Biochemistry MCQs with Answer and Explanations | Chapter 4

Answer: Gout

Gout is a condition caused by excess uric acid in the bloodstream. This excess uric acid can form crystals that deposit in joints, leading to inflammation and pain.

The other options are incorrect:

• Renal failure: While kidney problems can contribute to high uric acid levels, it’s not the only cause of gout.
• Addison’s disease: This disease affects the adrenal glands and doesn’t directly cause increased uric acid.
• Rickets: This condition is caused by vitamin D deficiency and affects bone development, not uric acid levels.

Answer: Obstructive lung disease

Obstructive lung disease (OLD) can lead to increased levels of PCO (partial pressure of carbon dioxide) in the blood. This happens because OLD makes it difficult to exhale CO2 effectively, causing it to build up in the bloodstream.

The other options are incorrect:

• Hypoxia: While hypoxia (low oxygen levels) can be a consequence of some lung diseases, it’s not directly related to increased PCO.
• Polycythemia: This condition refers to an abnormally high number of red blood cells, not impacting CO2 levels.
• Anaemia: Anaemia refers to a deficiency in red blood cells, affecting oxygen transport, not CO2 removal.

Answer: Beer- Lambert law

The Beer-Lambert Law combines both Beer’s Law and Lambert’s Law to describe the relationship between the amount of light absorbed by a solution and the concentration of the absorbing substance.

The other options are incorrect:

• Beer’s Law: This law individually states that the amount of light absorbed is directly proportional to the concentration of the absorbing substance in the solution.
• Lambert’s Law: This law individually states that the amount of light absorbed is directly proportional to the path length the light travels through the solution.
• None of the Above: Both Beer’s Law and Lambert’s Law contribute to the principle behind a spectrophotometer, and their combination is formalized in the Beer-Lambert Law.

Answer: Western blotting

Western blotting is a technique used to separate and identify proteins based on their size and the presence of specific protein antigens through electrophoretic separation.

The other options are incorrect:

• Southern blotting: Southern blotting is a method used to detect specific DNA sequences in a sample. It involves the transfer of DNA from a gel to a membrane and hybridization with a labeled probe.
• Northern blotting: Northern blotting is used to study gene expression by detecting specific RNA sequences. It involves separating RNA by gel electrophoresis and transferring it to a membrane for hybridization with a labeled probe.

Answer: GLC

GLC (Gas Chromatography) is an analytical technique used to separate and identify compounds based on their interaction with a stationary phase and a mobile gas carrier. It doesn’t rely on analyzing nucleic acids (DNA or RNA) for diagnosis.

The other options are incorrect:

• PCR (Polymerase Chain Reaction): This is a common nucleic acid-based technique for amplifying specific DNA sequences for detection or analysis.
• LCR (Ligase Chain Reaction): Similar to PCR, LCR is a nucleic acid-based technique that amplifies specific DNA sequences for detection.
• RFLP (Restriction Fragment Length Polymorphism): This technique analyzes variations in DNA fragments for diagnosis or genetic testing.

Answer: Protein

The biuret method specifically detects the presence of peptide bonds, which are the building blocks of proteins. When the biuret reagent interacts with the peptide bonds in an alkaline environment, it forms a characteristic purple color complex. The intensity of this color is directly proportional to the protein concentration in the sample.

The other options are incorrect:

• Sugar: While some complex sugars can interfere with the biuret test, it’s not a reliable method for detecting sugars. Sugars lack the peptide bonds the biuret reagent targets.
• Urea: Urea is a simple molecule that doesn’t contain peptide bonds. The biuret test wouldn’t react with urea.
• Cholesterol: Cholesterol is a lipid molecule with a completely different structure compared to proteins. The biuret reagent wouldn’t be able to detect cholesterol.

Answer: Specific gravity

A urinometer is a tool specifically designed to measure the specific gravity of urine. Specific gravity refers to the concentration of dissolved particles in the urine compared to the density of water. It provides valuable information about the kidneys’ ability to concentrate urine.

The other options are incorrect:

• Reaction: Urine can be acidic or alkaline, but a urinometer doesn’t measure its pH (acidity or alkalinity).
• Transparency: While cloudiness in urine can be a sign of an issue, a urinometer doesn’t directly measure transparency.
• Volume: Urine volume is typically measured in a separate container graduated in milliliters or liters.

