Biochemistry MCQs with Answer and Explanations | Chapter 1

Answer: Contain Fibrinogen.

Fibrinogen is a protein essential for blood clotting. When blood clots, fibrinogen is converted into fibrin, which forms the mesh of the clot. Since plasma is the liquid portion of blood before clotting, it contains all the components needed for clotting, including fibrinogen.

The other options are incorrect:

• Does not contain fibrinogen: This is incorrect. As explained above, plasma contains fibrinogen.
• Has more water: While both plasma and serum are mostly water, the difference in water content isn’t significant enough to be a defining characteristic.
• Contains Iron: Iron is primarily carried by red blood cells, which are removed during the process of obtaining both plasma and serum.

Answer: Uric Acid

Purines are broken down through a series of reactions, and uric acid is the final stable product excreted by the body in humans and some other primates.

The other options are incorrect:

• Urea: Urea is the primary end product of protein metabolism, not purine metabolism.
• Creatinine: Creatinine is a waste product derived from creatine, a molecule important for muscle function. It’s not directly related to purine breakdown.
• Ammonia: Ammonia is a toxic intermediate product formed during purine breakdown. However, it’s further converted into uric acid for safe excretion.

Answer: Sodium

Sodium is the major cation (positively charged ion) found in extracellular fluid. It plays a crucial role in maintaining fluid balance, nerve impulses, and muscle function.

The other options are incorrect:

• Potassium: Potassium is the major cation found inside cells (intracellular fluid). It’s essential for muscle function and nerve impulses but has a lower concentration in extracellular fluid compared to sodium.
• Magnesium: Magnesium is another important electrolyte found in both extracellular and intracellular fluids, but its concentration is much lower than sodium in the extracellular space.
• Zinc: Zinc is a trace element with various functions in the body but isn’t a major electrolyte and isn’t present in high concentrations in either extracellular or intracellular fluids.

Answer: LDL

Cholesterol itself isn’t inherently bad. It’s a fatty substance needed by the body for various functions. However, LDL cholesterol is often called “bad” cholesterol because high levels can contribute to fatty buildup in arteries, increasing the risk of heart disease and stroke.

The other options are incorrect:

• Cholesterol: As mentioned earlier, cholesterol is a general term and not specific to “bad” or “good” types.
• Triglyceride: Triglycerides are another type of fat in the blood. While high triglyceride levels can also be a risk factor for heart disease, they aren’t the same as LDL cholesterol.
• HDL (High-Density Lipoprotein): HDL is known as “good” cholesterol because it helps remove LDL cholesterol from the arteries and transport it back to the liver for excretion.

Answer: Bilirubin

Bilirubin is a breakdown product of hemoglobin from red blood cells. It’s sensitive to light and can break down further when exposed, leading to inaccurate test results.

The other options are incorrect:

• Urea: Urea is not light-sensitive and doesn’t require special precautions regarding light exposure.
• Glucose: While some methods for glucose measurement might be affected by extreme temperatures, light exposure generally doesn’t significantly impact glucose testing.
• Calcium: Calcium testing is not typically affected by light exposure.

Answer: 3-hydroxy Butilic acid

The three types of ketone bodies produced during ketogenesis are acetoacetic acid, acetone, and 3-hydroxybutyric acid (also known as beta-hydroxybutyric acid). These are produced when the body breaks down fatty acids for energy during periods of low carbohydrate intake.

The other options are incorrect:

• Oxaloacetic acid: This is an intermediate product within the citric acid cycle (Krebs cycle) used for energy production and not a ketone body.
• Lactic Acid: Lactic acid is a byproduct of anaerobic respiration in muscles and isn’t a ketone body.
• Acetic Acid: While acetic acid is a type of acid, it’s not one of the three main ketone bodies produced by the liver.

Answer: LDH

LDH (Lactate Dehydrogenase) is an enzyme found in various tissues throughout the body, including the heart. When heart muscle is damaged, such as during a heart attack, LDH levels in the blood can increase. Therefore, LDH is used as a cardiac marker to help diagnose heart damage.

