous.

A reaction with a negative ΔG is non-spontaneous.

A reaction with a positive ΔG is neither spontaneous nor non-spontaneous.

How does the energy in the products compare to the energy in the reactants in an exergonic reaction?

The products have lower energy than the reactants. (C) Signup and view all the answers

What is the significance of the term 'spontaneous' when describing a chemical reaction?

The reaction will proceed without external input of energy. (C) Signup and view all the answers

What does the first law of thermodynamics state?

The total amount of energy in the universe always remains constant. (B) Signup and view all the answers

What is the Gibbs Free Energy (∆G) of a system?

The amount of energy available to do work. (A) Signup and view all the answers

What are some examples of energy forms that cells convert?

Electrochemical Potential, Light, Kinetic, and Chemical (A) Signup and view all the answers

Which of the following is NOT a process that cells use energy for?

Maintaining a stable body temperature (A) Signup and view all the answers

How does the First Law of Thermodynamics relate to cellular processes?

Cells transform energy from one form to another to perform work. (D) Signup and view all the answers

What is the relationship between Gibbs Free Energy (∆G) and Entropy (∆S) in living systems?

∆G and ∆S are indirectly proportional, meaning as one increases, the other decreases. (B) Signup and view all the answers

Why is it important to consider Gibbs Free Energy (∆G) when studying cellular processes?

∆G tells us how much energy is available to do work. (C) Signup and view all the answers

Which of the following is NOT a factor that affects Gibbs Free Energy (∆G)?

The mass of the reactants and products (B) Signup and view all the answers

What is the defining characteristic of living organisms that differentiates them from a closed system in terms of Gibbs free energy?

Living organisms exist in a state of constant disequilibrium, ensuring ongoing energy flow. (B) Signup and view all the answers

Which of the following scenarios would represent a reaction with a positive Gibbs free energy change (ΔG > 0)?

The synthesis of proteins from amino acids. (D) Signup and view all the answers

In the context of Gibbs free energy, what is the key distinction between an isolated hydroelectric system and an open hydroelectric system?

The open system maintains a constant energy flow while the isolated system eventually reaches equilibrium. (B) Signup and view all the answers

Which of the following statements accurately describes a catabolic pathway in a cell?

A catabolic pathway releases free energy through a series of reactions, resulting in a negative Gibbs free energy change (ΔG < 0). (D) Signup and view all the answers

Why is a negative Gibbs free energy change (ΔG < 0) associated with a spontaneous reaction?

Negative ΔG indicates the reaction releases energy and is therefore spontaneous. (C) Signup and view all the answers

What is the significance of the statement "Reactions in a closed system eventually reach equilibrium and then do no work" in relation to living organisms?

Living organisms are open systems, constantly exchanging matter and energy, thus preventing them from reaching equilibrium and ensuring ongoing work. (A) Signup and view all the answers

Which of the following choices would correctly represent the change in Gibbs free energy (ΔG) for a reaction that requires energy input to occur?

ΔG > 0 (A) Signup and view all the answers

Which of the following statements is the most accurate description of Gibbs free energy (ΔG)?

Gibbs free energy is the energy available to do useful work, and can be positive, negative, or zero. (A) Signup and view all the answers

What is the name for the process of breaking down complex molecules into simpler compounds?

Catabolism (A) Signup and view all the answers

Which of the following is an example of a metabolic pathway?

All of the above (D) Signup and view all the answers

What is the role of enzymes in metabolic pathways?

Enzymes speed up reactions. (C) Signup and view all the answers

Why is the regulation of metabolic pathways important?

All of the above (D) Signup and view all the answers

What is the main difference between catabolic and anabolic pathways?

Catabolic pathways require energy, while anabolic pathways release energy. (C) Signup and view all the answers

Why is metabolism considered an emergent property of life?

Metabolism is a property that arises from the interactions between molecules within a cell. (B) Signup and view all the answers

What is the role of ATP in metabolism?

ATP is a molecule that plays a role in both anabolic and catabolic reactions. (D) Signup and view all the answers

According to the second law of thermodynamics, what is the tendency of energy transfer and transformations?

Every energy transfer or transformation increases the entropy of the universe. (A) Signup and view all the answers

What does the Gibbs Free Energy (ΔG) represent in a chemical reaction?

