You have isolated a previously unstudied protein, identified its complete structure in detail and determined that it catalyzes the breakdown of a large substrate. You notice it has two binding sites. One of theses is large, apparently the bonding site for the large substrate; the other is small, possibly a binding site for a regulatory molecule. What do these finding tell you about the mechanism of this protein?

You have isolated a previously unstudied protein, identified its complete structure in detail and determined that it catalyzes the breakdown of a large substrate. You notice it has two binding sites. One of theses is large, apparently the bonding site for the large substrate; the other is small, possibly a binding site for a regulatory molecule. What do these finding tell you about the mechanism of this protein?

a. it is probably an enzyme that works through allosteric regulation
b. it is probably an enzyme that works through competitive inhibition
c. it is probably a cell membrane transport protein-like an ion channel
d. it is probably a structural protein that is involved in cell-to-cell adhesion

Answer: A

With respect to the enzyme that converts X to Y, substance A functions as _____.

With respect to the enzyme that converts X to Y, substance A functions as _____.

a. a competitive inhibitor
b. an allosteric inhibitor
c. the substrate
d. an intermediate

Answer: B

What is substance X?

What is substance X?

a. the product
b. a substrate
c. an allosteric inhibitor
d. an intermediate





Answer: B

In the figure, why does the reaction rate plateau at higher reactant concentrations?

In the figure, why does the reaction rate plateau at higher reactant concentrations?

a. the reaction nears equilibrium at high reactant concentrations
b. the rate of the reverse reaction increases with reactant concentration
c. feedback inhibition by product occurs at high reactant concentrations
d. most enzyme molecules are occupied by substrate at high reactant concentrations

Answer: D

A noncompetitive inhibitor decreases the rate of an enzyme reaction by____.

A noncompetitive inhibitor decreases the rate of an enzyme reaction by____.

a. binding at the active site of the enzyme
b. acting as a coenzyme for the reaction
c. changing the free energy change of the reaction
d. changing the shape of the enzyme's active site

Answer: D

According to the induced fit hypothesis of enzyme catalysis, ______.

According to the induced fit hypothesis of enzyme catalysis, ______.

a. the binding of the substrate changes the shape of the enzyme's active site
b. some enzymes change their structure when activators bind to the enzyme
c. the active site created a microenvironment ideal for the reaction
d. the binding of the substrate depends on the shape of the active site

Answer: A

The lock-and-key analogy for enzymes applies to the specificity of enzymes____.

The lock-and-key analogy for enzymes applies to the specificity of enzymes____.

a. interacting with ions
b. as they form their tertiary and quaternary structure
c. interacting with water
d. binding to their substrate

Answer: D

Which of the following is true of enzymes?

Which of the following is true of enzymes?

a. enzyme function is independent of physical and chemical environmental factors such as pH and temperature
b. enzyme function is increased if the 3-D structure or conformation of an enzyme is altered
c. enzymes increase the rate of chemical reaction by lowering activation barriers
d. enzymes increase the rate of chemical reaction by providing activation energy to the substrate

Answer: C

What compound provides the reducing power for Calvin cycle reactions?

What compound provides the reducing power for Calvin cycle reactions?

a. ATP
b. NADH
c. NADPH
d. NADP+

Answer: C

Which of the following does NOT occur during the Calvin cycle?

Which of the following does NOT occur during the Calvin cycle?

a. regeneration of the CO2 acceptor
b. oxidation of NADPH
c. release of oxygen
d. consumption of ATP

Answer: C

Which of the following sequences correctly represents the flow of electrons during photosynthesis?

Which of the following sequences correctly represents the flow of electrons during photosynthesis?

a. NADPH-chlorophyll-calvin cycle
b. NADPH-O2-CO2
c. H2O-NADPH-Calvin cycle
d. NADPH- electron transport chain- O2

Answer: C

Refer to the figure. If the carbon atom of each of the incoming CO2 molecules is labeled with a radioactive isotope of carbon, which organic molecules will be radioactively labeled after one cycle?

Refer to the figure. If the carbon atom of each of the incoming CO2 molecules is labeled with a radioactive isotope of carbon, which organic molecules will be radioactively labeled after one cycle?

a. C,D, and E only
b. B,C,D, and E
c. B and C only
d. C only

Answer: B

In the process of carbon fixation, RuBP attaches a CO2 to produce a six-carbon molecule, which is then split to produce two molecules of 3-phosphoglycerate. After phosphorylation and reduction produces G3P, what more needs to happen to complete the Calvin cycle?

In the process of carbon fixation, RuBP attaches a CO2 to produce a six-carbon molecule, which is then split to produce two molecules of 3-phosphoglycerate. After phosphorylation and reduction produces G3P, what more needs to happen to complete the Calvin cycle?

a. regeneration of NADP+
b. regeneration of RuBP
c. regeneration of ATP from ADP
d. addition of a pair of electrons from NADPH

Answer: B

What is the primary function of the Calvin Cycle?

What is the primary function of the Calvin Cycle?

a. synthesize simple sugars from carbon dioxide
b. split water and release oxygen
c. use NADPH to release carbon dioxide
d. transport RuBP out of the chloroplast

Answer: A

Where does the Calvin cycle take place?

Where does the Calvin cycle take place?

a. interior of the thylakoid (thylakoid space)
b. outer membrane of the chloroplasts
c. stroma of the chloroplasts
d. thylakoid membrane

Answer: C

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin Cycle?

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin Cycle?

a. CO2 and glucose
b. ADP, Pi, and NADP+
c. ATP and NADPH
d. H2O and O2

Answer: C

Which process is most directly driven by light energy?

Which process is most directly driven by light energy?

a. removal of electrons from chlorophyll molecules
b. reduction of NADP+ molecules
c. creation of a pH gradient by pumping protons across the thylakoid membrane
d. carbon fixation in the stroma

Answer: A

In a plant, the reactions that produce molecular oxygen (O2) take place in_____.

In a plant, the reactions that produce molecular oxygen (O2) take place in_____. 

a. the light reactions and the Calvin Cycle
b. neither the light reactions nor the Calvin Cycle
c. the light reactions alone
d. the Calvin Cycle alone

Answer: C

Which of the following statements best describes the relationship between photosynthesis and respiration?

Which of the following statements best describes the relationship between photosynthesis and respiration?

a. photosynthesis stores energy in complex organic molecules; respiration releases energy from complex organic molecules
b. photosynthesis occurs only in plants; respiration occurs only in animals
c. photosynthesis is catabolic; respiration is anabolic
d. respiration runs the biochemical pathways of photosynthesis in reverse

Answer: A

In mitochondria, chemiosmosis moves protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis moves protons from the ____.

In mitochondria, chemiosmosis moves protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis moves protons from the ____.

a. thylakoid space to the stroma
b. matrix to the stroma
c. inter membrane space to the matrix
d. stroma to the thylakoid space

Answer: D