Answer: Blood urea

Blood urea nitrogen (BUN) is a waste product created from the breakdown of protein in your body. The kidneys are responsible for filtering BUN from the blood and excreting it in urine. A BUN test measures the amount of BUN present in the blood and can be used to assess kidney function.

The other options are incorrect:

• Blood sugar: A blood sugar test measures the level of glucose (sugar) in the blood and isn’t a direct indicator of kidney function.
• Serum bilirubin: This test measures the level of bilirubin, a yellow pigment produced by the breakdown of red blood cells, in the blood. It’s primarily used to assess liver function.
• Total cholesterol: A total cholesterol test measures the total amount of cholesterol in the blood and isn’t directly related to kidney function.

Answer: 2 hr after intake of food

A Post-Prandial Blood Sugar (PPBS) test specifically measures blood sugar levels after you’ve eaten. The goal is to assess how your body processes glucose (sugar) from a meal. Typically, doctors recommend taking the PPBS sample two hours after consuming a standardized meal.

• ¼ hr after intake of food: Blood sugar levels typically rise gradually after eating, peaking around the one-hour mark. So, ¼ hr wouldn’t capture the peak level.
• After 12 hrs of fasting: This would be a fasting blood sugar test, not a PPBS test. A fasting blood sugar test measures your blood sugar level after not eating for at least 8 hours.
• At anytime after intake of food: While blood sugar does fluctuate after eating, a specific timeframe (usually 2 hours) is chosen for PPBS tests to ensure consistency and reliable interpretation of results.

Answer: Albumin

Albumin is the most abundant protein found in blood plasma, accounting for roughly 55-60% of total plasma protein. It plays crucial roles in maintaining blood volume (oncotic pressure) and transporting various substances throughout the body, including fatty acids, hormones, and certain medications.

The other options are incorrect:

• Globulin: Globulins are another major group of plasma proteins, but they are less abundant than albumin, making up about 35-40% of the total. They primarily function in the immune system by acting as antibodies and transporting various molecules.
• Bence Jones Protein: This is an abnormal protein produced by some plasma cell cancers. It’s not a major component of healthy blood plasma.
• Fibrinogen: Fibrinogen is another essential plasma protein, but its concentration is much lower than albumin and globulins (around 4-7%). It plays a critical role in blood clotting by converting into fibrin, the main component of blood clots.

Answer: Bile pigment

Gmelin’s test is used to detect the presence of bile pigments (such as bilirubin) in urine. It involves adding nitric acid to the urine sample, resulting in a color change from yellow to green or blue-green in the presence of bile pigments.

The other options are incorrect:

• Sugar: Gmelin’s test is not designed to detect sugars in urine. Specific tests like Benedict’s test or Clinitest are used for sugar detection.
• Ketone bodies: Ketones are byproducts of fat metabolism and can be detected in urine using tests like the nitroprusside test (Gerhardt’s test). Gmelin’s test wouldn’t react with ketone bodies.
• Bile salts: While bile salts are produced by the liver and can be present in urine under certain conditions, Gmelin’s test wouldn’t detect them. Tests like Hay’s sulfur test are used for bile salt detection.

Answer: Urea

Urea is the major nitrogenous waste product produced by the breakdown of protein in the body. The liver synthesizes urea, which is then transported by the blood to the kidneys for excretion in urine.

The other options are incorrect:

• Sugar: Small amounts of sugar (glucose) might be present in urine under certain conditions (e.g., diabetes), but it’s not a normal constituent of healthy urine.
• Bile salt: Bile salts are produced by the liver to aid in fat digestion, but they are not normally found in urine. Their presence can indicate liver or gallbladder problems.
• Ketone bodies: Ketone bodies are produced by the liver during periods of limited glucose availability (e.g., starvation, diabetic ketoacidosis). While they can be found in urine under these conditions, they are not normal constituents of healthy

Answer: Purple

The standard color code used for EDTA (ethylenediaminetetraacetic acid) anticoagulant bottles is purple. EDTA is a common anticoagulant that prevents blood clotting by chelating calcium ions.

The other options are incorrect:

• Green: Green is typically used for blood collection tubes containing sodium heparin, another anticoagulant.
• Grey: Grey tubes might be used for specific tests requiring sodium fluoride and potassium oxalate as additives, not EDTA.
• Red: Red tubes are generally used for serum tests and don’t contain any anticoagulant.

