PRACTICE QUESTIONS

During a laboratory experiment you discover that an enzyme-catalyzed reaction has a delta G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the delta G for the new reaction? a. -20 kcal/mole b. -40 kcal/mole c. +40 kcal/mole d. +20 kcal/mole

-20 kcal/mole

How many more electrons do hydrogen atoms need to complete their valence shell? a. 5 b. 1 c. 2 d. 8

1

The proportion of Hydrogen to Oxygen to Carbon in a monosaccharide is a. 1:1:1 b. 1:2:1 c. 2:1:1 d. 1:1:2

2:1:1

How many covalent bonds do carbon atoms need to form with other atoms to complete their valence shell? a. 4 b. 1 c. 2 d. 3

4 - - - - - Carbon atoms have 4 electrons in their valence shell, which is the 2nd electron shell. The total number of electrons needed to fill the 2nd electron shell is 8, so carbon needs to form 4 covalent bonds so that it is sharing a total of 8 electrons (2 electrons per covalent bond).

How many molecules of glycerol (C3H8O3; molecular mass = 92) would be present in 1 L of a 1 M (molar) glycerol solution? a. 92 × 1023 b. 92 × 6.02 × 1023 c. 14 × 6.02 × 1023 d. 6.02 × 1023

6.02 × 1023 - - - - - - A one molar solution contains 1 mole of solute per liter of solution. So, 1 L of a 1 molar solution will contain 1 mole of solute. Remember that a mole is a number just like a "dozen" is a number. A "dozen" means "12", and a "mole" means "6.02 X 1023". So, 1 L of a 1 molar glycerol solution will have 1 mole, or 6.02 X 1023, glycerol molecules.

Approximately what percentage of the cells in your body are human cells? a. 99% b. 98% c. 100% d. < 50%

< 50%

What is the best description of a carbonyl group? a. A nitrogen and two hydrogens joined to a carbon by covalent bonds b. A carbon atom joined to an oxygen by a double covalent bond c. A carbon joined to a hydroxyl group by a single covalent bond d. An oxygen joined to a carbon by a single covalent bond

A carbon atom joined to an oxygen by a double covalent bond

Which of the following provides the most accurate definition of a polymer? a. A polymer is a long molecule consisting of many similar or identical building blocks linked by covalent bonds. b. A polymer is a long molecule consisting of many similar or identical building blocks linked by hydrogen bonds. c. A polymer is a long molecule consisting of many similar or identical building blocks held together by van der Waals forces. d. A polymer is a long molecule consisting of many similar or identical building blocks linked by covalent or ionic bonds.

A polymer is a long molecule consisting of many similar or identical building blocks linked by covalent bonds.

Which of the following statements describes enzyme cooperativity? a. The reaction of several substrate molecules can be catalyzed simultaneously by the same enzyme. b. A multi-enzyme complex contains all the enzymes of a metabolic pathway. c. A substrate molecule bound to the active site of one subunit alters the conformation of that subunit and of the other subunits in a multi-subunit enzyme in such a way that the other subunits are able to bind substrate molecules more easily. d. A substrate molecule binds to an active site and inhibits cooperation between enzymes in a metabolic pathway.

A substrate molecule bound to the active site of one subunit alters the conformation of that subunit and of the other subunits in a multi-subunit enzyme in such a way that the other subunits are able to bind substrate molecules more easily.

Which of the following statements about ATP and ADP is TRUE? a. ATP acts as an allosteric inhibitor of many enzymes in catabolic pathways while ADP acts as an allosteric activator of many enzymes in catabolic pathways. b. ATP acts as an allosteric activator of many enzymes in catabolic pathways while ADP acts as an allosteric inhibitor of many enzymes in catabolic pathways. c. ATP and ADP act as allosteric inhibitors of many enzymes in anabolic pathways. d. ATP acts as an allosteric inhibitor of many enzymes in anabolic pathways while ADP acts as an allosteric activator of many enzymes in anabolic pathways.

ATP acts as an allosteric inhibitor of many enzymes in catabolic pathways while ADP acts as an allosteric activator of many enzymes in catabolic pathways.

How can one increase the rate of a chemical reaction? a. Increase the activation energy needed. b. Increase the entropy of the reactants. c. Add a catalyst d. Cool the reactants.

Add a catalyst

An allosteric regulator a. usually acts on multi-subunit enzymes b. All of these answers are correct. c. may increase the activity level of the enzymes it regulates d. may decrease the activity level of the enzymes it regulates

All of these answers are correct.

Chloroplasts a. are self-replicating. b. contain some of their own DNA. c. are believed to have arisen from symbiotic cyanobacteria (prokaryotes) that somehow survived endocytosis (being engulfed) by another cell. d. All of these answers are correct.

All of these answers are correct.

Enzyme cofactors a. All of these answers are correct. b. are not protein molecules. c. include vitamins. d. are needed for some enzymes to be active.

All of these answers are correct.

If ATP levels decrease and ADP levels increase a. All of these answers are correct. b. The rates of many catabolic reactions will increase due to increased allosteric activation by ADP. c. The rates of many catabolic reactions will increase due to decreased allosteric inhibition by ATP. d. The rates of many anabolic reactions will decrease due to decreased allosteric activation by ATP.

All of these answers are correct.

Which of the following statements about moles is true? a. One mole of hydrogen molecules (H2) weighs 2 g b. One mole of hydrogen atoms weighs 1 g c. A mole is 6.02 X 1023 d. All of these answers are correct.

All of these answers are correct.

If ATP levels increase and ADP levels decrease a. The rates of many anabolic reactions will increase due to increased allosteric activation by ATP. b. The rates of many catabolic reactions will decrease due to decreased allosteric activation by ADP. c. All of these answers are correct. d. The rates of many catabolic reactions will decrease due to increased allosteric inhibition by ATP.

