Effects Of Insulin And Glucagon! Biochemistry Trivia Quiz
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- 1.
What cells in the pancreas release insulin?
- A.
Pancreatic Alpha cell
- B.
Pancreatic Beta cell
- C.
Parietal cells
- D.
Mucous cells
Correct Answer
B. Pancreatic Beta cellExplanation
The correct answer is Pancreatic Beta cell. These cells are responsible for releasing insulin in the pancreas. Insulin plays a crucial role in regulating blood sugar levels by allowing cells to take in glucose from the bloodstream. When blood sugar levels are high, beta cells release insulin to lower them. Dysfunction or destruction of these cells can lead to insulin deficiency and the development of diabetes.Rate this question:
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- 2.
In the pancreatic beta-cell:
- A.
Preproinsulin is processed to pronsulin and then to insulin that is secreted
- B.
Proinsulin is processed to insulin and then preproinsulin
- C.
Preproinsulin is degraded into insulin and then secreted
- D.
Preproinsulin is processed by proinsulin and then by insulin to be secreted
Correct Answer
A. Preproinsulin is processed to pronsulin and then to insulin that is secretedExplanation
In the pancreatic beta-cell, preproinsulin undergoes processing to form proinsulin, which is then further processed to form insulin. This processed insulin is then secreted from the pancreatic beta-cell.Rate this question:
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- 3.
What cells in the pancreas release glucagon?
- A.
Pancreatic Alpha cells
- B.
Pancreatic Beta cells
- C.
Hepatic Acrine cells
- D.
Insulin-dependent cells
Correct Answer
A. Pancreatic Alpha cellsExplanation
Pancreatic Alpha cells release glucagon. Glucagon is a hormone that helps to regulate blood sugar levels. When blood sugar levels are low, the alpha cells in the pancreas release glucagon, which signals the liver to convert stored glycogen into glucose and release it into the bloodstream. This helps to increase blood sugar levels.Rate this question:
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- 4.
Which of the following statements is true about Glucagon?
- A.
Secreted by acinar cells into the pancreatic duct
- B.
Secreted by Beta cells of the Islets of Langerhan into the pancreatic duct
- C.
Secreted by Islets of Langerhan cells into blood vessels
- D.
Secreted by Alpha cells of the Islets of Langerhan into blood vessels
Correct Answer
D. Secreted by Alpha cells of the Islets of Langerhan into blood vesselsExplanation
Glucagon is a hormone that is secreted by the alpha cells of the Islets of Langerhans into the blood vessels. It is not secreted by acinar cells into the pancreatic duct, beta cells of the Islets of Langerhans into the pancreatic duct, or Islets of Langerhans cells into blood vessels.Rate this question:
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- 5.
The islets of Langerhans only make up about 1-2% of the total pancreas cells.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The islets of Langerhans are specialized regions within the pancreas that are responsible for producing and releasing hormones such as insulin and glucagon. These hormones play a crucial role in regulating blood sugar levels. The pancreas is composed of various types of cells, and the islets of Langerhans make up only a small percentage, approximately 1-2%, of the total pancreatic cells. Therefore, the statement that the islets of Langerhans only make up about 1-2% of the total pancreas cells is true.Rate this question:
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- 6.
Insulin is secreted out of the islet of Langerhan cells directly into blood vessels, but glucagon is not.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Glucagon is actually secreted out of the islet of Langerhans cells directly into blood vessels, just like insulin. Therefore, the statement is incorrect and the correct answer is False.Rate this question:
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- 7.
Which of the following statements about the pancreas is true?
- A.
Insulin and glucagon are secreted by the exocrine portion of the pancreas.
- B.
The endocrine pancreas consists of groups of cells known as islets of Langehans whch are embeded in the exocrine portion of the gland.
- C.
The exocrine portion consists of islets of langerhan cells that release hormones such as somatostatin into the pancreatic duct.
- D.
Delta cells of the islets of Langerhans secrete glucagon into blood vessels.
Correct Answer
B. The endocrine pancreas consists of groups of cells known as islets of Langehans whch are embeded in the exocrine portion of the gland.Explanation
The correct answer is that the endocrine pancreas consists of groups of cells known as islets of Langehans which are embedded in the exocrine portion of the gland. This means that the cells responsible for secreting insulin and glucagon are located within the exocrine portion of the pancreas, rather than in a separate part of the gland.Rate this question:
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- 8.
Which of the following is not a stimulator of insulin secretion
- A.
Scarcity of food
- B.
Glucose in blood
- C.
Amino acids in blood
- D.
