5551 to 5600 MCQs for Lab Technician and Technologist Exam Preparation
5000 Plus MCQs for Lab Technician and Technologists are designed to test the knowledge and proficiency of laboratory professionals who work in the field of clinical laboratory science. These questions cover a wide range of topics related to laboratory science, including anatomy, physiology, microbiology, chemistry, and hematology.
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Questions 5551 to 5600
Lymphocytes are responsible for the formation of
- a) Serum
- b) Plasma
- c) Antibody
- d) Calcium
Explanation:
Lymphocytes (a type of white blood cell) play a crucial role in the immune system by producing antibodies to fight against antigens like bacteria, viruses, and toxins.
Why other options are incorrect:
Why other options are incorrect:
- • Serum: This is the liquid component of blood after clotting factors have been removed.
- • Plasma: This is the liquid matrix of blood, primarily composed of water, proteins, and salts.
- • Calcium: This is a mineral stored in bones and teeth; it is not produced by lymphocytes.
Platelets contain an enzyme which has important role in clotting in blood. This enzyme is known as
- a) Cholinesterase
- b) Transaminase
- c) Decarboxylase
- d) Thrombokinase
Explanation:
Thrombokinase (also known as thromboplastin or factor Xa) is an enzyme released by platelets that converts prothrombin into thrombin, which is essential for blood coagulation.
Why other options are incorrect:
Why other options are incorrect:
- • Cholinesterase: An enzyme that breaks down neurotransmitters like acetylcholine.
- • Transaminase: An enzyme that catalyzes the transfer of an amino group from an amino acid to a keto acid.
- • Decarboxylase: An enzyme that catalyzes the removal of a carboxyl group from organic compounds.
Treatment of pentoses with a concentrated mineral acid yields a cyclic aldehyde known as
- a) Pentaldehyde
- b) Cyclopental
- c) Hexaldehyde
- d) Furfural
Explanation:
When pentoses (five-carbon sugars) are heated with concentrated mineral acids (like HCl), they undergo dehydration to form a cyclic aldehyde called furfural (furan-2-carboxaldehyde).
Why other options are incorrect:
Why other options are incorrect:
- • Pentaldehyde: A general term for a five-carbon aldehyde, but not the specific cyclic product of this reaction.
- • Cyclopental: This is not the standard chemical name for the product formed in this dehydration process.
- • Hexaldehyde: This is a six-carbon chain aldehyde, derived from hexoses rather than pentoses.
Isoelectric pH is that pH at which protein is electrically:
- a) Neutral
- b) Anionic
- c) Cationic
- d) None of these
Explanation:
The isoelectric point (pI) is the pH at which a protein carries no net electrical charge. At this pH, the number of positive charges equals the number of negative charges, making the molecule electrically neutral.
Why other options are incorrect:
Why other options are incorrect:
- • Anionic: This occurs when the pH is above the isoelectric point, giving the protein a net negative charge.
- • Cationic: This occurs when the pH is below the isoelectric point, giving the protein a net positive charge.
- • None of these: Since “Neutral” is the correct physical state of a protein at its isoelectric pH, this option is incorrect.
About 6.25 g of haemoglobin is produced and destroyed in the body each day and the total amount of haemoglobin in a normal healthy 70 kg weighing male adult is
- a) 250 g
- b) 150 g
- c) 100 g
- d) 70 g
Explanation:
In a healthy adult male, the total body haemoglobin content is approximately 150 grams. Since the average lifespan of a red blood cell is about 120 days, roughly 1/120th of this amount is turned over daily (approx 6.25g).
Why other options are incorrect:
Why other options are incorrect:
- • 250 g: This is significantly higher than the standard physiological range for an average adult.
- • 100 g: This amount is generally too low and would likely indicate a state of clinical anaemia.
- • 70 g: This is far below the normal range, as 70 kg refers to the body weight, not the haemoglobin content.
Pancreatic juice contains all of the following except
- a) Trypsinogen
- b) Lipase
- c) Cholecystokinin
- d) Chymotrypsinogen
Explanation:
Cholecystokinin (CCK) is a hormone produced by the cells of the duodenum (small intestine), not a digestive enzyme secreted in the pancreatic juice. It acts to stimulate the pancreas to release its juices.
Why other options are incorrect:
Why other options are incorrect:
- • Trypsinogen: A proenzyme secreted by the pancreas that is activated into trypsin to digest proteins.
- • Lipase: An enzyme secreted by the pancreas to break down dietary fats.
- • Chymotrypsinogen: A pancreatic zymogen that is converted to active chymotrypsin to digest proteins.