Answer: EDTA

EDTA (Ethylenediaminetetraacetic acid) is also known by the trade names Versene and Sequestrene. It’s a common anticoagulant that works by chelating calcium ions, preventing them from participating in the blood clotting cascade.

The other options are incorrect:

• Heparin: Heparin is another widely used anticoagulant, but it has a different mechanism of action and is not known by the trade name Versene.
• Double oxalate: Double oxalate is a combination of potassium oxalate and ammonium oxalate, used as an anticoagulant for specific blood tests. It doesn’t have the trade name Versene.
• ACD (Acid-Citrate-Dextrose): ACD is a solution containing citric acid, sodium citrate, and dextrose, used as an anticoagulant for some blood banking procedures. It’s not known by the trade name Versene.

Answer: Sugar in urine

Melituria is the medical term specifically referring to the presence of sugar (glucose) in the urine.

The other options are incorrect:

• Protein in urine: The presence of protein in urine is called proteinuria.
• Blood in urine: The presence of blood in urine is called hematuria.
• Ketone bodies in urine: The presence of ketone bodies in urine is called ketonuria.

Answer: low sodium level in blood

Hyponatremia refers to a condition where the concentration of sodium (Na+) ions in your blood is abnormally low. Sodium plays a crucial role in maintaining fluid balance and nerve function in the body.

The other options are incorrect:

• Low potassium level in blood: Low potassium levels are called hypokalemia.
• Low calcium level in blood: Low calcium levels are called hypocalcemia.
• Low bicarbonate level in blood: Low bicarbonate levels are part of a condition called metabolic acidosis.

Answer: Biuret method

The Biuret method is commonly used for the estimation of total protein in blood and other biological fluids. It relies on the principle that the peptide bonds in proteins react with copper ions in an alkaline solution, forming a colored complex that can be measured spectrophotometrically.

The other options are incorrect:

• GOD-POD method: This method (Glucose Oxidase-Peroxidase) is specifically used to measure blood glucose (sugar) levels, not total protein.
• CHOD-PAP method: Similar to GOD-POD, this method (Cholesterol Oxidase-Peroxidase) is used for cholesterol measurement, not total protein.
• Jaffe method: The Jaffe method is typically used for measuring creatinine levels in blood or urine, not total protein.

Answer: Serum Bilirubin

The Van den Bergh reaction is used for the estimation of serum bilirubin levels. It involves the reaction of bilirubin with diazotized sulfanilic acid under acidic conditions to produce a colored azo compound, which can be measured spectrophotometrically.

The other options are incorrect:

• Total protein: The Van den Bergh reaction is specific for bilirubin and doesn’t measure total protein in the blood. The Biuret method is commonly used for total protein estimation.
• Serum creatinine: Serum creatinine levels are typically measured using an enzymatic assay to assess kidney function.
• Serum uric acid: Serum uric acid levels are measured to evaluate gout or monitor urate-lowering therapy. A specific enzymatic method is used for this purpose.

Answer: F

Among the given species, fluoride ion (F-) has the smallest size. This is because fluoride ion has the highest effective nuclear charge (due to its high electronegativity) and the fewest number of electron shells compared to the other ions listed.

The other options are incorrect:

• O-2 (Oxide ion): Although oxygen shares electrons and gains a negative charge, it still has 8 electrons compared to fluorine’s 7. This extra electron adds slightly to the overall size of the ion.
• Mg2+ (Magnesium ion): Magnesium has lost two electrons, resulting in a smaller radius compared to the neutral atom. However, it still has 10 protons in its nucleus, exerting a stronger attraction on the remaining electrons, leading to a larger size than F-.
• Al+3 (Aluminum ion): Similar to magnesium, aluminum loses three electrons, but it has 13 protons in its nucleus. The stronger nuclear pull on the remaining electrons makes the Al+3 ion larger than F-.

Answer: Kjeldhal’s method

Kjeldahl’s method is a widely used method for the estimation of total protein in a sample. It involves digestion of the protein with sulfuric acid, which converts nitrogen in the protein to ammonium sulfate. The ammonia released is then distilled and titrated with a standard acid or base to determine .