Glucokinase in beta cells
Correct Answer
A. Scarcity of foodExplanation
Insulin secretion is stimulated by high levels of glucose and amino acids in the blood, as well as the presence of glucokinase in beta cells. However, scarcity of food does not stimulate insulin secretion. When food is scarce, the body conserves energy by reducing insulin secretion, as insulin promotes the storage of nutrients and energy. Therefore, scarcity of food is not a stimulator of insulin secretion.Rate this question:
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- 9.
Which of the following are stimulators of insulin secretion?
- A.
Secretion from intestine following food intake
- B.
Epinephrine releases during stress, infection or fever
- C.
Amino acids in blood (esp. arginine)
- D.
Glucose in blood
- E.
Scarcity of food
Correct Answer(s)
A. Secretion from intestine following food intake
C. Amino acids in blood (esp. arginine)
D. Glucose in bloodExplanation
Insulin is primarily secreted in response to elevated blood glucose levels. When food is consumed, the intestine secretes certain hormones, such as incretins, which stimulate insulin secretion. Amino acids, especially arginine, also stimulate insulin secretion. Additionally, glucose itself is a potent stimulator of insulin secretion. Therefore, secretion from the intestine following food intake, amino acids in the blood (esp. arginine), and glucose in the blood are all stimulators of insulin secretion.Rate this question:
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- 10.
Which of the following stimulate the secretion of glucagon by the pancreas?
- A.
High Glucose in blood
- B.
Decrease in plasma glucose
- C.
Increase in epinephrine
- D.
Insulin
- E.
Increase in plasma Amino Acid from a protein -rich meal
- F.
Increase in norepinephrine due to stress, trauma, intense exercise
- G.
Food intake (carbohydrate-rich meal)
Correct Answer(s)
B. Decrease in plasma glucose
C. Increase in epinephrine
E. Increase in plasma Amino Acid from a protein -rich meal
F. Increase in norepinephrine due to stress, trauma, intense exerciseExplanation
The pancreas secretes glucagon in response to a decrease in plasma glucose levels, as it helps to raise blood sugar levels. Epinephrine, norepinephrine, and an increase in plasma amino acids from a protein-rich meal also stimulate the secretion of glucagon. Epinephrine and norepinephrine are released during stress, trauma, and intense exercise, while an increase in plasma amino acids indicates the presence of food intake, specifically a protein-rich meal. These factors all contribute to the stimulation of glucagon secretion by the pancreas.Rate this question:
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- 11.
Look at the image and select the correct order of Insulin synthesis from the options given.
- A.
A, B, C, D, E, F, G
- B.
G, F, E, D, C, B, A
- C.
A, F, D, B, G, C, E
- D.
B, A, D, C, E, F, G
Correct Answer
C. A, F, D, B, G, C, E -
- 12.
To form proinsulin from preproinsulin:
- A.
The signal sequence is cleaved but A & B sequences and C-peptide remain, with disulfide bonds added to join A domain to B domain.
- B.
The C-peptide is cleaved leaving the A and B domains linked via disulfide bonds and the signal sequence.
- C.
The C-peptide and signal sequence remain following the cleavage of the A and B domains
- D.
Only the A and B domains remain bonded via hydrogen bonds to the C- peptide
Correct Answer
A. The signal sequence is cleaved but A & B sequences and C-peptide remain, with disulfide bonds added to join A domain to B domain.Explanation
After the signal sequence is cleaved, the A and B sequences and the C-peptide remain. Disulfide bonds are then added to join the A domain to the B domain. This means that the A and B domains are still connected to each other through disulfide bonds, while the C-peptide and signal sequence are also present.Rate this question:
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- 13.
In the formation of insulin, which of the following occurs?
- A.
C-Peptide is cleaved leaving ONLY the A & B disulfide bond linked insulin
- B.
The A and B domains are inverted and joined to the C-Peptide via H-bonds
- C.
The C-Peptide is rejoined to form proinsulin from insulin
- D.
Preproinsulin is cleaved to form insulin with no intermediate form
Correct Answer
A. C-Peptide is cleaved leaving ONLY the A & B disulfide bond linked insulin -
- 14.
Which of the following pathways are activated by insulin?
- A.
Glucose uptake in muscle and adipose tissue
- B.
Cellular respiration
- C.
Glycogenolysis
- D.
Glycogenesis in liver and muscle
- E.
Protein degradation
- F.
Amino Acid uptake
- G.
