Chemical Reactions and Thermodynamics Quiz

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Questions and Answers

Which of the following represents two general factors that determine the fate of a chemical reaction in the living cells?

Its direction and rate (correct)

Its energy and entropy

Its rate and equilibrium

Its temperature and pressure

Water held behind a dam would best reflect ____.

Thermal energy

Potential energy (correct)

Mechanical energy

Kinetic energy

All of the following have potential energy EXCEPT

Stretched rubber band

Water in a reservoir

Nitrogen (correct)

Compressed spring

According to the first law of thermodynamics

Energy cannot be created or destroyed Signup and view all the answers

The amount of available energy that can be used to promote change or do work is called

Free energy Signup and view all the answers

Which of the following is TRUE for a reaction that has a ΔGATP?

It has a change in free energy that is greater than 0 Signup and view all the answers

A chemical reaction that has a positive ΔG is correctly described as

Endergonic Signup and view all the answers

Which of the following is TRUE for ALL exergonic reactions?

The reaction proceeds with a net release of free energy Signup and view all the answers

Which of the following statements is a logical consequence of the second law of thermodynamics?

Every chemical reaction must increase the total entropy of the universe Signup and view all the answers

Which of the following statements about enzymes is FALSE?

They are consumed in a reaction Signup and view all the answers

How does an enzyme work to catalyze a reaction?

It lowers the energy barrier needed for reactants to achieve the transition state Signup and view all the answers

Altering the 3-D structure of an enzyme might

Prevent the substrate from binding the enzyme's active site Signup and view all the answers

The primary function of an enzyme or any biological catalyst is to

Reduce the energy of activation and increase the rate of a reaction Signup and view all the answers

How can one increase the rate of a chemical reaction?

All of the above Signup and view all the answers

Which of the following statements regarding enzymes is true?

Enzymes increase the rate of a reaction Signup and view all the answers

Which of the following would best reflect the general steps of an enzyme-catalyzed reaction?

Substrates bind to enzyme -> enzyme undergoes conformational changes -> substrates are converted to products -> products are released Signup and view all the answers

Which term most precisely describes the process of building larger molecules from smaller ones?

Anabolism Signup and view all the answers

Which of the following is NOT true of ATP?

Its production requires an exergonic reaction Signup and view all the answers

Which of the following statements about catabolic reactions is FALSE?

They usually require an input of energy Signup and view all the answers

Which of the statements is INCORRECT about the following reaction? Phosphoenolpyruvate + ADP -> Pyruvate + ATP

It's anabolic Signup and view all the answers

For the generalized equation Ae- + B -> A + Be-, where e- represents an electron. Which of the following statements is TRUE?

Molecule A is oxidized and molecule B is reduced Signup and view all the answers

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

Catabolism Signup and view all the answers

Which of the following statements about feedback inhibition in metabolic pathways is most CORRECT?

The product of the pathways inhibits its own production by noncompetitively inhibiting the binding of a substrate to the active site of an enzyme within the metabolic pathway Signup and view all the answers

In the biochemical regulation of metabolic pathways, how would one overcome the effects of a competitive inhibitor on enzyme activity?

Increase the amount of substrate for the enzyme Signup and view all the answers

Which of the following structures or molecular machines is important for protein degradation in eukaryotes?

Proteasome Signup and view all the answers

Which is the correct sequence of events for protein degradation in eukaryotes?

Ubiquitin binds target protein -> protein directed to proteasome -> protein unfolds and enters proteasome -> protein digested -> amino acids released and recycled Signup and view all the answers

Which two are primary complexes for protein synthesis and degradation in eukaryotes?

Ribosomes and proteasomes Signup and view all the answers

Study Notes

Chemical Reactions and Energy

Two general factors that determine a chemical reaction's fate: direction and rate.
Water behind a dam represents potential energy.
All entities have potential energy except nitrogen.

Thermodynamics Principles

First law of thermodynamics: energy cannot be created or destroyed.
Free energy is the energy available to promote change or do work.
A reaction with ΔG > 0 indicates a change in free energy.

Reaction Types

A positive ΔG signifies an endergonic reaction.
Exergonic reactions always result in a net release of free energy.
Second law of thermodynamics dictates that every chemical reaction increases the universe's total entropy.

Enzymes and Catalysis

Enzyme substrate binding usually occurs with high affinity (false that it binds with low affinity).
Enzymes catalyze reactions by lowering energy barriers, facilitating the transition state.
Changes in an enzyme's 3-D structure can prevent substrate binding to the active site.
The primary role of an enzyme: reduce activation energy and speed up reactions.
Adding a catalyst is a common method to increase the rate of chemical reactions.

Enzyme Mechanisms

Enzyme-catalyzed reactions flow as: substrate binding → enzyme conformational change → conversion to products → product release.
Anabolic processes involve building larger molecules from smaller precursors.
It's not true that ATP production requires an exergonic reaction.

Catabolic Reactions

Catabolic reactions typically release energy, not requiring an input of energy.
Reaction for phosphoenolpyruvate and ADP is not anabolic, it is catabolic.
In the equation involving electron transfer, molecule A is oxidized while molecule B is reduced.

Feedback Inhibition and Regulation

Feedback inhibition in metabolic pathways features the product inhibiting its own production by affecting substrate binding.
Overcoming competitive inhibition requires increasing substrate concentration.

Protein Synthesis and Degradation

Proteasomes play a crucial role in protein degradation in eukaryotic cells.
Sequence of protein degradation: ubiquitin binds → targeted protein sent to proteasome → unfolds → digested → amino acids released for recycling.
Primary complexes for protein synthesis and degradation in eukaryotes are ribosomes and proteasomes.

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Description

Test your knowledge on chemical reactions, energy principles, and thermodynamics. This quiz covers key concepts such as endergonic and exergonic reactions, the laws of thermodynamics, and the role of enzymes in catalysis. Challenge yourself to better understand how these fundamental ideas interconnect in chemistry.