The energy available to do work in a system. (D) Signup and view all the answers

Which statement correctly describes the relationship between enthalpy (H), entropy (S), and Gibbs Free Energy (ΔG)?

ΔG = H - TΔS (D) Signup and view all the answers

What does it mean if the Gibbs Free Energy (ΔG) for a reaction is less than zero (ΔG < 0)?

The reaction is spontaneous. (A) Signup and view all the answers

In a biological system, how do the changes in enthalpy (H) and entropy (S) typically manifest in living cells?

Enthalpy increases, entropy decreases. (C) Signup and view all the answers

Which of the following is NOT a component of the thermodynamic driving force of a chemical reaction?

Kinetic Energy (D) Signup and view all the answers

What is the main reason why energy is lost as heat during energy transfer or transformation?

The tendency for energy to disperse into a more spread-out state. (D) Signup and view all the answers

Which of the following represents the correct interpretation of the Gibbs Free Energy equation: ΔG = H - TΔS?

The Gibbs Free Energy is equal to the enthalpy minus the product of temperature and entropy. (D) Signup and view all the answers

Study Notes

Biology 1 - Cells, Molecular Biology and Genetics (Biol 1000)

Course instructor: Dr. Michael Cardinal-Aucoin
Course offering: Winter 2025
Course code: Biol 1000

Metabolism (Chapter 8)

Metabolism is the totality of an organism's chemical reactions
Metabolism transforms matter and energy
Metabolism is an emergent property of life that arises from interactions between molecules within the cell.
Metabolic pathways are organized into steps catalyzed by specific enzymes, which are typically regulated at the level of one of these enzymes.

Overview of Metabolism

Catabolism breaks down substances, such as in digestion
Anabolism builds up substances, for example protein synthesis in muscle
Catabolic pathways release energy by breaking down complex molecules into simpler compounds
Cellular respiration involves the breakdown of glucose in the presence of oxygen to form CO2, water, and ATP.

Basic Thermodynamics and Energy

All chemical systems (e.g., organisms, cells) contain energy, which is also referred to as enthalpy (H).
Cells convert energy from one form to another. Forms include kinetic energy (movement), chemical energy (stored in chemical bonds), light energy, and electrochemical potential energy (e.g., concentration gradient).
Energy can be transferred or transformed but it cannot be created or destroyed (First Law of Thermodynamics).
During every energy transfer or transformation, some energy is unusable and is often lost as heat (Second Law of Thermodynamics).
Entropy is a measure of disorder.
Gibbs free energy (ΔG) is the proportion of a system's energy that can perform work. A negative ΔG means the reaction is spontaneous. A positive ΔG means the reaction is non-spontaneous.

Exergonic and Endergonic Reactions

Exergonic reactions release energy (ΔG < 0) and are spontaneous.
Endergonic reactions absorb energy (ΔG > 0) and are non-spontaneous.
Gibbs free energy is the difference in energy between reactants and products.

Enzymes

Enzymes are proteins that accelerate a chemical reaction by decreasing the activation energy (Ea).
Enzymes do not alter the free energy (ΔG) of the reaction.
The activation energy (Ea) is the minimum amount of energy required before collisions between reactants will give rise to products.
The active site is the region of an enzyme where the substrate binds.
Induced fit of a substrate allows the enzyme to better catalyze the reaction.
Enzymes can be affected by cofactors and coenzymes.
Enzymes are specific and can exhibit different optimal conditions such as temperature and pH.
Feedback inhibition involves the end product of a metabolic pathway inhibiting an earlier step in the pathway.
Enzymes can be regulated through phosphorylation.

Enzyme Action

Various factors can affect enzyme activity, including substrate concentration, competitive inhibition, allosteric activation, and phosphorylation.

ATP

ATP is the energy currency of the cell and is used to do work.
Cells use ATP to do chemical work (e.g., polymerization), transport work (e.g., transporting substances), and mechanical work (e.g., moving structures like cilia).
ATP drives endergonic reactions by the reaction of ATP hydrolysis (breaking down)
ATP is a renewable resource regenerated in the cell by adding a phosphate group to ADP.

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Description

Test your knowledge on Chapter 8 of Biology 1, focusing on metabolism, including catabolic and anabolic pathways. Explore how organisms convert matter and energy through various chemical reactions and understand the principles of basic thermodynamics involved in metabolic processes.