Protein Synthesis
Correct Answer(s)
A. Glucose uptake in muscle and adipose tissue
B. Cellular respiration
D. Glycogenesis in liver and muscle
F. Amino Acid uptake
G. Protein SynthesisExplanation
Insulin activates the pathway of glucose uptake in muscle and adipose tissue by promoting the translocation of glucose transporter proteins to the cell membrane, allowing for the uptake of glucose from the bloodstream. It also activates cellular respiration by stimulating the uptake of glucose into cells, which is then used as a fuel source for ATP production. Insulin promotes glycogenesis in the liver and muscle by activating the enzyme glycogen synthase, which converts glucose into glycogen for storage. It also promotes amino acid uptake by enhancing the transport of amino acids into cells. Finally, insulin stimulates protein synthesis by activating signaling pathways that promote the translation of mRNA into proteins.Rate this question:
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- 15.
Which of the following pathways are inhibited by insulin?
- A.
Lipolysis
- B.
Glucose uptake
- C.
Lipoproteins uptake in Adipose tissue
- D.
Protein degradation
- E.
Cellular respiration
- F.
Glycogenolysis
- G.
Protein synthesis
- H.
Protein synthesis
Correct Answer(s)
A. Lipolysis
D. Protein degradation
F. GlycogenolysisExplanation
Insulin inhibits lipolysis, which is the breakdown of fats into fatty acids. It also inhibits glycogenolysis, which is the breakdown of glycogen into glucose. Additionally, insulin inhibits protein degradation, which is the breakdown of proteins into amino acids. These inhibitory effects of insulin help to promote energy storage and anabolic processes in the body.Rate this question:
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- 16.
Which of the labeled subunits are involved in binding the receptor to the insulin molecule?
- A.
B
- B.
A
Correct Answer
B. AExplanation
The labeled subunit A is involved in binding the receptor to the insulin molecule.Rate this question:
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- 17.
Which of the following is NOT an intracellular effector involved in insulin function?
- A.
Alpha subunit
- B.
IRS
- C.
Adaptors
- D.
Enzyme effectors
Correct Answer
A. Alpha subunitExplanation
The alpha subunit is not an intracellular effector involved in insulin function. Insulin signaling involves the activation of insulin receptor substrate (IRS), which acts as a docking protein for downstream signaling molecules. Adaptors are also involved in insulin signaling by facilitating the interaction between different signaling molecules. Enzyme effectors, such as phosphatidylinositol 3-kinase (PI3K), play a crucial role in mediating the metabolic effects of insulin. However, the alpha subunit is not directly involved in insulin signaling and is not considered an intracellular effector in this context.Rate this question:
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- 18.
Identify the cellular responses to insulin present:
- A.
Increased glucose uptake
- B.
Regulation of transcription
- C.
Activation of enzymes
- D.
Covalent modification and up-regulation
- E.
Decreased glucose uptake
Correct Answer(s)
A. Increased glucose uptake
B. Regulation of transcription
C. Activation of enzymes
D. Covalent modification and up-regulationExplanation
Insulin is a hormone that plays a crucial role in regulating glucose levels in the body. When insulin is present, it triggers various cellular responses. Increased glucose uptake refers to the process where cells take in more glucose from the bloodstream, which helps to lower blood sugar levels. Regulation of transcription involves insulin influencing the expression of certain genes, leading to changes in protein production. Activation of enzymes refers to insulin activating specific enzymes involved in various metabolic processes. Covalent modification and up-regulation refer to insulin modifying proteins through chemical bonds and increasing their production. Decreased glucose uptake is not a cellular response to insulin.Rate this question:
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- 19.
In the control of insulin receptor, Autophosphorylation ____________, while Dephosphorylation _____________.
Correct Answer(s)
Activates
InactivatesExplanation
Autophosphorylation of the insulin receptor activates it, meaning that it enhances its function and signaling. On the other hand, dephosphorylation of the insulin receptor inactivates it, meaning that it reduces its function and signaling.Rate this question:
- 20.
Another way of controlling the insulin receptor is by insulin binding and subsequent dissociation. TRUE OR FALSE?
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Insulin receptor can be controlled by insulin binding and subsequent dissociation. When insulin binds to the receptor, it triggers a cascade of signaling events that regulate various cellular processes, including glucose uptake and metabolism. Once the desired effects are achieved, insulin dissociates from the receptor, allowing the receptor to become available for further signaling events. Therefore, the statement is true.Rate this question:
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- 21.
Insulin binding activates tyrosine kinase activity in the intracellular domain of the beta subunit of the insulin receptor.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Insulin binding to the insulin receptor activates tyrosine kinase activity in the intracellular domain of the beta subunit. This means that when insulin binds to the receptor, it triggers a signaling cascade that leads to the activation of tyrosine kinase enzymes. These enzymes play a crucial role in various cellular processes, including glucose uptake and metabolism. Therefore, the statement is true.Rate this question:
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- 22.
