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Example Questions
Example Question #1 : Krebs Cycle
Within the Krebs cycle, L-malate and NAD+ come together to form oxaloacetate, NADH, and H+. What type of chemical reaction is responsible for this step in the cycle?
Oxidation
Dehydration
Decarboxylation
Hydration
Oxidation
In order for oxaloacetate to be formed, malate must lose electrons, which is the definition of an oxidation reaction. Alternately, NAD+ is reduced (gains electrons) to form NADH and H+.
Example Question #301 : Organic Chemistry, Biochemistry, And Metabolism
During cellular respiration, where is NADH produced?
The nucleus
The mitochondrial intermembrane space
The endoplasmic reticulum
The cytosol
The cytosol and mitochondrial matrix
The cytosol and mitochondrial matrix
NADH is produced during glycolysis, which occurs in the cytoplasm. NADH is also produced during the Krebs cycle, which occurs in the mitochondrial matrix. The protons generated in the production of NADH are later used in the intermembrane space to power ATP synthase during oxidative phosphorylation.
Example Question #1 : Krebs Cycle
If the Krebs cycle is overstimulated, the body will produce too much of which of the following molecules?
Oxygen
Acetyl CoA
Glucose
Carbon dioxide
Pyruvate
Carbon dioxide
Of the answer choices, only carbon dioxide is a product of the Krebs cycle. If the cycle is overstimulated, too much of the products will be formed and the body will have too much carbon dioxide.
Glucose is the reactant that fuels glycolysis to produce pyruvate, which is then converted to acetyl CoA for the Krebs cycle. As such, each of these would be depleted as reactants fueling an overstimulation of the Krebs cycle.
Example Question #1 : Krebs Cycle
Where is the Krebs cycle carried out in eukaryotic cells?
Mitochondrial matrix
Cytosol
Inner membrane of the mitochondria
Nucleus
Mitochondrial matrix
During the Krebs cycle, or citric acid cycle, acetyl CoA is oxidized to CO2 and NAD+ and FADH are reduced to NADH and FADH2, respectively. This process is carried out in the mitochondrial matrix of eukaryotic cells.
The electron transport chain is carried out in the inner membrane of the mitochondria, while glycolysis is carried out in the cytosol.
Example Question #1691 : Mcat Biological Sciences
Cellular respiration is the set of metabolic reactions that occur in cells to produce energy in the form of ATP. During cellular respiration, high energy intermediates are created that can then be oxidized to make ATP. During what stage are these intermediates produced?
Glycolysis
Oxidative phosphorylation and the citric acid cycle
Oxidative phosphorylation
The citric acid cycle
The citric acid cycle and glycolysis
The citric acid cycle and glycolysis
The citric acid (Krebs) cycle and glycolysis yield high energy intermediates that can then be used to make ATP. Each turn of the citric acid cycle generates NADH and FADH2, and each cycle of glycolysis generates NADH. These intermediates can then donate their electrons and become oxidized in the electron transport chain. Production of these electron donors is essential to the function of the electron transport chain.
Example Question #16 : Biochemistry And Metabolism
Acetyl-CoA is a react in the citric acid cycle, while and
are products. If twelve molecules of
are produced over a period of time, how many
molecules are produced during this period?
Twenty-four
Two
Four
Twelve
Four
Each turn of the citric acid cycle is powered by one molecule of acetyl-CoA, resulting in three and one
. The net reaction is:
Since twelve are produced, there must have been an input of four acetyl-CoA molecules and four total turns in the cycle. As a result, four
molecules were produced.
Example Question #1 : Krebs Cycle
Which statement is false regarding the citric acid cycle?
6 GTP molecules would be produced starting with 3 glucose molecules
It occurs in the mitochondrial matrix for eukaryotes
All of these
Another name for it is the Krebs cycle
Oxygen is directly required for the citric acid cycle to occur
Oxygen is directly required for the citric acid cycle to occur
Oxygen is needed for the electron transport chain to occur which oxidizes and
. If there is no oxygen available then Krebs cycle would not occur since there would be no oxidized electron carriers. Therefore oxygen is only indirectly required for the Krebs cycle to occur, not directly.
Example Question #1 : Krebs Cycle
James took a neural sample and separated the cell body from the axon. He noticed that when he placed both parts on a glucose plate, the cell body began releasing carbon dioxide. What could explain the result?
The cell body is degrading
None of these
The cell body contains mitochondria
The carbon dioxide came from the plate
The carbon dioxide is used as a messenger to communicate with the axon
The cell body contains mitochondria
The cell body of a neuron is where the mitochondria and all other organelles are located. Recall from the Krebs cycle that carbon dioxide is produced as a byproduct. Anaerobic respiration, which occurs in the cytoplasm does not release carbon dioxide (in humans) and produces lactic acid instead. Note that in certain organisms like yeast, fermentation produces ethanol (two-carbons) and carbon dioxide since pyruvate, the product of glycolysis is a three-carbon molecule.
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