Bio - study question on Lecture 8

"Conservation of energy" is another way of stating Select one: a. the first law of thermodynamics b. the second law of thermodynamics c. that the universe expends as little energy as possible in carrying out fundamental processes d. the third law of thermodynamics

a

A reaction has a ∆G of -5.6 kcal/mol. Which of the following would most likely be TRUE? Select one: a. The reaction would result in an increase in entropy (S) and a decrease in the energy content (H) of the system. b. The reaction would result in products with a greater free energy content than in the initial reactants. c. The reaction would result in a decrease in entropy (S) and an increase in the energy content (H) of the system. d. The reaction could be coupled to power an endergonic reaction with a ∆G of +8.8 kcal/mol.

a

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ________ is to ________. Select one: a. exergonic; endergonic b. free energy; entropy c. exergonic; spontaneous d. entropy; enthalpy

a

Free energy (G) Select one: a. is a measure of the energy in a system that is available to do work b. is a measure of the total energy of a system c. is a measure of the total energy of a biological system d. is a measure of disorder or randomness

a

If most metabolic reactions are reversible, why is equilibrium rarely reached for these reactions? Select one: a. Most of the products of the reactions are removed from the system. b. Because living organisms increase the entropy of the universe. c. The enzymes that catalyze these reactions drive the reactions more in one direction than in the other. d. The activation energy barrier for the reaction is lower in one direction than in the other.

a

Most cells cannot harness heat to perform work because Select one: a. temperature is usually uniform throughout a cell. b. heat can never be used to do work. c. cells do not have much heat; they are relatively cool. d. heat is not a form of energy.

a

The ATP used by the cell for energy coupling Select one: a. All of these answers are correct. b. has three phosphate groups. c. is identical to one of the four nucleotides used for RNA synthesis. d. is a high energy molecule due to having unstable covalent bonds

a

The amount of disorder or randomness is a system is represented by Select one: a. entropy (S) b. enthalpy (H) c. free energy (G) d. temperature (T)

a

The mathematical expression for the change in the free energy of a system is ∆G = ∆H - T∆S. Which of the following is (are) TRUE? Select one: a. T is the temperature in degrees Kelvin. b. ∆S is the change in enthalpy. c. ∆G is the change in entropy. d. ∆H is the change in free energy.

a

The mathematical expression for the change in the free energy of a system is ∆G = ∆H - T∆S. Which of the following is (are) TRUE? Select one: a. ∆H is the change in enthalpy. b. ∆S is the change in free energy. c. ∆G is the change in entropy. d. T is the temperature in degrees Celsius.

a

The total energy of a biological system is represented by Select one: a. enthalpy (H) b. temperature (T) c. free energy (G) d. entropy (S)

a

Which of the following is (are) TRUE for anabolic pathways? Select one: a. They consume energy to build up polymers from monomers. b. They are usually highly spontaneous chemical reactions. c. They release energy as they degrade polymers to monomers. d. They do not depend on enzymes.

a

Which of the following is TRUE for all endergonic reactions in open systems (e.g. a cell)? Select one: a. The products have more free energy than the reactants b. The products have more total energy than the reactants c. The products have less total energy than the reactants d. The products have less free energy than the reactants

a

Which of the following is most similar in structure to ATP? Select one: a. an RNA nucleotide b. an amino acid with three phosphate groups attached. c. an anabolic steroid d. a DNA helix

a

Which of the following most accurately describe kinetic and potential energy? Select one: a. kinetic energy is due to movement and potential energy is energy that is stored in matter that is not due to movement b. kinetic energy includes the energy in a stretched rubber band c. kinetic energy includes energy from the attraction of the earth to the moon d. potential energy includes energy from molecular movement

a

ATP is formed Select one: a. by many exergonic reactions b. All of these answers are correct. c. during hydrolysis of many biological polymers (e.g. carbohydrates, lipids and proteins) d. during many catabolic reactions

b

Are most chemical reactions at equilibrium in living cells? Select one: a. yes b. no c. most reactions, except those powered by ATP d. only the exergonic reactions

b

If I try to hit a hockey puck, but miss and hit the ice instead, isn't that a violation of the first law of thermodynamics because my stick is no longer moving and neither is the puck? Select one: a. This is a trick question since, of course, I NEVER miss the puck! b. No, because the kinetic energy from the motion of my stick will have been transferred/transformed into increased heat energy in the ice. c. A hockey game is a closed system. The first law of thermodynamics applies to the universe as a whole. d. None of these answers are correct.

b

The amount of energy in a system that is available to do work is represented by Select one: a. temperature (T) b. free energy (G) c. enthalpy (H) d. entropy (S)

b

The breakdown of polymers to their constituent monomers occurs during Select one: a. dehydration reactions b. catabolism c. condensation reactions d. anabolism

b

The hydrolysis of ATP to form ADP and Pi is Select one: a. slightly exergonic b. highly exergonic c. highly endergonic d. slightly endergonic

b

The hydrolysis of ATP: ATP + H2O → ADP + Pi is exergonic, with a ∆G of -7.3 kcal/mol under standard conditions. What is the source of the 7.3 kcal/mol released in this reaction? Select one: a. the increase in entropy from breaking apart ATP b. the difference between the potential energy in the bonds of ATP and the water molecule, minus the potential energy in the bonds of ADP and Pi. In other words: (potential energy in bonds of ATP + potential energy in bonds of H2O) - (potential energy in bonds of ADP + potential energy in bonds of Pi) = 7.3 kcal/mol c. breaking the terminal phosphate bond to form ATP d. both the energy released from breaking the terminal phosphate bond and the increase in entropy

b

The mathematical expression for the change in the free energy of a system is ∆G = ∆H - T∆S. Which of the following is (are) TRUE? Select one: a. ∆S is the change in enthalpy. b. ∆G is the change in free energy. c. ∆H is the change in entropy. d. T is the temperature in degrees Celsius.

b

The respiration (catabolism) of glucose is exergonic. C6H12O6 + 6 O2 → 6 CO2 + 6 H2O What is the source of the free energy released in this reaction? Select one: a. breaking the C-H covalent bonds b. 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 molecule + potential energy in bonds of 6 O2 molecules) - (potential energy in bonds of 6 CO2 molecules + potential energy in bonds of 6 H2O molecules) = positive number c. breaking the O-O covalent bonds d. breaking both the C-H and O-O covalent bonds

b

The synthesis of polymers from their constituent monomers occurs during Select one: a. all of these answers are correct b. anabolism c. catabolism d. hydrolysis

b

What is the change in free energy of a system at chemical equilibrium? Select one: a. greatly increasing b. no net change c. slightly increasing d. slightly decreasing

b

What is the difference, if any, between the structure of ATP and the structure of the precursor of the A nucleotide in RNA? Select one: a. The nitrogen-containing base is different. b. There is no difference. c. The number of phosphates is three instead of one. d. The sugar molecule is different.

b

What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways? Select one: a. bioenergetics b. energy coupling c. feedback regulation d. cooperativity

b

When glucose monomers are joined together by glycosidic linkages to form a cellulose polymer, the changes in free energy, enthalpy and entropy are as follows: Select one: a. -∆H, -∆S, +∆G b. +∆H, -∆S, +∆G c. +∆H, +∆S, +∆G d. +∆H, -∆S, -∆G

b

Which of the following is considered an open system? Select one: a. food cooking in a pressure cooker b. an organism c. a sealed terrarium d. liquid in a corked bottle

b

Which of the following shows the correct changes in thermodynamic properties for a chemical reaction in which amino acids are linked to form a protein? Select one: a. -∆S, -∆G b. -∆S, +∆G c. +∆S, +∆G d. +∆S, -∆G

b

Which of the following statements concerning catabolic pathways is TRUE? Select one: a. They are endergonic. b. They are usually coupled with anabolic pathways to which they supply energy in the form of ATP. c. They combine molecules into more energy-rich foods. d. They are spontaneous and do not need enzyme catalysis.

b

Which of the following statements is representative of the second law of thermodynamics? Select one: a. Every energy transformation by a cell decreases the entropy of the universe. b. Cells require a constant input of energy to maintain their high level of organization. c. Without an input of energy, organisms would tend toward decreasing entropy. d. Conversion of energy from one form to another is always accompanied by some gain of free energy.

b

Which of the following types of reactions would decrease the entropy of a cell? Select one: a. respiration b. dehydration reactions c. catabolism d. hydrolysis

b

You realize that, for a particular reaction to occur, the molecules participating in that reaction need to have a certain minimum free energy level to get over the activation energy barrier. After measuring the average free energy levels of the potential reactant molecules, you discover that their average free energy levels are a little below that required to surmount the activation barrier. Should you be surprised when you then realize that the reaction is occurring, even though it is only occurring at a relatively low rate? Select one: a. No, you should not be surprised because the energy level at the top of the activation barrier represents only an average amount of energy. So, the activation barrier will actually be lower for some of the reactant molecules and higher for others. b. No, you should not be surprised because you only measured the average free energy levels of the potential reactant molecules. Some of the molecules likely have more than the average amount of free energy, meaning that they have enough free energy to surmount the activation barrier. c. Yes, you should be surprised because someone must have published inaccurate data regarding the amount of energy needed to surmount the activation barrier. d. Yes, you should be surprised because the chemical reaction is apparently occurring in violation of the laws of thermodynamics.