Following insulin binding, tyrosine residues of the beta subunit are dephosphorylated.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Insulin binding does not lead to the dephosphorylation of tyrosine residues of the beta subunit. In fact, insulin binding activates the insulin receptor, leading to the phosphorylation of tyrosine residues on the beta subunit. This phosphorylation is an important step in the signaling cascade triggered by insulin binding, which ultimately leads to various cellular responses such as glucose uptake and metabolism. Therefore, the correct answer is false.Rate this question:
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- 23.
Receptor tyrosine kinase phosphorylates other proteins, for example, insulin receptor substrates (IRS).
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Receptor tyrosine kinase is a type of enzyme that plays a crucial role in cell signaling. It is responsible for phosphorylating other proteins, such as insulin receptor substrates (IRS). This phosphorylation process is important for the activation of downstream signaling pathways, ultimately leading to various cellular responses. Therefore, the statement that receptor tyrosine kinase phosphorylates other proteins, including IRS, is true.Rate this question:
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- 24.
After the autophosphorylation of tyrosine and the phosphorylation of intracellular proteins only one signaling pathway is activated by glucose.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
The statement is false because after the autophosphorylation of tyrosine and the phosphorylation of intracellular proteins, multiple signaling pathways can be activated by glucose. Glucose can activate various pathways such as the insulin signaling pathway, the AMP-activated protein kinase (AMPK) pathway, and the mammalian target of rapamycin (mTOR) pathway, among others. Therefore, it is not accurate to say that only one signaling pathway is activated by glucose.Rate this question:
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- 25.
Biological effects of insulin include all of the following except:
- A.
Increased glucose uptake
- B.
Increaased glycogen synthesis
- C.
Decreased glycogenesis
- D.
Decreased Lypolysis
- E.
Increased fat synthesis
- F.
Increased protein synthesis
- G.
Decreased Glycogenolysis
- H.
Decreased Gluconeogenesis
Correct Answer
C. Decreased glycogenesisExplanation
Insulin is a hormone produced by the pancreas that helps regulate blood sugar levels. It has several effects on the body, including increasing glucose uptake by cells, increasing glycogen synthesis (the storage form of glucose), decreasing glycogenolysis (the breakdown of glycogen), and decreasing gluconeogenesis (the production of glucose from non-carbohydrate sources). However, insulin does not decrease glycogenesis, which is the process of converting glucose into glycogen. Instead, insulin promotes glycogenesis. Therefore, the correct answer is "Decreased glycogenesis."Rate this question:
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- 26.
Two ways by which insulin affects enzyme activity are?
- A.
Covalent Modification
- B.
Allosteric regulation
- C.
Upregulation
- D.
Downregulaton
Correct Answer(s)
A. Covalent Modification
C. UpregulationExplanation
Insulin affects enzyme activity through covalent modification and upregulation. Covalent modification refers to the addition or removal of chemical groups to the enzyme, which can alter its activity. Insulin can phosphorylate or dephosphorylate enzymes, leading to changes in their function. Upregulation, on the other hand, involves increasing the production or availability of enzymes. Insulin can stimulate the synthesis of certain enzymes or increase their transport to the active site, resulting in enhanced enzyme activity.Rate this question:
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- 27.
In relation to the metabolic effects of insulin, which option corresponds to both muscle and liver?
- A.
Decreased gluconeogenesis
- B.
Increased glucose uptake
- C.
Increased glycogenesis
- D.
Decreased Glycogenolysis
Correct Answer
C. Increased glycogenesisExplanation
Insulin is a hormone that regulates blood sugar levels. It promotes the storage of glucose as glycogen in both muscle and liver cells. Therefore, increased glycogenesis, which refers to the synthesis of glycogen from glucose molecules, corresponds to both muscle and liver. This process helps to lower blood sugar levels by storing excess glucose for later use.Rate this question:
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- 28.
Which of these images correctly depicts the effects of insulin on the liver?
- A.
A
- B.
B
- C.
C
- D.
D
Correct Answer
C. C -
- 29.
Which of the following is an effect of insulin on the Liver, Adipose tissue and Muscle? Choose the most correct response.
- A.
A. Stimulation of glucose uptake
- B.
B. Stimulation of cellular respiration
- C.
C. Inhibition of lipolysis
- D.
