Quiz : How Much Do You Know About Biochemistry And Analytical Biochemistry?

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  • 1/58 Questions

    Pyruvate, the end product of glycolysis, enters the citric acid cycle after it has been converted to

    • Acetaldehyde
    • Lactic acid
    • Acetic acid
    • Acetyl-CoA
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About This Quiz

Are you a biochemistry student? Then, we highly encourage you to take our quiz! We're curious to know just how much you know about biochemistry & analytical chemistry. Can you correctly answer all the questions given in the quiz? Why don't you give it a try? The questions in the quiz are specially designed to brush up on your knowledge of the basics. You can take this quiz as often as possible to improve your score! We challenge you to get a high score; think you can do it? All the best!

Quiz : How Much Do You Know About Biochemistry And Analytical Biochemistry? - Quiz

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  • 2. 

    Most of the ATP made during cellular respiration is generated by:

    • Substrate-level phosphorylation.

    • Oxidative phosphorylation.

    • Glycolysis.

    • Photophosphorylation.

    Correct Answer
    A. Oxidative phosphorylation.
    Explanation
    Oxidative phosphorylation is the process by which most of the ATP is generated during cellular respiration. It occurs in the mitochondria and involves the transfer of electrons from NADH and FADH2 to the electron transport chain, which leads to the synthesis of ATP. Substrate-level phosphorylation occurs during glycolysis and the Krebs cycle, but it only accounts for a small portion of the ATP produced. Glycolysis is the initial step of cellular respiration and produces a small amount of ATP, while photophosphorylation is a process that occurs in photosynthetic organisms, not during cellular respiration.

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  • 3. 

    Where is the site of most gluconeogenesis in mammals?

    • Liver

    • Pancreas

    • Kidney

    • Small Intestine

    Correct Answer
    A. Liver
    Explanation
    Gluconeogenesis is the process of synthesizing glucose from non-carbohydrate sources. The liver is the primary site of gluconeogenesis in mammals. It has the necessary enzymes and metabolic pathways to convert substances like lactate, amino acids, and glycerol into glucose. The liver plays a crucial role in maintaining blood glucose levels during fasting or low-carbohydrate conditions by producing glucose for energy. The pancreas produces insulin and glucagon, which regulate blood sugar levels but do not directly participate in gluconeogenesis. The kidney and small intestine have limited contributions to gluconeogenesis compared to the liver.

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  • 4. 

    Fatty acids are broken down into:

    • Carbon

    • Acetyl CoA

    • NADH

    • Lipase

    Correct Answer
    A. Acetyl CoA
    Explanation
    Fatty acids are broken down through a process called beta-oxidation, which occurs in the mitochondria of cells. During this process, fatty acids are sequentially broken down into two-carbon units called acetyl CoA. Acetyl CoA then enters the citric acid cycle (also known as the Krebs cycle) to produce energy in the form of ATP. Therefore, the correct answer is Acetyl CoA.

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  • 5. 

    In Glycolysis, the metabolism of 3 molecules of Glucose will consume how many molecules of ATP?

    • 2

    • 6

    • 12

    • 36

    Correct Answer
    A. 6
    Explanation
    In Glycolysis, the metabolism of 3 molecules of Glucose will consume 6 molecules of ATP. Glycolysis is the first step in cellular respiration, where glucose is broken down into pyruvate. During this process, ATP is required to convert glucose into two molecules of pyruvate. Each molecule of glucose requires 2 molecules of ATP, so when 3 molecules of glucose are metabolized, a total of 6 molecules of ATP are consumed.

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  • 6. 

    Gluconeogenesis uses the same enzymatic reactions of glycolysis except for

    • Pyruvate Kinase

    • 4 Irreversible reactions in glycolysis

    • 3 Irreversible reactions in glycolysis

    • 2 Irreversible reactions in glycolysis

    Correct Answer
    A. 3 Irreversible reactions in glycolysis
    Explanation
    Gluconeogenesis is a metabolic pathway that synthesizes glucose from non-carbohydrate sources. It is essentially the reverse of glycolysis, with a few key differences. One major difference is that gluconeogenesis bypasses three irreversible reactions in glycolysis, namely the reactions catalyzed by hexokinase, phosphofructokinase, and pyruvate kinase. These reactions are bypassed because they are highly exergonic and therefore not reversible under physiological conditions. By bypassing these reactions, gluconeogenesis ensures that glucose synthesis can occur even when the substrates for glycolysis are limited or unavailable.

