OS 201 Exam 2 Flashcards
(103 cards)
1
Q
Which statement BEST describes the first law of thermodynamics?
A. The total entropy of a system must increase if a process is to occur spontaneously.
B. Within a total system, energy may increase when transferred to one part or another.
C. One form of energy may be transformed into another kind of energy.
D. In an isolated system, the total entropy change is negative.
A
C. One form of energy may be transformed into another kind of energy.
2
Q
Which statement BEST describes the change in free energy (DG) of a reaction?
A. A thermodynamic property of a reaction that is indicative of the reaction rates.
B. It is a measure of the decree of randomness in a system.
C. It is a measure of the energy associated with work in biological system.
D. It is a measure of the reaction energy when the concentration of reactants and products are one molar at any temperature.
A
C. It is a measure of the energy associated with work in biological system.
3
Q
Which thermodynamic term best describes a metabolic reaction that is spontaneous? A. It has a high enthalpy. B. It has a negative free energy value. C. It has a positive free energy value. D. It has low entropy.
A
B. It has a negative free energy value.
4
Q
How are endergonic cellular reactions driven to completion in the cell?
A. By coupling with an exergonic reaction
B. By increasing enzyme concentration
C. By increasing the temperature
D. By binding with ADP
A
A. By coupling with an exergonic reaction
5
Q
Which of the following processes is exergonic? A. Nervous excitation B. Active transport C. Muscular contraction D. Fuel oxidation
A
D. Fuel oxidation
6
Q
Most major metabolic pathways are considered to be either mainly anabolic or catabolic. Which of the following pathways is considered amphibolic? A. Lipolysis B. Glycolysis C. Citric acid cycle D. Gluconeogenesis
A
C. Citric acid cycle
7
Q
Which of the following statements BEST describes the TCA cycle?
A. It is the principal source of reducing equivalents for the electron transport chain
B. It has both anabolic and catabolic phases.
C. It is the final common pathway for the catabolism of glucose, fatty acids and
amino acids.
D. All of the above.
A
D. All of the above.
8
Q
Which of the compounds below are the products of the oxidation of acetyl CoA in the citric acid cycle? A. Oxaloacetate and NAD B. GTP and Acetyl CoA C. NADH, FADH2 and CO2 D. Water, CO2 and ATP
A
C. NADH, FADH2 and CO2
9
Q
How many high-energy phosphates (ATP) can be obtained from the over-all reaction:
Isocitrate --- > ----- > ------ > Fumarate + 2CO2 + 2 H2O
A. 7
B. 8
C. 9
D. 10
A
C. 9
10
Q
Which pathway does not provide reducing equivalents /electrons to the electron transport chain? Cit A. Citric acid cycle B. Glycogenolysis C. Beta-oxidation D. Aerobic glycolysis
A
B. Glycogenolysis
11
Q
Which of the following are/ is NOT TRUE of the Electron Transport System?
A. O2 is used to form water at the end of electron transport.
B. Substrate-level formation of ATP occurs during electron transport.
C. Reduced FAD and NAD contribute electrons to electron transport.
D. The Electron Transport System is localized in the mitochondrion.
A
B. Substrate-level formation of ATP occurs during electron transport.
12
Q
Which reaction/s is/are involved the synthesis of ATP? A. Oxidative phosphorylation B. Substrate level phosphorylation C. Covalent modification D. All of the above E. A and B only.
A
E. A and B only.
13
Q
Muscle contraction causes an immediate increase in the rate of oxidative phosphorylation. Which statement BEST explain the effect of contraction?
A. It increases the pH.
B. It increases the NAD+ concentration.
C. It increases the activity of phosphofructokinase.
D. It increases the ADP concentration.
A
D. It increases the ADP concentration.
14
Q
A gas-well worker was exposed to a high concentration of hydrogen sulfide. He lost consciousness and suffered cardiopulmonary arrest. What is biochemical explanation for the effect of hydrogen sulfide?
A. Inhibition of cytochrome oxidase (complex IV)
B. Inhibition of cytochromes bc(complex III)
C. Uncoupling of mitochondrial electron transport chain
D. Inhibition of pyruvate dehydrogenase
A
A. Inhibition of cytochrome oxidase (complex IV)
15
Q
When oxidative phosphorylation is uncoupled by dinitrophenol, which one of the following actions takes place?