The other options are incorrect:

• Acid Phosphatase: This enzyme is found in various tissues like the prostate and red blood cells, and isn’t specifically indicative of cardiac function.
• Creatinine: Creatinine is a waste product from muscle metabolism and doesn’t directly reflect damage to the heart muscle itself.
• ALT (Alanine Aminotransferase): ALT is primarily a liver enzyme and is elevated in cases of liver damage, not necessarily indicative of cardiac problems.

Answer: Calcium

EDTA (ethylenediaminetetraacetic acid) is an anticoagulant used in EDTA tubes. It works by chelating calcium ions, meaning it binds to them and prevents them from clotting the blood. This can slightly decrease the measured calcium concentration in the blood sample compared to what it would be without EDTA.

The other options are incorrect:

• Glucose: EDTA doesn’t significantly interfere with the measurement of glucose in most standard tests.
• Urea: The breakdown of red blood cells (which can be minimally affected by EDTA) doesn’t impact the measurement of urea, a waste product from protein metabolism.
• Cholesterol: EDTA doesn’t directly affect cholesterol measurement in the blood.

Answer: Vitamin A

Vitamin A plays a crucial role in vision, particularly in the production of rhodopsin, a pigment necessary for seeing in low light conditions. Deficiency in vitamin A leads to night blindness, where seeing in dim light becomes difficult.

The other options are incorrect:

• Vitamin C: Vitamin C is essential for immune function and collagen synthesis but isn’t directly linked to night blindness.
• Vitamin B12: Vitamin B12 deficiency can cause various neurological problems but doesn’t typically cause night blindness.
• Vitamin B6: Vitamin B6 is involved in energy metabolism and nervous system function, and deficiency doesn’t cause night blindness.

Answer: CK

Creatine kinase (CK), specifically the CK-MB isoenzyme, is one of the first enzymes to elevate in the blood following a myocardial infarction, typically rising within 3-6 hours of the event.

The other options are incorrect:

• LDH: Lactate dehydrogenase (LDH) levels rise later than CK, typically 12-24 hours after a myocardial infarction, and remain elevated for a longer period.
• ALT: Alanine aminotransferase (ALT) is primarily a liver enzyme and is not a specific marker for myocardial infarction.
• AST: Aspartate aminotransferase (AST) can rise after a myocardial infarction, but it typically elevates later than CK and is not as specific for cardiac muscle damage.

Answer: ALT

ALT is more specific for detecting liver damage in cases of acute hepatitis. It is primarily found in hepatocytes (liver cells), and its levels rise significantly when there is liver injury or inflammation.

The other options are incorrect:

• AST (Aspartate Aminotransferase): While AST levels can also rise in acute hepatitis, they are less specific to liver damage as AST is found in other organs, such as the heart and muscles.
• ALP (Alkaline Phosphatase): ALP is an enzyme found in various tissues, including the liver, bones, and bile ducts. While ALP levels may rise in acute hepatitis, they are not as specific to liver damage as ALT.
• Both ALT and AST: While both ALT and AST levels may increase in acute hepatitis, ALT is more specific to liver damage compared to AST.

Answer: Glycolysis

Glycolysis is the metabolic pathway that converts glucose, a six-carbon sugar molecule, into pyruvate or lactate. It’s the first stage of cellular respiration and occurs in the cytoplasm of all cells.

The other options are incorrect:

• Glycopenesis: This term doesn’t exist in standard biochemical terminology.
• Glycogenolysis: This process refers to the breakdown of glycogen, a stored form of glucose, back into glucose molecules. It’s the opposite of glycogenesis (storing glucose as glycogen).
• Gluconeogenesis: This is the process of creating new glucose molecules from non-carbohydrate precursors like amino acids or lactate. It’s not directly related to the conversion of glucose itself.

Answer: Hemolytic Diseases

An elevated urine urobilinogen and a negative test for urine bilirubin are characteristic of hemolytic diseases. In hemolytic conditions, there is an increased breakdown of red blood cells, leading to higher levels of urobilinogen in urine, while bilirubin levels may remain normal or low.