b

A consequence of the 1st and 2nd laws of thermodynamics is Select one: a. that, according to some theories, at some point in the far distant future there will be no more energy in the universe that is available to do work. b. that, according to some theories, at some point in the far distant future the temperature across the universe will be ~ constant. c. all of these answers are correct d. that the total amount of energy in the universe that is available to perform work is always decreasing.

c

A consequence of the fact that Gibb's free energy must decrease in a spontaneous reaction is Select one: a. that all reactions may proceed in only one direction unless ATP is added to the system. b. that all reactions may proceed spontaneously in only one direction. c. that a given reaction may proceed spontaneously in both directions, due to the fact that different reactant and product molecules will have slightly different energies. d. that all reactions may proceed in only one direction unless there is an input of energy into the system to drive the reaction in the other direction.

c

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? Select one: a. A reaction that would otherwise be endergonic 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. c. Both A and B are correct. d. None of these answers are correct.

c

At zero degrees Kelvin, in theory, Select one: a. water will be frozen b. you will be frozen c. all of these answers are correct d. entropy will reach a minimum value

c

How does energy from ATP allow some of the reactions of anabolism to occur? Select one: a. Energy from ATP is used to increase the potential energy of a reactant molecule, such that the total free energy of the reactant molecules is now greater than the total free energy of the product molecules that would be formed by the reaction. b. 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 molecule. c. All of these answers are correct. d. A phosphate group is transferred from ATP to a reactant molecule, raising the energy level of that reactant molecule.

c

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? Select one: a. It is not possible to know without more information about "A", "B" and "C". b. Each step in the pathway will likely be catalyzed by the same enzyme. c. Each step in the pathway will likely be catalyzed by a different enzyme. d. Some steps in the pathway may be catalyzed by the same enzyme and some steps may be catalyzed by different enzymes.

c

Many of the reactions that occur during metabolism are reversible. Given the laws of thermodynamics, how is that possible? Select one: a. Energy is used to drive a reversible reaction in one of the two possible directions. b. These reactions are reversible in theory, but proceed in only one direction so that the laws of thermodynamics are not violated. c. Even in the same solution, some of the molecules of a particular species may have more energy than others. d. The free energy of the system will decrease when the reaction proceeds in one direction, but the total energy of the system will decrease when the reaction proceeds in the other direction.

c

The mathematical expression for the change in the free energy of a system is ∆G = ∆H - T∆S. Which of the following is (are) TRUE? Select one: a. T is the temperature in degrees Celsius. b. ∆G is the change in enthalpy. c. ∆S is the change in entropy. d. ∆H is the change in free energy.

c

The rate of flow of materials through a metabolic pathway can be altered by Select one: a. changing the activity level(s) of one or more of the enzymes that catalyze steps in that pathway. b. altering the amount of product for the reaction c. all of these answers are correct d. altering the amount of substrate for the reaction

c

When sodium chloride (table salt) crystals dissolve in water, the temperature of the solution decreases. This means that, for dissociation of Na+ and Cl- ions, Select one: a. The change in enthalpy (∆H) is negative. b. The reaction cannot occur spontaneously. c. The change in enthalpy (∆H) is positive, but the change in entropy is greater. d. The reaction is endergonic, because it absorbs heat.

c

Whenever energy is transformed, there is always an increase in the Select one: a. Free energy of the universe b. Free energy of the system c. Entropy of the universe d. Entropy of the system

c

Which of the following is a statement of the second law of thermodynamics? Select one: a. Every energy transfer or transformation increases the free energy of the universe b. Every energy transfer or transformation increases the enthalpy of the universe c. Every energy transfer or transformation increases the entropy of the universe d. Energy cannot be created or destroyed

c

Which of the following is an example of potential rather than kinetic energy? Select one: a. water flowing in a river b. an increase in air temperature as a meteor passes through the atmosphere c. a food molecule d. a hockey puck hitting the boards

c

Which of the following is considered an open system? Select one: a. a clam b. an animal cell c. all of these answers are correct d. a plant cell with a strong cell wall

c

Which of the following statements about biological systems is FALSE? Select one: a. The total energy in a biological system can increase b. The entropy of a biological system can decrease c. The total energy in a biological system cannot increase or decrease d. The total energy in a biological system can decrease

c

"Every energy transfer or transformation increases the entropy of the universe" Select one: a. is true, except for living organisms b. is a statement of the first law of thermodynamics c. is a statement of the third law of thermodynamics d. is a statement of the second law of thermodynamics

d

A chemical reaction that has a positive ∆G is correctly described as Select one: a. none of these answers are correct b. spontaneous c. exergonic d. endergonic

d

Chemical reactions Select one: a. always increase the entropy of an open system. b. always decrease the amount of energy in the universe that is available to do work. c. all of these answers are correct d. always decrease the amount of energy in an open system that is available to do work.