A. Phosphorylation of adenosine diphosphate (ADP) accelerates.
B. ATP production continues but oxygen uptake stops.
C. ATP production stops but oxygen uptake continues.
D. Both phosphorylation of ADP and oxygen uptake stop.
A
C. ATP production stops but oxygen uptake continues.
16
Q
, Which of the following is not TRUE about the compound ADP?
A. It is a product of ATP hydrolysis.
B. It is positive effector of both glycolysis and the citric acid cycle.
C. It signals low energy level in the cell.
D. It is form by substrate level phosphorylation.
A
D. It is form by substrate level phosphorylation.
17
Q
The major production of ATP during aerobic metabolism occurs when electrons from \_\_\_\_\_ and \_\_\_\_\_ are transferred to \_\_\_\_\_\_\_. Choose the best answer from the items below.
A. FADH2 + NADH - H2 0
B. FADH2 + O2 - NAOH
C. NADH + O2 - FADH2
D. FADH2 and NADH - O2
A
D. FADH2 and NADH - O2
18
Q
ATP synthase can produce ATP using which of the following as a direct energy source?
A. Energy from conversion of glucose to pyruvate.
B. Energy from the oxidation of pyruvate producing CO2 and H2O.
C. Energy from a proton gradient established in mitochondria.
D. Energy derived from the breakdown of NADH and FADH2.
A
C. Energy from a proton gradient established in mitochondria.
19
Q
During a heart attack, blood flowing to the heart muscle is interrupted by blockage of a coronary artery. How would you expect the metabolism in the heart to change?
A. Oxidative phosphorylation would slow down in the mitochondria.
B. The rate of production of lactic acid would be stimulated.
C. The use of glucose by the muscle tissue would increase.
D. All of the above
A
D. All of the above
20
Q
What cellular compartment becomes acidic (high concentration of hydrogen ions) during mitochondrial electron transport?
A. Mitochondrial stroma
B. Cytoplasm
C. Endoplasmic reticulum
D. Space between inner and outer mitochondrial membrane
A
D. Space between inner and outer mitochondrial membrane
21
Q
Which of the following statements is/are TRUE regarding KM ?
A. KM is expressed in units of concentration (e.g., moles per liter).
B. KM is the substrate concentration at which an enzyme is saturated.
C. As the affinity of enzyme for substrate decreases, KM also decreases.
D. both A and B
A
A. KM is expressed in units of concentration (e.g., moles per liter).
22
Q
From which of the following biochemical components are coenzymes typically derived? A. Vitamins B. Minerals C. Proteins D. Both A and B
A
A. Vitamins
23
Q
Which of the following statements is/are TRUE regarding enzyme inhibition?
A. Competitive inhibition and noncompetitive inhibition are both reversible.
B. Competitive inhibition is reversed by addition of excess substrate.
C. Reversible inhibition typically entails covalent bond formation.
D. Both A and B
A
D. Both A and B
24
Q
Which of the following enzymes utilizes molecular oxygen as an electron acceptor? A. Catalase B. Cytochrome c oxidase C. Glutathione peroxidase D. Superoxide dismutase
A
B. Cytochrome c oxidase
25
```
Which of the following proteins directly catalyzes the hydrolysis of fibrin to yield soluble peptide fragments?
A. Fibrinogen
B. Plasminogen
C. Plasmin
D. Tissue plasminogen activator (tPA)
```
C. Plasmin
26
By definition, which of the following statements is/are TRUE regarding a pair of isozymes?
A. They catalyze the same chemical reaction.
B. Their amino acid sequences are identical.
C. Their molecular masses are identical.
D. Both A and B
A. They catalyze the same chemical reaction.
27
Which of the following statements is/are TRUE regarding competitive inhibition?
A. It typically entails an apparent increase in the value of KM.
B. The inhibitor is typically a structural analog of a substrate or transition state.
C. The inhibitor typically binds to an allosteric site.
D. Both A and B
D. Both A and B
28
```
What is the typical function of pyridoxal phosphate as a cofactor?
