AP Biology Chapter 8 Test

What is the change in free energy of a system at chemical equilibrium?

No net change

Which of the following metabolic process can occur without a net influix of energy from some other process?

glucose plus oxygen carbon dioxide plus water

The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is known as ______

Feedback inhibition

When chemical, transport, or mechanical work is done by an organism, what happens to the the heat generated?

It is lost to the enviroment

Why is ATP an important molecule in metabolism?

It provides energy coupling between exergonic and endergonic reactions

How can one increase the rate of a chemical reaction?

Add a catalyst

Which of the following is most similar in structure to ATP?

An RNA nucleotide

When glucose monomers are joined together by glycosdic linkages to form a cellulose polymer, the changes in free energy, total energy, and entropy are as follows:

+G, +H, -S

Which of the following shows the correct changes in thermodynamic properties for a chemical reactions in which amino acids are linked to form a protein?

+H, -S, +G

During a lab experiment, you discover that an enzyme-catalyzed reaction has a G of -20. If you double the amount of enzyme in the reaction, what will be the G for the new reaction?

-20

Chemical equilibrium is relatively rare in living cells. Which of the following could be an example of a reaction at chemical equilibrium in a cell?

A chemical reaction in which both the reactants and products are only used in a metabolic pathway that is completely inactive

Which of the following is an example of potential rather than kinetic energy?

A food molecule made up of energy-rich macromolecules

Which of the following is an example of cooperativity?

A molecule binding at one unit of a tetramer allowing faster binding at each of the other three

Which of following statements best describes enzyme cooperativity?

A substrate molecule bound to an active site affects the active site of several subunits

If an enzyme solution is saturated with substrate, the most effective way to obtain a faster yield of products is to

Add more enzyme

Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reactions's ____________

Activation energy

Some enzymatic regulation is allosteric. In such cases, which of the following would usually be found?

An enzyme with more than one subunit

Which of the following is likely to lead to an increase in the concentration of ATP in a cell?

An increase in a cell's catabolic activity

Which of the following is considered an open system?

An organism

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?

As a consequence of growing, organisms create more disorder in their environment than the decrease in entropy associated with their growth

Sucrose is a disaccharide, composed of the monosaccharides glucose and fructose. The hydrolysis of a sucrose by the enzyme sucrase results in___________

Breaking the bond between glucose and fructose and forming new bonds from the atoms of water

How does a noncompetitve inhibitor decrease the rate of an enzyme reaction?

By changing the shape of a reactant

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

Catabolism

Which of the following statements is representative of the second law of thermodynamics?

Cells require a constant input of energy to maintain their high level of organization

When you have a severe fever, what may be a grave consequence if this is not controlled?

Change in the folding of enzymes

Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxylpeptidase. The zinc most likely functions as a ______________

Cofactor necessary for enzyme activity

Besides turning enzymes on or off, what other means does a cell use to control enzymatic activity?

Compartementalization of enzymes into defined organelles

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?

Competitive inhibition

Catabolism is to anabolism as ___________ is to ___________________

Exergonic; Endergonic

Which of the following types of reactions would decrease the entropy within a cell?

Dehydration reactions

A chemical reaction that has a positive G is correctly described as __________

Endergonic

Which of the following is a statement of the first law of thermodynamics?

Energy cannot be created or destroyed

What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways?

Energy coupling

Whenever energy is transformed, there is always an increase in the _________________

Entropy of the universe

Which of the following is true of enzymes?

Enzymes increase the rate of chemical reaction by lowering activation energy barriers

Which of the following statements regarding enzymes is true?

Enzymes increase the rate of reaction

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

Every chemical reaction must increase the total entropy of the universe

The mathematical expression for the change in free energy of a system is G=H-T,S. Which of the following is correct?

G is the change in free energy

The organization of organisms has become increasingly complex with time. This statement _______

Is consistent with the second law of thermodynamics

The active site of an enzyme is the region that _______

Is involved in the catalytic reaction of the enzyme

When ATP releases some energy, it also releases inorganic phosphate. What purpose foes this serve in the cell?

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

Which of the following is true of metabolism in its entirety?

Metabolism is a property of organismal life

If an enzyme is added to a solution where its substrate and product are in equilibrium, what would occur?

Nothing

When 10,000 molecules of ATP are hydrolyzed to ADP and Pi in a test tube, about twice as much heat is liberated as when a cell hydrolyzes the same amount of ATP. Which of the following is the best explanation for this observation?

Reactant and product concentrations are not the same

Most cells cannot harness heat to perform work because _________________

Temperature is usually uniform throughout a cell

Competitive inhibitors block the entry of substrate into the active site of an enzyme. On which of the following properties of an active site does this primarily depend?

The ability of an enzyme to form a template for holding and joining molecules

A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because_________

The activation energy barrier for this reaction cannot be surmounted

ATP and tRNA stuff. What must occur in order for the final attachment to occur?

The binding of the first two molecules must cause a 3-dimensional change that opens another active site on the enzyme.

According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?

The binding of the substrate changes the shape of the enzyme's active site

Among enzymes, kinases catalyze phosphorylation while phosphatases catalyze removal of phosphates. A cells use of these enzymes can therefore function as an on-off switch for various processes. Which of the following is probably involved?

The change in a protein's charge leading to a conformational change

Which of the following best describes enthalpy?

The heat content of a chemical system

For living organisms, which of the following is an important consequence of the first law of thermodynamics?

The organism ultimately must obtain all of the necessary energy for life from its enviroment

Which of the following statements is true about enzyme-catalyzed reactions?

The reaction is faster than the same reaction in the absence of the enzyme

Which of the following is true for all exergonic reactions?

The reaction proceeds with a net release of free energy

Assume that the reaction has a G of -5.6. Which of the following is true?

The reaction would result in an increase in entropy and a decrease in the total energy content of the system

Some bacteria are metabolically active in hot springs because

Their enzymes have high optimal temperature

What must be the difference between the structure of ATP and the structure of the precursor of the A nucleotide in DNA and RNA?

There is no difference

Which of the following statements is true concerning catabolic pathways?

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

Which of the following is true for anabolic pathways?

They consume energy to build up polymers from monomers

An important group of peripheral membrane proteins are enzymes, such as the phopholipases that attack the head groups of phospholipids leading to the degradation of damaged membranes. What properties must these enzymes exhibit?

Water solubility