BIOLOGY101- chapter 6

Enzymes are described as catalysts, which means that they __________.

increase the rate of a reaction without being consumed by the reaction

Which of the following statements best describes the critical role that ATP plays in cellular metabolism? The covalent bond on the terminal phosphate of ATP is particularly strong, so it releases extra energy when hydrolyzed. ATP hydrolysis provides the energy used to power exergonic reactions in the cell. ATP serves as an energy shuttle in the cell, coupling exergonic and endergonic reactions. It is one of the four building nucleotides required for DNA synthesis.

ATP serves as an energy shuttle in the cell, coupling exergonic and endergonic reactions.

Which of the following is a statement of the first law of thermodynamics? The entropy of the universe is constant. Energy cannot be transferred or transformed. Energy cannot be created or destroyed. The entropy of the universe is decreasing.

Energy cannot be created or destroyed.

Which of the following statements regarding enzymes is true? Enzymes increase the rate of a reaction by lowering the activation energy barrier. Enzymes change the equilibrium point of the reactions they catalyze. Enzymes increase the rate of a reaction by reducing the rate of reverse reactions. Enzymes increase the rate of a reaction by making the reaction more exergonic.

Enzymes increase the rate of a reaction by lowering the activation energy barrier.

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

It is released to the environment.

Why might a severe fever result in death if it is not brought under control?

It may alter the tertiary and quaternary structures of cellular enzymes.

A mutation that results in a single amino acid substitution in the active site of an enzyme may have which of the following consequences?

It may change the substrate specificity of the enzyme.

Which of the following is NOT a way in which an enzyme can speed up the reaction that it catalyzes? The active site of the enzyme can provide a microenvironment with a different pH that facilitates the reaction. The binding of two substrates in the active site provides the correct orientation for them to react to form a product. The enzyme binds a cofactor that interacts with the substrate to facilitate the reaction. The active site can provide heat from the environment that raises the energy content of the substrate. Binding of the substrate to the active site can stretch bonds in the substrate that need to be broken.

The active site can provide heat from the environment that raises the energy content of the substrate.

Which of the following statements best describes the induced fit model of enzyme activity? The binding of a competitive inhibitor changes the shape of the active site so that it binds substrate less tightly. The binding of substrate depends on the conformation of the active site. The binding of substrate changes the conformation of the active site to bind substrate more tightly. The binding of an activator alters the conformation of the active site to bind products more tightly.

The binding of substrate changes the conformation of the active site to bind substrate more tightly.

Which of the following statements about ATP (adenosine triphosphate) is correct? The hydrolysis of ATP can supply energy needed for catabolic pathways. The cycling between ATP and ADP + Pi provides an energy coupling between catabolic and anabolic pathways. The energy release on hydrolysis of ATP is the result of breaking a high-energy bond. Almost all of the free energy released on the hydrolysis of ATP is released as heat. The hydrolysis of ATP is an endergonic process.

The cycling between ATP and ADP + Pi provides an energy coupling between catabolic and anabolic pathways.

What is the difference (if any) between the structure of ATP and the structure of the A nucleoside triphosphate used to make RNA?

There is no difference; they are the same molecule.

The process of cellular respiration, which converts simple sugars such as glucose into CO2 and water, is an example of __________.

a catabolic pathway

Which of the following is an example of an anabolic pathway? a set of reactions that combine monomers into larger, more energy-rich polymers a set of coupled reactions that are exergonic a set of reactions that release energy that can be used to drive cellular work a set of reactions that break covalent bonds between molecules to release free energy

a set of reactions that combine monomers into larger, more energy-rich polymers

The cellular process of synthesizing large molecules from smaller ones is defined as

anabolism

A noncompetitive inhibitor decreases the rate of an enzymatic reaction by

changing the shape of the enzyme active site.

Which of the following reactions tend to require an input of energy? catabolic exergonic hydrolysisde hydration

dehydration

A chemical reaction that has a positive ΔG is best described as

endergonic.

Which of the following processes would be an example of a catabolic pathway? production of complex molecules such as protein from simpler compounds providing energy that can be used to drive cellular work any endergonic reaction in a cell combining small molecules into larger, more energy-rich molecules

providing energy that can be used to drive cellular work