D. Inhibition of amino acid uptake
Correct Answer
B. B. Stimulation of cellular respirationExplanation
The correct answer is B. Stimulation of cellular respiration occurs to all three target tissues.Rate this question:
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- 30.
Which of the following effects of Insulin occur in the Liver and adipose tissue only?
- A.
A. Stimulation of protein synthesis
- B.
B. Stimulation of lipoproteins uptake
- C.
C. Stimulation of fatty acid and trygliceride synthesis
- D.
D. Inhibition of protein degradation.
Correct Answer
C. C. Stimulation of fatty acid and trygliceride synthesisExplanation
Correct Answer: C. Stimulation of Fatty acid and TAG synthesis occurs in the liver and adipose tissue. A. occurs in all three tissues (liver, adipose, muscle). B. occurs in Adipose tissue only. D. occurs in all three tissues.Rate this question:
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- 31.
Insulin causes the stimulation of glycogenesis and the inhibition of glycogenolysis in which of the following tissues/ organs listed below? I. Liver II. Pancreas III. Adipose tissue IV. Muscle
- A.
I, III & IV only
- B.
I, II & III only
- C.
II, III & IV only
- D.
I, II & IV only
- E.
I, II, III & IV
Correct Answer
A. I, III & IV onlyExplanation
Insulin causes the stimulation of glycogenesis (the formation of glycogen) and the inhibition of glycogenolysis (the breakdown of glycogen) in the liver, adipose tissue, and muscle. This means that insulin promotes the storage of glucose as glycogen in these tissues and prevents the breakdown of glycogen back into glucose. The pancreas is not affected by insulin in terms of glycogenesis and glycogenolysis. Therefore, the correct answer is I, III & IV only.Rate this question:
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- 32.
Insulin Stimulates amino acid uptake in which of the following tissues/organs?
- A.
A. Liver
- B.
B. Adipose
- C.
C. Pancreas
- D.
D. Muscle
- E.
E. Brain
Correct Answer
D. D. MuscleExplanation
Insulin stimulates amino acid uptake in muscle tissues. This is because insulin promotes the transport of glucose and amino acids into muscle cells, where they can be used for energy and protein synthesis. In contrast, insulin does not have a significant effect on amino acid uptake in the liver, adipose tissue, pancreas, or brain.Rate this question:
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- 33.
Which one of the following is a result of insulin signaling?
- A.
A. Decrease in Glucose uptake by the muscles
- B.
B. Decrease TAG synthesis in the liver.
- C.
C. Increase amino acid uptake by the skeletal muscles.
- D.
D. Decrease in the activity of Lipoprotein lipase
- E.
E. Increase in the activity of Hormone Sensitive Lipase.
Correct Answer
C. C. Increase amino acid uptake by the skeletal muscles.Explanation
Insulin signaling plays a crucial role in regulating glucose and nutrient metabolism in the body. It promotes glucose uptake by muscles and adipose tissue, but inhibits glucose production in the liver. Insulin also stimulates protein synthesis and inhibits protein breakdown in skeletal muscles. Therefore, the correct answer is C, as an increase in amino acid uptake by the skeletal muscles is a result of insulin signaling.Rate this question:
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- 34.
Which one of the following is a result of insulin signaling?
- A.
A. Up-regulation of HMG CoA Reductase
- B.
B. Release of glucose from the liver
- C.
C. Decrease in the activity of Hormone Sensitive Lipase.
- D.
D. Inhibits Glycogenesis
- E.
E. Decrease in the amount of Cytosolic Citrate
Correct Answer
A. A. Up-regulation of HMG CoA ReductaseExplanation
Insulin signaling leads to the up-regulation of HMG CoA Reductase. Insulin is a hormone that is released by the pancreas in response to high blood glucose levels. It plays a crucial role in regulating glucose metabolism in the body. HMG CoA Reductase is an enzyme involved in the synthesis of cholesterol. Insulin signaling increases the expression and activity of HMG CoA Reductase, leading to an increase in cholesterol synthesis. This is an important mechanism for maintaining cholesterol homeostasis in the body.Rate this question:
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- 35.
Which one of the following inhibits insulin secretion from the pancreatic beta cells?
- A.
A. Active Glucokinase in the beta cell of the pancreas
- B.
B. High level of Arginine in the blood.
- C.
C. High blood glucose level.
- D.
D. Secretin secretion from the small intestine.
- E.
E. Ca2+ ions pumped into the β cell of the pancrease.
- F.