The other options are incorrect:

• Acute Hepatic Toxicity: While liver damage can cause both elevated urobilinogen and bilirubin, a negative bilirubin test with elevated urobilinogen suggests the liver isn’t necessarily failing to conjugate bilirubin (as seen in severe liver damage).
• Biliary Obstruction: This can cause elevated bilirubin in both blood and urine due to problems with bile excretion. However, it wouldn’t necessarily lead to significantly elevated urine urobilinogen.
• Urinary Tract Infection (UTI): UTIs typically wouldn’t cause abnormalities in either bilirubin or urobilinogen levels.

Answer: Tungusten Lamp

The most common light source for spectrophotometry in the visible range is a Tungsten Lamp. Tungsten lamps provide a continuous spectrum of light in the visible range, making them suitable for a wide range of applications in spectrophotometry.

The other options are incorrect:

• Didymium Lamp: Didymium lamps emit sharp peaks at specific wavelengths and aren’t ideal for broad spectrum analysis in the visible range.
• Deuterium Lamp: Deuterium lamps are commonly used for ultraviolet (UV) spectroscopy due to their strong emission in the UV range. While they might emit some visible light, it’s not their primary function in spectrophotometry.
• Hydrogen discharge lamp: Hydrogen discharge lamps can emit light in the visible range, but their emission spectrum might not be as continuous or intense as a Tungsten lamp for optimal use in spectrophotometry.

Answer: Ferritin

Ferritin is the major iron storage compound found in most living organisms. It’s a protein complex that can safely store large amounts of iron in a soluble and non-toxic form within cells.

The other options are incorrect:

• Hemosodium: This term isn’t a recognized compound for iron storage.
• Siderotic Granules: These are aggregates or clumps of iron deposits that can form in tissues due to excess iron but aren’t the primary storage form.
• Transferrin: Transferrin is a transport protein in the blood that carries iron throughout the body. It doesn’t store iron itself but delivers it to cells that need it.

Answer: Albumin

In electrophoresis, proteins migrate based on their net charge and size. Albumin is the smallest and most negatively charged protein in blood plasma. Due to its high negative charge, it migrates most rapidly towards the positive electrode (anode) during electrophoresis.

The other options are incorrect:

• Beta: Beta globulins migrate at an intermediate speed in protein electrophoresis.
• Gamma: Gamma globulins, including immunoglobulins (antibodies), migrate more slowly than albumin towards the anode.
• Alpha 1: Alpha-1 globulins migrate at a slower rate than albumin but faster than beta and gamma globulins.

Answer: Glycosylated Haemoglobin

HbA1c is the gold standard test for monitoring long-term blood sugar control in diabetic patients. It measures the percentage of hemoglobin (a protein in red blood cells) that is coated with glucose. Since red blood cells live for about 3 months, the HbA1c test reflects the average blood sugar levels over that timeframe.

The other options are incorrect:

• Glucose Tolerance Test (GTT): A GTT is used to diagnose diabetes, not specifically for long-term monitoring. It involves measuring blood sugar levels after drinking a sugary drink and doesn’t reflect average blood sugar control over a long period.
• Fasting Blood Sugar: While fasting blood sugar is a helpful tool, it only provides a snapshot of blood sugar levels at a single point in time. HbA1c offers a more comprehensive picture of average blood sugar control.
• Postprandial Blood Sugar: Similar to fasting blood sugar, this test measures blood sugar levels after a meal but doesn’t offer the same long-term perspective as HbA1c.

Answer: number of peptide bond

The Biuret method for determining serum total protein relies on the reaction of copper ions with the peptide bonds in proteins. The intensity of the color produced is proportional to the number of peptide bonds present, allowing for the quantification of total protein concentration.

The other options are incorrect:

• Amino acid content: While proteins are composed of amino acids, the Biuret test specifically reacts with the peptide bonds linking them, not the individual amino acids themselves.
• Nitrogen content: Proteins do contain nitrogen atoms, but the Biuret test doesn’t directly measure total nitrogen content. It focuses on the specific arrangement of nitrogen within peptide bonds.
• Protein precipitation: The Biuret test doesn’t involve protein precipitation as a primary step. It relies on the formation of a colored complex between the copper ions and the peptide bonds in solution.

