Biology - topic 8-9 study questions
When glucose monomers are joined together by glycosidic linkages to form a cellulose polymers, the charges in free energy, enthalpy and entropy are as follows:
+ ΔH, -ΔS, +ΔG
Which of the following is an example of potential energy rather than kinetic energy?
A food molecule
Which of the following is an example of potential rather than kinetic energy
A food molecule
Which of the following is considered an open system?
All of these (a clam; an animal cell; a plant cell with a strong cell wall) and an organism
How does energy from ATP allow some of the reactions of anabolism to occur?
All of these (a phosphate group is transferred from ATP to a reactant molecule, raising the energy level of that reactant molecule; energy from ATP is used to increase the potential energy...; some of the energy from a high energy covalent bond in the ATP molecule is used to form a high energy covalent bond in a substrate molecules)
The rate of flow of materials through a metabolic pathway can be altered by...
All of these (altering the amount of substrate or product; and changing the activity level(s) of one or more of the enzymes that catalyze steps in that pathway
ATP is formed...
All of these (by many exergonic reactions; during hydrolysis of many biological polymers (eg. carbohydrates, lipids, and proteins); during many catabolic reactions)
The ATP used by the cell for energy coupling...
All of these (is identical to one of the four nucleotides used for RNA synthesis; is a high energy molecule due to having unstable covalent bonds; has three phosphate groups)
The breakdown of polymers to their constituent monomers occurs during...
Catabolism
Which term precisely describes the cellular process of breaking down large molecules into smaller ones?
Catabolism
Which of the following statements is representative of the 2nd law of thermodynamics?
Cells require a constant input of energy to maintain their high level of organization.
Spontaneous reactions...
Do not require an energy input to occur
In a particular metabolic pathway, "A" is converted to "B", which is converted to "C", which of the following is likely to be true about catalysis of the steps in this pathway?
Each step in the pathway will likely be catalyzed by a different enzyme
A chemical reaction that has a positive ΔG is correctly described as...
Endergonic
Wi=hitch of the following is a statement of the first law of thermodynamics?
Energy cannot be created nor destroyed
What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways?
Energy coupling
The total energy of a biological system is represented by...
Enthalpy (H)
The amount of disorder or randomness in a system is represented by...
Entropy (S)
Whenever energy is transformed, there is always an increase in the...
Entropy of the universe
Many of the reactions that occur during metabolism are reversible. Given the laws of thermodynamics, how is that possible?
Even in the same solution, some of the molecules of a particular species may have more energy than others.
The amount of energy in a system that is available to do work is represented by...
Free energy (G)
Which of the following statements is FALSE?
Hydrolysis of ATP to form ADP and inorganic phosphate is a highly endergonic reaction
Which of the following best describes enthalpy (H)?
In biological systems, enthalpy is equivalent to total energy
Entropy...
Is a measure of disorder or randomness
When ATP releases some energy, it also releases inorganic phosphate. What purpose, if any, does this serve in the cell?
It can be added to other molecules in order to activate them
When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?
It is lost to the environment
Why is ATP an important molecule in metabolism?
It provides energy coupling between exergonic and endergonic reactions.
Which of the following most accurately describes kinetic and potential energy?
Kinetic energy is due to movement and potential energy is energy that is stored in matter that is not due to movement
How do living organisms create macromolecules, organelles, cells, tissues, and complex higher-order structures?
Living organisms create order locally, but the energy transformations generate waste heat that increases the entropy of the universe.
If most metabolic reactions are reversible, why is equilibrium rarely reached for these reactions?
Most of the products of the reactions are removed from the system
If most metabolic reactions are reversible, why is equilibrium rarely reached for these reactions?
Most of the products of the reactions are removed from the system.
Are most chemical reactions at equilibrium in living cells?
No
Energy that goes to increase the entropy of the universe is...
No longer available to preform work
What is the change in free energy of a system at chemical equilibrium?
No net change
If I try to hit a hockey puck, but miss...
No, because the kinetic energy from the motion of my stick will have been transferred/transformed into increased heat energy in the ice
The mathematical expression for the change in the free energy of a system is ΔG = ΔH - TΔS. Which of the following is TRUE?
T is the temperature in degrees Kelvin
Most cells cannot harness heat to preform work because...
Temperature is usually uniform throughout a cell
A consequence of the fact that Gibbs free energy must decrease in a spontaneous reaction is...
That a given reaction may proceed spontaneously in both directions, due to the fact that different reactants and product molecules will have slightly different energies
The respiration (catabolism) of glucose is emergencies. C6H12O6 + 6O2 -> 6CO2 + 6H2O, what is the source of the free energy released in this reaction?
The difference between the potential energy in the bonds of the glucose and oxygen molecules, minus the potential energy in the bonds of the carbon dioxide and water molecules. In other words: (potential energy in bonds of 1 glucose molecules + potential energy in bonds of 6O2 molecules) - (potential energy in bonds of 6CO2 molecules + potential energy in bonds of 6H2O molecules) = a positive number
A reaction has a ∆G of -5.6 kcal/mol. Which of the following would most likely be true?
The reaction would result in an increase in entropy (S) and a decrease in the energy content (H) of the system.
Which of the following statements about biological systems is FALSE?
The total energy in a biological system cannot increase or decrease
Which of the following is TRUE for anabolic pathways?
They consume energy to build up polymers from monomers.
Living organisms don't violate the 2nd law of thermodynamics because...
They typically increase the entropy of their surroundings
Which of the following is most similar in structure to ATP?
an RNA nucleotide
anabolism results in the production of molecules with high amounts of potential energy stored in their chemical bonds. How can the reactions of anabolism occur without violating the requirement that all reactions must result in a decrease in free energy?
c) both A and B are correct (A) a reaction that would otherwise be endecrgonic is combined with an exergonic reaction. The overall reaction than occurs in multiple steps, each of which involves an exergonic reaction; (B) energy from ATP is often used to help combine an exergonic reaction with a reaction that would otherwise be endergonic
Which term precisely describes the cellular process of breaking down large molecules into smaller ones?
catabolism
Which of the following types of reactions would decrease the entropy of a cell?
dehydration reactions
What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways?
energy coupling
The hydrolysis of ATP to form ADP and Pi is
highly exergonic
the hydrolysis of ATP: ATP + H2O → ADP + Pi is exergonic, with a ΔG = -7.3kcal/not under standard conditions. What is the source of the 7.3 kcal 1m01 released in this reaction?
the difference between the potential energy in the bonds of ATP and the water molecule, minus the potential energy in the bonds of APP and Pi. In other words: (PE in bonds of ATP + PE in bonds of H2O) - (PE in bonds of ADP t PE in bonds of Pi) = 7.3 kcal 1mol
The mathematical expression for the change in the free energy of a system is ΔG = ΔH - TΔS. Which of the following is TRUE?
ΔG is the change in free energy
The mathematical expression for the change in the free energy of a system is ΔG = ΔH - TΔS. Which of the following is TRUE?
ΔH is the change in enthalpy
The mathematical expression for the change in the free energy of a system is ΔG = ΔH - TΔS. Which of the following is TRUE?
ΔS is the change in entropy