The other options are incorrect:

• Nesslerization: This technique is commonly used for the specific detection and quantification of ammonia in a sample. While it can be involved in Kjelddahl’s method for ammonia measurement after digestion, it’s not the complete method for total protein estimation.
• Salkowsky reaction: This reaction is typically used for qualitative detection of cholesterol in a sample, not for total protein estimation.
• Van den Bergh reaction: This reaction is specific for measuring bilirubin, a yellow pigment in the blood, not for total protein.

Answer: copper sulphate

The deep blue color of Benedict’s reagent arises from the presence of copper (Cu) ions in the form of copper sulfate (CuSO₄). These copper ions are in the +2 oxidation state (Cu²⁺).

The other options are incorrect:

• Sodium citrate: Sodium citrate acts as a complexing agent in Benedict’s solution. It helps prevent precipitation of certain metal ions like copper by forming soluble complexes. While it plays a role in the solution’s stability, it doesn’t contribute directly to the blue color.
• Ammonium sulphate: Ammonium sulfate is not typically included in Benedict’s reagent. It’s a salt commonly used in protein precipitation techniques.
• Sodium carbonate: Sodium carbonate acts as an alkaline agent in Benedict’s solution, creating a basic environment necessary for the reaction between the copper ions and reducing sugars. It doesn’t contribute directly to the blue color.

Answer: colourless

Schiff’s reagent itself is typically colorless or has a very pale yellow hue. It doesn’t have an inherent color.However, Schiff’s reagent reacts with aldehydes to form a colored product, usually appearing pink or red. This color change is used as a test for the presence of aldehydes in a sample.

The other options are incorrect:

• Yellow: While a very pale yellow color might be present in some Schiff’s reagent solutions due to impurities, it’s not the characteristic color.
• Blue: Schiff’s reagent doesn’t exhibit a blue color.
• Pink: This is the color of the product formed when Schiff’s reagent reacts with an aldehyde, but it’s not the color of the reagent itself.

Answer: 100-200 mg%

The normal range for total cholesterol in the blood is typically considered to be 150-250 mg% (milligrams per deciliter). This range may vary slightly depending on the reference values used by different laboratories or health organizations.

The other options are incorrect:

• 150-250 mg%: While some sources might use milligrams per percent (mg%), mg/dL is the more common unit. Even in mg%, 250 mg% would be considered high.
• 250-350 mg%: This range is well above the recommended healthy cholesterol level.
• 120-180 mg/dL: While closer to the normal range, some sources might recommend even lower levels for optimal heart health.

Answer: Quartz

Standard Borosilicate glass cuvettes are not suitable for the UV range of light because they absorb UV light. Quartz cuvettes, on the other hand, are made from a special type of silicon dioxide that allows transmission of UV wavelengths. This makes them ideal for colorimetric measurements involving UV-visible light.

The other options are incorrect:

• Borosilicate: While Borosilicate glass is a common material for cuvettes used in the visible and near-infrared range, it absorbs UV light.
• None of the above: Quartz is the recommended material for cuvettes used in the UV range.

Answer: Heat and acetic acid test

Bence Jones proteins are light chains of immunoglobulins that can be detected in urine using the heat and acetic acid test. In this test, urine is heated to 60-70°C and then a few drops of glacial acetic acid are added. If Bence Jones proteins are present, a precipitate or turbidity forms due to the denaturation of the proteins.

The other options are incorrect:

• Pandy’s test: This test is used to detect the presence of globulins in cerebrospinal fluid (CSF), not Bence Jones proteins in urine.
• SSA test: This is likely referring to the Serum Serum Agglutination (SSA) test, an autoimmune antibody test not specific for Bence Jones proteins.
• Bradshaws test: Bradshaw’s test is not a common test used in clinical practice. It’s possible it’s an outdated or less-established method for protein detection in urine.

Answer: Dry tubes without any chemicals

To separate serum from blood, samples are typically collected in tubes without any anticoagulants or additives. These tubes allow the blood to clot naturally, and after centrifugation, the clot retracts and pulls the serum away from the clot. The resulting serum can then be collected for various biochemical analyses.

The other options are incorrect:

• EDTA: EDTA is a common anticoagulant that chelates calcium ions necessary for blood clotting. Blood collected in EDTA tubes remains unclotted and is used for tests requiring whole blood or plasma (the liquid portion of unclotted blood).
• Heparin: Similar to EDTA, Heparin is another anticoagulant that works through a different mechanism. Blood collected in Heparin tubes also remains unclotted for tests requiring whole blood or plasma.
• Sodium citrate: Sodium citrate is an anticoagulant that binds calcium ions. It’s used in specific blood tests for coagulation studies but not for routine serum separation.