Answer: ↓pCO2 , ↓ HCO3 , ↓PH

A patient in diabetic ketoacidosis (DKA) typically exhibits respiratory compensation in response to metabolic acidosis. This compensation leads to a decrease in pCO2 (partial pressure of carbon dioxide) as the patient hyperventilates to try to blow off excess CO2. Meanwhile, there is a decrease in HCO3- (bicarbonate) due to its consumption in buffering the excess acids, resulting in a decrease in pH (acidemia).

The other options are incorrect:

• ↑pCO2, ↑HCO3-, ↑pH: This is the opposite of what happens in DKA. Increased pCO2 and HCO3- would indicate metabolic acidosis with respiratory compensation, not DKA.
• Normal pCO2, ↑HCO3-, ↓pH: Normal pCO2 wouldn’t be expected in DKA due to Kussmaul breathing. An increase in HCO3- is unlikely in uncompensated metabolic acidosis.
• Normal pCO2, ↓HCO3-, ↑pH: Normal pCO2 wouldn’t be present, and a decrease in HCO3- indicates metabolic acidosis, not an increase in pH.

Answer: Boric Acid

Boric acid is a commonly used preservative for urine samples. It helps prevent bacterial growth and degradation of certain analytes (components being measured) in the urine over a short period of time, typically up to 24 hours.

The other options are incorrect:

• Formaldehyde: Formaldehyde is a strong fixative and can interfere with some urine tests. It’s not a recommended preservative for routine urine analysis.
• Gluteraldehyde: Similar to formaldehyde, glutaraldehyde is a strong fixative and can denature proteins and enzymes in urine, making it unsuitable for most urine chemistry tests.
• Picric Acid: Picric acid is a strong acid and can also precipitate proteins in urine, rendering it unsuitable as a preservative for most routine urine tests.

Answer: Nephelometry

Nephelometry is a technique that measures the intensity of light scattered by suspended particles in a solution at specific angles, typically 90 degrees (right angle) to the incident light beam. This scattered light intensity is indirectly related to the concentration and size of the particles in the solution.

The other options are incorrect:

• Fluorometry: Fluorometry measures the light emitted by a fluorescent molecule after it absorbs light of a specific wavelength. It doesn’t rely on scattered light.
• Turbidimetry: Similar to nephelometry, turbidimetry measures the reduction in intensity of the transmitted light due to scattering by particles. However, it doesn’t distinguish the scattering angle and measures total attenuation of light, not light scattered at a specific angle.
• Osmometry: Osmometry is a technique used to measure the osmotic pressure of a solution, which reflects the concentration of dissolved particles. It doesn’t involve measuring light scattering.

Answer: Electrophoresis

Electrophoresis is the method of physical separation of proteins based on their ionic charge and molecular size. Proteins are subjected to an electric field, causing them to migrate through a gel matrix according to their charge and size.

The other options are incorrect:

• Spectrophotometer: Spectrophotometer is a device used to measure the absorbance or transmittance of light by a sample at different wavelengths, not for the physical separation of proteins.
• Fluorometry: Fluorometry measures the fluorescence emitted by a sample when excited by light of a specific wavelength, not for the physical separation of proteins based on charge and size.
• Osmometry: Osmometry measures the osmotic concentration of a solution, typically by determining the freezing point depression or vapor pressure depression caused by solutes dissolved in the solution. It is not used for the separation of proteins.

Answer: Both “2” and “3”

Both the third trimester of pregnancy and obstructive jaundice can lead to increased levels of alkaline phosphatase (ALP) in the blood. In pregnancy, ALP levels rise due to placental production, while in obstructive jaundice, ALP is released from damaged hepatocytes and obstructed bile ducts.

The other options are incorrect:

• Hepatitis Only: As mentioned above, elevated ALP isn’t a universal finding in all hepatitis cases. Other liver enzymes might be more indicative.