All of these answers are correct. Catabolic pathways tend to produce ATP from ADP whereas anabolic pathways tend to produce ADP from ATP. If ATP levels in the cell are high, it makes sense to slow down catabolic pathways as the cell doesn't need to be producing more ATP at that point. As a consequence, many catabolic enzymes evolved so that they are inhibited by ATP. For a similar reason, many catabolic enzymes are activated by ADP. Conversely, because anabolic pathways require ATP and generate ADP, many of the enzymes that catalyze anabolic reactions are activated by ATP and inhibited by ADP.

Which of the following statements comparing allosteric regulators and non-competitive inhibitors is FALSE? a. Both allosteric regulators and non-competitive inhibitors bind at sites that are distinct from the active site(s) they regulate. b. Inhibition by allosteric inhibitors is reversible. c. Allosteric regulators always inhibit (decrease) the activity levels of the enzymes they regulate. d. Non-competitive inhibitors always inhibit (decrease) the activity levels of the enzymes they regulate.

Allosteric regulators always inhibit (decrease) the activity levels of the enzymes they regulate.

Which of the following statements comparing allosteric regulators and non-competitive inhibitors is TRUE? a. Inhibition by allosteric regulators is irreversible. b. Allosteric regulators may increase or decrease an enzyme's activity level. c. Only non-competitive inhibitors bind at a site that is distinct from the active site(s) they are regulating. d. Only allosteric regulators bind at a site that is distinct from the active site(s) they are regulating.

Allosteric regulators may increase or decrease an enzyme's activity level.

Which of the following hydrocarbons has a double bond in its carbon skeleton? a. C2H4 b. C2H6 c. C3H8 d. C2H2

C2H4 - - - To find the right answer, try drawing the different molecules, remembering that each carbon atom must have a total of 4 covalent bonds and each hydrogen atom must form just a single covalent bond.

Which of the following metabolic processes can occur without a net influx of energy from some other process? a. ADP + Pi → ATP + H2O b. 6 CO2 + 6 H2O → C6H12O6 + 6 O2 c. C6H12O6 + 6 O2 → 6 CO2 + 6 H2O d. amino acids → protein

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O

Which of the molecules listed below can form isomers? CH4 C3H8 C4H10 a. None of them can form isomers. b. All of them can form isomers c. CH4 cannot form isomers, but C3H8 and C4H10 can form isomers d. CH4 and C3H8 cannot form isomers, but C4H10 can form isomers

CH4 and C3H8 cannot form isomers, but C4H10 can form isomers

Which of the following statements about the cytoskeleton is FALSE? a. For certain cell types, the cytoskeleton acts in movement of whole cells. b. The cytoskeleton acts in movement of parts of cells. c. The cytoskeleton acts as a support system for the cell. d. Calcium atoms form a major part of the structure of the cytoskeleton

Calcium atoms form a major part of the structure of the cytoskeleton

On what basis are different molecules grouped as "lipids"? a. Compounds designated as lipids are grouped together because they have a glycerol backbone. b. Compounds designated as lipids are grouped together because they are formed from fatty acids. c. Compounds designated as lipids are grouped together because they are located in membranes. d. Compounds designated as lipids are grouped together because they mix poorly, if at all, with water.

Compounds designated as lipids are grouped together because they mix poorly, if at all, with water.

Nitrogen (N) is more electronegative than hydrogen (H). Which of the following statements is correct about ammonia (NH3)? a. Each hydrogen atom has a partial positive charge. b. There are covalent bonds between the hydrogen atoms. c. The nitrogen atom has a strong positive charge. d. Each hydrogen atom has a slight negative charge.

Each hydrogen atom has a partial positive charge. There is one covalent bond between the nitrogen atom and each of the three hydrogen atoms. Because nitrogen is more electronegative than hydrogen, the electrons in each of these three covalent bonds are more strongly attracted to the nitrogen atom than to the hydrogen atom. So, each pair of electrons that forms the covalent bond between the nitrogen atom and one of the hydrogen atoms will spend more time near the nitrogen atom. As a result, the nitrogen atom will have a partial negative charge and each hydrogen atom will have a partial positive charge.

Which of the following statements regarding atomic particles is correct? a. Electrons are negatively charged, protons are positively charged and neutrons are positively charged. b. Electrons are negatively charged, protons are positively charged and neutrons are negatively charged. c. Electrons are negatively charged, protons are neutral and neutrons are neutral. d. Electrons are negatively charged, protons are positively charged and neutrons are neutral.

Electrons are negatively charged, protons are positively charged and neutrons are neutral.

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

Energy cannot be created or destroyed

Which of the following statements about enzymes is TRUE? a. Enzymes alter the activation energy barrier for a reaction. b. Enzymes alter ∆G for a reaction. c. Enzymes alter ∆S for a reaction. d. Enzymes alter ∆H for a reaction.

Enzymes alter the activation energy barrier for a reaction.

Which of the following statements regarding enzymes is FALSE? a. Enzyme function is dependent on the pH and temperature of the reaction environment. b. Enzymes alter the free energy change (ΔG) of the reactions which they catalyze. c. Enzyme function is dependent on the three-dimensional structure or conformation of the enzyme. d. Enzyme activity can be inhibited if the enzyme is bound by a noncompetitive inhibitor.

Enzymes alter the free energy change (ΔG) of the reactions which they catalyze.

Which of the following statements about enzymes is FALSE? a. Enzymes increase the free energy of the reactants. b. RNA molecules may act as enzymes c. Enzymes are not used up by the reactions they catalyze d. Proteins may act as enzymes

Enzymes increase the free energy of the reactants.

Which of the following is the best explanation for how enzymes speed up the rates of reactions? a. Enzymes lower the energy required for reactant molecules to reach their transition state. Enzymes do not alter the free or total energies of the reactant or product molecules. b. Enzymes increase the energy of the reactant molecules. c. Enzymes lower the free energy change of the reaction. d. Enzymes increase the enthalpy of the reactant molecules.

Enzymes lower the energy required for reactant molecules to reach their transition state. Enzymes do not alter the free or total energies of the reactant or product molecules.

