EXAM 2 online quizzes

Which process is most directly driven by light energy? reduction of NADP+ molecules ATP synthesis removal of electrons from chlorophyll molecules creation of a pH gradient by pumping protons across the thylakoid membrane

removal of electrons from chlorophyll molecules

How does an enzyme increase the rate of the chemical reaction it catalyzes? An enzyme reduces the free energy of activation (EA) of the reaction it catalyzes. An enzyme reduces the free-energy change (ΔG) of the reaction it catalyzes. An enzyme's active site binds only the reactants, and not the products of a reaction, pushing the equilibrium for the reaction far to the right.

An enzyme reduces the free energy of activation (EA) of the reaction it catalyzes.

Which of the following sequences correctly represents the flow of electrons during photosynthesis? NADPH → electron transport chain → O2 NADPH → O2 → CO2 H2O → NADPH → Calvin cycle H2O → photosystem I → photosystem II

H2O → NADPH → Calvin cycle

A glucose molecule is completely broken down to carbon dioxide and water in glycolysis and the citric acid cycle, but together these two processes yield only a few molecules of ATP. What happened to most of the energy that the cell obtains from the oxidation of glucose? It is stored in pyruvate. It is stored in the ATP that was formed by glycolysis and the citric acid cycle. It is stored in the carbon dioxide and water molecules released by these processes. It is stored in NADH and FADH2 It was lost as heat.

It is stored in NADH and FADH2

Select all that apply. The basic function of fermentation is the production of ethyl alcohol or lactic acid. The basic function of fermentation is the production of additional ATP by further oxidation of the products of glycolysis. The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis. Select all that apply. The basic function of fermentation is the production of ethyl alcohol or lactic acid. The basic function of fermentation is the production of additional ATP by further oxidation of the products of glycolysis. The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis.

The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis.

Which of the following statements about the chemiosmotic synthesis of ATP is correct? The energy for production of ATP from ADP comes directly from a gradient of electrons across the inner mitochondrial membrane. Oxygen participates directly in the reaction that makes ATP from ADP and P. The chemiosmotic synthesis of ATP requires that the electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane. The chemiosmotic synthesis of ATP occurs only in eukaryotic cells because it occurs in mitochondria. Chemiosmotic ATP synthesis requires oxygen.

The chemiosmotic synthesis of ATP requires that the electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane.

The binding of a compound to an enzyme is observed to slow down or stop the rate of the reaction catalyzed by the enzyme. Increasing the substrate concentration reduces the inhibitory effects of this compound. Which of the following could account for this observation? The compound forms a covalent bond with one of the amino acid residues needed for enzyme activity. The compound is a competitive inhibitor. The compound is an allosteric inhibitor. The compound reduces disulfide bonds, causing the enzyme molecules to partially unfold. The compound causes a cofactor to be lost from the enzyme.

The compound is a competitive inhibitor.

When electrons flow along the electron transport chains of mitochondria, which of the following changes occur? NAD+ is oxidized. The pH of the matrix increases. The electrons gain free energy. ATP synthase pumps protons by active transport.

The pH of the matrix increases.

n mechanism, photophosphorylation is most similar to __________. In mechanism, photophosphorylation is most similar to __________. carbon fixation substrate-level phosphorylation in glycolysis oxidative phosphorylation in cellular respiration reduction of NADP+

oxidative phosphorylation in cellular respiration

In the absence of oxygen, what is the net gain of ATP for each glucose molecule that enters glycolysis? four ATP none, because all of the available energy remains in either lactate or ethanol none, because in the absence of oxygen, no ATP can be made two ATP up to 30 ATP

two ATP