Answer: Apoenzyme

The protein portion of an enzyme, without its cofactor or prosthetic group, is called the apoenzyme. Enzymes often require non-protein components (cofactors or prosthetic groups) to function properly. The apoenzyme itself is typically inactive unless it binds with its required cofactor or prosthetic group.

The other options are incorrect:

• Prosthetic group: While a prosthetic group is a type of non-protein cofactor that binds tightly to the apoenzyme, it’s not the entire protein portion of the enzyme.
• Co-factor: This is a broader term encompassing both prosthetic groups and coenzymes.
• Coenzyme: Similar to a prosthetic group, it’s a non-protein cofactor, but it typically binds loosely to the apoenzyme and can be recycled in enzymatic reactions.

Answer: Heparin

Green colored vacutainer tubes typically contain heparin as an anticoagulant. Heparin works by inhibiting thrombin formation, thereby preventing blood clotting. This allows for the separation of plasma, the liquid portion of blood, for various tests.

The other options are incorrect:

• Fluoride: Fluoride is typically used in grey-topped tubes to inhibit glycolysis (sugar breakdown) and preserve blood glucose levels for testing.
• EDTA: EDTA is commonly used in purple-topped tubes as an anticoagulant for complete blood cell (CBC) count and other tests requiring whole blood or plasma.
• Citrate: Sodium citrate is used in light blue-topped tubes as an anticoagulant for coagulation studies.

Answer: Alpha 1-4 linkage

The glycosidic linkage in maltose involves an alpha 1-4 linkage. Maltose is a disaccharide composed of two glucose molecules linked together through an alpha 1-4 glycosidic bond. This linkage allows for the formation of maltose from two glucose molecules, contributing to its biochemical properties and digestion pathway.

The other options are incorrect:

• Beta 1-4 linkage: This type of linkage is found in some other disaccharides like lactose. In beta 1-4, the anomeric carbon of the first unit has a beta configuration.
• Alpha 1-6 linkage: This type of linkage is less common but can be found in some complex carbohydrates like starches. Here, the C1 of the first glucose links to the C6 of the second glucose.
• Alpha 1-2 linkage: This linkage is also less prevalent but can be present in some disaccharides and polysaccharides. In this case, the C1 of the first glucose connects to the C2 of the second glucose.

Answer: All the above

Creatinine synthesis involves three amino acids:

• Glycine: This amino acid donates its carbon skeleton for the formation of the core creatinine structure.
• Arginine: It donates its guanidino group, which becomes a key functional group in creatinine.
• Methionine: While not directly part of the creatinine structure, it acts as a methyl donor through S-adenosylmethionine (SAM) for a methylation step in the synthesis pathway.

Answer: CKMB (mass)

CKMB (mass), also known as CK-MB (mass), is the best marker of myocardial ischemia. Creatine kinase MB isoenzyme (CKMB) is specifically found in the heart muscle. Elevated levels of CKMB in the blood indicate damage to the heart muscle, which can occur during myocardial ischemia (inadequate blood flow to the heart) or myocardial infarction (heart attack).

The other options are incorrect:

• ALP (Alkaline phosphatase): ALP is an enzyme found in various tissues throughout the body, including the liver, bones, kidneys, and intestines. Elevated levels of ALP can indicate liver or bone disease, but it is not specific to myocardial ischemia.
• GGT (Gamma-glutamyl transferase): GGT is an enzyme found in many tissues, with higher concentrations in the liver. Elevated levels of GGT are associated with liver disease and alcohol consumption. It is not specific to myocardial ischemia.
• Cystatin C: Cystatin C is a marker of kidney function and is used to estimate glomerular filtration rate (GFR). It is not specific to myocardial ischemia or heart-related conditions.

Answer: 30-300 mg Albumin/day

Microalbuminuria is defined as the presence of a moderately increased amount of albumin in the urine. Specifically, it is typically defined as an albumin excretion rate (AER) of 30-300 mg/day or an albumin-to-creatinine ratio (ACR) of 30-300 mg/g in a spot urine sample. It is an early marker of kidney damage or dysfunction, often associated with conditions like diabetes mellitus or hypertension.