A. Carrier for long-chain fatty acids
B. Carrier for acetyl groups
C. Carrier for methyl groups
D. Carrier for amino groups
```
D. Carrier for amino groups
29
Which of the following reactions is catalyzed by a racemase?
A. Interconversion of cis and trans double bonds in fatty acid chains
B. Interconversion of alpha-D-glucopyranose and beta-D-glucopyranose
C. Interconversion of L-alanine and D-alanine
D. Interconversion of NADH and NADPH
C. Interconversion of L-alanine and D-alanine
30
Which of the following statements is TRUE regarding trypsin?
A. It is secreted in its catalytically active form.
B. Its catalytic triad includes a serine residue.
C. It functions optimally at acidic pH.
D. It serves primarily to hydrolyze triglycerides.
B. Its catalytic triad includes a serine residue.
31
```
Which one of the following organs has the highest demand for glucose as a fuel?
A. Brain
B. Muscle (skeletal)
C. Heart
D. Liver
```
A. Brain
32
Why is the skeletal muscle glycogen NOT involved in blood glucose regulation?
A. The muscle does not have enough glycogen content for this function.
B. Muscle glycogen content fluctuates widely and cannot provide adequate substrate for glucose formation
C. The muscle does not contain any glucose-6-phosphatase and is therefore unable to release glucose in the blood.
D. Muscle glycogen is mainly used to maintain glucose levels during starvation.
C. The muscle does not contain any glucose-6-phosphatase and is therefore unable to release glucose in the blood.
33
```
Which of the following is NOT an insulin counter-regulatory hormone?
A. Glucagon
B. Epinephrine
C. Cortisol
D. IGF-1
```
D. IGF-1
34
```
After digestion of pancake that contains flour, milk, and sucrose, the major carbohydrate products entering the blood are which of the following?
A. Glucose
B. Fructose and galactose
C. Galactose and glucose
D. Fructose and glucose
E. Glucose, galactose and fructose
```
E. Glucose, galactose and fructose
35
Which of the following statements does NOT describe gluconeogenesis?
A. Gluconeogenesis happens in the liver and kidneys, and does not occur in the skeletal muscle
B. Not all enzymes involved in gluconeogenesis are in the cytosol.
C. Gluconeogenesis produces glucose from other metabolites for use as fuel source by the brain, testes, erythocytes and kidneys.
D. Gluconeogenesis in human beings describes how glucose is formed from acetyl coA derived from free fatty acids.
D. Gluconeogenesis in human beings describes how glucose is formed from acetyl coA derived from free fatty acids.
36
Which of the following processes is NOT involved in regulating glycolysis?
A. Covalent modulation, wherein pyruvate kinase is inhibited by high ATP concentration, and activated in the presence of low energy states.
B. Allosteric control where phosphofructokinase assumes either an R or T state governing its affinity to fructose 6 phosphate.
C. Product inhibition, where hexokinase in the liver cells is inhibited by glucose 6 phosphate.
D. Hormonal regulation, wherein gluconeogenesis starts when glucagon increases the intracellular cAMP, causing the phosphorylation and inactivation of pyruvate kinase.
C. Product inhibition, where hexokinase in the liver cells is inhibited by glucose 6 phosphate.
37
```
Which of the following could NOT be utilized in glycolysis as substitute for glucose?
A. Fructose
B. Galactose
C. Mannose
D. Free Fatty Acid
```
D. Free Fatty Acid
38
Which statement is TRUE regarding carbohydrate metabolism?
A. The pentose phosphate pathway is a catabolic pathway since this oxidizes glucose into nucleotides.
B. Gluconeogenesis makes glucose from non-carbohydrate precursors to maintain glucose levels during starvation
C. In glycolysis, glucose is hyrolyzed to form glucose 6 phosphate in a reaction catalyzed by glucose-6-phosphatase.
D. Complete aerobic conversion of 1 molecule of glucose yields 2 ATP’s and 2 lactate
B. Gluconeogenesis makes glucose from non-carbohydrate precursors to maintain glucose levels during starvation
39
```
A patient diagnosed to have a tumour in the pancreas underwent CT-guided biopsy. Histopathologic findings revealed an “insulinoma” (insulin-secreting tumour). Which of the following would you expect to see in a patient with such a tumour?