d

Energy that goes to increase the entropy of the universe is Select one: a. all of these answers are correct b. stored as potential energy c. lost forever d. no longer available to perform work

d

How do living organisms create macromolecules, organelles, cells, tissues, and complex higher-order structures? Select one: a. Living organisms create order by using energy from the sun. b. Living organisms create order using energy from food molecules. c. The laws of thermodynamics do not apply to living organisms. d. Living organisms create order locally, but the energy transformations generate waste heat that increases the entropy of the universe as a whole.

d

In an isolated system Select one: a. matter, but not energy, can leave the system. b. energy, but not matter, can leave the system. c. heat, but not other forms of energy or matter, can leave the system. d. neither energy nor matter can leave the system.

d

Living organisms don't violate the 2nd law of thermodynamics because: Select one: a. Trick question, living organisms do violate the 2nd law of thermodynamics b. They increase the free energy of their surroundings c. They typically increase their own entropy d. They typically increase the entropy of their surroundings

d

Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics? Select one: a. Living organisms do not follow the laws of thermodynamics. b. As a consequence of growing, organisms create an amount of disorder in their environment that is equal to the decrease in entropy associated with their growth. c. Living organisms create lots of entropy after they die and the molecules in their bodies dissociate, which makes up for the decrease in entropy created while they were alive. d. As a consequence of growing, organisms create more disorder in their environment than the decrease in entropy associated with their growth.

d

Spontaneous reactions Select one: a. always occur, and do not require an energy input b. all of these answers are correct c. always proceed rapidly d. do not require an energy input to occur

d

The statement "energy cannot be created or destroyed" Select one: a. is a statement of the second law of thermodynamics b. is a statement of the third law of thermodynamics c. is true for closed and open systems, but not for the universe as a whole d. is a statement of the first law of thermodynamics

d

When ATP releases some energy, it also releases inorganic phosphate. What purpose, if any, does this serve in the cell? Select one: a. It is released as excretory waste. b. It can only be used to generate more ATP. c. It can enter the nucleus and affect gene expression. d. It can be added to other molecules in order to activate them.

d

When chemical, transport or mechanical work is done by an organism, what happens to the heat generated? Select one: a. It is used to power yet more cellular work. b. It is used to store more energy as ATP. c. It is transported to specific organs such as the brain. d. It is lost to the environment.

d

Which of the following best describes enthalpy (H)? Select one: a. the total kinetic energy of a system b. the condition of a cell that is not able to react c. the system's entropy d. in biological systems, enthalpy is equivalent to total energy

d

Which of the following is TRUE for ALL exergonic reactions? Select one: a. A net input of energy from the surroundings is required for the reactions to proceed. b. The products have more total energy than the reactants. c. The reactions are nonspontaneous. d. If the reaction proceeds there will be a net decrease in free energy.

d

Which of the following is TRUE for all exergonic reactions in open systems (e.g. a cell)? Select one: a. The products have more entropy than the reactants b. The products have less total energy than the reactants c. The products have less entropy than the reactants d. The products have less free energy than the reactants

d

Which of the following is a statement of the first law of thermodynamics? Select one: a. The entropy of the universe is decreasing b. The entropy of the universe is increasing. c. The entropy of the universe is constant. d. Energy cannot be created or destroyed

d

Which of the following statements is FALSE? Select one: a. Phosphorylation of a molecule usually makes the molecule less stable. b. Phosphorylation of a molecule usually raises the potential energy of the molecule, making it more energetically favorable for that molecule to undergo spontaneous reactions. c. Hydrolysis of ATP to form ADP and inorganic phosphate is a highly exergonic reaction d. Hydrolysis of ATP to form ADP and inorganic phosphate is a highly endergonic reaction

d

Which term precisely describes the cellular process of breaking down large molecules into smaller ones? Select one: a. anabolism b. metabolism c. catalysis d. catabolism

d

Why is ATP an important molecule in metabolism? Select one: a. All of these answers are correct. b. It helps drive exergonic reactions. c. It is formed by endergonic reactions. d. It provides energy coupling between exergonic and endergonic reactions.

d