The other options are incorrect:

• < 10 mg Albumin/day: This is considered the normal range for albumin excretion in urine.
• 1-3 gm Albumin/day: This is a very high level of albumin excretion, exceeding the range for both microalbuminuria and macroalbuminuria. It suggests significant kidney dysfunction.
• > 1-3 mg/day: This notation is imprecise. Microalbuminuria is typically defined within a specific range (30-300 mg/day).

Answer: 1,2, and 3

All three enzymes listed (LDH, CPK, and SGOT) are present in heart muscle and can be elevated in the blood following heart damage, such as a myocardial infarction (heart attack).

The other options are incorrect:

• 1 and 2 only (LDH and CPK): While both LDH and CPK are present in heart muscle, SGOT can also be elevated in myocardial infarction.
• 2 only (CPK): CPK is a good indicator, but LDH and SGOT can also be elevated in heart damage.
• 2 and 3 only (CPK and SGOT): LDH is another enzyme present in heart muscle and can be elevated during myocardial infarction.

Answer: Higher the concentration of the analyte

Beer’s law, also known as the Beer-Lambert law, states that the absorbance (A) of light at a particular wavelength by a solution is directly proportional to the concentration (C) of the absorbing substance in the solution and the path length (l) that the light travels through the solution.

The other options are incorrect:

• Lower concentration of the analyte: With a lower concentration, less light is absorbed, and more light is transmitted, leading to a lighter color solution.
• Longer wavelength required: Beer’s Law doesn’t dictate the wavelength needed. The chosen wavelength should be appropriate for the analyte being measured.
• More light transmitted: As explained above, higher concentration leads to less light transmitted and a darker solution.

Answer: Uric acid

In humans, the end product of purine metabolism is uric acid. Purines are essential components of nucleic acids (DNA and RNA) and are also involved in energy metabolism (ATP).

The other options are incorrect:

• Creatine: Creatine is a molecule found in muscles and plays a role in energy production. It’s not the end product of purine metabolism.
• Creatinine: Creatinine is a waste product derived from creatine breakdown in muscles. It’s filtered by the kidneys and excreted in urine, but it’s not the final product of purine metabolism.
• Urea: Urea is the primary nitrogenous waste product in the urea cycle, formed from the breakdown of ammonia in the liver. It’s not directly related to purine metabolism.

Answer: Osmotic pressure of body fluids

Sodium (Na⁺) plays a crucial role in maintaining the osmotic pressure of body fluids. It helps regulate the movement of water across cell membranes, maintaining proper hydration and preventing cells from swelling or shrinking excessively. Sodium is an essential electrolyte involved in fluid balance, nerve function, and muscle contraction.

The other options are incorrect:

• Blood coagulation: While some chemicals like calcium are involved in blood clotting, sodium doesn’t directly participate in this process.
• Salt intake: This refers to dietary sodium consumption, not a physiological function of sodium in the body.
• Cardiac muscle contractions: Calcium plays a more significant role in regulating cardiac muscle contractions, while sodium helps maintain the electrical gradient across cell membranes.

Answer: Obstructive jaundice

Alkaline phosphatase (ALP) is an enzyme found in various tissues throughout the body, including the liver, bones, kidneys, and intestines. In obstructive jaundice, there is a blockage in the bile ducts that prevents bile from flowing out of the liver.

The other options are incorrect:

• Liver disease: While liver disease can elevate ALP, the degree of elevation may vary depending on the specific condition.
• Kidney disease: Kidney disease is not a major cause of a GREATLY elevated ALP level.
• Myocardial infarction: A heart attack typically doesn’t significantly impact ALP levels.

Answer: Freezing point depression

Osmolality of a solution refers to the concentration of osmotically active particles (osmoles) per kilogram of solvent. It is typically measured by determining the freezing point depression of the solution compared to the freezing point of the pure solvent. The more solute particles present in the solution, the lower the freezing point of the solution relative to the pure solvent.

The other options are incorrect:

• Ionic strength: Ionic strength reflects the concentration of charged particles (ions) in a solution. While it can be related to osmolality in some cases, it’s not a direct measurement of total osmoles.
• Refractive index: Refractive index is a property related to how light bends as it passes through a solution. It can be used for estimating concentration in some solutions, but it’s not specific for osmolality and might be influenced by other factors.
• Specific gravity: Specific gravity compares the density of a solution to the density of water. While it can provide some information about concentration, it doesn’t directly measure osmolality and may not be sensitive enough for all solutions.