A. Overweight patient
B. Hyperglycemic symptoms
C. Both A and B
D. Neither A nor B
```
A. Overweight patient
40
```
A sprinter missed breakfast prior to his morning training. Which pathways are expected to take over for proper muscle contraction?
A. Cori cycle
B. Glucose-alanine cycle
C. Glycogenesis
D. A and B only
```
D. A and B only
41
```
Which pair of amino acids is LEAST likely to be transported by a common Na+ dependent transporter?
A. Lysine and aspartate
B. Arginine and lysine
C. Valine and leucine
D. Serine and threonine
E. Phenylalanine and tyrosine
```
A. Lysine and aspartate
42
```
Which product pair will be formed from the transamination of aspartate and alpha ketoglutarate?
A. Alanine + alpha-ketoglutarate
B. Oxaloacetate + glutamate
C. Pyruvate + oxaloacetate
D. Glutamate + oxaloacetate
```
B. Oxaloacetate + glutamate
43
```
Which of the following pair of compounds is utilized to transport ammonia produced in muscles and other peripheral tissues to the liver?
A. Alanine and urea
B. Alpha-ketoglutarate and glutamate
C. Alanine and glutamine
D. Pyruvate and urea
```
C. Alanine and glutamine
44
Which one of the following diets is probably being consumed if a person's urine contains unusually high concentrations of urea?
A. High CHO, very low CHON
B. Very high CHO, no CHON, no fat
C. Very very high fat, high CHO, no CHON
D. Very high fat, very low CHON
E. Very low CHO, very high CHON
E. Very low CHO, very high CHON
45
```
What is the classification of an amino acid that yields acetoacetyl CoA during the catabolism of its carbon skeleton?
A. Glycogenic
B. Ketogenic
C. Glycogenic and ketogenic
D. Essential
E. Non-essential
```
B. Ketogenic
46
Which of the following will explain why arginine is considered a semi essential amino acid?
A. It can be synthesized from urea cycle pathways in other tissues.
B. The requirement for this amino acid is dependent on the health status and the stage of development.
C. The normal diet is usually deficient in arginine.
D. All of the above
E. A and B only
E. A and B only
47
```
In amino acid metabolism, which of the following is NOT involved in metabolism of one-carbon compounds?
A. Tetrahydrofolate
B. S-adenosyl methionine
C. Tetrahydrobipterin
D. Methylcobalamin
```
C. Tetrahydrobipterin
48
```
Some of the signs and symptoms of the genetic disorder phenylketonuria include mental retardation and other neurological deficits. Physical development is below normal and hair, although dark, may contain patches of white. Which of the following reactions is defective in phenylketonuria?
A. Adenosine Inosine
B. Phenylalanine Tyrosine
C. Phenylalanine Phenylpyruvate
D. Homocysteine Methionine
```
B. Phenylalanine Tyrosine
49
```
Which of the following amino acids should be supplemented in the diet of phenylketonurics?
A. Phenylalanine
B. Tyrosine
C. Alanine
D. Glutamine
```
B. Tyrosine
50
```
The mental retardation and other neurological symptoms among phenylketonurics have been related to the unavailability of which neurotransmitters derived from tyrosine?
A. Epineprine
B. Norepineprine
C. Dopamine
D. All of the above
E. A and B only
```
D. All of the above
51
```
Which set of three amino acids donate amino groups for the purine biosynthesis?
A. Glycine, glutamine, aspartate
B. Glycine, methionine, aspartate
C. Glycine, alanine, asparagine
D. Glutamate, glutamine, aspartate
```
A. Glycine, glutamine, aspartate
52
Which activated sugar is utilized for both purine and pyrimidine de novo synthesis?
A. UDP-glucose
B. Glucose-6-phosphate
C. 5-Phosphoribosyl-1- pyrophosphate (PRPP)
D. Deoxyphosphoribosyl pyrophosphate
C. 5-Phosphoribosyl-1- pyrophosphate (PRPP)
53
The conversion of IMP to GMP and AMP is tightly regulated to ensure production of equimolar amounts of both purine nucleotides.
True
54
Deoxyribonucleotides are formed by reduction of C2’ of the four different ribonucleoside diphosphates.