The milk protein in the stomach in an adult is digested by
- a) Pepsin
- b) Rennin
- c) HCl
- d) Chymotrypsinogen
Explanation:
In adults, milk protein (casein) is digested by the enzyme Pepsin in the presence of stomach acid. While “Rennin” (chymosin) is responsible for curdling milk in infants, it is largely absent or inactive in the adult human stomach.
Why other options are incorrect:
Why other options are incorrect:
- • Rennin: This enzyme is specific to the stomachs of young mammals (infants) and is not functional in adults.
- • HCl: Hydrochloric acid provides the acidic environment for digestion, but it is not an enzyme and does not digest protein itself.
- • Chymotrypsinogen: This is a pancreatic zymogen, which functions in the small intestine, not the stomach.
Carboxypeptidase, an enzyme of pancreatic juice, contains
- a) Mn
- b) Zinc
- c) Magnesium
- d) Manganese
Explanation:
Carboxypeptidase is a metalloenzyme that contains a zinc (Zn²⁺) ion in its active site. This metal ion is essential for the catalytic activity of the enzyme, which acts by cleaving amino acids from the carboxyl terminus of proteins.
Why other options are incorrect:
Why other options are incorrect:
- • Mn/Manganese: While manganese is a cofactor for some enzymes, it is not the metal cofactor for carboxypeptidase.
- • Magnesium: Magnesium is commonly associated with enzymes involved in ATP reactions (kinases), but it is not the structural metal in carboxypeptidase.
The zymogen from trypsinogen of pancreatic juice is converted to active trypsin by
- a) Pepsin
- b) Enterocrinin
- c) Enterokinase
- d) Rennin
Explanation:
Trypsinogen is an inactive zymogen secreted by the pancreas. It is activated into trypsin in the duodenum by the enzyme enterokinase (also known as enteropeptidase), which is produced by the intestinal mucosa.
Why other options are incorrect:
Why other options are incorrect:
- • Pepsin: A gastric enzyme responsible for protein digestion in the stomach, not for activating pancreatic enzymes.
- • Enterocrinin: A hormone that stimulates the secretion of intestinal juice, not an enzyme that activates zymogens.
- • Rennin: A milk-coagulating enzyme found in the stomachs of young mammals.
Inactive zymogens are precursors of all the following gastrointestinal enzymes except
- a) Carboxypeptidase
- b) Pepsin
- c) Amino peptidase
- d) Chymotrypsin
Explanation:
Aminopeptidase is an intestinal brush-border enzyme that is typically already in its active form when associated with the intestinal membrane, whereas Carboxypeptidase (from procarboxypeptidase), Pepsin (from pepsinogen), and Chymotrypsin (from chymotrypsinogen) are all synthesized and secreted as inactive zymogens.
Why other options are incorrect:
Why other options are incorrect:
- • Carboxypeptidase: Secreted as procarboxypeptidase.
- • Pepsin: Secreted as pepsinogen by the gastric chief cells.
- • Chymotrypsin: Secreted as chymotrypsinogen by the pancreas.
Rennin acts on casein of milk in infants in presence of
- a) Mg++
- b) Zn++
- c) Co++
- d) Ca++
Explanation:
Rennin (chymosin) converts the soluble milk protein casein into insoluble paracasein. This coagulation process requires the presence of calcium ions (Ca++), which form calcium paracaseinate, effectively curdling the milk to slow its passage through the infant’s digestive system.
Why other options are incorrect:
Why other options are incorrect:
- • Mg++: Magnesium is essential for many enzymatic reactions (especially those involving ATP), but it is not the cofactor for rennin-mediated milk curdling.
- • Zn++ / Co++: These are trace elements required for various other enzymatic processes but play no direct role in the conversion of casein by rennin.
All the following are true about phenylketonuria except
- a) Deficiency of phenylalanine hydroxylase
- b) Mental retardation
- c) Increased urinary excretion of p-hydroxyphenyl pyruvic acid
- d) Decrease serotonin formation
Explanation:
In phenylketonuria (PKU), the primary defect is a deficiency of phenylalanine hydroxylase, leading to the accumulation of phenylalanine and its derivatives (like phenylpyruvate). The excretion of p-hydroxyphenyl pyruvic acid is associated with Tyrosinemia, not PKU.
Why other options are correct features of PKU:
Why other options are correct features of PKU:
- • Deficiency of phenylalanine hydroxylase: This is the hallmark enzymatic defect of PKU.
- • Mental retardation: If left untreated, high levels of phenylalanine are neurotoxic, causing significant cognitive impairment.
- • Decrease serotonin formation: High levels of phenylalanine competitively inhibit the transport of tryptophan (the precursor of serotonin) into the brain, reducing serotonin synthesis.