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  • 7. 

    Fatty acids are stored in the form of:

    • Monosaturates

    • Monoglycerides

    • Triglycerides

    • Polysaturates

    Correct Answer
    A. Triglycerides
    Explanation
    Fatty acids are stored in the form of triglycerides. Triglycerides are the main type of fat found in the body and in the diet. They consist of three fatty acids attached to a glycerol molecule. This form of storage allows for efficient energy storage and release when needed. Monosaturates and polysaturates refer to the degree of saturation of the fatty acids, while monoglycerides are a different type of fat molecule that consists of only one fatty acid attached to a glycerol molecule.

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  • 8. 

    Pyruvate, the end product of glycolysis, enters the citric acid cycle after it has been converted to

    • Acetaldehyde.

    • Lactic acid.

    • Acetic acid.

    • Acetyl-CoA.

    Correct Answer
    A. Acetyl-CoA.
    Explanation
    Pyruvate, the end product of glycolysis, enters the citric acid cycle after it has been converted to Acetyl-CoA. Acetyl-CoA is formed when pyruvate undergoes a decarboxylation reaction, catalyzed by the enzyme pyruvate dehydrogenase. This reaction results in the removal of a carbon dioxide molecule and the formation of Acetyl-CoA. Acetyl-CoA then enters the citric acid cycle, where it is further oxidized to generate energy in the form of ATP. Therefore, Acetyl-CoA is the correct answer as it is the intermediate molecule that connects glycolysis to the citric acid cycle.

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  • 9. 

    In Eukaryotic cells, the enzymes of glycolysis are located in the

    • Plasma membrane

    • Inner mitochondrial membrane

    • Cytosol

    • Mitochondrial matrix

    Correct Answer
    A. Cytosol
    Explanation
    The correct answer is cytosol because glycolysis is the process of converting glucose into pyruvate, and it occurs in the cytosol of eukaryotic cells. The enzymes responsible for this process are soluble and do not require any specific organelle or membrane for their function. Therefore, they are found in the cytosol, the fluid portion of the cell where many metabolic reactions take place.

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  • 10. 

    The enzymes responsible for fatty acid synthesis are located in the cell:

    • Surface

    • Membrane

    • Cytoplasm

    • Mitochondria

    Correct Answer
    A. Cytoplasm
    Explanation
    The enzymes responsible for fatty acid synthesis are located in the cytoplasm of the cell. Fatty acid synthesis is a process that occurs in the cytoplasm and involves the conversion of acetyl-CoA into fatty acids. This process is carried out by a series of enzymes, including acetyl-CoA carboxylase and fatty acid synthase, which are all located in the cytoplasm. The cytoplasm is the fluid-filled region of the cell where many metabolic reactions take place, including fatty acid synthesis.

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  • 11. 

    Which of the following enable an enzyme to bind its substrate?

    • Electrostatic interactions

    • Hydrogen bonds

    • Hydrophobic interactions

    • All of the above

    Correct Answer
    A. All of the above
    Explanation
    All of the above enable an enzyme to bind its substrate. Electrostatic interactions involve the attraction between positively and negatively charged amino acid residues in the enzyme and the substrate. Hydrogen bonds form between specific amino acid residues in the enzyme and the substrate, creating a stable binding interaction. Hydrophobic interactions occur between nonpolar regions of the enzyme and the substrate, promoting binding. Together, these interactions play a crucial role in facilitating the binding of the enzyme to its substrate, allowing for catalytic activity to occur.

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  • 12. 

    Which of the following is classed as a catecholamine hormone:

    • Insulin

    • Epinephrine

    • Testosterone

    • Glucagon

    Correct Answer
    A. Epinephrine
    Explanation
    Epinephrine is classed as a catecholamine hormone because it is derived from the amino acid tyrosine and belongs to the catecholamine family. Catecholamines are a type of hormone that are produced by the adrenal glands and have important roles in the body's response to stress. Epinephrine, also known as adrenaline, is involved in the fight or flight response, increasing heart rate, blood pressure, and energy levels. Insulin, testosterone, and glucagon are not catecholamine hormones as they have different functions and are not derived from tyrosine.

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  • 13. 