F. High ADP inside the β cell of the pancreas.
Correct Answer
F. F. High ADP inside the β cell of the pancreas.Explanation
High ADP inside the β cell of the pancreas inhibits insulin secretion. When blood glucose levels are high, glucose is taken up by the β cells of the pancreas and undergoes glycolysis, producing ATP. The ATP is then converted to ADP by the enzyme ATPase. The high levels of ADP inhibit ATP-sensitive potassium channels, which leads to depolarization of the β cell membrane and the subsequent release of insulin. Therefore, high levels of ADP inside the β cell inhibit insulin secretion.Rate this question:
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- 36.
Which one of the following is NOT a metabolic effect of Glucagon secretion?
- A.
A. Increased glycogenolysis
- B.
B. Increased Amino acid uptake by the liver.
- C.
C. Increase in the activity of Adenylate cyclase
- D.
D. Increase in gluconeogenesis
- E.
E. Increase in the activity of HMG CoA Synthase in the liver mitochondria
- F.
F. Increased Amino acid uptake by the muscles
Correct Answer
F. F. Increased Amino acid uptake by the musclesExplanation
Glucagon is a hormone that is released by the pancreas in response to low blood sugar levels. It acts to increase blood sugar levels by promoting various metabolic processes. The metabolic effects of glucagon secretion include increased glycogenolysis (breakdown of glycogen into glucose), increased amino acid uptake by the liver, increased activity of adenylate cyclase (an enzyme involved in cellular signaling), increased gluconeogenesis (production of glucose from non-carbohydrate sources), and increased activity of HMG CoA Synthase in the liver mitochondria (an enzyme involved in cholesterol synthesis). However, glucagon does not increase amino acid uptake by the muscles.Rate this question:
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- 37.
Which one of the following statements describe what happens during the post absorptive period as compared to the postprandial period?
- A.
A. Absorption of nutrients from the grastrointestinal tract increases
- B.
B. Translocation of Glut 4 transporters to cell surface
- C.
C. Glucagon secretion increases
- D.
D. Anabolic enzymes are active
- E.
E. Amino Acids uptake by the Muscles increases
Correct Answer
C. C. Glucagon secretion increasesExplanation
During the post absorptive period, the body is in a fasting state and is not actively digesting and absorbing nutrients from the gastrointestinal tract. Glucagon, a hormone released by the pancreas, increases during this period to stimulate the breakdown of glycogen in the liver and release glucose into the bloodstream. This helps to maintain blood sugar levels during fasting. Therefore, the statement "C. Glucagon secretion increases" accurately describes what happens during the post absorptive period as compared to the postprandial period.Rate this question:
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- 38.
After Epinephrine binds to a beta-adrenergic receptor of the liver, given the events below, arrange them in the order of occurrence: 1. Alpha subunit replaces GDP with GTP 2. Gs Apha subunit activates AC 3. cAMP activates PKA 4. Gs alpha subunit dissociates
- A.
A. 1,2,3,4
- B.
B. 2,4,3,1
- C.
C. 4,1,2,3
- D.
D. 1,4,2,3
Correct Answer
D. D. 1,4,2,3 -
- 39.
Which one of the following activates the secretion of Insulin from the Pancreas?
- A.
A. Insulin binding
- B.
B. High ADP inside the Beta cells
- C.
C. Low blood Glucose level
- D.
D. Active Glucokinase inside the Beta cells
Correct Answer
D. D. Active Glucokinase inside the Beta cellsExplanation
Active Glucokinase inside the Beta cells activates the secretion of Insulin from the Pancreas. Glucokinase is an enzyme that helps in the metabolism of glucose. When glucose is metabolized by Glucokinase inside the Beta cells of the Pancreas, it leads to the production of ATP. This increase in ATP levels triggers the release of Insulin from the Pancreas. Therefore, the presence of active Glucokinase inside the Beta cells is necessary for the secretion of Insulin.Rate this question:
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- 40.
Insulin will do one of the following:
- A.
A. Stimulates Hormone Sensitive Lipase
- B.
B. Stimulates Glycogen phosphorylase
- C.
C. Stimulates Tyrosine Kinase
- D.
D. Stimulates Protein Kinase A
- E.
E. Increases the release of Glucose from the liver
Correct Answer
C. C. Stimulates Tyrosine KinaseExplanation
Insulin stimulates tyrosine kinase, an enzyme that plays a crucial role in insulin signaling pathways. When insulin binds to its receptor on the cell surface, it activates the receptor's tyrosine kinase activity. This leads to the phosphorylation of tyrosine residues on intracellular proteins, initiating a cascade of signaling events that ultimately result in the uptake of glucose into cells and the regulation of various metabolic processes. Therefore, option C is the correct answer as it accurately describes the effect of insulin on tyrosine kinase.Rate this question:
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- 41.