Answer: 1,2, and 3

Carbohydrates are organic compounds composed of carbon (C), hydrogen (H), and oxygen (O) atoms in the ratio of 1:2:1, respectively. This means that for every carbon atom, there are two hydrogen atoms and one oxygen atom present in carbohydrates. These elements are essential for the structure and function of carbohydrates, which serve as important sources of energy and structural components in living organisms.

The other options are incorrect:

• 1 and 2 only (Carbon and Hydrogen): While these are essential components, carbohydrates also contain oxygen.
• 2 and 3 only (Hydrogen and Oxygen): Carbohydrates also contain carbon as the central element.
• 1 and 3 only (Carbon and Oxygen): Hydrogen is another crucial element in carbohydrates.

Answer: Immunoelectrophoresis

Immunoelectrophoresis is a technique that combines electrophoresis with immunodiffusion to separate and detect proteins based on their antigenic properties. It is widely used in clinical laboratories to study protein abnormalities associated with various diseases by identifying abnormal protein patterns.

The other options are incorrect:

• Isoenzyme electrophoresis: Isoenzyme electrophoresis separates enzymes based on their different forms (isozymes) rather than proteins. It is used primarily to study enzyme variations and is not specific for protein abnormalities.
• Blood viscosity studies: Blood viscosity studies measure the thickness or stickiness of blood, which can be affected by factors such as hematocrit and plasma proteins but does not directly analyze protein abnormalities at the molecular level.
• Electrophoresis of penicillamine-treated serum: Electrophoresis of penicillamine-treated serum is a specialized technique used to study metal-binding proteins or proteins affected by penicillamine treatment. It is not a general method for studying protein abnormalities but rather specific to certain conditions treated with penicillamine.

Answer: Alkaline picrate

Most methods for the determination of blood creatinine are based on the reaction of creatinine with alkaline picrate, forming a colored complex that can be measured spectrophotometrically.

The other options are incorrect:

• Acetic anhydride: Acetic anhydride is not typically used in methods for the determination of blood creatinine. It is used in other chemical reactions and derivatization methods, not specifically for creatinine determination.
• Sulfuric acid: Sulfuric acid is not used in methods for the determination of blood creatinine. It is a strong acid used in various chemical reactions and processes, but not in creatinine assays.
• Ammonium hydroxide: Ammonium hydroxide is not used in methods for the determination of blood creatinine. It is a weak base and is used in different chemical reactions and solutions, but not in creatinine assays.

Answer: Sodium

Sodium (Na⁺) is the major cation found in the extracellular fluid (ECF), playing a crucial role in maintaining osmotic balance, regulating water distribution, and influencing nerve and muscle function.

The other options are incorrect:

• Chloride: Chloride (Cl⁻) is an anion, not a cation. It is the most abundant anion in the extracellular fluid, balancing the positive charge of sodium.
• Potassium: Potassium (K⁺) is the major cation found inside cells (intracellular fluid, ICF), not in the extracellular fluid. It plays a critical role in cellular function and membrane potential.
• Bicarbonate: Bicarbonate (HCO₃⁻) is an anion involved in the regulation of pH in the body, primarily found in the blood and extracellular fluid. It is not a cation and does not play a major role as the major cation in extracellular fluid.

Answer: Higher the concentration of the analyte

Beer’s law states that the absorbance (A) of light by a substance in solution is directly proportional to its concentration (C). Therefore, the higher the concentration of the analyte, the more light is absorbed by the specimen.

The other options are incorrect:

• Longer the wavelength required: Beer’s law does not state that longer wavelengths are required for higher concentrations. The wavelength used for measurement is chosen based on the specific absorption characteristics of the analyte, not its concentration.
• More light transmitted: Beer’s law states that more light is absorbed as the concentration of the analyte increases, resulting in less light being transmitted through the specimen, not more.
• Lower the concentration of the analyte: Beer’s law indicates that lower concentrations of the analyte result in lower absorbance values and less light being absorbed, not darker colors or higher absorbance values.

Answer: Obstructive jaundice

Alkaline phosphatase (ALP) is greatly elevated in obstructive jaundice due to obstruction of bile flow, which leads to leakage of ALP from liver cells and bile ducts into the bloodstream.