Answer: Both “2” and “3”

• Unconjugated bilirubin: This is the indirect bilirubin, formed in the breakdown of heme from red blood cells. It’s insoluble in water and needs to be conjugated for excretion.
• Conjugated Bilirubin: This is the direct bilirubin, formed when the liver attaches a molecule (conjugates) to unconjugated bilirubin, making it water-soluble. This allows it to be transported in bile to the intestines for elimination.

The other options are incorrect:

• Unconjugated bilirubin: Unconjugated bilirubin is bilirubin that has not yet undergone conjugation in the liver. It is lipid-soluble and bound to albumin for transport to the liver.

Answer: Uric Acid

Purine metabolism breaks down purine nucleotides, which are essential components of RNA and DNA. The final stable end product excreted by the body in humans and some other primates is uric acid.

The other options are incorrect:

• Urea: Urea is the primary end product of protein metabolism, not purine metabolism.
• Xanthine: Xanthine is an intermediate product formed during the breakdown of purines. It’s further converted to uric acid for excretion.
• Guanine: Guanine is one of the purine bases found in nucleotides. It’s broken down through various steps, ultimately leading to uric acid formation.

Answer: 3

Creatinine kinase (CK) has three isoenzymes: CK-MM (found primarily in skeletal muscle), CK-MB (found mainly in cardiac muscle), and CK-BB (found predominantly in the brain).

The other options are incorrect:

• 1: Creatinine kinase has three isoenzymes, not one.
• 2: While there are three main isoenzymes, the answer is the total number, which is 3.
• None: As explained above, there are multiple isoenzymes of CK.

Answer: Sodium Fluoride (NaF)

Sodium fluoride (NaF) is commonly used as an anticoagulant for glucose estimation because it inhibits glycolysis, preventing the degradation of glucose in the sample during storage.

The other options are incorrect:

• EDTA: EDTA is a strong chelating agent that binds calcium ions, preventing blood clotting. However, it can slightly decrease measured calcium concentration, which can indirectly affect some glucose measurement methods.
• Sodium Citrate: Sodium Citrate is another anticoagulant that binds calcium ions. While it doesn’t affect calcium measurement as much as EDTA, it’s not typically used for glucose estimation because it can interfere with some enzymatic methods used for glucose measurement.
• Heparin: Heparin is a commonly used anticoagulant, but it can interfere with some glucose measurement assays. It’s generally not recommended for blood sugar testing.

Answer: Liver

The urea cycle is a series of biochemical reactions that occur primarily in the liver. It’s responsible for converting toxic ammonia, a byproduct of protein metabolism, into urea, a less toxic compound that can be excreted in the urine.

The other options are incorrect:

• Kidney: While the kidneys play a crucial role in filtering and excreting urea produced by the liver, they aren’t the primary site of the urea cycle itself.
• Heart: The heart doesn’t participate significantly in the urea cycle. Its primary function is to pump blood throughout the body.
• Brain: The brain does have some ammonia metabolism, but it doesn’t carry out the complete urea cycle.

Answer: Vitamin B

Vitamin B is water-soluble, meaning it dissolves in water and can be excreted by the body if consumed in excess. Fat-soluble vitamins, on the other hand, dissolve in fat and are stored in the body’s fatty tissues.

The other options are incorrect:

• Vitamin A: Correctly identified as fat-soluble.
• Vitamin D: Correctly identified as fat-soluble.
• Vitamin E: Correctly identified as fat-soluble.

Answer: Urea

Liver Function Tests (LFTs) typically include tests such as serum bilirubin, SGPT (also known as ALT), albumin, and other liver enzymes. Urea, however, is a measure of kidney function and is not considered a part of LFTs.

The other options are incorrect:

• S. Bilirubin: Serum bilirubin is commonly included in LFTs, as it provides information about liver and bile duct function.
• SGPT: Serum Glutamate Pyruvate Transaminase (SGPT), also known as ALT, is an enzyme found in the liver and is often included in LFTs to assess liver health.
• Albumin: Albumin is a protein synthesized by the liver and is often included in LFTs to assess liver function and nutritional status.

Answer: Diabetic

HbA1c test, also known as glycated hemoglobin test, is performed to monitor blood sugar levels in diabetic patients over time. It provides an average of blood sugar levels over the past two to three months, helping in the management of diabetes.

The other options are incorrect:

• Tuberculosis: HbA1c test is not typically performed for tuberculosis. It is primarily used for monitoring diabetes.
• Arthritis: HbA1c test is not typically performed for arthritis. It is primarily used for monitoring diabetes.
• Anaemia: HbA1c test is not typically performed for anemia. It is primarily used for monitoring diabetes.

Answer: Protein

Amino acids are the building blocks of proteins. Proteins are macromolecules composed of long chains of amino acids linked together by peptide bonds.

The other options are incorrect:

• Carbohydrate: Carbohydrates are composed of monosaccharides, not amino acids.
• Lipid: Lipids are composed of fatty acids and glycerol, not amino acids.
• Nucleic Acid: Nucleic acids, such as DNA and RNA, are composed of nucleotides, not amino acids.

Answer: All Options

All the mentioned clotting factors, II (prothrombin), VII, IX, and X, are dependent on vitamin K for their synthesis. Vitamin K plays a crucial role in the post-translational modification of these clotting factors, allowing them to function effectively in the coagulation cascade.

Answer: Heparin

Heparin is not a calcium chelator. It works as an anticoagulant by binding to antithrombin III, thereby accelerating its inhibition of thrombin and other clotting factors. It does not directly chelate calcium ions.

The other options are incorrect:

• EDTA: EDTA (ethylenediaminetetraacetic acid) is a calcium chelator commonly used as an anticoagulant in blood collection tubes. It prevents blood clotting by chelating calcium ions necessary for the coagulation cascade.
• Oxalate: Oxalate is another calcium chelator used as an anticoagulant in blood collection tubes. It forms insoluble calcium oxalate complexes, preventing the clotting process.
• Citrate: Citrate is a calcium chelator used as an anticoagulant in blood collection tubes, particularly for coagulation studies. It works by binding to calcium ions, thereby inhibiting the coagulation cascade.
• A

Answer: Glycogen

Glycogen serves as the primary carbohydrate reserve in the human body. It is a polysaccharide composed of glucose molecules and is stored mainly in the liver and muscles.

The other options are incorrect:

• Glucose: Glucose is a monosaccharide and serves as an immediate energy source in the body. It is not stored in large quantities as a reserve.
• Starch: Starch is a polysaccharide found in plants and is a major dietary source of carbohydrates for humans. It is not stored as a reserve in the human body.
• Lactose: Lactose is a disaccharide found in milk and dairy products. It is not stored as a reserve in the human body.

Answer: Liver

Bile is primarily secreted by the liver. It is then stored and concentrated in the gallbladder before being released into the small intestine to aid in the digestion and absorption of fats.

The other options are incorrect:

• Gall Bladder: The gallbladder stores and concentrates bile produced by the liver but does not secrete bile itself.
• Pancreas: The pancreas secretes digestive enzymes such as amylase, lipase, and proteases into the small intestine, but it does not secrete bile.
• Salivary Gland: Salivary glands secrete saliva, which contains enzymes such as amylase to initiate the digestion of carbohydrates in the mouth. They are not involved in bile secretion.

Answer: Centrifuge

A centrifuge is used for the separation of liquid from solid sediments through the process of centrifugation. It spins samples at high speeds, creating centrifugal force, which causes denser particles to settle at the bottom of the tube, separating them from the liquid component.

The other options are incorrect:

• Autoclave: An autoclave is a device used for sterilization at high pressure and temperature, not for separating mixtures.
• Analytical Balance: An analytical balance is a very precise instrument used for measuring mass accurately. It’s not designed for separation purposes.
• Microtome: A microtome is a specialized instrument used to create thin slices of biological tissue for microscopic examination. It’s not used for separating liquids and solids.