True
55
The salvage pathways for purine and pyrimidine nucleotides require more energy than the de novo pathways
False
56
The hyperuricemia associated with disorders such as Lesch-Nyhan syndrome and gout may result from a deficiency of which enzyme?
A. PRPP synthetase
B. Hypoxanthine –guanine phosphoribosyl transferase
C. Glutamine:PRPP amidotransferase.
D. Carbamoyl phosphate synthetase II
B. Hypoxanthine –guanine phosphoribosyl transferase
57
57. Xanthine -> Uric Acid A. 5-fluorouracil
58. Folate -> Tetrahydrofolate B. Allopurinol
59. dUMP -> TMP C. Methotrexate
D. dATP
//BCA
58
Which of the following conditions will be observed in a healthy adult immediately after undergoing appendectomy?
A. There will be increased excretion of nitrogenous excretory product primarily urea.
B. There will be a shift towards positive nitrogen balance.
C. The nitrogen balance will remain in equilibrium.
D. All of the above
E. A and B only
A. There will be increased excretion of nitrogenous excretory product primarily urea.
59
```
Eating food rich in fats may have several effects in our body. Which of the following dietary fatty acids is known for its health benefits in lowering serum triglycerides?
A. Palmitic acid
B. Oleic acid
C. Linoleic acid
D. Eicosapentaoic acid
```
D. Eicosapentaoic acid
60
```
Which of the following digestive enzymes is responsible for hydrolyzing triacylglycerols to form free fatty acids and monoacylgycerols? It is also the enzyme inhibited by the anti-obesity drug Orlistat.
A. Lingual lipase
B. Gastric lipase
C. Pancreatic lipase
D. Lipoprotein lipase
```
C. Pancreatic lipase
61
```
What is the only mechanism by which cholesterol is excreted in the human body?
A. Via the secretion of sweat
B. Via the synthesis of lipoproteins
C. Via the formation of bile salts
D. Via the secretion of lipases
```
C. Via the formation of bile salts
62
Which of the following statements regarding the digestion and absorption of cholesterol is FALSE?
A. Liver synthesis of cholesterol exceeds the amount of cholesterol obtained from the diet
B. Fifty percent of cholesterol that enters the ileum is absorbed in the body.
C. Dietary cholesterol is incorporated into micelles together with triglycerides.obtained from the diet.
D. Cholesterol in the enterocytes is excreted back in the intestinal lumen as cholesteryl esters.
D. Cholesterol in the enterocytes is excreted back in the intestinal lumen as cholesteryl esters.
63
```
Which of the following lipoproteins is synthesized by both the liver and the intestines?
A. Chylomicrons
B. VLDL
C. LDL
D. HDL
```
D. HDL
64
```
Which of the following apoproteins serves as an inhibitor of the lipoprotein lipase (LPL)?
A. Apoprotein A-I
B. Apoprotein C-I
C. Apoprotien C-II
D. Apoprotein C-III
```
D. Apoprotein C-III
65
```
Which of the following apoproteins is important in the degradation of LDL in the liver by serving as the recognition protein of the LDL receptor?
A. Apo B-48
B. Apo B-100
C. Apo C-I
D. Apo E
```
B. Apo B-100
66
```
Which of the following organs receives the LEAST amount of fatty acids from the hydrolysis of chylomicrons by lipoprotein lipase?
A. Heart
B. Adipose tissue
C. Skeletal muscles
D. Liver
```
D. Liver
67
Bab was curious to know what her cholesterol profile was after listening to the lecture on lipid digestion. She knows that hypercholesterolemia runs in her family. She had a fasting lipid profile done at PGH and the results were as follows:
Total cholesterol: 300 mg/dl
HDL: 65 mg/dl
Triglycerides: 175 mg/dl
```
However, there was no mention of the LDL level. Help Bab compute for her LDL value.
A. LDL = 190 mg/dl
B. LDL = 410 mg/dl
C. LDL = 112 mg/dl
D. LDL = 200 mg/dl
```
D. LDL = 200 mg/dl
68
What enzyme is very important in the cholesterol transport and which serves to transfer cholesterol from HDL to VLDL and LDL, which can be returned to the liver for endocytosis?