What gives rise to the cohesiveness of water molecules? a. Hydrogen bonds b. Ionic bonds c. Hydrophobic interactions d. Nonpolar covalent bonds

Hydrogen bonds - - - - Water molecules stick to each other because the oxygen atom in a water molecule carries a partial negative charge and the two hydrogen atoms each carry a partial positive charge. As a result, the partially positively charged hydrogen atoms of one water molecule are attracted to the partially negatively charged oxygen atoms of other water molecules. The reason that the hydrogen atoms carry partial positive charges and the oxygen atoms carry partial negative charges is that the covalent bonds within a water molecule are polar. Each electron pair forming a covalent bond between an oxygen atom and a hydrogen atom spends more time near oxygen than near hydrogen, as oxygen atoms are more electronegative than hydrogen atoms.

Which of the following statements about electron microscopy (em) is correct? a. In scanning em the electron beam is focused across the surface of the specimen b. In transmission em the electron beam is focused across the surface of the specimen c. In transmission em the electron beam is focused across the surface of the specimen or through the specimen. d. In scanning em the electron beam is focused across the surface of the specimen or through the specimen.

In scanning em the electron beam is focused across the surface of the specimen

Which of the following statements is TRUE? a. Inhibition of catabolic enzymes by ATP is an example of feedback inhibition. b. All of these answers are correct. c. Inhibition of catabolic enzymes by ADP is an example of feedback inhibition. d. Inhibition of anabolic enzymes by ATP is an example of feedback inhibition.

Inhibition of catabolic enzymes by ATP is an example of feedback inhibition. Catabolic pathways tend to produce ATP from ADP whereas anabolic pathways tend to produce ADP from ATP. If ATP levels in the cell are high, it makes sense to slow down catabolic pathways as the cell doesn't need to be producing more ATP at that point. As a consequence, many catabolic enzymes evolved so that they are inhibited by ATP (and activated by ADP). This is an example of feedback inhibition, as a product of the catabolic pathway, namely ATP, is inhibiting enzymes that catalyze early steps in the catabolic pathway. Similarly, many anabolic enzymes evolved so that they are inhibited by ADP (and activated by ATP). So, ADP (not ATP) acts as a feedback inhibitor of anabolic pathways. If you have trouble remembering the difference between catabolism and anabolism, picture a cat tearing something up to remember that catabolism is the breakdown of large, energy-rich molecules to produce smaller, less energy-rich molecules. Anabolism is the opposite (i.e. production of large, energy-rich molecules from smaller, less complex and less energy-rich molecules).

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

It can be added to other molecules in order to activate them

How quickly do spontaneous reactions occur? a. It depends on the reaction. Some spontaneous reactions almost never occur. b. Somewhat quickly c. Extremely quickly d. Very quickly

It depends on the reaction. Some spontaneous reactions almost never occur.

Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid. What role does malonic acid play in this reaction? a. It blocks the binding of fumarate. b. It is a noncompetitive inhibitor. c. It is a competitive inhibitor. d. It replaces the usual enzyme.

It is a competitive inhibitor.

Why isn't the mitochondrion classified as part of the endomembrane system? a. It is not involved in protein synthesis. b. It is not attached to the outer nuclear envelope. c. It has two membrane layers. d. Its structure is not derived from the endoplasmic reticulum (ER).

Its structure is not derived from the endoplasmic reticulum (ER).

Which of the following statements is FALSE? a. Lipids comprise >90% of membrane material b. Hypertonic solutions have higher solute concentrations than the solution inside the cell c. Membranes allow formation of subcellular compartments with different chemical compositions d. The net flow of water across a membrane will be from the solution with the lower solute concentration to the solution with the higher solute concentration.

Lipids comprise >90% of membrane material - - - - - Membranes are composed of approximately 50% lipid and 50% protein, with a little bit of carbohydrate thrown in.

Firefly luciferase catalyzes the reaction: What is the role of luciferase?

Luciferase lowers the transition energy of the reaction.

Which of the following statements about membrane synthesis is TRUE? a. Membrane proteins are synthesized in the smooth ER but phospholipids for membranes are synthesized in the rough ER. b. Both membrane proteins and phospholipids for membranes are synthesized in the smooth ER. c. Membrane proteins are synthesized in the rough ER and phospholipids for membranes are synthesized in the Golgi apparatus. d. Membrane proteins are synthesized in the rough ER and membrane lipids are synthesized in both the rough and smooth ER

Membrane proteins are synthesized in the rough ER and membrane lipids are synthesized in both the rough and smooth ER

Which of the following statements about substrate molecules in their transition state is FALSE? a. Energy is needed to move molecules from their normal to their transition states. b. Molecules in their transition states have higher energies than when they are not in their transition states. c. Molecules in their transition states are contorted into unusual shapes. d. Molecules in their transition states have increased stability.

Molecules in their transition states have increased stability.

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

Most of the products of the reactions are removed from the system.

Which of the following membrane activities requires a direct input of energy from ATP hydrolysis? a. movement of water into a cell b. Nat+ ions moving out of the cell c. facilitated diffusion d. movement of glucose molecules

Nat+ ions moving out of the cell

A noncompetitive inhibitor for a particular enzyme a. None of these answers are correct. b. may be "out competed" for binding at the enzyme's binding site by adding a higher concentration of substrate molecules. c. will have a 3-dimensional structure that is similar to that of the enzyme's substrate. d. will bind to the enzyme's active site, preventing binding of substrate molecules.

None of these answers are correct.

If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur? a. Nothing; the reaction will stay at equilibrium. b. The free energy of the system will change. c. Additional product will be formed. d. The reaction will change from endergonic to exergonic.

Nothing; the reaction will stay at equilibrium.

Which of the following structures makes sense? a. O=C=O b. H-C=C=O c. H-C=O d. H-C-H

O=C=O

Which of the following statements about protein structure is most accurate? a. Secondary structure is determined by interactions between amino acid side chains and tertiary structure is determined by interactions between the repeating constituents of the polypeptide backbone. b. Secondary structure is determined by interactions between the repeating constituents of the polypeptide backbone and tertiary structure is determined by interactions between amino acid side chains. c. Secondary and tertiary structures are determined by interactions between amino acid side chains. d. Secondary and tertiary structures are determined by interactions between the repeating constituents of the polypeptide backbone.