Hypoglycemia is identified by:
- A.
A. Blood Glucose is > 120 mg/dl
- B.
B. Blood Glucose between 70 - 100 mg/dl
- C.
C. Increase the release of Glucagon and Epinephrine
- D.
D. Increase the release of Insulin
- E.
E. Blood Glucose is > 5 mM
- F.
F. Free Fatty acids in the blood are < 1 mM
- G.
G. Blood Glucose is < 55 mg/dl
Correct Answer
G. G. Blood Glucose is < 55 mg/dlExplanation
Hypoglycemia is identified by a blood glucose level that is below 55 mg/dl. This indicates that the individual has low blood sugar levels, which can lead to symptoms such as dizziness, confusion, and weakness. Monitoring blood glucose levels is important in identifying and managing hypoglycemia.Rate this question:
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- 42.
During early stages of fasting:
- A.
A. Liver release ketone Bodies to the Blood
- B.
B. Brain uses Beta hydroxyl butyrate for energy
- C.
C. Glycogen is degraded in the Muscles
- D.
D. Glucose is released from the liver
- E.
E. Red Blood Cells Use FA release by the Fat Cells for energy
Correct Answer
D. D. Glucose is released from the liverExplanation
During the early stages of fasting, the body needs a constant source of energy to function properly. Since glucose is the primary source of energy for the body, the liver releases stored glucose into the bloodstream to ensure a steady supply. This process is known as glycogenolysis, where glycogen (stored glucose) is broken down into glucose molecules. By releasing glucose from the liver, the body can maintain normal blood sugar levels and provide energy to various organs and tissues.Rate this question:
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- 43.
During sudden flight or fight situation:
- A.
A. Glycogen degradation is inhibited in the Liver
- B.
B. Gluconeogenesis is inhibited in the liver
- C.
C. Glycolysis is initiated in the Liver
- D.
D. Protein phosphatase is active
- E.
E. Muscles will release Glucose to the blood
- F.
F. Glycogenolysis activated in the Muscles
Correct Answer
F. F. Glycogenolysis activated in the MusclesExplanation
During sudden flight or fight situations, the body requires a rapid source of energy to fuel the muscles. Glycogenolysis is the process by which glycogen stored in the muscles is broken down into glucose, which can then be used as a fuel source. This process is activated in the muscles to provide the necessary energy for physical activity during these situations. Therefore, option F is the correct answer.Rate this question:
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- 44.
In which one of the following scenarios would one expect to observe an increase in liver fructose 2,6-bisphosphate levels?
- A.
(A) After the release of epinephrine
- B.
(B) In an individual who had just finished running a marathon
- C.
(C) In a patient exhibiting diabetic ketoacidosis
- D.
(D) After the consumption of a large bowl of ice cream
- E.
(E) In a patient with kwashiorkor
Correct Answer
D. (D) After the consumption of a large bowl of ice creamExplanation
After the consumption of a large bowl of ice cream, one would expect to observe an increase in liver fructose 2,6-bisphosphate levels. This is because ice cream contains a high amount of sugar, which is broken down into fructose in the body. Fructose is then converted into fructose 1-phosphate, which is further converted into fructose 1,6-bisphosphate. Fructose 1,6-bisphosphate is then converted into fructose 2,6-bisphosphate, which is an allosteric activator of the enzyme phosphofructokinase-1 (PFK-1). PFK-1 is a key enzyme in glycolysis, and its activation by fructose 2,6-bisphosphate leads to an increase in glycolysis and the production of ATP. Therefore, after consuming a large amount of fructose from ice cream, the liver would increase its production of fructose 2,6-bisphosphate to enhance glycolysis and ATP production.Rate this question:
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- 45.
A patient presents with dizziness, fatigue, and tremors. A fingerstick test indicates a blood glucose level of 36 mmol/L. Of the allosteric activators of glycolysis in the liver, which one of the following is the most important in allowing the liver to maintain a normal blood glucose level?
- A.
(A) Citrate
- B.
(B) ATP
- C.
(C) Fructose 2,6-bisphosphate
- D.
(D) Glucose 6-phosphate
- E.
(E) Acetyl CoA
Correct Answer
C. (C) Fructose 2,6-bisphosphateExplanation
The answer is C. The major regulated step of glycolysis is the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate, catalyzed by the enzyme PFK-1. PFK1 is activated by both F- 2,6-BP and AMP and inhibited by ATP and citrate. The modulation of F-2,6-BP levels in the liver is controlled by the insulin-to-glucagon ratio in the blood, which is tied to the regulation of PFK- 2, the enzyme that both produces and degrades F-2,6-BP. Glucose 6-phosphate acts by negative
feedback inhibition on hexokinase (an enzyme not present in liver), whereas acetyl CoA is an inhibitor of the pyruvate dehydrogenase reaction.Rate this question:
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- 46.