    A biological redox reaction always involves:

    • A loss of electrons

    • A gain of electrons.

    • A reducing agent.

    • All of the above.

    Correct Answer
    A. All of the above.
    Explanation
    A biological redox reaction always involves a loss of electrons, a gain of electrons, and a reducing agent. In a redox reaction, one molecule or atom loses electrons (oxidation) while another molecule or atom gains those electrons (reduction). This transfer of electrons is facilitated by a reducing agent, which donates electrons to the oxidized molecule or atom. Therefore, all three statements - loss of electrons, gain of electrons, and a reducing agent - are true for a biological redox reaction.

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  • 14. 

    In Glycolysis, the metabolism of 3 molecules of Glucose will consume how many molecules of ATP?

    • 2

    • 6

    • 12

    • 36

    Correct Answer
    A. 6
    Explanation
    In glycolysis, the metabolism of 3 molecules of glucose will consume 6 molecules of ATP. This is because glycolysis is the process of breaking down glucose into pyruvate, and each molecule of glucose requires 2 molecules of ATP to initiate the process. Therefore, when 3 molecules of glucose are metabolized, a total of 6 molecules of ATP are consumed.

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  • 15. 

    Most of the ATP made during cellular respiration is generated by:

    • Substrate-level phosphorylation.

    • Oxidative phosphorylation.

    • Glycolysis.

    • Photophosphorylation.

    Correct Answer
    A. Oxidative phosphorylation.
    Explanation
    Oxidative phosphorylation is the process by which most of the ATP is generated during cellular respiration. It occurs in the inner mitochondrial membrane and involves the transfer of electrons from NADH and FADH2 to the electron transport chain. As the electrons are transported along the chain, proton gradients are generated, which drive the synthesis of ATP by ATP synthase. This process is highly efficient and produces the majority of ATP in aerobic organisms. Substrate-level phosphorylation occurs during glycolysis and the Krebs cycle, but it only accounts for a small fraction of the ATP produced. Glycolysis is the initial step in cellular respiration and produces a small amount of ATP, while photophosphorylation is the process by which ATP is generated in photosynthesis, not cellular respiration.

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  • 16. 

    Hormonal induction of PEP carboxykinase refers to

    • The increase of enzyme activity by glucagon

    • The decrease of enzyme activity by insulin

    • Triggering gene expression increasing transcription

    • The elevation of cAMP on fasting

    Correct Answer
    A. Triggering gene expression increasing transcription
    Explanation
    Hormonal induction of PEP carboxykinase refers to the process by which certain hormones trigger the expression of the PEP carboxykinase gene, leading to an increase in transcription of the gene. This increase in transcription ultimately results in an increase in the activity of the PEP carboxykinase enzyme.

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  • 17. 

    The regulation of the glycolytic pathway involves

    • Feedback inhibition by ATP.

    • Allosteric inhibition by ATP.

    • Allosteric stimulation by ADP

    • All three are correct.

    Correct Answer
    A. All three are correct.
    Explanation
    The regulation of the glycolytic pathway involves feedback inhibition by ATP, which means that when ATP levels are high, it inhibits the enzymes involved in glycolysis to prevent further production of ATP. Allosteric inhibition by ATP also plays a role in regulating the pathway, as ATP can bind to allosteric sites on enzymes and inhibit their activity. Additionally, allosteric stimulation by ADP occurs, where ADP can bind to allosteric sites and stimulate the activity of enzymes in the pathway. Therefore, all three statements are correct in describing the regulation of the glycolytic pathway.

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  • 18. 

    Fatty acids are broken down into:

    • Carbon

    • Acetyl CoA

    • NADH

    • Lipase

    Correct Answer
    A. Acetyl CoA
    Explanation
    Fatty acids are broken down through a process called beta-oxidation, which occurs in the mitochondria of cells. During beta-oxidation, fatty acids are broken down into two-carbon units called acetyl CoA. Acetyl CoA then enters the citric acid cycle (also known as the Krebs cycle) to produce energy in the form of ATP. Therefore, the correct answer is Acetyl CoA.

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  • 19. 