Secondary structure is determined by interactions between the repeating constituents of the polypeptide backbone and tertiary structure is determined by interactions between amino acid side chains.

The molecules shown below are best described as a. Structural isomers b. Enantiomers c. Geometric isomers d. Isotopes

Structural isomers

A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because a. Starch hydrolysis is nonspontaneous. b. Starch cannot be hydrolyzed in the presence of so much water. c. The activation energy barrier cannot be surmounted. d. The hydrolysis of starch to sugar is endergonic.

The activation energy barrier cannot be surmounted.

For the reaction described in the figure shown below, arrow "B" represents a. The decrease in free energy over the course of the reaction b. The activation energy for the noncatalyzed reaction. c. The activation energy for the enzyme-catalyzed reaction. d. The increase in energy of the products (C and D).

The activation energy for the enzyme-catalyzed reaction.

For the reaction described in the figure shown below, arrow "C" represents a. The increase in energy of the products (C and D). b. The decrease in free energy over the course of the reaction c. The activation energy for the enzyme-catalyzed reaction. d. The activation energy for the noncatalyzed reaction.

The activation energy for the noncatalyzed reaction.

Wood does not burst into flame on its own. Yet, once you start a campfire, the wood continues to burn. What is going on? a. The burnt part of the wood releases ash and smoke, raising the entropy of the system. b. The combustion of wood is an exergonic process. Once you start the wood burning, heat is released by the burning wood. That heat increases the energy of other molecules in the wood, so that they now have sufficient energy to overcome the activation energy barrier and begin to burn as well. c. The burnt part of the wood releases ash and smoke, raising the entropy of the products of the reaction. d. The combustion of wood is an endergonic process. Once you start the wood burning, heat is released by the burning wood. That heat increases the energy of other molecules in the wood, so that they now have sufficient energy to overcome the activation energy barrier and begin to burn as well.

The combustion of wood is an exergonic process. Once you start the wood burning, heat is released by the burning wood. That heat increases the energy of other molecules in the wood, so that they now have sufficient energy to overcome the activation energy barrier and begin to burn as well.

Which of the following statements about the nucleotides used in DNA synthesis is correct? a. The nucleotides used in DNA synthesis have deoxyribose as their sugar component and do not include nucleotides that have uracil as their nitrogenous base. b. The nucleotides used in DNA synthesis have deoxyribose as their sugar component and do not include nucleotides that have thymine as their nitrogenous base. c. The nucleotides used in DNA synthesis have ribose as their sugar component and do not include nucleotides that have uracil as their nitrogenous base. d. The nucleotides used in DNA synthesis have ribose as their sugar component and do not include nucleotides that have thymine as their nitrogenous base.

The correct answer is: The nucleotides used in DNA synthesis have deoxyribose as their sugar component and do not include nucleotides that have uracil as their nitrogenous base.

Which of the following is NOT found in RNA molecules?

The correct answer is: thymine RNA molecules have uracil instead of thymine.

Hair is extremely flammable, so why doesn't your hair spontaneously burst into flame? a. The molecules in your hair lack sufficient energy at room temperature to overcome the activation energy barrier for this reaction. b. Burning hair is an exergonic reaction that requires energy from fire to drive it. c. Since your hair is generally a mess, burning it would result in a decrease in the total entropy of the universe, which would be a violation of the second law of thermodynamics. d. Burning hair is an endergonic reaction that requires energy from fire to drive it.

The molecules in your hair lack sufficient energy at room temperature to overcome the activation energy barrier for this reaction.

Which of the following statements about valence shells is FALSE? a. The number of valence shells contained by a particular atom is dependent on how many electrons that atom has. b. The valence shell is the highest energy electron shell an atom has. c. The valence shell is the outermost electron shell of an atom. d. Electrons in the valence shell (i.e. valence electrons) are primarily responsible for the chemical behavior of atoms.

The number of valence shells contained by a particular atom is dependent on how many electrons that atom has. - - - - Each atom has only one valence shell, corresponding to its outermost electron shell. Because the electrons in the valence shell are the outermost electrons and the energy level of an electron increases the further it is from the nucleus, the valence shell is the highest energy electron shell an atom has. Also, because atoms react to complete their valence shells, the valence electrons are primarily responsible for the chemical behavior of atoms.

Polar molecules are often able to dissolve in water because a. Polar molecules are able to fill their valence shells by transferring electrons from water molecules. b. The polar molecules attract each other, allowing water molecules to adsorb to them. c. The partially charged regions of polar molecules are able to form hydrogen bonds with water molecules. d. The polar molecules repel each other, allowing them to interact with the water molecules.

The partially charged regions of polar molecules are able to form hydrogen bonds with water molecules.

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

The products have more free energy than the reactants - - - The definition of an endergonic reaction is a reaction where there is an increase in FREE energy. So, in an endergonic reaction the products of the reaction will have more FREE energy than the reactants used in the reaction. The fact that a reaction is an "endergonic" reaction does NOT tell you what the change in TOTAL energy, as opposed to FREE energy, will be.

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

There is no difference.

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

They are usually coupled with anabolic pathways to which they supply energy in the form of ATP.

Which of the following statements regarding integral membrane proteins is TRUE? a. They are loosely bound to the surface of the bilayer. b. They are not mobile within the bilayer. c. They are usually transmembrane proteins. d. They serve only a structural role in membranes.

They are usually transmembrane proteins.

According to the fluid mosaic model of cell membranes, which of the following statements about membrane phospholipids is TRUE?

They can move laterally along the plane of the membrane. - - - - Membrane phospholipids can move laterally in the plane of the membrane but it is rare for them to flip-flop from one side of the membrane to the other because that would require that their phosphate head group, which is quite hydrophilic, pass through the hydrophobic core of the membrane that is formed by the fatty acid chains of the phospholipids. Membrane proteins occur in a "mosaic" and may be embedded in the membrane (integral membrane proteins) or attached to its surface (peripheral membrane proteins).