The other options are incorrect:

• Myocardial infarction: ALP levels are not greatly elevated in myocardial infarction. Elevations in ALP are primarily associated with liver and bone disorders rather than cardiac events.
• Liver disease: ALP levels can be elevated in liver disease, but they are greatly elevated in obstructive jaundice due to impaired bile flow and ALP release from liver and bile duct cells.
• Kidney disease: ALP levels are not significantly elevated in kidney disease. Elevated ALP levels are mainly seen in conditions affecting the liver and bile ducts, not kidney dysfunction.

Answer: Freezing point depression

Osmolality of a solution is determined by measuring the freezing point depression, which is the decrease in the freezing point of a solvent caused by the presence of dissolved particles.

The other options are incorrect:

• Ionic strength: Ionic strength is a measure of the total concentration of ions in a solution and does not directly determine osmolality based on freezing point depression. It is related to the sum of the concentrations of all ions in the solution.
• Refractive index: Refractive index is a measure of how much light is bent (refracted) as it passes through a substance and is not used to determine osmolality based on freezing point depression. It measures the optical properties of a substance.
• Specific gravity: Specific gravity is a measure of the density of a solution compared to the density of water and is not used to determine osmolality based on freezing point depression. It is a measure of relative density.

Answer: Uric acid

Uric acid is the end-product of purine metabolism in humans, derived from the breakdown of purine nucleotides.

The other options are incorrect:

• Creatinine: Creatinine is not an end-product of purine metabolism. It is formed from the breakdown of creatine phosphate in muscle tissue.
• Creatine: Creatine is synthesized from amino acids in the liver and kidneys and is not an end-product of purine metabolism.
• Urea:Urea is the end-product of protein metabolism in humans, formed in the liver from ammonia and excreted by the kidneys. It is not derived from purine metabolism.
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Answer: Immunoelectrophoresis

Immunoelectrophoresis is a method used to study protein abnormalities by combining electrophoresis with immunodiffusion to detect and characterize proteins based on their antigen-antibody interactions

The other options are incorrect:

• Isoenzyme electrophoresis: Isoenzyme electrophoresis is used to separate and identify different forms (isozymes) of enzymes based on their electrophoretic mobility, not proteins.
• Electrophoresis of penicilliamine-treated serum: Penicilliamine is a medication used to treat heavy metal poisoning. Electrophoresis of serum treated with this drug wouldn’t be a standard method for studying general protein abnormalities.
• Blood viscosity studies: Blood viscosity mainly measures the thickness of blood. While abnormal protein levels can affect blood viscosity in some cases, it’s not a specific or direct method for studying protein abnormalities.

Answer: Osmotic pressure of body fluids

Sodium plays a crucial role in maintaining the osmotic pressure of body fluids, helping to regulate water balance and fluid distribution within cells and tissues.

The other options are incorrect:

• Cardiac muscle contractions: While sodium is involved in nerve impulses that trigger muscle contractions, including those in the heart, it’s not the sole factor. Calcium also plays a vital role in this process.
• Blood coagulation: Blood coagulation involves a cascade of proteins and other factors. While some proteins might be indirectly affected by sodium imbalances, it’s not a primary player in blood clotting.
• Salt intake: Salt intake is the dietary source of sodium, not a function of sodium itself within the body.

Answer: Heparin

Heparin is the preferred anticoagulant for the Osmotic Fragility Test (OFT) because it minimally affects the red blood cell membranes being evaluated.

The other options are incorrect:

• EDTA: While EDTA is a common anticoagulant, it can alter the osmotic fragility of red blood cells, making it unsuitable for the OFT.
• Citrate: Similar to EDTA, citrate can also affect red blood cell membranes and isn’t ideal for the OFT.
• Sodium fluoride-potassium oxalate mixture: This combination is used to inhibit specific enzymes and prevent glycolysis in blood cells. It’s not an anticoagulant and wouldn’t be used for the OFT.

Answer: All of the above

Hypocupremia (low copper levels) can occur in various conditions, including:

• Osteoporosis, nephrotic disease: Both can lead to decreased copper absorption.
• Sprue, celiac disease: These are malabsorption syndromes that can interfere with copper uptake.
• Cardiovascular disease, colon cancer: While less common, these conditions can also be associated with copper deficiency due to factors like inflammation or malnutrition.