Which of the following correctly illustrates the allosteric effects of Fructose 2, 6 bisphosphate during the absorptive state?
- A.
A. Stimulates phosphofructokinase 1 and increases glycolysis
- B.
B. inhibits fructose 1,6- bisphosphatase thus increasing gluconeogenesis
- C.
C. inhibits fructose 1,6- bisphosphatase thus inhibiting glycolysis
- D.
D. Stimulates phosphofructokinase 1 thus inhibiting Lipolysis
- E.
E. Stimulates phosphofructokinase 1 thus inhibiting gluconeogenesis
Correct Answer
A. A. Stimulates phosphofructokinase 1 and increases glycolysisExplanation
Fructose 2, 6 bisphosphate is known to be a potent activator of phosphofructokinase 1 (PFK-1), an enzyme involved in glycolysis. By stimulating PFK-1, fructose 2, 6 bisphosphate increases the rate of glycolysis, leading to the production of ATP and other metabolic intermediates. This is consistent with option A, which states that fructose 2, 6 bisphosphate stimulates PFK-1 and increases glycolysis.Rate this question:
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- 47.
In the fed state most regulated metabolic enzymes are:
- A.
Dephosphorylated and active
- B.
Dephosphorylated and inactive
- C.
Phosphorylated and active
- D.
Phosphorylated and inactive
Correct Answer
A. Dephosphorylated and activeExplanation
In the fed state, when there is an abundance of nutrients available, the body promotes anabolic processes such as glycogen synthesis and fatty acid synthesis. These processes require the activation of metabolic enzymes. Phosphorylation is a common mechanism used to regulate enzyme activity. In this case, the correct answer suggests that in the fed state, the metabolic enzymes are dephosphorylated and active, meaning that they are in their active form and ready to facilitate the anabolic processes necessary for nutrient storage and utilization.Rate this question:
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- 48.
During the fed state, all of the following are inactive in the dephosphorylated form except:
- A.
A. Glycogen phosphorylase
- B.
B. Glycogen synthase
- C.
C. Fructose Bisphosphate phosphatase-2
- D.
D. Hormone-sensitive lipase
- E.
E. FBP-2 phosphatase
Correct Answer
B. B. Glycogen synthaseExplanation
During the fed state, when there is an abundance of nutrients, the body is in an anabolic state, meaning it is building and storing energy. Glycogen synthase is responsible for the synthesis of glycogen, which is the storage form of glucose in the body. Therefore, it would be active and phosphorylated during the fed state to facilitate the storage of excess glucose as glycogen. The other options listed are enzymes that would be inactive and dephosphorylated during the fed state as they are involved in processes that break down energy stores or promote the release of stored energy.Rate this question:
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- 49.
Which of the following enzymes are inactive in their dephosphorylated state?
- A.
Glycogen synthase
- B.
Phosphofructokinase-2
- C.
Fructose bisphosphate phosphatase- 2
- D.
Glycogen phosphorylase kinase
Correct Answer
D. Glycogen phosphorylase kinaseExplanation
Glycogen phosphorylase kinase is inactive in its dephosphorylated state. This enzyme plays a crucial role in the regulation of glycogenolysis, the breakdown of glycogen into glucose. When the enzyme is phosphorylated, it becomes activated and can catalyze the phosphorylation of glycogen phosphorylase, which in turn activates glycogenolysis. However, in its dephosphorylated state, glycogen phosphorylase kinase is unable to phosphorylate glycogen phosphorylase, rendering it inactive and preventing the breakdown of glycogen.Rate this question:
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- 50.
Which of the following enzymes are inactive in their dephosphorylated state?
- A.
Pyruvate kinase
- B.
Hormone- sensitive lipase
- C.
Glycogen phosphorylase kinase
- D.
Glycogen synthase
Correct Answer
C. Glycogen phosphorylase kinaseExplanation
Glycogen phosphorylase kinase is inactive in its dephosphorylated state. This enzyme is responsible for phosphorylating and activating glycogen phosphorylase, which in turn breaks down glycogen into glucose. When glycogen phosphorylase kinase is dephosphorylated, it cannot phosphorylate glycogen phosphorylase, resulting in the inhibition of glycogen breakdown. Therefore, the correct answer is glycogen phosphorylase kinase.Rate this question:
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