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

They consume energy to build up polymers from monomers - - - - Anabolic pathways build polymers from monomers. They are endergonic pathways as the free energy of the products (polymers) is greater than the free energy of the reactants (monomers). As a consequence, anabolic pathways are nonspontaneous pathways that require an energy input, such as from ATP, to occur. The reactions in anabolic pathways are catalyzed by enzymes.

Which of the following statements about the Golgi apparatus is TRUE? a. Vesicles that bud off from the trans side of the Golgi apparatus have molecules on their surfaces that can recognize "docking" sites on the surface of the plasma membrane. b. Vesicles that bud off from the trans side of the Golgi apparatus always travel to the plasma membrane. c. Vesicles that bud off from the cis side of the Golgi apparatus have molecules on their surfaces that can recognize "docking" sites on the surface of the plasma membrane. d. Vesicles that bud off from the cis side of the Golgi apparatus always travel to the plasma membrane.

Vesicles that bud off from the trans side of the Golgi apparatus have molecules on their surfaces that can recognize "docking" sites on the surface of the plasma membrane. - - - - Some of the vesicles that bud off from the trans side of the Golgi apparatus travel to the plasma membrane, but some travel to other organelles within the cell instead.

The following functional group is known as https://ay17.moodle.umn.edu/pluginfile.php/1699768/question/questiontext/1381372/4/2145534/image0134f15df9f.jpg a. a hydrocarbon group b. a carboxyl group c. a carbonyl group d. a hydroxyl group

a carbonyl group

The following functional group is known as https://ay17.moodle.umn.edu/pluginfile.php/1699768/question/questiontext/1380971/3/2145535/image0144f15df9f.jpg

a carboxyl group

Which of the following is likely to lead to an increase in the concentration of ATP in a cell? a. an increased flux of cofactor molecules b. a decrease in a cell's catabolic activity c. a decrease in a cell's anabolic activity d. an increased amino acid concentration

a decrease in a cell's anabolic activity

Muscle contraction occurs as a result of a. a motor protein known as myosin "walks" along actin filaments, causing the actin and myosin filaments to slide past one another b. a motor protein known as myosin "walks" along microtubules, causing the microtubules and myosin filaments to slide past one another c. a motor protein known as myosin "walks" along intermediate filaments, causing the intermediate filaments and myosin filaments to slide past one another d. a motor protein known as myosin "walks" along myosin filaments, causing different myosin filaments to slide past one another

a motor protein known as myosin "walks" along actin filaments, causing the actin and myosin filaments to slide past one another

The subunit of polypeptides contains all of the following EXCEPT a. nitrogen. b. a phosphate. c. an "R" group connected to one of the carbons. d. a carboxyl group.

a phosphate.

A cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane and mitochondria. It could be a cell from a. any kind of organism b. a plant or an animal c. a plant or a bacteria d. an animal or a bacteria

a plant or an animal - - - - All cells have enzymes, DNA, ribosomes and a plasma membrane. However, only plant and animal cells have mitochondria.

A series of enzymes catalyzes the series of reactions shown below. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. What is substance X? https://ay17.moodle.umn.edu/pluginfile.php/1699768/question/questiontext/1380971/17/2146087/image0064f340679.jpg a. an allosteric inhibitor b. a coenzyme c. a substrate d. an intermediate

a substrate

Which of the following is an example of cooperativity? a. binding of an ATP molecule along with one of the substrate molecules in an active site b. the function of a polypeptide at one site affected by binding of a molecule at another of its active sites c. a substrate molecule binding at one unit of a tetramer allowing faster substrate binding at each of the other three subunits. d. the binding of an end product of a metabolic pathway to the first enzyme that acts in the pathway.

a substrate molecule binding at one unit of a tetramer allowing faster substrate binding at each of the other three subunits.

A competitive inhibitor for a particular enzyme

a. All of these answers are correct. b. will be more effective the higher its concentration c. will have a 3-dimensional structure that is similar to that of the enzyme's substrate d. will compete with the enzyme's substrate for binding to the enzyme's active site

If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to a. add a noncompetitive inhibitor. b. heat the solution to 90°C. c. add more of the enzyme. d. add more substrate.

add more of the enzyme.

Compounds with carbonyl groups are known a. ketones and hydrocarbons b. alcohols and hydrocarbons c. aldehydes or ketones d. aldehydes and hydrocarbons

aldehydes or ketones

Different enzymes may lower energy activation barriers by a. providing a basic environment for the reaction b. providing an acidic environment for the reaction c. forming a covalent bond with a substrate molecule d. All of these answers are correct.

all

Extracellular matrix a. all of these answers are correct b. is found outside of animal cells c. plays an important role during development d. provides tracks along which certain cells move during development

all of these answers are correct

Microfilaments a. help cells resist tension, or pulling forces b. play an important role in ameboid movement c. all of these answers are correct d. play an important role in muscle cells

all of these answers are correct

Microtubules a. form tracks along which motor proteins move organelles and other structures b. help cells resist compression c. form the centrioles of animal cells d. all of these answers are correct

all of these answers are correct

Which of the following are commonly made by the rough endoplasmic reticulum (ER)? a. membrane proteins b. all of these answers are correct c. membranes d. secreted proteins

all of these answers are correct

In science, a "theory" a. is supported by a large body of evidence b. tends to generate new hypotheses c. all of these answers are correct d. is broad in scope

all of these answers are correct - - - - The word "theory" does not the mean the same thing when talking about science as it does when talking about everyday life. In everyday life, "theory" is often used to mean an untested speculation. In science, a "theory" is an explanation that is broad in scope, generates new hypotheses and is supported by a large body of evidence.