    The chemical name for table sugar is -------- and its is a---------

    • Lactose; monosaccharide

    • Lactose; disaccharide

    • Sucrose; monosaccharide

    • Sucrose: disaccharide

    Correct Answer
    A. Sucrose: disaccharide
    Explanation
    Sucrose is the chemical name for table sugar, and it is classified as a disaccharide. This means that it is composed of two sugar molecules, glucose and fructose, joined together by a glycosidic bond. Lactose, on the other hand, is a different type of sugar found in milk and is also a disaccharide. Monosaccharides, such as glucose and fructose, are single sugar molecules that are not present in table sugar. Therefore, the correct answer is Sucrose: disaccharide.

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  • 20. 

    Which of the following is an example of the secondary structure of a protein?

    • Interaction with other polypeptide chains

    • The sequence ala-cys-gly-ser

    • Beta sheets

    • The overall three dimensional folding of the protein

    Correct Answer
    A. Beta sheets
    Explanation
    Beta sheets are an example of the secondary structure of a protein. Secondary structure refers to the regular patterns of folding that occur within a protein chain. Beta sheets are formed when neighboring segments of the protein chain align and form hydrogen bonds, creating a sheet-like structure. This secondary structure is characterized by its stability and plays a crucial role in determining the overall shape and function of the protein. Interaction with other polypeptide chains refers to quaternary structure, the sequence ala-cys-gly-ser refers to primary structure, and the overall three-dimensional folding of the protein refers to tertiary structure.

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  • 21. 

    Which one of the following is not known under the term ketone bodies:

    • Acetone

    • Acetoacetate

    • Palmitic acid

    • β-hydroxybutyrate

    Correct Answer
    A. Palmitic acid
    Explanation
    Palmitic acid is not known under the term ketone bodies. Ketone bodies are compounds produced during the breakdown of fatty acids in the liver. Acetone, acetoacetate, and β-hydroxybutyrate are all examples of ketone bodies. Palmitic acid, on the other hand, is a saturated fatty acid commonly found in animal and plant fats. It is not a ketone body and does not participate in the same metabolic processes as acetone, acetoacetate, and β-hydroxybutyrate.

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  • 22. 

    In Eukaryotic cells, the enzymes of glycolysis are located in the

    • Plasma membrane

    • Inner mitochondrial membrane

    • Cytosol

    • Mitochondrial matrix

    Correct Answer
    A. Cytosol
    Explanation
    The enzymes of glycolysis are located in the cytosol of eukaryotic cells. Glycolysis is the process by which glucose is broken down into pyruvate and energy. It is the first step in cellular respiration and occurs in the cytosol, which is the fluid portion of the cell outside of the organelles. This allows for easy access to glucose and other molecules involved in glycolysis. The other options, such as the plasma membrane, inner mitochondrial membrane, and mitochondrial matrix, are not the correct locations for glycolysis to occur.

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  • 23. 

    Which of the following statements concerning proteins is correct?

    • Not all proteins achieve quaternary level structure

    • Secondary structure refers to the linear sequence of amino acids

    • Primary structure refers to alpha helices and beta-pleated sheet.

    • A proteins comprised of just one polypeptide chain is said to be oligomeric

    Correct Answer
    A. Not all proteins achieve quaternary level structure
    Explanation
    Quaternary structure refers to the arrangement of multiple protein subunits to form a functional protein complex. Not all proteins have this level of structure. Some proteins are made up of a single polypeptide chain and do not interact with other subunits to form a complex. Therefore, the statement that not all proteins achieve quaternary level structure is correct.

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  • 24. 

    Gluconeogenesis is

    • The formation of glycogen

    • The formation of starches

    • The formation of glucose from non-carbohydrates

    • The formation of glucose from other carbohydrates

    Correct Answer
    A. The formation of glucose from non-carbohydrates
    Explanation
    Gluconeogenesis is the process of synthesizing glucose from non-carbohydrate sources, such as amino acids, lactate, and glycerol. This metabolic pathway occurs primarily in the liver and to a lesser extent in the kidneys. It is an essential mechanism for maintaining blood glucose levels during fasting or prolonged exercise when glucose stores are depleted. Gluconeogenesis helps to provide a constant supply of glucose to the brain and other tissues that rely on glucose as their primary energy source.

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  • 25. 

