51 Questions
According to the laws of thermodynamics, which statement best describes biological processes?
Biological processes obey the laws of thermodynamics, with energy transformations subject to physical laws.
How does ATP power cellular work?
By coupling exergonic reactions to endergonic reactions.
How do enzymes speed up metabolic reactions?
By lowering the activation energy required for the reaction to occur.
What does the free-energy change of a reaction tell us?
Whether or not the reaction occurs spontaneously.
What is the equation to calculate the free-energy change (ΔG) for a chemical reaction?
$ΔG = ΔH - TΔS$
What conditions can affect the ΔG value of a chemical reaction?
pH and temperature
What type of processes are observed in nature?
Processes with a negative ΔG
What does a negative ΔG indicate?
A loss of free energy and increased stability in the final state
What does free energy serve as a measure of?
A system's instability and tendency to change to a more stable state
What is the state of maximum stability?
Equilibrium
How are chemical reactions classified based on their free-energy changes?
Exergonic (release of free energy) or endergonic (absorption of free energy)
Can systems at equilibrium perform work?
No, systems at equilibrium cannot perform work
What type of reactions occur spontaneously due to the release of free energy?
Exergonic reactions
What is free energy harnessed for in spontaneous changes?
To perform work
Why is understanding free energy crucial in the study of metabolism?
To determine which reactions can supply energy for cellular work
What is the first law of thermodynamics?
Energy can be transferred and transformed, but not created or destroyed
What is the second law of thermodynamics primarily concerned with?
Increasing the entropy of the universe
What is metabolism?
The totality of an organism’s chemical reactions and an emergent property of life
What are metabolic pathways?
A series of defined steps that alter specific molecules, catalyzed by enzymes
What do catabolic pathways do?
Release energy by breaking down complex molecules
What do anabolic pathways do?
Consume energy to build complicated molecules from simpler ones
What is energy?
The capacity to cause change and exists in various forms
What is chemical energy?
The potential energy available for release in a chemical reaction; high in complex molecules like glucose
How do catabolic reactions release energy?
By breaking bonds and forming new ones, resulting in lower-energy breakdown products
What are the waste products of the transformation of chemical energy in biological systems?
Carbon dioxide and water
What does bioenergetics study?
How energy flows through living organisms
Why is a basic knowledge of energy necessary to understand how the living cell works?
Because energy is the capacity to cause change
What does the first law of thermodynamics state?
Energy can be transferred and transformed, but not created or destroyed
What is the second law of thermodynamics primarily concerned with?
Increase in disorder (entropy) of the universe
What is entropy a measure of?
Molecular disorder
What does the second law of thermodynamics state about energy transfer or transformation?
It increases the disorder (entropy) of the universe
What is the study of energy transformations in matter called?
Thermodynamics
What is the system in the context of thermodynamics?
Universe
What is the surroundings in the context of thermodynamics?
Everything outside the universe
What is the loss of usable energy as heat to the surroundings responsible for?
Increasing entropy
When can a system put thermal energy to work?
When there is a temperature difference
What does the second law of thermodynamics state about the universe as a whole?
There is an unstoppable trend toward randomization
What do organisms act as in the context of energy transformations?
Energy transformers
What does the study of energy transformations in matter enable cells to do?
Release chemical energy from food molecules
Which law helps predict energetically favorable processes and spontaneous vs. nonspontaneous processes?
Second law of thermodynamics
What type of energy flow into ecosystems and exits as heat, contributing to the overall increase in entropy?
Light energy
What is a good analogy for an increase in entropy according to the text?
The disintegration of a system’s organized structure
What is the symbol used to represent Gibbs free energy?
G
What does the increase in biological order over time not violate?
The second law of thermodynamics
What does the concept of entropy refer to in a system?
Increase in disorder
What do living systems do to the entropy of their surroundings?
Increase it
What is the form in which energy flows into ecosystems, contributing to the overall increase in entropy?
Light
What does the depletion of chemical energy in organisms account for?
Heat generated during metabolism
What does the evolution of biological order align with?
The second law of thermodynamics
What does the increase in disorder result from in biological processes?
Conversion of chemical energy to heat and less ordered forms of matter
What does Gibbs free energy measure the portion of?
Energy that can perform work when temperature and pressure are uniform
Study Notes
Metabolism and Energy in Living Organisms
- The first law of thermodynamics states that energy can be transferred and transformed, but not created or destroyed
- The second law of thermodynamics states that every energy transfer or transformation increases the entropy of the universe
- Metabolism is the totality of an organism’s chemical reactions and is an emergent property of life
- Metabolic pathways are a series of defined steps that alter specific molecules, catalyzed by enzymes
- Catabolic pathways release energy by breaking down complex molecules, such as in cellular respiration
- Anabolic pathways consume energy to build complicated molecules from simpler ones
- Energy is the capacity to cause change and exists in various forms, including kinetic, thermal, light, and potential energy
- Chemical energy is the potential energy available for release in a chemical reaction; high in complex molecules like glucose
- Catabolic reactions release energy by breaking bonds and forming new ones, resulting in lower-energy breakdown products
- The transformation of chemical energy also occurs in biological systems, producing carbon dioxide and water as waste products
- These principles apply to bioenergetics, the study of how energy flows through living organisms
- A basic knowledge of energy is necessary to understand how the living cell works
Understanding Entropy and Biological Order
- Entropy refers to the increase in disorder in a system, illustrated by the decay of an unmaintained building over time.
- The concept of entropy helps explain energetically favorable processes and spontaneous vs. nonspontaneous processes.
- Living systems increase the entropy of their surroundings, as predicted by thermodynamic law.
- Despite increasing entropy, cells create ordered structures from less organized starting materials through various biological processes.
- Energy flows into ecosystems in the form of light and exits as heat, contributing to the overall increase in entropy.
- The increase in biological order over time does not violate the second law of thermodynamics; organisms are islands of low entropy in an increasingly random universe.
- The physical disintegration of a system’s organized structure is a good analogy for an increase in entropy.
- Biological processes convert chemical energy to kinetic energy, increasing disorder by producing heat and less ordered forms of matter.
- Some spontaneous processes, such as an explosion, may be virtually instantaneous, while others, such as the rusting of an old car over time, are much slower.
- The depletion of chemical energy in organisms is accounted for by heat generated during metabolism.
- The evolution of biological order is consistent with the laws of thermodynamics.
- Gibbs free energy, symbolized by G, is a useful function that measures the portion of a system’s energy that can perform work when temperature and pressure are uniform throughout the system.
Test your knowledge of metabolism, energy transformations, and thermodynamics with this quiz. Explore the first and second laws of thermodynamics, metabolic pathways and energy flow in living organisms. Gain a deeper understanding of bioenergetics and the principles that govern energy transfer and transformation in biological systems.
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