Answer: Azospermia

Azospermia refers to the absence of spermatozoa in the semen. It can be classified as either obstructive azoospermia, where there is a blockage preventing sperm from reaching the semen, or non-obstructive azoospermia, where there is a problem with sperm production.

The other options are incorrect:

• Oligospermia: Oligospermia refers to a low sperm count in the semen, but sperm are still present.
• Hypospermia: Hypospermia refers to a decreased volume of semen, but sperm may still be present.
• Hyperspermia: Hyperspermia refers to an increased volume of semen, but sperm may still be present.

Answer: Ascorbic Acid

Ascorbic acid is the scientific name for vitamin C. It’s an organic compound with antioxidant properties and plays a crucial role in human health.

The other options are incorrect:

• Retinol: This is the chemical name for vitamin A, another essential nutrient but with different functions than vitamin C.
• Folic Acid: This is vitamin B9, important for cell division and growth.
• Riboflavin: This is vitamin B2, which helps convert food into energy.

Answer: Bile Pigment

Fouchet’s Reagent is a specific test used to detect the presence of bile pigments, particularly bilirubin, in urine. Bile pigments are waste products from the breakdown of red blood cells by the liver.

The other options are incorrect:

• Sugar: Tests like Benedict’s reagent or dipsticks are commonly used for detecting sugar (glucose) in urine.
• Keton Body: Tests like Rothera’s test or nitroprusside tablets are used to identify ketone bodies in urine.
• Protein: Heat Coagulation Test, Sulfosalicylic Acid Test, or Heller’s Nitric Acid Test are some methods for detecting protein in urine.

Answer: All of above

A colorimeter is a scientific instrument that measures the amount of light absorbed by a colored solution. The principle behind its operation relies on two key laws:

• Beer’s Law: This law states that the concentration of a colored compound in a solution is directly proportional to the amount of light it absorbs.
• Lambert’s Law: This law states that the intensity of light passing through a medium decreases exponentially with the thickness of the medium.

Answer: Hay’s Test

Hay’s Test is a simple and qualitative test used to detect the presence of bile salts in urine. It relies on the ability of bile salts to lower the surface tension of liquids. When sulfur powder is sprinkled on the surface of urine, it will typically float due to surface tension. However, if bile salts are present, they reduce the surface tension, causing the sulfur powder to sink.

The other options are incorrect:

• Rothera’s Test: This test is specifically designed to detect ketone bodies in urine, not bile salts.
• Benedict’s Method: This method is used to detect the presence of reducing sugars like glucose in urine, not bile salts.
• Biuret Method: This test is used to detect the presence of proteins in a sample, not bile salts. It relies on the reaction between peptide bonds in proteins and copper sulfate solution to produce a characteristic color change.

Answer: Catabolism

Catabolism is the set of metabolic processes that break down large molecules into smaller, simpler ones. This breakdown releases energy that cells can use to power various functions.

The other options are incorrect:

• Anabolism: This is the opposite of catabolism. It refers to the building up of complex molecules from smaller units, requiring energy input.
• Destruction: This is a more general term that doesn’t necessarily involve a specific metabolic pathway.
• Cutting: This is too vague and doesn’t capture the essence of controlled breakdown and energy release in catabolism.

Answer: Green

In standard blood collection practice, the color code for heparin is green. Tubes containing heparin are anticoagulants, used to prevent blood from clotting during sample collection for various tests.

The other options are incorrect:

• Yellow: Yellow tubes typically contain sodium citrate, another anticoagulant used for specific coagulation testing.
• Black: Black tubes are less common but may contain specific additives for blood cultures or other specialized tests.
• Red: Red tubes are serum separator tubes containing no additives and are used to collect blood samples that will clot and allow separation of serum for various chemistry tests.

Answer: Volumetric flask

A volumetric flask is the most appropriate glassware for preparing a precise volume (in this case, 100 mL) of a solution. It has a clearly defined marking at the neck that indicates the exact volume it can hold.