A. Lecithin:cholesterol acyltransferase (LCAT)
B. Cholesteryl ester transfer protein (CETP)
C. Lipoprotein lipase (LPL)
D. Acyl-coenzyme A:cholesterol acyltransferase (ACAT)
B. Cholesteryl ester transfer protein (CETP)
69
Which of the following statements regarding beta-oxidation is FALSE?
A. It is the most important pathway for oxidation of fatty acids.
B. NADP serves as the oxidizing agent.
C. The end product of this process is acetylCoA.
D. The process occurs in the mitochondria.
B. NADP serves as the oxidizing agent.
70
```
Fatty acids need certain substrates to facilitate transport through the intracellular compartments to generate energy in the form of ATP. What substrate is necessary for the entry of fatty acids from the intermitochondrial space to the mitochondrial matrix?
A. Co-enzyme A
B. Carnitine
C. Citrate
D. Co-enzyme Q
```
B. Carnitine
71
```
Which of the following processes involved in beta-oxidation splits off 2-carbon units from the carboxy-end of the fatty acids?
A. Dehydrogenation
B. Hydration
C. Oxidation
D. Thiolysis
```
D. Thiolysis
72
```
During periods of starvation, our body mobilizes the fats in our body for energy production and glucose formation. What is the only substrate in fatty acid metabolism that is capable of being converted to glucose?
A. Acetyl CoA
B. FADH2
C. NADH
D. Propionyl CoA
```
D. Propionyl CoA
73
```
What substrate in the citric acid cycle serves as the entry point for the glucogenic (glucose formation) transformation of fats?
A. Isocitrate
B. α-Ketoglutarate
C. Succinate
D. Malate
```
C. Succinate
74
Which of the following statements regarding the control of fatty acid oxidation is FALSE?
A. Hormones control the availability of fatty acid substrates for oxidation.
B. Epinephrine regulates triacylglycerol lipase by controlling the cAMP regulatory cascades.
C. Glucagon leads to the consumption of fatty acids.
D. Malonyl-CoA controls uptake of fatty acyl-CoAs by inhibiting carnitine
acyltransferase I.
C. Glucagon leads to the consumption of fatty acids.
75
Which of the following statements regarding fatty acid synthesis is TRUE?
A. The process mainly occurs in the adipose tissue.
B. It occurs whenever there is a caloric deficiency in the diet.
C. The major source of carbon is dietary carbohydrates.
D. The main pathway occurs in the mitochondria.
C. The major source of carbon is dietary carbohydrates.
76
```
Acetyl CoA carboxylase catalyzes the rate-limiting step of fatty acid synthesis. What is the product of this step?
A. Acetyl CoA
B. Propionyl CoA
C. Malonyl CoA
D. Palmitoyl CoA
```
C. Malonyl CoA
77
Which of the following statements is/are TRUE regarding the process of elongation of a fatty acid?
A. Elongation occurs in the endoplasmic reticulum
B. The process uses NADPH as reductant
C. Malonyl CoA lengthens the fatty acid by donating 2 carbons
D. All of the above
D. All of the above
78
Omega 3 fatty acids have become a craze for good health. Several commercial products claim to contain these so-called “beneficial fats”. Which of the following is true regarding these fatty acids?
A. They can be synthesized by the human body de novo.
B. They are found only in deep sea fishes and not in plants.
C. They can be synthesized in the human body only when the initial substrates are acquired from the diet.
D. The initial substrate which must be obtained in the diet is oleic acid.
C. They can be synthesized in the human body only when the initial substrates are acquired from the diet.
79
Which of the following statements describe why metabolism is regulated?
A. The amount of food that is available is always fixed and predictable
B. The type of food that is available can come in many combinations
C. The amount of energy needed by the body rarely changes.
D. The body needs to store energy when the demand is high.
B. The type of food that is available can come in many combinations
80
Which of the following statements BEST describes fats in caloric homeostasis?
A. Fats compose the least amount in our diet but the most of our energy stores
B. Fats produce more energy because they are hydrophobic.
C. Fats pass easily through the cell membrane and are easily transported.
D. Fat stores in our bodies are almost entirely derived from ketogenic amino acids.
A. Fats compose the least amount in our diet but the most of our energy stores
81
Which of the following statements is TRUE about energy stores in our body?
