Lecture 4 & 5 Flashcards
The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction _____.
a. gains electrons and gains potential energy
b. gains electrons and loses potential energy
c. loses electrons and loses potential energy
d. loses electrons and gains potential energy
c. loses electrons and loses potential energy
When electrons move closer to a more electronegative atom, what happens? The more electronegative atom is _____.
a. oxidized, and energy is released
b. oxidized, and energy is consumed
c. reduced, and energy is consumed
d. reduced, and energy is released
d. reduced, and energy is released
Which of the following describes the process of glycolysis?
a. It converts one glucose molecule to two molecules of pyruvate and carbon dioxide.
b. It represents the first stage in the chemical oxidation of glucose by a cell.
c. It requires ATP and NADH.
d. Glycolysis occurs in the mitochondria.
e. Glycolysis produces 30 ATP from each molecule of glucose.
b. It represents the first stage in the chemical oxidation of glucose by a cell.
Which kind of metabolic poison would most directly interfere with glycolysis?
a. an agent that reacts with oxygen and depletes its concentration in the cell
b. an agent that reacts with NADH and oxidizes it to NAD+
c. an agent that closely mimics the structure of glucose but is not metabolized
d. an agent that binds to pyruvate and inactivates it
c. an agent that closely mimics the structure of glucose but is not metabolized
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?
a. It was lost as heat.
b. It is stored in NADH and FADH2
c. It is stored in the ATP that was formed by glycolysis and the citric acid cycle.
d. It is stored in the carbon dioxide and water molecules released by these processes.
e. It is stored in pyruvate.
b. It is stored in NADH and FADH2
Which statement about the citric acid cycle is correct?
a. The citric acid cycle oxidizes glucose to carbon dioxide.
b. The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.
c. The citric acid cycle produces most of the ATP that is subsequently used by the electron transport chain.
d. The citric acid cycle depends on the availability of NAD+, which is a product of glycolysis.
e. The oxidation of compounds by the citric acid cycle requires molecular oxygen.
b. The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.
The electrons stripped from glucose in cellular respiration end up in which compound?
a. water
b. carbon dioxide
c. oxygen
d. ATP
e. NADH
a. water
The chemiosmotic hypothesis is an important concept in our understanding of cellular metabolism in general because it explains _____.
a. how ATP is synthesized by a proton motive force
b. the sequence of the electron transport chain molecules
c. how electron transport can fuel substrate-level phosphorylation
d. the reduction of oxygen to water in the final steps of oxidative metabolism
a. how ATP is synthesized by a proton motive force
One function of both alcohol fermentation and lactic acid fermentation is to _____.
a. reduce NAD+ to NADH
b. oxidize NADH to NAD+
c. reduce FAD+ to FADH2
d. reduce FADH2 to FAD+
b. oxidize NADH to NAD+
In autotrophic bacteria, where is chlorophyll located?
a. in the nucleoid
b. in the ribosomes
c. in chloroplast membranes
d. in the infolded plasma membrane
d. in the infolded plasma membrane
Photosynthesis is a redox reaction. This means that H2O is _____ during the light reactions and CO2 is _____ during the Calvin cycle.
a. reduced…oxidized
b. reduced…reduced
c. oxidized…reduced
d. consumed…consumed
e. consumed…reduced
c. oxidized…reduced
P680+ is said to be the strongest biological oxidizing agent. Given its function, why is this necessary?
a. It is the receptor for the most excited electron in either photosystem of photosynthesis.
b. It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has.
c. It is the molecule that transfers electrons to plastoquinone (Pq) of the electron transfer system.
d. It transfers its electrons to reduce NADP+ to NADPH.
b. It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has.
Which of the following sequences correctly represents the flow of electrons during photosynthesis?
a. NADPH → O2 → C O2
b. NADPH → electron transport chain → O2
c. H2O → NADPH → Calvin cycle
d. NADPH → chlorophyll → Calvin cycle
c. H2O → NADPH → Calvin cycle