    At high glucagon concentrations, gluconeogenesis will be favoured over glycolysis

    • True

    • False

    Correct Answer
    A. True
    Explanation
    At high glucagon concentrations, gluconeogenesis will be favored over glycolysis because glucagon is a hormone that promotes the breakdown of glycogen and the synthesis of glucose. Gluconeogenesis is the process of synthesizing glucose from non-carbohydrate sources, such as amino acids and glycerol, while glycolysis is the breakdown of glucose to produce energy. When glucagon levels are high, it signals the body to release stored glucose and produce new glucose through gluconeogenesis, ensuring a steady supply of glucose for energy production. This makes the statement "True."

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  • 26. 

    In a eukaryotic cell, most of the enzymes of the citric acid cycle are located in the

    • Mitochondrial matrix

    • Inner mitochondrial membrane.

    • Intermembrane space.

    • Outer mitochondrial membrane.

    Correct Answer
    A. Mitochondrial matrix
    Explanation
    The correct answer is the mitochondrial matrix. The citric acid cycle, also known as the Krebs cycle, is a series of chemical reactions that occur in the mitochondria of eukaryotic cells. The enzymes responsible for catalyzing these reactions are primarily located in the mitochondrial matrix, which is the innermost compartment of the mitochondria. This compartment is where the citric acid cycle takes place, allowing for the production of ATP, the cell's main source of energy.

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  • 27. 

    During electron transport, protons are pumped out of the mitochondrion at each of the major sites except for:

    • Complex I

    • Complex II

    • Complex III

    • Complex IV

    Correct Answer
    A. Complex II
    Explanation
    During electron transport, protons are pumped out of the mitochondrion at each of the major sites except for Complex II. Complex II, also known as succinate dehydrogenase, is not involved in pumping protons across the inner mitochondrial membrane. Instead, it participates in the electron transport chain by transferring electrons to coenzyme Q, but does not contribute to the generation of the proton gradient used for ATP synthesis.

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  • 28. 

    The sequence of glucose oxidation to lactate in peripheral tissues, delivery of lactate to the liver, formation of glucose from lactate in the liver, and delivery of glucose back to peripheral tissues is known as the…

    • Glyoxylate cycle

    • Krebs cycle

    • Cori Cycle

    • Gluconeogenesis cycle

    Correct Answer
    A. Cori Cycle
    Explanation
    The Cori Cycle is the correct answer. The Cori Cycle is a metabolic pathway that describes the sequence of events in glucose metabolism. In peripheral tissues, glucose is oxidized to lactate. The lactate is then transported to the liver, where it is converted back into glucose through gluconeogenesis. Finally, the glucose is delivered back to the peripheral tissues. This cycle allows for the recycling of lactate and the maintenance of glucose levels in the body.

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  • 29. 

    What is the effect of Glucocorticoid (cortisol) on protein balance?

    • It increases breakdown of protein

    • It has no effect on protein balance

    • It increases the synthesis of protein

    Correct Answer
    A. It increases breakdown of protein
    Explanation
    Glucocorticoid (cortisol) increases the breakdown of protein. This hormone is known to have catabolic effects, meaning it promotes the breakdown of tissues, including proteins. This can lead to a negative protein balance, where protein breakdown exceeds protein synthesis.

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  • 30. 

    Glycogenolysis (breakdown of glycogen) occurs in

    • Muscle

    • Liver

    • Muscle and liver

    • Pancreas

    Correct Answer
    A. Muscle and liver
    Explanation
    Glycogenolysis, the breakdown of glycogen, occurs in both muscle and liver. Muscle glycogenolysis is important during exercise when muscles need glucose for energy. Liver glycogenolysis is crucial for maintaining blood glucose levels, especially during periods of fasting or low blood sugar. Both muscle and liver store glycogen and can release glucose when needed. Therefore, the correct answer is muscle and liver.

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  • 31. 

    The Michaelis constant, Km, is

    • The maximum velocity that any given enzyme reaction can achieve

    • The substrate concentration at which the enzyme is saturated

    • The substrate concentration when the reaction is half the way toward the maximal velocity

    Correct Answer
    A. The substrate concentration when the reaction is half the way toward the maximal velocity
    Explanation
    The Michaelis constant, Km, is the substrate concentration when the reaction is half the way toward the maximal velocity. This means that at Km, the enzyme is functioning at half of its maximum speed. It is a measure of the affinity between the enzyme and the substrate, with a lower Km indicating a higher affinity. This constant is important in determining the efficiency of an enzyme and understanding the kinetics of enzyme-substrate interactions.

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  • 32. 

    In a eukaryotic cell, most of the enzymes of the electron transport chain are located in the

    • Cytosol

    • Outer mitochondrial membrane.

    • Intermembrane space.

    • Inner mitochondrial membrane.

    Correct Answer
    A. Inner mitochondrial membrane.
    Explanation
    The correct answer is the inner mitochondrial membrane. The electron transport chain is a series of protein complexes located in the inner mitochondrial membrane. This is where the majority of ATP synthesis occurs in eukaryotic cells. The inner mitochondrial membrane is highly folded, forming structures called cristae, which provide a large surface area for the enzymes of the electron transport chain to carry out their function of transferring electrons and generating a proton gradient.

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  • 33. 

    1. The glycolytic pathway (glucose to 2 Pyruvate) is found

    • In most living organisms

    • In all living organisms

    • Primarily in animals

    • Only in eukaryotes

    Correct Answer
    A. In all living organisms
    Explanation
    The glycolytic pathway, which converts glucose to 2 pyruvate molecules, is found in all living organisms. This pathway is a fundamental metabolic process that occurs in the cytoplasm of cells and is essential for energy production. It is a conserved pathway that has been evolutionarily conserved across different species, including bacteria, archaea, and eukaryotes. The glycolytic pathway provides a source of ATP and intermediates for other metabolic pathways, making it a crucial process in all living organisms.

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  • 34. 

    Which of the following pairs of monosaccharides are enatiomers?

    • D-glucose; D-galactose

    • D-glucose; L-galactose

    • L-glucose; D-galactose

    • L-glucose; D-glucose

    Correct Answer
    A. L-glucose; D-glucose
    Explanation
    L-glucose and D-glucose are enantiomers because they are mirror images of each other. Enantiomers are a type of stereoisomer that have the same molecular formula and connectivity, but differ in their spatial arrangement. In this case, L-glucose and D-glucose have the same atoms and bonds, but their three-dimensional arrangement is a mirror image of each other. This is due to the presence of a chiral carbon, which is a carbon atom bonded to four different groups. The other pairs of monosaccharides listed do not have this mirror image relationship and therefore are not enantiomers.

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  • 35. 

    Regulation of the tricarboxylic acid cycle activity in vivo may involve the concentration of all of the followingEXCEPT

    • Acetyl CoA

    • ADP

    • ATP

    • CoA

    Correct Answer
    A. CoA
    Explanation
    The regulation of the tricarboxylic acid cycle activity in vivo may involve the concentration of acetyl CoA, ADP, and ATP. CoA, on the other hand, is not directly involved in regulating the activity of the cycle. CoA is primarily responsible for carrying acetyl groups during various metabolic reactions, but its concentration does not directly affect the regulation of the tricarboxylic acid cycle.

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  • 36. 

    Insulin works in tandem with which hormone to regulate lipid metabolism:

    • Adrenalin

    • Glucagon

    • Thyroxin

    • Cortisone

    Correct Answer
    A. Glucagon
    Explanation
    Insulin works in tandem with glucagon to regulate lipid metabolism. Insulin is responsible for promoting the storage of glucose as glycogen in the liver and muscles, while glucagon stimulates the breakdown of glycogen into glucose and the release of glucose into the bloodstream. This balance between insulin and glucagon helps to maintain stable blood sugar levels and regulate lipid metabolism. Adrenalin, thyroxin, and cortisone do not directly participate in this process.

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  • 37. 

    The enzyme which catalyzes the key regulatory step in glycogen biosynthesis is

    • Glycogen synthase

    • Debranching enzyme

    • Phosphoglucomutase

    • UDP-glucose pyrophosphorylase

    Correct Answer
    A. Glycogen synthase
    Explanation
    Glycogen synthase is the enzyme that catalyzes the key regulatory step in glycogen biosynthesis. This enzyme is responsible for adding glucose units to the growing glycogen chain, creating the branched structure of glycogen. It is regulated by various factors, including hormonal signals and the availability of glucose-6-phosphate, which controls the rate of glycogen synthesis. Without the activity of glycogen synthase, glycogen biosynthesis would be impaired, leading to a decrease in glycogen storage in cells.

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  • 38. 

    The irreversible reactions of glycolysis include that catalysed by

    • Phosphoglucose isomerase

    • Phosphofructokinase

    • Fructose bisphosphate aldolase

    • Glyceraldehydes 3-phosphate dehydrogenase

    Correct Answer
    A. Phosphofructokinase
    Explanation
    Phosphofructokinase is an irreversible enzyme in glycolysis that catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate. This reaction is a key regulatory step in glycolysis and is irreversible because it involves the transfer of a phosphate group from ATP to fructose-6-phosphate. Once fructose-1,6-bisphosphate is formed, it is committed to further metabolism in glycolysis and cannot be easily converted back to fructose-6-phosphate. Therefore, the reaction catalyzed by phosphofructokinase is irreversible in glycolysis.

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  • 39. 

    Which molecule cannot be directly transported from the mitochondria to the cytosol?

    • Oxaloacetate

    • Acetate

    • Malate

    • Phosphoenolpyruvate

    Correct Answer
    A. Oxaloacetate
    Explanation
    Oxaloacetate cannot be directly transported from the mitochondria to the cytosol. This is because oxaloacetate is a molecule involved in the citric acid cycle, which takes place in the mitochondria. It is converted into malate before being transported out of the mitochondria. Therefore, malate can be transported from the mitochondria to the cytosol, unlike oxaloacetate. Acetate and phosphoenolpyruvate are not directly involved in the citric acid cycle and can be transported between the mitochondria and cytosol.

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  • 40. 

    The β-oxidation cycle consists of a set of how many reactions:

    • 4

    • 6

    • 3

    • 2

    Correct Answer
    A. 4
    Explanation
    The β-oxidation cycle is a metabolic pathway that breaks down fatty acids to produce energy. It involves a series of reactions that occur in the mitochondria. The correct answer is 4 because there are four main reactions in the β-oxidation cycle: oxidation, hydration, oxidation, and thiolysis. These reactions occur repeatedly until the fatty acid is completely broken down into acetyl-CoA molecules, which can enter the citric acid cycle for further energy production.

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  • 41. 

    The binding of the hormone glucagon to its receptor on the cell membrane surface, starts a sequence of reactions within the cell which results in

    • Activation of glycogen synthesis through phosphorylation of the glycogen synthase enzyme

    • Activation of glycogen synthesis through de-phosphorylation of the glycogen synthase enzyme

    • Activation of glycogen breakdown through phosphorylation of glycogen phosphorylase

    Correct Answer
    A. Activation of glycogen breakdown through phosphorylation of glycogen phosphorylase
    Explanation
    When glucagon binds to its receptor on the cell membrane surface, it triggers a series of reactions that lead to the activation of glycogen breakdown. This is achieved through the process of phosphorylation of glycogen phosphorylase. Phosphorylation adds a phosphate group to the enzyme, causing it to become active and catalyze the breakdown of glycogen into glucose. Therefore, the correct answer is the activation of glycogen breakdown through phosphorylation of glycogen phosphorylase.

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  • 42. 

    Hormones can act by binding to membrane bound receptors that interact with:

    • Y proteins

    • G proteins

    • Beta proteins

    • Alpha proteins

    Correct Answer
    A. G proteins
    Explanation
    Hormones can act by binding to membrane bound receptors that interact with G proteins. G proteins are a family of proteins that play a crucial role in transmitting signals from the cell surface to the inside of the cell. When a hormone binds to its membrane bound receptor, it causes a conformational change in the receptor, which in turn activates the associated G protein. This activation triggers a cascade of intracellular signaling events, ultimately leading to the desired cellular response to the hormone. Therefore, G proteins are essential mediators of hormone signaling.

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  • 43. 

    Glycogen Synthase is (more/less) active when phosphorylated and it is (activated/inhibited) by glucose 6 phosphate

    • More; activated

    • Less; activated

    • More; inhibited

    • Less; inhibited

    Correct Answer
    A. Less; activated
    Explanation
    When Glycogen Synthase is phosphorylated, it becomes less active. This means that phosphorylation inhibits the activity of Glycogen Synthase. On the other hand, glucose 6 phosphate activates Glycogen Synthase. Therefore, when Glycogen Synthase is phosphorylated, it is less active and when it is activated by glucose 6 phosphate, it becomes more active.

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  • 44. 