The enzyme phosphofructokinase catalyzes the conversion of fructose-6-phosphate and adenosine triphosphate (ATP) to fructose 1,6-bisphosphate and adenosine diphosphate (ADP). Adenosine monophosphate (AMP) activates the enzyme phosphofructokinase (PFK) by binding at a site distinct from the substrate-binding site. This is an example of a. allosteric activation b. cooperative activation c. activation by an enzyme cofactor d. the coupling of exergonic and endergonic reactions

allosteric activation

In contrast to non-competitive inhibitors, competitive inhibitors of enzyme activity a. can NOT have their effects reversed by addition of more substrate. b. always utilize an enzyme's active site. c. act allosterically. d. cause enzymes to denature.

always utilize an enzyme's active site.

A series of enzymes catalyzes the series of reactions shown below. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. Substance A functions as a. a coenzyme b. an allosteric inhibitor c. an intermediate d. a substrate

an allosteric inhibitor

For the reaction depicted in the figure below, the activation energy barrier for converting C and D to A and B via the enzyme catalyzed reaction is represented by a. arrow C b. arrow A c. arrow B d. arrow E

arrow A

For the reaction described in the figure shown below, which of the following represents the difference between the free energy content of the reactants and the free energy content of the products? https://ay17.moodle.umn.edu/pluginfile.php/1699768/question/questiontext/1370874/17/2146077/image0024f340679.jpg a. arrow E b. arrow B c. arrow A d. arrow D

arrow D

For the reaction described in the figure shown below, which of the following represents the ∆G of the reaction?

arrow D

The active site of an enzyme a. is activated by binding of ATP b. binds product molecules c. binds substrate molecules d. all of these answers are correct

binds substrate molecules

One mole (mol) of glucose (molecular mass = 180 daltons) is a. both 180 grams of glucose and 6.02 × 1023 molecules of glucose. b. 1 kg of glucose dissolved in 1 L of solution. c. 180 kilograms of glucose. d. 180 × 1023 molecules of glucose.

both 180 grams of glucose and 6.02 × 1023 molecules of glucose. - - - - @ A mole is a number just like a "dozen" is a number. A "dozen" means "12", and a "mole" means "6.02 X 1023". The weight of a molecule in daltons is equal to the weight of a mole of those same molecules in grams. In other words, if a single molecule of glucose weighs 180 daltons, than a mole of glucose molecules (i.e. 6.02 X 1023 glucose molecules) will weigh 180 grams.

How does a noncompetitive inhibitor decrease the rate of an enzyme reaction? a. by acting as a coenzyme for the reaction b. by binding at the active site of the enzyme c. by changing the free energy change of the reaction d. by changing the shape of the enzyme

by changing the shape of the enzyme

A hypothesis a. can NOT be proven to be correct b. can be proven to be correct or incorrect, depending on experimental results c. can NOT be proven to be correct or incorrect, regardless of experimental results d. can be proven to be correct

can NOT be proven to be correct

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

catabolism

Which of the following relationships between cell structures and their respective functions is correct? a. chloroplasts; chief sites of cellular respiration b. ribosomes; secretion c. chromosomes: cytoskeleton of the nucleus d. cell wall; support, protection

cell wall; support, protection

Which of the following is NOT a method that cells use to regulate enzyme activities? a. allosteric regulation b. compartmentalization of enzymes in specific organelles c. cessation of all enzyme formation d. noncompetitive inhibition

cessation of all enzyme formation

Kinases are enzymes that catalyze phosphorylation (the addition of a phosphate group) whereas phosphatases are enzymes that catalyze the removal of phosphate groups. A cell can use these enzymes like on-off switches for the activities of various proteins. Which of the following is probably involved? a. a change in the optimal pH at which a reaction will occur b. a change in the optimal temperature at which a reaction will occur c. changes in a protein's charge leading to cleavage d. changes in a protein's charge leading to conformational changes

changes in a protein's charge leading to conformational changes

When you have a severe fever, what may be a grave consequence if this is not controlled? a. removal of amine groups from your proteins b. changes in the folding of enzymes c. binding of enzymes to inappropriate substrates d. destruction of your enzyme's primary structure

changes in the folding of enzymes

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following? a. denaturization of the enzyme b. allosteric inhibition c. competitive inhibition d. insufficient cofactors

competitive inhibition

Vioxx and other prescription nonsteroidal anti-inflammatory drugs (NSAIDs) are potent inhibitors of the cyclooxygenase-2 (COX-2) enzyme. High substrate concentrations reduce the efficacy of inhibition by these drugs. These drugs are a. noncompetitive inhibitors b. competitive inhibitors c. allosteric regulators d. feedback inhibitors

competitive inhibitors

Unsaturated fats a. contain at least one covalent double bond joining two carbon atoms (i.e. C=C) b. contain at least one branched fatty acid molecule c. contain at least on cyclical fatty acid molecule d. are missing at least one hydrogen atom

contain at least one covalent double bond joining two carbon atoms (i.e. C=C)

Motor proteins provide for molecular motion in cells by interacting with what types of cellular structures? a. cytoskeletons b. membrane lipids c. cellulose fibers in cell walls d. membrane proteins

cytoskeletons

Sucrose-H+ cotransporters transport sucrose and H+ from outside to inside of a cell. Which of the following would increase the rate of sucrose transport into the cell? a. adding a substance that makes the membrane more permeable to H+ b. increasing the pH of the solution outside of the cell c. decreasing the pH of the solution outside of the cell d. decreasing the concentration of sucrose outside of the cell

decreasing the pH of the solution outside of the cell - - - Decreasing the pH of the solution outside of the cell would increase the concentration of H+ outside of the cell. Therefore decreasing the pH outside of the cell would increase the H+ gradient from the outside to the inside of the cell and would thus increase the rate at which H+ and sucrose are transported into the cell.