Which of the amino acid produces a vasodilator on decarboxylation?
- a) Glutamic acid
- b) Histidine
- c) Ornithine
- d) Cysteine
Explanation:
The decarboxylation of the amino acid Histidine produces Histamine. Histamine is a powerful vasodilator that plays a significant role in inflammatory responses and the regulation of gastric acid secretion.
Why other options are incorrect:
Why other options are incorrect:
- • Glutamic acid: Decarboxylation produces GABA (gamma-aminobutyric acid), which acts as a neurotransmitter.
- • Ornithine: Decarboxylation produces Putrescine, a polyamine involved in cell division.
- • Cysteine: Decarboxylation leads to the formation of Cysteamine, which is a component of Coenzyme A.
Neutral amino acid is
- a) Leucine
- b) Lysine
- c) Aspartic acid
- d) Histidine
Explanation:
Leucine is a neutral amino acid because its side chain (R-group) is non-polar and hydrophobic, containing no acidic or basic functional groups that would ionize at physiological pH.
Why other options are incorrect:
Why other options are incorrect:
- • Lysine: A basic amino acid due to the presence of an extra amino group in its side chain.
- • Aspartic acid: An acidic amino acid due to the presence of an extra carboxyl group in its side chain.
- • Histidine: A basic amino acid due to the imidazole ring in its side chain, which can act as a proton acceptor.
The amino acid containing hydroxy group:
- a) Glycine
- b) Isoleucine
- c) Arginine
- d) Threonine
Explanation:
Threonine (along with Serine and Tyrosine) is a hydroxylated amino acid. It contains a hydroxyl (-OH) group on its side chain, which makes it polar and capable of participating in hydrogen bonding and phosphorylation.
Why other options are incorrect:
Why other options are incorrect:
- • Glycine: The simplest amino acid with a hydrogen atom as its side chain.
- • Isoleucine: A branched-chain, non-polar, hydrophobic amino acid.
- • Arginine: A basic amino acid containing a guanidino group in its side chain.
The amino acid which synthesizes many hormones:
- a) Valine
- b) Phenylalanine
- c) Alanine
- d) Histidine
Explanation:
Phenylalanine is a precursor for the synthesis of tyrosine, which in turn is the starting material for several important hormones and neurotransmitters, including thyroxine (thyroid hormone) and the catecholamines (dopamine, norepinephrine, and epinephrine).
Why other options are incorrect:
Why other options are incorrect:
- • Valine: A branched-chain amino acid primarily used for protein synthesis and energy production.
- • Alanine: Primarily involved in the glucose-alanine cycle and nitrogen transport.
- • Histidine: Primarily used to synthesize histamine, which acts as a signaling molecule but is not classified as a hormone in the same biosynthetic category as catecholamines or thyroid hormones.
Insulin degradation of disulfide bond formation is effected by
- a) Pyruvate dehydrogenase
- b) Xylitol reductase
- c) Glutathione reductase
- d) Xanthine oxidase
Explanation:
Insulin contains two peptide chains linked by disulfide bonds. The enzyme “glutathione-insulin transhydrogenase” (often involving the action of Glutathione reductase) is responsible for the reductive cleavage (degradation) of these disulfide bonds, which is a key step in the catabolism and inactivation of the insulin hormone in the liver and kidneys.
Why other options are incorrect:
Why other options are incorrect:
- • Pyruvate dehydrogenase: Involved in the conversion of pyruvate to acetyl-CoA in cellular respiration.
- • Xylitol reductase: Involved in the polyol pathway of carbohydrate metabolism.
- • Xanthine oxidase: An enzyme involved in purine metabolism, catalyzing the oxidation of hypoxanthine to xanthine and then to uric acid.
A protein reacts with biuret reagent which indicates 2 or more
- a) Blood clotting
- b) Peptide bond
- c) Disulphide bonds
- d) Hydrophobic bonds
Explanation:
The Biuret test is a chemical test used to detect the presence of peptide bonds. The copper(II) ions in the Biuret reagent form a violet-colored complex with substances containing two or more peptide bonds, making it an excellent indicator for proteins and peptides.
Why other options are incorrect:
Why other options are incorrect:
- • Blood clotting: This is a physiological process, not a chemical structure detected by colorimetric reagents.
- • Disulphide bonds: These are covalent bonds between sulfur atoms (cysteine residues) and are not detected by the Biuret test.
- • Hydrophobic bonds: These are weak interactions between non-polar side chains, not the target of the Biuret reagent.