    The main class of lipid found in mammalian membranes is:

    • Phosphoglycerides

    • Ceramides

    • Triacylglycerols

    • Gangliosides

    Correct Answer
    A. Phosphoglycerides
    Explanation
    Phosphoglycerides are the main class of lipids found in mammalian membranes. They are composed of a glycerol backbone, two fatty acid chains, and a phosphate group. The phosphate group gives the molecule a polar head, making it amphipathic and able to interact with both water and lipid molecules. This property allows phosphoglycerides to form the lipid bilayer structure of cell membranes, providing a barrier that separates the internal environment of the cell from the external environment. Additionally, phosphoglycerides can have various functional groups attached to the phosphate group, allowing for the incorporation of different types of molecules into the lipid bilayer.

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  • 45. 

    The enzymes responsible for fatty acid synthesis are located in the cell:

    • Surface

    • Membrane

    • Cytoplasm

    • Mitochondria

    Correct Answer
    A. Cytoplasm
    Explanation
    Fatty acid synthesis occurs in the cytoplasm of the cell. This process involves a series of enzymatic reactions that convert acetyl-CoA into fatty acids. The enzymes responsible for this synthesis, such as fatty acid synthase, are located in the cytoplasm where they can interact with the necessary substrates and cofactors. The cytoplasm provides the necessary environment for the enzymatic reactions to occur and for the synthesis of fatty acids to take place.

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  • 46. 

    Gluconeogenesis uses the same enzymatic reactions of glycolysis except for

    • Pyruvate Kinase

    • 4 irreversible reactions in glycolysis

    • 3 irreversible reactions in glycolysis

    • 2 irreversible reactions in glycolysis

    Correct Answer
    A. 3 irreversible reactions in glycolysis
    Explanation
    Gluconeogenesis is a metabolic pathway that allows the synthesis of glucose from non-carbohydrate sources. It is essentially the reverse of glycolysis, with a few key differences. While most of the enzymatic reactions in gluconeogenesis are the same as those in glycolysis, there are three irreversible reactions in glycolysis that are bypassed in gluconeogenesis. These irreversible reactions are catalyzed by the enzymes hexokinase, phosphofructokinase-1, and pyruvate kinase. By bypassing these reactions, gluconeogenesis is able to produce glucose from non-carbohydrate precursors without going through the entire glycolytic pathway.

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  • 47. 

    Triacylglycerides-

    • Serve as energy storage in adipose tissue

    • Are the main precursor and building block for cholesterol and steroid-based compounds

    • Are an example of the group of lipids known as prostaglandins

    • Is comprised of glycerol, fatty acids and either a phosphoric acid or a phosphatidic ester

    Correct Answer
    A. Serve as energy storage in adipose tissue
    Explanation
    Triacylglycerides serve as energy storage in adipose tissue because they are composed of glycerol and fatty acids, which can be broken down and metabolized to release energy when needed. Adipose tissue, also known as fat tissue, is the primary site for storing excess energy in the form of triacylglycerides. When the body requires energy, these stored triacylglycerides can be hydrolyzed and the fatty acids can be oxidized to produce ATP, the energy currency of the body. Therefore, triacylglycerides play a crucial role in storing and providing energy for various physiological processes.

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  • 48. 

    Lysosomal proteases work best at:

    • Low (acidic) pH

    • High (basic) pH

    • Neutral (physiological) pH

    • In the cytosol of cells

    Correct Answer
    A. Low (acidic) pH
    Explanation
    Lysosomal proteases are enzymes that function within lysosomes, which are acidic organelles in cells. These proteases have evolved to work optimally at low pH levels because the acidic environment of the lysosome allows them to be more active and efficient in breaking down proteins. At high pH levels, the proteases would not be as effective, and in the cytosol of cells or at neutral pH, they may not function properly or may cause damage to other cellular components. Therefore, low (acidic) pH is the ideal condition for lysosomal proteases to perform their enzymatic functions.

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  • 49. 

    Which one of the following statements is false about patients suffering from Type 1 diabetes mellitus?

    • The patient is dependent on insulin injections for survival

    • The patient is likely to be older than 40 years old at the time of disease onset

    • The patient is likely to possess antibodies against insulin

    • The patient’s pancreatic beta-cells have been destroyed and cannot produce insulin

    Correct Answer
    A. The patient is likely to be older than 40 years old at the time of disease onset
    Explanation
    Type 1 diabetes mellitus is typically diagnosed in children and young adults, not in individuals older than 40 years old.

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  • Sep 03, 2023
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