A. Most of the amino acids from the diet are stored as proteins in muscle.
B. There are very little fatty acid stores because they are hydrophobic and hard to transport.
C. The glycogen stored in muscle is not used to replenish serum glucose.
D. Carbohydrates from the diet are mainly stored as glycogen in the liver.
C. The glycogen stored in muscle is not used to replenish serum glucose.
82
Which of the following BEST describes fatty acid stores?
A. Fats comprise the smallest part in our diet so that our body stores very little of it.
B. Deamination of ketogenic amino acids is a major source of fatty acid stores.
C. Serum free fatty acid levels are highest in starvation due to mobilization of triglycerides.
D. Another reason very little fatty acids are stored is their large molecular weight.
C. Serum free fatty acid levels are highest in starvation due to mobilization of triglycerides.
83
Which of the following statements BEST describe the central role of glucose in caloric metabolism?
A. Most of our energy stores can be traced back to glucose which is abundant in our diet.
B. Most of the glucose we eat actually ends up as structural components and little as energy.
C. Glucose can be derived from amino acids and fatty acids, but not the other way around.
D. Glucose is able to store the most amount of energy per weight.
A. Most of our energy stores can be traced back to glucose which is abundant in our diet.
84
Which of the following statements BEST describes the importance of glucose homeostasis?
A. Important organs like the brain and the heart use glucose almost entirely.
B. Important organs use glucose because it is the largest amount of energy store in our body.
C. Erythrocytes use glucose because they lack oxygen.
D. Glucose is the only major biomolecule that can be metabolized anaerobically
D. Glucose is the only major biomolecule that can be metabolized anaerobically
85
Which of the following statements BEST describes “amplification”?
A. This refers to small biomolecules giving rise to larger and more complex molecules
B. This is a cascade or series of non-covalent modification of allosteric sites.
C. Repeated formation of non-covalent bonds is necessary to make this happen
D. This is a phenomenon which allows small hormone signals to manifest as large effects.
D. This is a phenomenon which allows small hormone signals to manifest as large effects.
86
Which of the following statements BEST describes glycogen as an energy store?
A Glycogen stores can provide as much as 1 week worth of energy
B Glycogen in the liver are mainly used for replenishing serum glucose
C Glycogen is easily mobilized by being broken down into smaller keto-acids
D Glycogen stores are replenished by breaking down amino acids
B Glycogen in the liver are mainly used for replenishing serum glucose
87
Which of the following statements BEST describes the enzyme hexokinase?
A. This enzyme is active only when serum glucose levels are high.
B. This enzyme makes it possible to release glucose from extra-hepatic tissues
C. This enzyme is NOT inhibited by high levels of glucose-6-phosphate
D. This enzyme has high activity even if serum glucose levels are low.
D. This enzyme has high activity even if serum glucose levels are low.
88
Which of the following reactions is regulated in glucose metabolism?
A. Entry of glucose into the mitochondrion.
B. Conversion of glucose-6-phosphate to fructose-6-phosphate
C. Conversion of pyruvate to phosphoenol-pyruvate
D. Phosphorylation of fructose-6-phosphate to fructose-2,6-biphosphate
D. Phosphorylation of fructose-6-phosphate to fructose-2,6-biphosphate
89
Conversion of fructose-6-phosphate (F6P) to fructose-1,6-biphosphate (F-1,6-P) in glycolysis is an example of a substrate cycle. Which of the following statements BEST describes substrate cycles?
A. Substrate cycles are synonymous to futile cycles.
B. Substrate cycles can be wasteful.
C. The same enzyme catalyzes both reactions in a substrate cycle.
D. The TCA cycle is another example of a substrate cycle.
B. Substrate cycles can be wasteful.
90
Which of the following statements describes the regulation of the F6P – F-1,6-P cycle?
A. Excess F-6-P leads to stimulation of the phosphofructokinase 2 enzyme.
B. Glucagon leads to phosphorylation of phosphofructokinase 1 enzyme.
C. Fructose biphosphatase enzyme 2 is active in the phosphorylated state.
D. Insulin leads to dephosphorylation of phosphofructokinase 1 enzyme.
C. Fructose biphosphatase enzyme 2 is active in the phosphorylated state.
91
A key molecule in the regulation of this substrate cycle is fructose-2,6-biphosphate (F-2,6-P). Which of the following statements is true about the role of F-2,6-P?