In many proteins the hydrogen bonding produces a regular coiled arrangement which is called as
- a) β-Helix
- b) α-Helix
- c) Both (β-Helix) and (α-Helix)
- d) Spiral
Explanation:
The α-helix is the most common secondary structure in proteins, characterized by a regular coiled arrangement maintained by hydrogen bonding between the carbonyl oxygen and the amide hydrogen of the polypeptide backbone.
Why other options are incorrect:
Why other options are incorrect:
- • β-Helix: This is a very rare structural motif in proteins; the common secondary structure involving beta sheets is the “beta-pleated sheet,” not a helix.
- • Spiral: While the α-helix appears spiral-like, “α-helix” is the specific scientific term used in biochemistry to describe this regular coiled arrangement.
The milk protein in the stomach of the infants is digested by
- a) Pepsin
- b) Trypsin
- c) Chymotrypsin
- d) Rennin
Explanation:
Rennin (also known as chymosin) is a proteolytic enzyme found specifically in the gastric juice of infants. It acts on the milk protein casein, converting it into insoluble paracasein (curdling), which allows the protein to remain in the stomach longer for efficient digestion by pepsin.
Why other options are incorrect:
Why other options are incorrect:
- • Pepsin: While pepsin also digests protein, it is not the specialized enzyme responsible for the initial curdling of milk in infants.
- • Trypsin & Chymotrypsin: These are pancreatic enzymes that function in the small intestine, not the stomach.
Protein anabolism is stimulated by
- a) ACTH
- b) Testosterone
- c) Glucagon
- d) Epinephrine
Explanation:
Testosterone is a well-known anabolic steroid hormone. It promotes protein synthesis (anabolism) in muscle and bone tissue, leading to increased muscle mass and strength, which is why it is classified as an anabolic hormone.
Why other options are incorrect:
Why other options are incorrect:
- • ACTH: Adrenocorticotropic hormone stimulates the adrenal cortex to release cortisol, which is generally catabolic (promoting protein breakdown).
- • Glucagon: A catabolic hormone that promotes glycogenolysis and gluconeogenesis, often leading to protein breakdown for energy.
- • Epinephrine: Primarily involved in the “fight or flight” response, promoting catabolic processes to mobilize energy quickly.
The number of helices present in a collagen molecule is
- a) 1
- b) 2
- c) 3
- d) 4
Explanation:
The fundamental unit of collagen is the tropocollagen molecule, which consists of three polypeptide chains (alpha chains) wound around each other to form a stable triple-helical structure.
Why other options are incorrect:
Why other options are incorrect:
- • 1: A single helix would not provide the structural stability or tensile strength required for connective tissues.
- • 2: A double helix structure is characteristic of DNA, not the collagen protein molecule.
- • 4: There is no biological structure in the collagen molecule composed of four helices.
Which bond is present in the primary structure of protein?
- a) Ester
- b) Hydrogen
- c) Ionic bond
- d) Peptide
Explanation:
The primary structure of a protein refers to the linear sequence of amino acids in the polypeptide chain. These amino acids are covalently linked to one another by peptide bonds formed between the carboxyl group of one amino acid and the amino group of the next.
Why other options are incorrect:
Why other options are incorrect:
- • Ester: These are generally found in lipids or nucleic acids, not as the backbone linkage of proteins.
- • Hydrogen: These are weak bonds responsible for secondary (alpha-helix, beta-sheets) and tertiary structures.
- • Ionic bond: These occur in the tertiary and quaternary structures due to interactions between charged side chains.
Sakaguchi reaction is specific for
- a) Guanidine group
- b) Phenolic group
- c) Carboxylic group
- d) None of these
Explanation:
The Sakaguchi reaction is a chemical test used for the detection of arginine. It specifically reacts with the guanidine group present in the side chain of arginine to produce a red-colored complex.
Why other options are incorrect:
Why other options are incorrect:
- • Phenolic group: This is typically detected by the Millon’s test (specific for Tyrosine).
- • Carboxylic group: These are common acidic groups and are not the target of the specific Sakaguchi test.
In protein structure the α-helix and β-pleated sheets are example of
- a) Primary structure
- b) Secondary structure
- c) Tertiary structure
- d) Quaternary structure
Explanation:
The secondary structure of a protein refers to the local spatial arrangement of the polypeptide backbone. The α-helix and β-pleated sheets are the two most common types of regular secondary structures, both stabilized by hydrogen bonding between atoms of the peptide backbone.
Why other options are incorrect:
Why other options are incorrect:
- • Primary structure: This refers solely to the linear amino acid sequence held by peptide bonds.
- • Tertiary structure: This refers to the overall three-dimensional folding of the entire polypeptide chain.
- • Quaternary structure: This refers to the arrangement and interaction of multiple polypeptide subunits in a multi-subunit protein.