The other options are incorrect:

• Beaker: Beakers are cylindrical containers commonly used for mixing, holding, and heating solutions. While they have volume markings, they are not as accurate as volumetric flasks for precise measurements.
• Erlenmeyer flask: Erlenmeyer flasks are conical flasks used for various purposes like titrations or holding solutions during reactions. They don’t have a specific volume marking for precise measurement.
• Graduated cylinder: Graduated cylinders are used for measuring the volume of liquids. However, they are not ideal for preparing a specific final volume due to their wider opening, leading to potential pouring losses.

Answer: solute

In a solution, the substance that is dissolved is called the solute. Here, potassium oxalate is the solid being dissolved in the distilled water (the solvent) to form a new mixture.

The other options are incorrect:

• Solvent: Distilled water is the liquid that dissolves the potassium oxalate. It provides the medium for the solute particles to disperse.
• Reagent: Reagent is a more general term for any substance used in a chemical reaction. Potassium oxalate can be a reagent if it’s involved in a chemical reaction, but in this specific context, it’s the solute being dissolved.
• Solution: The solution is the final mixture formed by dissolving the potassium oxalate in distilled water. It refers to the entire combined mixture after dissolving.

Answer: serum

Serum is the liquid portion of blood remaining after a clot has formed. During clotting, fibrinogen, a protein in plasma, gets converted into fibrin fibers which form the clot. Other blood cells like red blood cells and white blood cells get trapped in the fibrin mesh. Serum lacks fibrinogen and some clotting factors compared to plasma.

The other options are incorrect:

• Buffy Coat: The buffy coat is a thin, white layer visible in centrifuged blood between the red blood cells (bottom) and plasma (top). It primarily consists of white blood cells and platelets.
• Plasma: Plasma is the liquid portion of whole blood that contains various dissolved components like proteins, electrolytes, nutrients, and waste products. It also includes clotting factors like fibrinogen. However, unlike serum, plasma contains all these components before clotting.
• Lymph: Lymph is a fluid that transports waste products, fluids, and immune cells throughout the body. It’s a clear liquid distinct from blood and doesn’t contain red blood cells.

Answer: clotting factors

Serum is separated from whole blood after clotting. During clotting, several proteins in plasma, including clotting factors, are consumed and become part of the clot. Therefore, serum lacks the clotting factors present in whole blood or plasma, making tests for clotting factors unsuitable for serum samples.

The other options are incorrect:

• Iron: Iron tests can be performed on serum samples to assess iron levels in the blood.
• Vitamin B12: Vitamin B12 tests can also be done on serum samples to measure vitamin B12 levels.
• Total Lipids: Total lipid tests can be performed on serum samples to analyze the overall fat content in the blood.

Answer: mmol/L

The standard unit for reporting blood glucose results is millimoles per liter (mmol/L). This unit reflects the concentration of glucose molecules in the blood volume.

The other options are incorrect:

• g/mmol: This unit conversion wouldn’t be commonly used for reporting blood glucose. It expresses grams of glucose per millimole, which is less common in clinical settings.
• g/L: While grams per liter (g/L) can be used for concentration, mmol/L is the preferred unit for blood glucose due to its alignment with international standards and easier interpretation of millimole values for electrolytes and other analytes.
• g/mL: Grams per milliliter (g/mL) is less common for reporting blood glucose concentrations. Milliliters (mL) represent a smaller volume unit compared to liters (L), making mmol/L more practical for expressing concentration in blood.

Answer: Vitamin B

Vitamin B (including all B vitamins such as B1, B2, B3, B5, B6, B7, B9, and B12) are water-soluble vitamins, not fat-soluble. They dissolve in water and are not stored in the body to the same extent as fat-soluble vitamins.

The other options are incorrect:

• Vitamin A is a fat-soluble vitamin that plays a critical role in vision, immune function, and cell growth.
• Vitamin D: Vitamin D is a fat-soluble vitamin that helps regulate calcium and phosphate levels in the body, crucial for bone health.
• Vitamin E: mVitamin E is a fat-soluble antioxidant that protects cells from damage caused by free radicals and plays a role in immune function.