A. F-2,6-P is formed by isomerization of fructose-1,6- biphosphate
B. F-2,6-P prevents the phosphorylation of fructose-6-phosphate
C. Glucagon promotes the biphosphatase activity of enzyme 2
D. Phosphorylation of enzyme 2 leads to more F-2,6-P
C. Glucagon promotes the biphosphatase activity of enzyme 2
92
```
Which of the following enzymes is active in the phosphorylated state?
A. Phosphofructokinase enzyme 2
B. Pyruvate kinase
C. Glycogen phosphorylase
D. Glycogen synthetase
```
C. Glycogen phosphorylase
93
Which of the following accurately describes the fate of glucose?
A. Glucose can not be converted to fatty acids.
B. Glucose from the diet is stored as glycogen mostly in the liver
C. Glucose may be converted to lactate when oxygen is not available
D. Glucose is the sole energy source of erythrocytes and the liver
C. Glucose may be converted to lactate when oxygen is not available
94
The Phosphoenol Pyruvate (PEP) – Pyruvate pseudocycle is an important initial step in gluconeogenesis which allows the conversion of pyruvate and acetyl CoA to PEP. Which of the following statements is true about the enzymes involved in this pseudocycle?
A. Increased ADP stimulates pyruvate carboxylase
B. Increased ADP inhibits PEP carboxykinase
C. Increased Acetyl CoA inhibits pyruvate carboxylase
D. Glucagon stimulates pyruvate kinase
B. Increased ADP inhibits PEP carboxykinase
95
Which of the following accurately describes the regulation of pyruvate dehydrogenase?
A. It is active in the dephosphorylated form.
B. Acetyl CoA inhibits the enzyme
C. Glucagon stimulates the enzyme which helps in conversion of Acetyl CoA to fatty acids
D. Excess ATP stimulates the enzyme
B. Acetyl CoA inhibits the enzyme
96
Which of the following explains why glycogen breakdown does not occur at the same time as glycogen synthesis?
A. Phosphorylation activates glycogen synthase while it inactivates glycogen phosphorylase
B. Insulin promotes dephosphorylation of glycogen synthase and glycogen phosphorylase
C. Calmodulin inhibits glycogen phosphorylase and stimulates glycogen synthase
D. Glucagon promotes dephosphorylation of glycogen synthase and glycogen phosphorylase
A. Phosphorylation activates glycogen synthase while it inactivates glycogen phosphorylase
97
Which of the following statements best describe hormone sensitive lipase?
A. Hormone sensitive lipase breaks the C-H bonds found in fatty acids
B. Hormone sensitive lipase is located in the endothelial cells lining blood vessel walls
C. Hormone sensitive lipase is active in the phosphorylated form
D. Hormone sensitive lipase is activated by Insulin
C. Hormone sensitive lipase is active in the phosphorylated form
98
What mainly occurs in the fetus/embryo during the first 8 weeks of pregnancy?
A. Differentiation of few cells to various cells types
B. Cellular enlargement
C. Cellular proliferation of homogenous cell population
D. Formation of mature gametes
A. Differentiation of few cells to various cells types
99
```
What is the main source of nutrition of the developing fetus in first trimester before the maternal circulation is established?
A. Maternal blood
B. Placenta
C. Yolk sac
D. Uterus
```
C. Yolk sac
100
```
What is the MOST important nutritional advice for a woman in the first trimester of pregnancy?
A. Prevent under/malnutrition
B. Increased protein intake
C. Increase caloric intake
D. Take anti-vomiting drugs
```
A. Prevent under/malnutrition
101
```
Which of the following is NOT RECOMMENDED as part of nutrition for women in their first trimester of pregnancy?
A. Fishes
B. Meat
C. Folic acid
D. Red wine
```
D. Red wine
102
```
Which is/are the MOST IMPORTANT role/s of dietary proteins for the fetus during the first trimester?
A. Source of essential amino acids
B. Precursor of nucleic acids
C. Energy source
D. All of the above
E. A and B only
```
E. A and B only
103
```
In what organ is docosahexanoic acid important as a supplement during its development?
A. Limbs
B. Eye
C. Heart
D. Brain
```
D. Brain