Which of the following structures acts to fasten together neighboring cells into sheets of tissue? a. extracellular matrix b. gap junctions c. desmosomes d. tight junctions

desmosomes

What are two methods of scientific inquiry? a. hypothesis-based science and experimental planning b. experimental planning and theoretical design c. discovery science and experimental planning d. discovery science and hypothesis-based science

discovery science and hypothesis-based science

Which of the following terms best describes the reaction described in the figure below?

exergonic

The mechanism by which the end product of a metabolic pathway inhibits an enzyme that catalyzes an earlier step in the pathway is known as a. feedback inhibition b. allosteric inhibition c. noncooperative inhibition d. metabolic inhibition

feedback inhibition

Discovery science a. focuses on formulating hypotheses b. focuses on testing predictions c. focuses on answering specific questions d. focuses on accurately describing natural structures or processes

focuses on accurately describing natural structures or processes - - - - - Discovery science describes natural structures and processes as accurately as possible through careful observations and data analysis. Discovery science does NOT involve formulating hypotheses, making predictions based on those hypotheses and then testing those predictions. That is part of the process followed when doing hypothesis-based science.

Channel proteins a. form "corridors" that allow any small molecule to cross membranes b. channel small ions to specific subcellular compartments c. form "corridors" that allow specific ions or molecules to cross membranes d. form tracks within a cell that help direct movement of vesicles

form "corridors" that allow specific ions or molecules to cross membranes Channel proteins form channels that allow specific ions or molecules to cross membranes.

Carbon atoms typically complete their valence shells by a. transferring four electrons to other atoms b. forming ionic bonds with H+ cations c. transferring four electrons from other atoms d. forming four covalent bonds with other atoms

forming four covalent bonds with other atoms

Which of the following are storage polysaccharides? a. starch and chitin b. glycogen and starch c. cellulose and chitin d. glycogen and cellulose

glycogen and starch

Intermediate filaments a. have diameters that are larger than those microfilaments but smaller than those microtubules b. are synthesize after microfilaments but before microtubules c. play a role that is in between the roles played by microtubules and microfilaments d. are located between microfilaments and microtubules

have diameters that are larger than those microfilaments but smaller than those microtubules

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

in biological systems, enthalpy is equivalent to total energy

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

is a measure of the energy in a system that is available to do work

A hypothesis a. is a tentative answer to a question b. is a specific question formulated by scientists after making many careful observations c. is a prediction scientists make based on many careful observations d. is the same thing as a theory

is a tentative answer to a question

The active site of an enzyme is the region that a. binds the products of the catalytic reaction b. binds allosteric regulators of the enzyme c. is involved in the catalytic reaction of the enzyme d. is inhibited by the presence of a coenzyme or cofactor

is involved in the catalytic reaction of the enzyme

Feedback inhibition is used by cells to a. slow down the rate at which organisms consume food. b. decrease the free energy change of undesirable reactions. c. slow down the rate at which organisms excrete waste products. d. keep from producing unnecessarily high levels of different products.

keep from producing unnecessarily high levels of different products.

Which of the following contains hydrolytic enzymes? a. Golgi apparatus b. lysosome c. chloroplast d. mitochondrion

lysosome

The valence shell of an atom a. may correspond to the first, second, third, fourth, fifth, sixth or seventh electron shells, depending on how many electrons the atom has b. may contain no more than 2 electrons c. may occur at any distance from the nucleus, depending on how many electrons the atom has d. is always the lowest energy shell the atom has

may correspond to the first, second, third, fourth, fifth, sixth or seventh electron shells, depending on how many electrons the atom has

Binding of an allosteric regulator to the enzyme it regulates a. is at the enzyme's active site. b. is irreversible. c. may occur via covalent bonds. d. may occur via ionic bonds

may occur via ionic bonds

Which of the following components of the cytoskeleton is made from actin filaments? a. all of these answers are correct b. microfilaments c. microtubules d. intermediate filaments

microfilaments

Which structure-function pair is FALSE? a. ribosome; protein synthesis b. Golgi apparatus; protein trafficking c. lysosome; intracellular digestion d. microtubule; muscle contraction

microtubule; muscle contraction

Which structure is common to plant and animal cells?

mitochondrion

Which is one of the main energy transformers of cells? a. mitochondrion b. lysosome c. peroxisome d. vacuole

mitochondrion - - - - Think of mitochondria as the powerhouses of eukaryotic cells.

A lipid molecule that starts on the inside face of the ER membrane (i.e. the side of the ER membrane that is NOT in contact with the cytosol) and is then transported to the plasma membrane will a. be evenly distributed between the inside and outside faces of the plasma membrane b. most likely end up on the outside (extracellular) face of the plasma membrane c. it is impossible to tell without knowing more about the lipid molecule d. most likely end up on the inside (cytosolic) face of the plasma membrane

most likely end up on the outside (extracellular) face of the plasma membrane - - - - Lipids that are on the inside face of the ER membrane will end up on the inside face of the membrane of vesicles that bud off of the ER, than on the inside face of the Golgi apparatus membrane, then on the inside face of the membrane of vesicles that bud off of the Golgi apparatus and then on the extracellular face of the plasma membrane after the vesicle fuses with the plasma membrane (see figure below, paying special attention to the orientation of the small, green carbohydrates that are attached to the protein molecules in the rough ER to help you keep track of the orientation of membrane components). Also, remember that lipid molecules can diffuse laterally within 1 face of a membrane, but that it is very rare for a lipid molecule to flip-flop from on ½ (face) of a membrane to the other because for that to happen the hydrophilic part of the lipid molecule (e.g. the phosphate and groups attached to the phosphate of a phospholipid molecule) would need to pass through the hydrophobic core of the membrane.

For the reaction described in the figure shown below, which of the following best describes the reaction? https://ay17.moodle.umn.edu/pluginfile.php/1699768/question/questiontext/1382344/16/2146076/image0014f340679.jpg a. negative ∆G, spontaneous b. positive ∆G, nonspontaneous c. positive ∆G, exergonic d. ∆G of zero, chemical equilibrium

negative ∆G, spontaneous - - - The free energy of the reactant molecules (A and B) is greater than the free energy of the product molecules (C and D). So, the reaction of A and B to C and D will result in a decrease in free energy of the system (i.e. a negative ∆G). Reactions where the free energy decreases are known as exergonic, or spontaneous, reactions.

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

neither energy nor matter can leave the system. - - - - The definition of an isolated system is a system where neither energy nor matter can enter or leave the system.

What is the pH of a solution with a hydroxyl ion [OH-] concentration of 10-4 M?

pH 10

The process whereby science experts determine whether a manuscript is suitable for publication in a scientific journal is know as a. discovery science b. peer review c. hypothesis-based science d. prediction testing

peer review

Which of the following types of molecules are the major structural components of the cell membrane? a. proteins and cellulose b. glycoproteins and cholesterol c. phospholipids and proteins d. phospholipids and cellulose

phospholipids and proteins

Vacuoles may act as a. sites of lipid biosynthesis b. all of these answers are correct c. places to store reserves of important organic molecules d. sites of protein biosynthesis

places to store reserves of important organic molecules

The structural level of a protein that is least affected by a disruption in hydrogen bonding is the a. tertiary level b. quaternary level c. primary level d. secondary level

primary level

Which of the following membrane activities require energy from ATP hydrolysis? a. movement of solutes by channel proteins b. facilitated diffusion c. proton pumps d. movement of solutes by carrier proteins

proton pumps

Gap junctions function to a. provide cytoplasmic channels between cells b. fasten cells together into strong sheets c. prevent leakage of extracellular fluid between neighboring cells d. create spaces between cells

provide cytoplasmic channels between cells

Which types of RNA molecules are predominantly transcribed in a special region of the nucleus known as the nucleolus? a. mRNA b. tRNA c. rRNA d. all of these answers are correct

rRNA

What kinds of molecules can pass through a cell membrane most easily? Select one:

small and hydrophobic

Glucose and fructose are examples of a. geometric isomers b. structural isomers c. all of these answers are correct d. stereoisomers

structural isomers - - - - Glucose and fructose have the same molecular formula (C6H12O6), but different shapes, so you can see that they are isomers of some sort. To determine what type of isomers they represent, first look to see if the two molecules (glucose and fructose), share the same covalent partnerships. If you look at them, you will see that they do not share the same covalent partnerships. For example, the position of the carbon:oxygen double bond (C=O) is different for glucose and fructose. This means that glucose and fructose are examples of structural isomers. The other two types of isomers we studied, geometric isomers and enantiomers, do NOT differ in their covalent partnerships.

The tertiary structure of a protein refers to a. its amino acid sequence b. the folded and coiled segment of a polypeptide c. the 3-dimensional shape of a polypeptide d. the overall shape of the protein formed by the aggregation of the polypeptides in the protein

the 3-dimensional shape of a polypeptide

You notice that many of the anabolic reactions in a cell have speeded up. Upon further characterization of the cell, you are NOT surprised to find that a. both the ATP and ADP levels in the cell are low. b. the ATP levels in the cell are low and the ADP levels are high. c. the ATP levels in the cell are high and the ADP levels are low. d. both the ATP and ADP levels in the cell are high.

the ATP levels in the cell are high and the ADP levels are low.

You notice that many of the anabolic reactions in a cell have speeded up. Upon further characterization of the cell, you are NOT surprised to find that a. both the ATP and ADP levels in the cell are high. b. the ATP levels in the cell are high and the ADP levels are low. c. the ATP levels in the cell are low and the ADP levels are high. d. both the ATP and ADP levels in the cell are low.

the ATP levels in the cell are high and the ADP levels are low. CATabolic tears things down

You notice that many of the catabolic reactions in a cell have speeded up. Upon further characterization of the cell, you are NOT surprised to find that a. both the ATP and ADP levels in the cell are high. b. the ATP levels in the cell are high and the ADP levels are low. c. the ATP levels in the cell are low and the ADP levels are high. d. both the ATP and ADP levels in the cell are low.

the ATP levels in the cell are low and the ADP levels are high.

When a plant cell is submerged in a very hypotonic solution, what is likely to occur? a. the cell membrane will lyse b. the cell will become limp c. the cell will burst d. the cell will become turgid (solid, due to being inflated)

the cell will become turgid (solid, due to being inflated)

"Conservation of energy" is another way of stating a. the third 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 first law of thermodynamics

the first law of thermodynamics

The amino acid sequence of a protein allows you to determine a. the tertiary structure of that protein b. the secondary structure of that protein c. the primary structure of the protein d. the quaternary structure of that protein

the primary structure of the protein

In a particular reversible reaction, "A" and "B" may be converted to "C" and "D", or "C" and "D" may be converted to "A" and "B". The direction of this reversible reaction will be determined by a. whether the enzyme that catalyzes the reaction catalyzes the forward or reverse reactions b. the relative concentrations of "A" and "B" versus "C" and "D" c. Both "a" and "b" are correct. d. None of these answers are correct.

the relative concentrations of "A" and "B" versus "C" and "D"

Which action could produce a carbonyl group?

the replacement of the -O-H of a carboxyl group with hydrogen

Some bacteria are metabolically active in hot springs because a. their enzymes have high optimal temperatures. b. they are able to maintain a lower internal temperature. c. high temperatures make catalysis unnecessary. d. their enzymes are completely insensitive to temperature.

their enzymes have high optimal temperatures.

Use the diagram below to help answer this question. The diagram shows a U-tube, with the two arms of the tube separated at the bottom by a selectively permeable barrier. This selectively permeable barrier is permeable to water but not to any ions. If you add 1 liter of an aqueous solution containing 1 mole of MgCl2 to side "A" and you add 1 liter of an aqueous solution containing 1 mole of NaCl to side "B", at equilibrium USHAPE WITH LINE DOWN THE MIDDLE AND A & B https://ay17.moodle.umn.edu/pluginfile.php/1699768/question/questiontext/1370874/11/2145890/image0054f28631d.jpg

there will have been a net flow of water from side "B" to side "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? a. T is the temperature in degrees Celsius. b. ∆H is the change in entropy. c. ∆S is the change in enthalpy. d. ∆G is the change in free energy.

∆G is the change in free energy. - - - - - ∆G = the change in free energy (also known as Gibb's free energy, which explains why it is abbreviated by a "G"). ∆H = the change in enthalpy, which in biological systems is equivalent to total energy. T = the temperature in degrees Kelvin. ∆S = the change in entropy.