An essential amino acid in man is
- a) Proline
- b) Threonine
- c) Asparagine
- d) Tyrosine
Explanation:
Threonine is an essential amino acid, meaning it cannot be synthesized by the human body and must be obtained through dietary sources.
Why other options are incorrect:
Why other options are incorrect:
- • Proline: A non-essential amino acid that the body can synthesize on its own.
- • Asparagine: A non-essential amino acid synthesized from oxaloacetate.
- • Tyrosine: A semi-essential amino acid that can be synthesized in the body from the essential amino acid phenylalanine.
An amino acid that does not form an α-helix is
- a) Asparagine
- b) Tyrosine
- c) Tryptophan
- d) Proline
Explanation:
Proline is known as a “helix breaker” because its cyclic structure introduces a kink in the peptide chain and lacks the amide hydrogen necessary for hydrogen bonding, which is essential to stabilize the α-helix.
Why other options are incorrect:
Why other options are incorrect:
- • Asparagine: Can be found within α-helices, although it is sometimes considered a helix destabilizer.
- • Tyrosine: Possesses an aromatic side chain and can be incorporated into α-helical structures.
- • Tryptophan: Despite its bulky indole side chain, it is commonly found within α-helical segments of proteins.
The protein present in hair is
- a) Elastin
- b) Prolamine
- c) Keratin
- d) Gliadin
Explanation:
Keratin is a fibrous structural protein that serves as the key structural material making up the outer layer of human skin, hair, and nails.
Why other options are incorrect:
Why other options are incorrect:
- • Elastin: A protein in connective tissue that allows tissues in the body to resume their shape after stretching.
- • Prolamine: A group of plant storage proteins having a high proline content.
- • Gliadin: A class of proteins present in wheat and several other cereals within the genus Triticum.
Plasma protein can be separated by
- a) Salting out with (NH4)2SO4
- b) Ultracentrifugation
- c) Immuno electrophoresis
- d) All of these
Explanation:
Plasma proteins are a diverse group of molecules and can be separated using various biochemical techniques:
(NH4)2SO4 precipitation (salting out) relies on solubility, ultracentrifugation relies on molecular mass and density, and immuno-electrophoresis relies on electrical charge and specific antibody binding.
Why other options are correct:
Why other options are correct:
- • Salting out: A classic method to fractionate proteins based on their differential solubility in high salt concentrations.
- • Ultracentrifugation: Uses high-speed centrifugal force to separate proteins based on sedimentation coefficients.
- • Immuno electrophoresis: Combines electrophoresis with immunodiffusion to identify specific proteins based on their charge and immunological properties.
RNA does not contain
- a) Uracil
- b) Adenine
- c) Hydroxy methyl cytosine
- d) Phosphate
Explanation:
RNA typically consists of the bases Adenine, Guanine, Cytosine, and Uracil, held together by a phosphate-ribose backbone. Hydroxy methyl cytosine is not a standard base found in RNA; it is a modified base often associated with DNA (epigenetics) or specific viral genomes.
Why other options are incorrect:
Why other options are incorrect:
- • Uracil: A characteristic pyrimidine base found in RNA, replacing Thymine.
- • Adenine: A fundamental purine base present in both RNA and DNA.
- • Phosphate: The essential component of the sugar-phosphate backbone of the RNA chain.
In mammalian cells, ribosomal RNA is produced mainly in the
- a) Nucleus
- b) Nucleolus
- c) Ribosome
- d) Golgi apparatus
Explanation:
The nucleolus is a distinct, membrane-less sub-structure within the nucleus specifically dedicated to the synthesis of ribosomal RNA (rRNA) and the assembly of ribosomal subunits.
Why other options are incorrect:
Why other options are incorrect:
- • Nucleus: While rRNA is synthesized inside the nucleus, the nucleolus is the specific site where this activity is concentrated.
- • Ribosome: This is where protein synthesis occurs, not where the rRNA component itself is manufactured.
- • Golgi apparatus: This organelle is responsible for modifying, sorting, and packaging proteins, not for rRNA synthesis.
Which co-enzyme is not involved in oxidative decarboxylation of pyruvic acid?
- a) TPP
- b) Mg++
- c) Biotin
- d) CoA-SH
Explanation:
The conversion of pyruvate to Acetyl-CoA is catalyzed by the Pyruvate Dehydrogenase Complex, which requires five cofactors: TPP, Lipoate, Coenzyme A (CoA-SH), FAD, and NAD+. Biotin is not involved in this specific reaction; it is a coenzyme for carboxylase enzymes (e.g., Pyruvate Carboxylase).
Why other options are incorrect:
Why other options are incorrect:
- • TPP: Thiamine pyrophosphate is essential for the decarboxylation step.
- • Mg++: Acts as a necessary metallic cofactor for the enzymatic process.
- • CoA-SH: Coenzyme A is the acceptor of the acetyl group to form Acetyl-CoA.
A polymeric unit of starch which has a branched structure is
- a) Glucose
- b) Amylopectin
- c) Isomaltose
- d) Amylose
Explanation:
Starch is composed of two polysaccharides: amylose and amylopectin. Amylose is a linear chain, while amylopectin is a highly branched polymer consisting of glucose units linked by α-1,4-glycosidic bonds with α-1,6-glycosidic branches.
Why other options are incorrect:
Why other options are incorrect:
- • Glucose: This is the monomeric sugar unit, not a polymer.
- • Isomaltose: A disaccharide formed by the hydrolysis of amylopectin; it contains the α-1,6-linkage found at branch points.
- • Amylose: This is the other component of starch, which exists as an unbranched, helical chain.
The repeating unit in hyaluronic acid is
- a) Glucuronic acid and Galactosamine
- b) Glucuronic acid and Glucosamine
- c) Glucuronic acid and N-acetyl glucosamine
- d) Glucuronic acid and N-acetyl galactosamine
Explanation:
Hyaluronic acid is a non-sulfated glycosaminoglycan. Its structure consists of a repeating disaccharide unit composed of D-glucuronic acid and N-acetyl-D-glucosamine, linked via alternating β-1,4 and β-1,3 glycosidic bonds.
Why other options are incorrect:
Why other options are incorrect:
- • a & d: These combinations are typically found in other glycosaminoglycans like Chondroitin sulfate, which contains N-acetyl galactosamine.
- • b: While it contains the right sugar types, it lacks the acetyl group that is chemically essential to the actual structure of hyaluronic acid.
The repeating disaccharide unit in cellulose is
- a) Sucrose
- b) Maltose
- c) Dextrose
- d) Cellobiose
Explanation:
Cellulose is a linear polysaccharide of glucose residues. The repeating disaccharide unit within this chain is cellobiose, which consists of two glucose molecules linked by a β-1,4-glycosidic bond.
Why other options are incorrect:
Why other options are incorrect:
- • Sucrose: A disaccharide made of glucose and fructose; it is not a part of cellulose.
- • Maltose: A disaccharide of two glucose units linked by an α-1,4-glycosidic bond, which is found in starch, not cellulose.
- • Dextrose: This is simply another name for D-glucose, a monosaccharide.
An example of a hydroxy fatty acid is
- a) Ricinoleic acid
- b) Crotonic acid
- c) Butyric acid
- d) Oleic acid
Explanation:
Ricinoleic acid is an unsaturated omega-9 fatty acid that contains a hydroxyl group (-OH) at the 12th carbon position. It is the main component of castor oil.
Why other options are incorrect:
Why other options are incorrect:
- • Crotonic acid: An unsaturated short-chain carboxylic acid without a hydroxyl group.
- • Butyric acid: A saturated short-chain fatty acid (a simple alkanoic acid).
- • Oleic acid: A monounsaturated fatty acid that lacks the hydroxyl group found in hydroxy fatty acids.
An example of a saturated fatty acid is
- a) Palmitic acid
- b) Oleic acid
- c) Linoleic acid
- d) Erucic acid
Explanation:
Palmitic acid (hexadecanoic acid) is the most common saturated fatty acid found in animals, plants, and microorganisms. It contains no carbon-carbon double bonds in its chain.
Why other options are incorrect:
Why other options are incorrect:
- • Oleic acid: A monounsaturated fatty acid with one double bond.
- • Linoleic acid: A polyunsaturated fatty acid with two double bonds.
- • Erucic acid: A monounsaturated omega-9 fatty acid containing one double bond.
If the fatty acid is esterified with an alcohol of high molecular weight instead of glycerol, the resulting compound is
- a) Lipositol
- b) Plasmalogen
- c) Wax
- d) Cephalin
Explanation:
Waxes are esters of long-chain fatty acids with long-chain monohydroxy alcohols (high molecular weight alcohols). Unlike fats and oils, they do not contain glycerol.
Why other options are incorrect:
Why other options are incorrect:
- • Lipositol: A phospholipid containing inositol.
- • Plasmalogen: A type of phospholipid (ether lipid) found in cell membranes.
- • Cephalin: A phospholipid (phosphatidylethanolamine) found in biological membranes.
A fatty acid which is not synthesized in the body and has to be supplied in the diet is
- a) Palmitic acid
- b) Lauric acid
- c) Linolenic acid
- d) Palmitoleic acid
Explanation:
Linolenic acid (specifically alpha-linolenic acid) is an essential fatty acid. Humans lack the enzymes necessary to introduce double bonds at certain positions in the carbon chain (specifically beyond carbon 9), making it necessary to obtain these from dietary sources.
Why other options are incorrect:
Why other options are incorrect:
- • Palmitic acid: A common saturated fatty acid that the body can readily synthesize via fatty acid synthase.
- • Lauric acid: A medium-chain saturated fatty acid that can be synthesized by the body.
- • Palmitoleic acid: A monounsaturated fatty acid that the human body can synthesize from palmitic acid.
Essential fatty acid:
- a) Linoleic acid
- b) Linolenic acid
- c) Arachidonic acid
- d) All these
Explanation:
Linoleic acid and alpha-linolenic acid are essential fatty acids because the human body cannot synthesize them. Arachidonic acid is conditionally essential and may be required when its precursor, linoleic acid, cannot meet the body’s needs.
Why other options are incorrect:
Why other options are incorrect:
- • Linoleic acid: It is an essential fatty acid.
- • Linolenic acid: Alpha-linolenic acid is an essential fatty acid.
- • Arachidonic acid: It is generally considered conditionally essential rather than strictly essential.
The fatty acid present in cerebrosides is
- a) Lignoceric acid
- b) Valeric acid
- c) Caprylic acid
- d) Behenic acid
Explanation:
Cerebrosides are glycosphingolipids consisting of a ceramide backbone linked to a sugar. The fatty acids typically found in cerebrosides are long-chain fatty acids, with Lignoceric acid (a 24-carbon saturated fatty acid) being the most prominent.
Why other options are incorrect:
Why other options are incorrect:
- • Valeric acid: A short-chain (5-carbon) fatty acid not typically found in complex sphingolipids.
- • Caprylic acid: A medium-chain (8-carbon) fatty acid.
- • Behenic acid: While it is a long-chain fatty acid (22-carbon) found in some biological lipids, Lignoceric acid is the classic fatty acid associated with the structure of cerebrosides.
The number of double bonds in arachidonic acid is
- a) 1
- b) 2
- c) 4
- d) 6
Explanation:
Arachidonic acid is a 20-carbon polyunsaturated fatty acid (20:4), meaning it contains four carbon-carbon double bonds.
Why other options are incorrect:
Why other options are incorrect:
- • 1: Arachidonic acid contains more than one double bond.
- • 2: It contains four, not two, double bonds.
- • 6: Six double bonds are not present in arachidonic acid.
In humans, a dietary essential fatty acid is
- a) Palmitic acid
- b) Stearic acid
- c) Oleic acid
- d) Linoleic acid
Explanation:
Linoleic acid is a dietary essential fatty acid because humans lack the delta-12 desaturase enzyme required to introduce double bonds beyond the 9th carbon of the fatty acid chain. Therefore, it must be ingested through the diet.
Why other options are incorrect:
Why other options are incorrect:
- • Palmitic acid: A saturated fatty acid that is readily synthesized by the body.
- • Stearic acid: A common saturated fatty acid synthesized by the body.
- • Oleic acid: A non-essential monounsaturated fatty acid that the human body can synthesize.
A lipid containing alcoholic amine residue is
- a) Phosphatidic acid
- b) Ganglioside
- c) Glucocerebroside
- d) Sphingomyelin
Explanation:
Sphingomyelin is a phosphosphingolipid containing an alcoholic amine, usually phosphocholine, attached to the sphingosine backbone.
Why other options are incorrect:
Why other options are incorrect:
- • Phosphatidic acid: Contains glycerol, fatty acids and phosphate, but not an alcoholic amine residue.
- • Ganglioside: Contains complex carbohydrates and sialic acid residues rather than an alcoholic amine group.
- • Glucocerebroside: Contains glucose as its carbohydrate component and does not contain an alcoholic amine residue.
Cephalin consists of
- a) Glycerol, fatty acids, phosphoric acid and choline
- b) Glycerol, fatty acids, phosphoric acid and ethanolamine
- c) Glycerol, fatty acids, phosphoric acid and inositol
- d) Glycerol, fatty acids, phosphoric acid and serine
Explanation:
Cephalin (also known as phosphatidylethanolamine) is a phospholipid found in biological membranes. It is composed of a glycerol backbone, two fatty acid chains, a phosphate group, and the amino alcohol ethanolamine.
Why other options are incorrect:
Why other options are incorrect:
- • Choline: Phospholipids containing choline are called Lecithins (Phosphatidylcholine).
- • Inositol: Phospholipids containing inositol are called Phosphatidylinositol.
- • Serine: Phospholipids containing serine are called Phosphatidylserine.
In mammals, the major fat in adipose tissues is
- a) Phospholipid
- b) Cholesterol
- c) Sphingolipids
- d) Triacylglycerol
Explanation:
Triacylglycerols (also known as triglycerides) are the primary storage form of energy in mammals. They are stored in specialized cells called adipocytes, which make up adipose tissue.
Why other options are incorrect:
Why other options are incorrect:
- • Phospholipid: These are primarily structural components of cell membranes, not storage fats.
- • Cholesterol: This is a sterol important for membrane fluidity and hormone synthesis, not an energy storage lipid.
- • Sphingolipids: These are complex lipids mainly found in the myelin sheath and cell membranes; they do not serve as a primary energy reserve.
Glycosphingolipids are a combination of
- a) Ceramide with one or more sugar residues
- b) Glycerol with galactose
- c) Sphingosine with galactose
- d) Sphingosine with phosphoric acid
Explanation:
Glycosphingolipids consist of a ceramide unit (a sphingosine backbone linked to a fatty acid) with one or more sugar residues (such as glucose or galactose) attached to the primary hydroxyl group.
Why other options are incorrect:
Why other options are incorrect:
- • Glycerol with galactose: This does not describe a sphingolipid structure, as it lacks the sphingosine backbone.
- • Sphingosine with galactose: This is incomplete because a sphingolipid requires a fatty acid attached to the sphingosine (forming ceramide) before the sugar is added.
- • Sphingosine with phosphoric acid: This is a precursor to sphingomyelin, not a glycosphingolipid.
The importance of phospholipids as constituent of cell membrane is because they possess
- a) Fatty acids
- b) Both polar and nonpolar groups
- c) Glycerol
- d) Phosphoric acid
Explanation:
Phospholipids are amphipathic, meaning they possess both a hydrophilic (polar) head and hydrophobic (nonpolar) fatty acid tails. This property allows them to spontaneously form the lipid bilayer structure that acts as a barrier for cell membranes.
Why other options are incorrect:
Why other options are incorrect:
- • Fatty acids: While present, they only provide the hydrophobic portion and cannot form a bilayer alone.
- • Glycerol: This is simply the backbone structure for many lipids and does not provide the amphipathic property by itself.
- • Phosphoric acid: This contributes to the polar head, but it is the combination of the polar and nonpolar parts that makes the molecule essential for membrane structure.
In neutral fats, the unsaponificable matter includes
- a) Hydrocarbons
- b) Triacylglycerol
- c) Phospholipids
- d) Cholesterol
Explanation:
Unsaponifiable matter consists of lipid components that do not form soap when treated with alkali. Hydrocarbons are included in the unsaponifiable fraction of fats.
Why other options are incorrect:
Why other options are incorrect:
- • Triacylglycerol: This is a saponifiable lipid because it contains ester bonds that undergo hydrolysis with alkali.
- • Phospholipids: These contain ester bonds and are generally considered saponifiable lipids.
- • Cholesterol: Cholesterol is also unsaponifiable and can be present in the unsaponifiable fraction.
Higher alcohol present in waxes is
- a) Benzyl
- b) Methyl
- c) Ethyl
- d) Cetyl
Explanation:
Waxes are esters of long-chain fatty acids with long-chain monohydric alcohols (higher alcohols). Cetyl alcohol (a 16-carbon alcohol) is a very common constituent of many natural waxes, such as spermaceti wax.
Why other options are incorrect:
Why other options are incorrect:
- • Methyl and Ethyl: These are short-chain alcohols and do not form the high-molecular-weight esters that characterize natural waxes.
- • Benzyl: This is an aromatic alcohol and is not a standard component found in the structure of natural biological waxes.
Answer Key Summary
The questions are typically designed to assess the technical skills and knowledge required for the laboratory profession, including the ability to analyze laboratory test results, perform laboratory procedures, and maintain laboratory equipment.
To prepare for these MCQs, candidates should have a thorough understanding of the key concepts and principles of laboratory science. They should also be familiar with common laboratory equipment and procedures, as well as laboratory safety protocols.
Candidates may also benefit from studying specific laboratory science textbooks or taking online courses that cover the material tested in the MCQs. Additionally, practicing sample MCQs and reviewing the answers can help candidates identify areas where they may need to improve their knowledge or skills.
Overall, the MCQs for lab technologists are designed to be challenging and comprehensive, requiring candidates to demonstrate a high level of proficiency in the field of laboratory science.
📚 This article may have been prepared using trusted medical literature, clinical guidelines, textbooks, and peer-reviewed sources.
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