GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Biochemistry
Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology
All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources
Example Questions
Example Question #2 : Help With Metabolic Regulation And Hormones
Antidiuretic hormone (ADH) is produced in the pituitary gland and then secreted into the blood stream. What is the function of ADH?
Secreted ADH decreases the amount of water reabsorbed in the nephron by stimulating the ATP-dependent closure of aquaporins in the collecting duct
Secreted ADH stimulates the pancreas to secrete more insulin by binding specific receptors in pancreatic capillaries
Secreted ADH increases the amount of water reabsorbed from the nephron into the bloodstream by increasing the number of aquaporins in the collecting duct
Secreted ADH decreases the reabsorbtion of sodium and chloride in the ascending loop of Henle by binding and inhibiting the ATP-dependent sodium/chloride pumps
Secreted ADH stimulates the reabsorption of glucose by increasing the number of glucose-2 transporters in the nephron proximal tubule
Secreted ADH increases the amount of water reabsorbed from the nephron into the bloodstream by increasing the number of aquaporins in the collecting duct
Antidiuretic hormone (ADH) binds the ADH receptors in the basolateral membrane of the collecting duct, which, through an ATP-dependent signaling cascade, synthesizes and relocates aquaporin-2 to the apical membrane of the collecting duct epithelial cells. The increase of aquaporin-2 at this membrane location facilitates increased water reabsorbtion into the bloodstream.
Example Question #2 : Help With Metabolic Regulation And Hormones
Which of the following cellular processes is NOT stimulated by insulin?
Glycogenesis
Glycolysis
Lipolysis
Cholesterol synthesis
Lipolysis
Insulin is a hormone that can often be associated with post-meal metabolism. The body has just eaten a meal, and is sequestering all of the nutrients and vitamins in the food. As a result, insulin is often associated with anabolic processes: glycogenesis, cholesterol and protein synthesis, and lipogenesis. Lipolysis, or the breaking down of fatty acids, is observed in periods of starvation, and therefore would not be stimulated by insulin.
Example Question #3 : Help With Metabolic Regulation And Hormones
Which enzyme would be inhibited in the body following a carbohydrate-heavy meal?
Fructose-1,6-bisphosphatase
Glucokinase
Glycogen synthase
PFK-1
Fructose-1,6-bisphosphatase
After eating a carbohydrate-heavy meal, the body is not going to have any problem getting access to glucose. As a result, the body is going to activate enzymes needed for bringing glucose into cells and storing/using it. This includes glucokinase, PFK-1, and glycogen synthase. Fructose-1,6-bisphosphatase is an enzyme used in gluconeogenesis. Since the body does not need to create glucose following the meal, this enzyme is inhibited.
Example Question #121 : Biochemistry
What is the primary purpose of fermentation?
Generate oxygen
Generate ATP
Generate ethanol
Regenerate NAD+
Regenerate NAD+
The primary purpose of fermentation is to regenerate the NAD+ that was reduced to NADH during glycolysis. This is essential because the cell will need that NAD+ to be able to go through glycolysis. In anaerobic environments, the Krebs cycle and electron transport chain cease to function, leaving glycolysis as the primary metabolic process for the cell to generate ATP. NAD+ is an essential reactant for glycolysis, but is rapidly consumed when the electron transport chain is not running. Fermentation takes place in order to replenish this reactant and allow glycolysis to continue.
Ethanol and lactic acid can be products of fermentation, but are not the primary purpose for fermentation. No oxygen or ATP is generated during this process.
Example Question #1 : Help With Other Metabolic Processes
In comparison to anaerobic metabolism, aerobic metabolism of glucose produces __________.
less carbon dioxide
fewer protons for pumping in mitochondria
more ATP per glucose
pyruvate
more oxidized coenzymes
more ATP per glucose
During aerobic metabolism, a single glucose molecule produces significantly more ATP molecules than during anaerobic metabolism. The exact number depends on a number of things, including the organism, cell type, and NADH shuttle. Aerobic metabolism of glucose produces more reduced coenzymes, which drop off their electrons at the electron transport chain in the mitochondria. Electron transport provides energy to pump protons from the mitochondrial matrix into the intermembrane space. Both processes produce pyruvate.
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All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources
