5701 to 5750 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 5701 to 5750
Creatinine EDTA clearance is a test to measure:
- a) Renal plasma flow
- b) Filtration fraction
- c) Glomerular filtration rate
- d) Tubular function
Explanation:
Creatinine clearance and substances like EDTA (often used as markers like Cr-EDTA) are standard clinical methods used to estimate the Glomerular Filtration Rate (GFR), which indicates how well the kidneys are filtering blood.
Why other options are incorrect:
Why other options are incorrect:
- • Renal plasma flow: Usually measured using clearance of Para-aminohippuric acid (PAH).
- • Filtration fraction: This is the ratio of GFR to renal plasma flow.
- • Tubular function: Measured by concentration and dilution tests or the excretion/reabsorption rates of specific electrolytes.
The normal PAH clearance for a surface area of 1.73 sqm. is:
- a) 200 ml/min
- b) 300 ml/min
- c) 400 ml/min
- d) 574 ml/min
Explanation:
Para-aminohippuric acid (PAH) clearance is used to measure Effective Renal Plasma Flow (ERPF). In a healthy adult with a standard body surface area of 1.73 m², the normal value is approximately 574 ml/min (often cited in the range of 550–650 ml/min).
Why other options are incorrect:
Why other options are incorrect:
- • 200 ml/min, 300 ml/min, and 400 ml/min: These values are significantly lower than the standard ERPF and would suggest a decrease in renal blood flow or pathological impairment.
Para amino hippurate is:
- a) Filtered at glomeruli and secreted by the tubules
- b) Filtered at glomeruli and not secreted by the tubules
- c) Filtered at glomeruli and reabsorbed completely
- d) Not removed completely during a single circulation of the blood through the kidney
Explanation:
Para-aminohippuric acid (PAH) is handled by the kidneys through both glomerular filtration and, more importantly, active tubular secretion. Because it is nearly completely cleared from the renal plasma in a single pass through the kidneys, it is the standard marker used to estimate Effective Renal Plasma Flow (ERPF).
Why other options are incorrect:
Why other options are incorrect:
- • Filtered and not secreted: This describes substances like Inulin, used to measure GFR.
- • Filtered and reabsorbed completely: This describes substances like Glucose in healthy individuals.
- • Not removed completely: PAH is highly extracted (about 90% extraction ratio), making it an excellent marker for plasma flow, effectively representing the total renal plasma flow.
The Tm for PAH i.e the maximal secretory capacity of the tubule for PAH can be used to gauge the:
- a) Extent of tubular damage
- b) Impairment of the capacity of the tubule to perform osmotic work
- c) Impairment of renal plasma flow
- d) Glomerular filtration rate
Explanation:
The Tubular maximum (Tm) for PAH represents the maximum rate at which the renal tubules can actively transport PAH from the blood into the urine. Because this process depends on the functional mass of the tubular cells, a reduction in the Tm for PAH serves as an index of the functional tubular mass and is used to estimate the extent of tubular damage.
Why other options are incorrect:
Why other options are incorrect:
- • Impairment of renal plasma flow: This is measured by the clearance of PAH at low plasma concentrations, not by its Tm.
- • Glomerular filtration rate: This is measured by substances like Inulin or Creatinine, not by tubular secretory capacity.
- • Osmotic work: This relates to the concentrating and diluting ability of the kidney (counter-current mechanism), not the secretory transport of PAH.
The normal Tm in mg/min/1.73 sqm for PAH is:
- a) 20
- b) 40
- c) 60
- d) 80
Explanation:
The normal value for the tubular maximal secretory capacity (Tm) for Para-aminohippuric acid (PAH) in a healthy adult with a body surface area of 1.73 m² is approximately 80 mg/min (typically reported in the range of 75–85 mg/min).
Why other options are incorrect:
Why other options are incorrect:
- • 20, 40, 60: These values are below the established physiological standard for human tubular secretory capacity of PAH and would indicate a significant loss of functional tubular mass.
The normal range of filtration fraction in an adult is:
- a) 0.10–0.15
- b) 0.16–0.21
- c) 0.25–0.30
- d) 0.35–0.40
Explanation:
The filtration fraction is the ratio of the Glomerular Filtration Rate (GFR) to the Renal Plasma Flow (RPF). Mathematically: Filtration Fraction = GFR / RPF. In a healthy adult, the GFR is approximately 125 ml/min and the RPF is approximately 600–700 ml/min, resulting in a normal filtration fraction of about 0.16 to 0.21 (or 16–21%).
Why other options are incorrect:
Why other options are incorrect:
- • 0.10–0.15: This represents a low filtration fraction, which can occur in certain renal diseases or low-flow states.
- • 0.25–0.40: These represent high filtration fractions, often seen in conditions like renal artery stenosis or volume depletion where RPF decreases more significantly than GFR.
The filtration factor tends to be normal in:
- a) Early essential hypertension
- b) Malignant phase of hypertension
- c) Glomerulonephritis
- d) Acute nephritis
Explanation:
In early essential hypertension, the renal blood flow and glomerular filtration rate (GFR) are usually maintained within the normal range, resulting in a normal filtration fraction (ratio of GFR to renal plasma flow).
Why other options are incorrect:
Why other options are incorrect:
- • Malignant phase of hypertension: Often involves severe renal vascular damage, leading to significant changes in GFR and renal plasma flow.
- • Glomerulonephritis & Acute nephritis: These conditions involve direct inflammation or damage to the glomeruli, which typically causes a disproportionate decrease in GFR relative to renal plasma flow, altering the filtration fraction.
The filtration factor is increased in:
- a) Glomerulonephritis
- b) Malignant phase of hypertension
- c) Early essential hypertension
- d) Acute nephritis
Explanation:
The filtration fraction (FF = GFR/RPF) is increased in conditions where there is a marked decrease in Renal Plasma Flow (RPF) that is disproportionately greater than the decrease in Glomerular Filtration Rate (GFR). This is characteristic of the malignant phase of hypertension, where severe vasoconstriction of the efferent arterioles helps maintain glomerular capillary pressure (and thus GFR) despite a significantly reduced renal blood flow.
Why other options are incorrect:
Why other options are incorrect:
- • Glomerulonephritis / Acute nephritis: These conditions typically involve primary damage to the glomeruli, which usually leads to a decrease in GFR that is more significant than the reduction in RPF, often resulting in a decreased filtration fraction.
- • Early essential hypertension: As previously noted, renal hemodynamics are often preserved, keeping the filtration fraction in the normal range.
The filtration factor is decreased in:
- a) Glomerulonephritis
- b) Early essential hypertension
- c) Malignant phase of hypertension
- d) Starvation
Explanation:
The filtration fraction (FF) is the ratio of GFR to Renal Plasma Flow (RPF). In Glomerulonephritis, there is primary damage to the glomerular capillary wall and a reduction in the total surface area available for filtration. This leads to a substantial decrease in GFR. While renal plasma flow may also be affected, the decline in GFR is typically more pronounced, causing the overall filtration fraction to decrease.
Why other options are incorrect:
Why other options are incorrect:
- • Early essential hypertension: Usually exhibits a normal filtration fraction.
- • Malignant phase of hypertension: Typically causes an increased filtration fraction due to efferent arteriolar constriction maintaining GFR despite low flow.
- • Starvation: Does not typically result in a primary decrease in the filtration fraction; it is more associated with reduced glomerular size or metabolic changes rather than the glomerular pathology seen in nephritis.
Excretion of phenolsulphanpthalein (PSP) reflects
- a) Glomerulonephritis
- b) Maximal tubular excretory capacity
- c) Filtration factor
- d) Renal plasma flow
Explanation:
Phenolsulphonphthalein (PSP) is rapidly removed from the blood by the kidneys, mainly through tubular secretion. Its excretion is used as an indicator of effective renal plasma flow and tubular function.
Why other options are incorrect:
Why other options are incorrect:
- • Glomerulonephritis: PSP excretion is not a specific test for diagnosing glomerulonephritis.
- • Maximal tubular excretory capacity: PSP is handled by tubular secretion, but the PSP test is classically used as an indicator of effective renal plasma flow.
- • Filtration factor: PSP clearance does not directly measure the filtration fraction or filtration factor.
Which of the following is a polyunsaturated fatty acid?
- a) Palmitic acid
- b) Palmitoleic acid
- c) Linoleic acid
- d) Oleic acid
Explanation:
Linoleic acid (18:2, Δ9,12) is a polyunsaturated fatty acid (PUFA) because it contains two or more double bonds in its hydrocarbon chain. It is also an essential fatty acid for humans.
Why other options are incorrect:
Why other options are incorrect:
- • Palmitic acid: A saturated fatty acid (16:0) with no double bonds.
- • Palmitoleic acid: A monounsaturated fatty acid (16:1) with only one double bond.
- • Oleic acid: A monounsaturated fatty acid (18:1) with only one double bond.
Which of the following is an omega-3 polyunsaturated fatty acid?
- a) Linoleic acid
- b) α-Linolenic acid
- c) γ-Linolenic acid
- d) Arachidonic acid
Explanation:
α-Linolenic acid (ALA) is an essential omega-3 (n-3) polyunsaturated fatty acid. It has three double bonds, with the first double bond located at the third carbon from the methyl (omega) end of the fatty acid chain.
Why other options are incorrect:
Why other options are incorrect:
- • Linoleic acid: An omega-6 fatty acid.
- • γ-Linolenic acid: An omega-6 fatty acid.
- • Arachidonic acid: An omega-6 fatty acid.
Triglycerides are:
- a) Heavier than water
- b) Major constituents of membranes
- c) Non-polar
- d) Hydrophilic
Explanation:
Triglycerides (triacylglycerols) are neutral fats consisting of a glycerol backbone esterified to three fatty acids. Because they lack charged or polar groups, they are highly non-polar and hydrophobic, which makes them ideal for energy storage in adipose tissue.
Why other options are incorrect:
Why other options are incorrect:
- • Heavier than water: Triglycerides are less dense than water and will float on top of it.
- • Major constituents of membranes: This describes phospholipids (which are amphipathic), not triglycerides.
- • Hydrophilic: Triglycerides are hydrophobic (water-fearing) due to their non-polar nature.
Cerebronic acid is present in:
- a) Glycerophospholipids
- b) Sphingo phospho lipids
- c) Galactosyl ceramide
- d) Gangliosides
Explanation:
Cerebronic acid (a 24-carbon hydroxy fatty acid) is a characteristic fatty acid found in cerebrosides, particularly galactosyl ceramide (galactocerebroside), which is highly abundant in the myelin sheath of the nervous system.
Why other options are incorrect:
Why other options are incorrect:
- • Glycerophospholipids: These contain a glycerol backbone, whereas cerebrosides are sphingolipids.
- • Sphingo phospho lipids: Such as sphingomyelin; while they are sphingolipids, they typically contain different fatty acid profiles compared to the specific hydroxy fatty acids of cerebrosides.
- • Gangliosides: These are complex glycosphingolipids containing sialic acid; while they are related to cerebrosides, cerebronic acid is most specifically identified as a marker component of galactocerebrosides.
Acylsphingosine is also known as:
- a) Sphingomyelin
- b) Ceramide
- c) Cerebroside
- d) Sulphatide
Explanation:
Ceramide is the simplest sphingolipid, formed by the attachment of a fatty acid to the amino group of sphingosine via an amide linkage. This structure is chemically defined as an N-acylsphingosine.
Why other options are incorrect:
Why other options are incorrect:
- • Sphingomyelin: A ceramide with a phosphocholine or phosphoethanolamine head group.
- • Cerebroside: A ceramide with a single sugar unit (glucose or galactose) attached.
- • Sulphatide: A galactocerebroside with a sulfate group attached to the sugar moiety.
The highest phospholipid content is found in:
- a) Chylomicrons
- b) VLDL
- c) LDL
- d) HDL
Explanation:
High-Density Lipoprotein (HDL) has the highest concentration of phospholipids among the major classes of plasma lipoproteins. HDL particles are composed of approximately 25-30% phospholipids, which help stabilize their structure while they transport cholesterol.
Why other options are incorrect:
Why other options are incorrect:
- • Chylomicrons: Primarily contain triglycerides (over 85-90%); they have the lowest protein and phospholipid density.
- • VLDL: Like chylomicrons, VLDL is rich in triglycerides, though to a lesser extent than chylomicrons.
- • LDL: Primarily composed of cholesterol esters, with a phospholipid content lower than that of HDL.
The major lipid in chylomicrons is:
- a) Triglycerides
- b) Phospholipids
- c) Cholesterol
- d) Free fatty acids
Explanation:
Chylomicrons are large lipoprotein particles synthesized in the intestine to transport dietary lipids. They are characterized by having the highest lipid-to-protein ratio and are composed of approximately 85-90% triglycerides, making triglycerides their major lipid component.
Why other options are incorrect:
Why other options are incorrect:
- • Phospholipids: While present in the outer shell, they are not the primary mass constituent.
- • Cholesterol: Present in smaller amounts compared to the massive triglyceride load.
- • Free fatty acids: These are usually transported bound to albumin in the blood, not within chylomicrons.
Number of carbon atoms in cholesterol is:
- a) 17
- b) 19
- c) 27
- d) 30
Explanation:
Cholesterol is a sterol (a type of lipid) with a characteristic four-ring steroid nucleus. It contains a total of 27 carbon atoms. This includes the steroid nucleus (17 carbons) plus an 8-carbon side chain and two methyl groups at positions 10 and 13.
Why other options are incorrect:
Why other options are incorrect:
- • 17: This is the number of carbons in the basic tetracyclic steroid nucleus (gonane), but it excludes the side chains found in cholesterol.
- • 19: This is the carbon count for Androgens (like testosterone).
- • 30: This is the carbon count for Squalene, which is the precursor to cholesterol.
The lipoprotein richest in cholesterol is:
- a) Chylomicrons
- b) VLDL
- c) LDL
- d) HDL
Explanation:
Low-Density Lipoprotein (LDL) is known as the primary carrier of cholesterol in the blood. It contains the highest percentage of cholesterol and cholesterol esters by mass among all the major lipoprotein classes, which is why it is often referred to as “bad cholesterol.”
Why other options are incorrect:
Why other options are incorrect:
- • Chylomicrons: Primarily composed of triglycerides (dietary fat).
- • VLDL: Primarily composed of endogenous triglycerides.
- • HDL: Contains a higher proportion of protein and phospholipids compared to LDL, though it is involved in “reverse cholesterol transport.”
The major storage form of lipids is
- a) Esterified cholesterol
- b) Glycerophospholipids
- c) Triglycerides
- d) Sphingolipids
Explanation:
Triglycerides (triacylglycerols) are the primary storage form of lipids in the human body, stored mainly in adipose tissue as a concentrated source of energy.
Why other options are incorrect:
Why other options are incorrect:
- • Esterified cholesterol: Used for cell membrane structure and as a precursor for hormones, not primarily for energy storage.
- • Glycerophospholipids: These are structural lipids that serve as the main component of biological membranes.
- • Sphingolipids: These are structural lipids primarily found in nerve tissue and cell membranes.
Cerebonic acid is present in
- a) Triglycerides
- b) Cerebrosides
- c) Esterified cholesterol
- d) Sphingomyelin
Explanation:
Cerebonic acid (also known as cerebronic acid) is a long-chain fatty acid (a hydroxy fatty acid) specifically found as a component of cerebrosides, which are glycosphingolipids found in the myelin sheaths of nerves.
Why other options are incorrect:
Why other options are incorrect:
- • Triglycerides: These consist of glycerol and three fatty acids, typically energy-storing fats, not cerebonic acid.
- • Esterified cholesterol: These are cholesterol molecules linked to fatty acids, not containing cerebonic acid.
- • Sphingomyelin: While it is a sphingolipid, it typically contains different fatty acids (like palmitic or stearic acid) rather than cerebonic acid.
The nitrogenous base in lecithin is
- a) Ethanolamine
- b) Choline
- c) Serine
- d) Betaine
Explanation:
Lecithin is chemically known as phosphatidylcholine. It consists of a glycerol backbone, two fatty acids, a phosphate group, and the nitrogenous base choline.
Why other options are incorrect:
Why other options are incorrect:
- • Ethanolamine: This base is found in phosphatidylethanolamine (cephalin), not lecithin.
- • Serine: This amino acid is found in phosphatidylserine, another type of glycerophospholipid.
- • Betaine: While related to choline metabolism, it is not the nitrogenous base that forms the structure of lecithin.
All the following are omega-6-fatty acids except
- a) Linoleic acid
- b) α-Linolenic acid
- c) γ-Linolenic acid
- d) Arachidonic acid
Explanation:
α-Linolenic acid is an omega-3 fatty acid, not an omega-6 fatty acid. The omega number indicates the position of the first double bond from the methyl end of the fatty acid chain.
Why other options are incorrect:
Why other options are incorrect:
- • Linoleic acid: An essential omega-6 fatty acid.
- • γ-Linolenic acid: A well-known omega-6 fatty acid (GLA).
- • Arachidonic acid: A polyunsaturated omega-6 fatty acid derived from linoleic acid.
All the following have 18 carbon atoms except
- a) Linoleic acid
- b) Linolenic acid
- c) Arachidonic acid
- d) Stearic acid
Explanation:
Arachidonic acid contains 20 carbon atoms (it is a C20:4 fatty acid). All the other options (Linoleic, Linolenic, and Stearic acid) contain 18 carbon atoms.
Why other options are incorrect:
Why other options are incorrect:
- • Linoleic acid: An 18-carbon polyunsaturated fatty acid (C18:2).
- • Linolenic acid: An 18-carbon polyunsaturated fatty acid (C18:3).
- • Stearic acid: An 18-carbon saturated fatty acid (C18:0).
A 20-carbon fatty acid among the following is
- a) Linoleic acid
- b) α -Linolenic acid
- c) β -Linolenic acid
- d) Arachidonic acid
Explanation:
Arachidonic acid is a polyunsaturated fatty acid with 20 carbon atoms and 4 double bonds (C20:4).
Why other options are incorrect:
Why other options are incorrect:
- • Linoleic acid: An 18-carbon fatty acid (C18:2).
- • α-Linolenic acid: An 18-carbon fatty acid (C18:3).
- • β-Linolenic acid: Also known as γ-linolenic acid, it is an 18-carbon fatty acid (C18:3).
Triglycerides are transported from liver to extrahepatic tissues by
- a) Chylomicrons
- b) VLDL
- c) HDL
- d) LDL
Explanation:
Very Low-Density Lipoproteins (VLDL) are synthesized in the liver to transport endogenous triglycerides to extrahepatic tissues (such as adipose and muscle tissue) for storage or energy production.
Why other options are incorrect:
Why other options are incorrect:
- • Chylomicrons: Transport dietary (exogenous) lipids from the intestine, not the liver.
- • HDL: Primarily involved in “reverse cholesterol transport,” moving cholesterol from tissues back to the liver.
- • LDL: Primarily transports cholesterol to peripheral tissues, not triglycerides.
Cholesterol is transported from liver to extrahepatic tissues by
- a) Chylomicrons
- b) VLDL
- c) HDL
- d) LDL
Explanation:
Low-Density Lipoprotein (LDL) is the primary lipoprotein responsible for delivering cholesterol from the liver to peripheral (extrahepatic) tissues, where it is utilized for cell membrane synthesis and hormone production. It is often referred to as “bad cholesterol.”
Why other options are incorrect:
Why other options are incorrect:
- • Chylomicrons: Transport dietary lipids from the intestines to the body.
- • VLDL: Primarily transports triglycerides from the liver to extrahepatic tissues.
- • HDL: Known as “good cholesterol,” it carries cholesterol away from tissues back to the liver for excretion or recycling.
Elevated plasma level of the following protects against atherosclerosis:
- a) Chylomicrons
- b) VLDL
- c) HDL
- d) LDL
Explanation:
High-Density Lipoprotein (HDL) is known as “good cholesterol” because it performs reverse cholesterol transport, picking up excess cholesterol from peripheral tissues and arteries and transporting it back to the liver to be excreted. This process helps prevent the buildup of plaque in the arteries (atherosclerosis).
Why other options are incorrect:
Why other options are incorrect:
- • Chylomicrons: Primarily transport dietary triglycerides and are not directly associated with protective anti-atherogenic effects.
- • VLDL: Elevated levels are associated with increased risk of cardiovascular disease as they are precursors to LDL.
- • LDL: Known as “bad cholesterol,” elevated levels promote the deposition of cholesterol in arterial walls, leading to atherosclerosis.
All the following amino acids are nonessential except
- a) Alanine
- b) Histidine
- c) Cysteine
- d) Proline
Explanation:
Histidine is classified as an essential amino acid (specifically, it is often termed semi-essential or conditionally essential in adults, but is essential in the diet for infants and children). The body cannot synthesize it in sufficient quantities to meet metabolic needs.
Why other options are incorrect:
Why other options are incorrect:
- • Alanine: A nonessential amino acid that the body can synthesize from pyruvate.
- • Cysteine: A nonessential amino acid that can be synthesized from methionine and serine.
- • Proline: A nonessential amino acid that the body can synthesize from glutamate.
Sulphydryl group is present in
- a) Cysteine
- b) Methionine
- c) Both (Cysteine) and (Methionine)
- d) None of these
Explanation:
Cysteine contains a free sulphydryl (-SH) group (also called a thiol group) in its side chain. This group is crucial for the formation of disulfide bonds, which stabilize the tertiary structure of many proteins.
Why other options are incorrect:
Why other options are incorrect:
- • Methionine: Contains a sulfur atom, but it is in the form of a thioether group (-S-CH3), not a free sulphydryl group.
- • Both: As stated above, only Cysteine possesses the free -SH group, while Methionine contains a thioether linkage.
Oligosaccharide-pyrophosphoryl dolichol is required for the synthesis of
- a) N-linked glycoproteins
- b) O-linked glycoproteins
- c) GPI-linked glycoproteins
- d) All of these
Explanation:
The precursor oligosaccharide-pyrophosphoryl-dolichol (also known as dolichol pyrophosphate oligosaccharide) is the key lipid-linked intermediate specifically used in the initial stages of N-glycosylation, where the oligosaccharide chain is transferred to an asparagine residue of a protein.
Why other options are incorrect:
Why other options are incorrect:
- • O-linked glycoproteins: These are synthesized by the sequential addition of sugars directly to serine or threonine residues without the involvement of dolichol-pyrophosphate intermediates.
- • GPI-linked glycoproteins: These are anchored by a different glycolipid structure (Glycosylphosphatidylinositol), not the dolichol-pyrophosphate oligosaccharide.
In N-linked glycoproteins, oligosaccharide is attached to protein through its
- a) Asparagine residue
- b) Glutamine residue
- c) Arginine residue
- d) Lysine residue
Explanation:
In N-linked glycosylation, the carbohydrate chain (oligosaccharide) is covalently linked to the nitrogen atom of the side-chain amide group of an Asparagine (Asn) residue, usually within the specific consensus sequence Asn-X-Ser/Thr.
Why other options are incorrect:
Why other options are incorrect:
- • Glutamine: Although it contains an amide group, it is not the standard site for N-linked glycosylation.
- • Arginine: Does not serve as an attachment point for oligosaccharides in glycoproteins.
- • Lysine: Primarily used for different modifications (like acetylation or ubiquitination), not for N-linked glycosylation.
De novo synthesis of fatty acids occurs in
- a) Cytosol
- b) Mitochondria
- c) Microsomes
- d) All of these
Explanation:
De novo synthesis of fatty acids (lipogenesis) primarily occurs in the cytosol of the cell, where the fatty acid synthase complex is located.
Why other options are incorrect:
Why other options are incorrect:
- • Mitochondria: While involved in fatty acid oxidation (beta-oxidation), they are not the site of de novo synthesis.
- • Microsomes: These are primarily involved in the elongation and desaturation of existing fatty acids, not de novo synthesis.
Acyl Carrier Protein contains the vitamin:
- a) Biotin
- b) Lipoic acid
- c) Pantothenic acid
- d) Folic acid
Explanation:
The Acyl Carrier Protein (ACP) contains a 4′-phosphopantetheine prosthetic group, which is derived from the vitamin Pantothenic acid (Vitamin B5). This group acts as a flexible arm to carry the growing fatty acid chain during synthesis.
Why other options are incorrect:
Why other options are incorrect:
- • Biotin: This is a cofactor for carboxylase enzymes (e.g., Acetyl-CoA carboxylase), not a component of ACP.
- • Lipoic acid: This is a cofactor for the pyruvate dehydrogenase complex and alpha-ketoglutarate dehydrogenase.
- • Folic acid: This is involved in one-carbon metabolism and nucleotide synthesis.
Which of the following is required as a reductant in fatty acid synthesis?
- a) NADH
- b) NADPH
- c) FADH2
- d) FMNH2
Explanation:
NADPH serves as the essential electron donor (reductant) for the reductive steps in fatty acid synthesis, catalyzed by the fatty acid synthase complex. It is primarily generated by the Pentose Phosphate Pathway.
Why other options are incorrect:
Why other options are incorrect:
- • NADH: Primarily involved in catabolic reactions and electron transport for ATP production, not biosynthetic reduction.
- • FADH2 / FMNH2: These are flavin coenzymes typically involved in dehydrogenation reactions (such as those in beta-oxidation or the TCA cycle), not as primary reductants for fatty acid synthesis.
Hepatic liponenesis is stimulated by:
- a) cAMP
- b) Glucagon
- c) Epinephrine
- d) Insulin
Explanation:
Insulin stimulates hepatic lipogenesis (fatty acid synthesis) by promoting the expression of key enzymes (such as Acetyl-CoA carboxylase and Fatty Acid Synthase) and by activating these enzymes via dephosphorylation.
Why other options are incorrect:
Why other options are incorrect:
- • cAMP: A secondary messenger that typically signals the activation of protein kinase A, which inhibits fatty acid synthesis.
- • Glucagon: Inhibits fatty acid synthesis by increasing intracellular cAMP levels and activating protein kinase A, which phosphorylates and inactivates key lipogenic enzymes.
- • Epinephrine: Similarly to glucagon, it stimulates lipolysis and inhibits fatty acid synthesis in the liver by activating the cAMP-dependent pathway.
De novo synthesis of fatty acids requires all of the following except
- a) Biotin
- b) NADH
- c) Pantothenic acid
- d) ATP
Explanation:
Fatty acid synthesis specifically requires NADPH as a reducing agent. NADH is primarily involved in catabolic (breakdown) pathways, such as glycolysis and the TCA cycle, rather than in the biosynthetic pathway of fatty acids.
Why other options are incorrect:
Why other options are incorrect:
- • Biotin: Essential as a cofactor for Acetyl-CoA carboxylase, which catalyzes the rate-limiting step of fatty acid synthesis.
- • Pantothenic acid: A component of the Acyl Carrier Protein (ACP) and Coenzyme A, both vital for the process.
- • ATP: Required for the activation of Acetyl-CoA carboxylase and the formation of Malonyl-CoA.
Acetyl CoA carboxylase regulates fatty acid synthesis by which of the following mechanism?
- a) Allosteric regulation
- b) Covalent modification
- c) Induction and repression
- d) All of these
Explanation:
Acetyl-CoA carboxylase (ACC) is the major regulatory enzyme of fatty acid synthesis. Its activity is controlled by allosteric regulation, covalent modification through phosphorylation/dephosphorylation, and long-term regulation through induction and repression of enzyme synthesis.
Why other options are incorrect:
Why other options are incorrect:
- • Allosteric regulation: ACC is activated by citrate and inhibited by long-chain fatty acyl-CoA.
- • Covalent modification: Phosphorylation generally decreases ACC activity, while dephosphorylation activates it.
- • Induction and repression: Hormonal and nutritional signals regulate ACC synthesis over longer periods.
β-Oxidation of fatty acids requires all the following coenzymes except
- a) CoA
- b) FAD
- c) NAD
- d) NADP
Explanation:
β-Oxidation requires CoA, FAD, and NAD⁺. FAD is used in the first oxidation step, while NAD⁺ is used in the third step. NADP⁺ is not required in the β-oxidation pathway.
Why other options are incorrect:
Why other options are incorrect:
- • CoA: Required for formation and utilization of fatty acyl-CoA and acetyl-CoA.
- • FAD: Required for the first oxidation reaction of β-oxidation.
- • NAD: NAD⁺ is required for the second oxidation reaction.
Which of the following can be oxidized by β-oxidation pathway?
- a) Saturated fatty acids
- b) Monosaturated fatty acids
- c) Polyunsaturated fatty acids
- d) All of these
Explanation:
The β-oxidation pathway is the primary mechanism for the breakdown of various fatty acids. While saturated fatty acids follow the standard pathway, unsaturated fatty acids (both mono- and polyunsaturated) are also oxidized after additional auxiliary enzymes (such as isomerases and reductases) handle the double bonds to prepare them for the pathway.
Why other options are correct:
Why other options are correct:
- • Saturated fatty acids: These are the classic substrates for β-oxidation.
- • Monounsaturated fatty acids: Require an isomerase to move/shift the double bond to the correct position for oxidation.
- • Polyunsaturated fatty acids: Require both an isomerase and a reductase to remove extra double bonds.
Propionyl CoA is formed on oxidation of
- a) Monounsaturated fatty acids
- b) Polyunsaturated fatty acids
- c) Fatty acids with odd number of carbon atoms
- d) None of these
Explanation:
During the β-oxidation of fatty acids with an odd number of carbon atoms, the final cycle of oxidation produces one molecule of Acetyl-CoA and one molecule of Propionyl-CoA (a 3-carbon unit), rather than two molecules of Acetyl-CoA.
Why other options are incorrect:
Why other options are incorrect:
- • Monounsaturated/Polyunsaturated fatty acids: These are oxidized to Acetyl-CoA units (after managing their double bonds), but they do not specifically generate Propionyl-CoA as a primary final product.
An enzyme required for the synthesis of ketone bodies as well as cholesterol is
- a) Acetyl CoA carboxylase
- b) HMG CoA synthetase
- c) HMG CoA reductase
- d) HMG CoA lyase
Explanation:
HMG CoA synthetase is the enzyme responsible for the condensation of Acetyl-CoA and Acetoacetyl-CoA to form HMG-CoA (3-hydroxy-3-methylglutaryl-CoA), which is a common intermediate in both ketogenesis (mitochondrial) and cholesterol synthesis (cytosolic).
Why other options are incorrect:
Why other options are incorrect:
- • Acetyl CoA carboxylase: Key regulatory enzyme for fatty acid synthesis, not ketogenesis.
- • HMG CoA reductase: Catalyzes the conversion of HMG-CoA to mevalonate, which is specific to cholesterol synthesis.
- • HMG CoA lyase: Catalyzes the conversion of HMG-CoA to Acetoacetate, which is specific to ketogenesis.
Ketone bodies are synthesized in
- a) Adipose tissue
- b) Liver
- c) Muscles
- d) Brain
Explanation:
Ketogenesis, the process of synthesizing ketone bodies (acetoacetate, beta-hydroxybutyrate, and acetone), occurs primarily in the mitochondrial matrix of liver cells (hepatocytes). The liver produces these to provide an alternative energy source for extrahepatic tissues during fasting or starvation.
Why other options are incorrect:
Why other options are incorrect:
- • Adipose tissue: Primarily stores triglycerides and releases fatty acids during lipolysis, but does not synthesize ketone bodies.
- • Muscles & Brain: These tissues are consumers of ketone bodies for energy, but they lack the necessary enzymes to synthesize them.
All the following statements about ketone bodies are true except:
- a) Their synthesis increases in diabetes mellitus
- b) They are synthesized in mitochondria
- c) They can deplete the alkali reserve
- d) They can be oxidized in the liver
Correct Answer: d) They can be oxidized in the liver
Explanation: The liver is the primary site of ketone body synthesis (ketogenesis), but it lacks the necessary enzymes (specifically succinyl-CoA-acetoacetate-CoA transferase) to utilize them. Therefore, ketone bodies cannot be oxidized in the liver; they are exported to peripheral tissues for energy.
Why other options are correct:
Explanation: The liver is the primary site of ketone body synthesis (ketogenesis), but it lacks the necessary enzymes (specifically succinyl-CoA-acetoacetate-CoA transferase) to utilize them. Therefore, ketone bodies cannot be oxidized in the liver; they are exported to peripheral tissues for energy.
Why other options are correct:
- • Synthesis increases in diabetes: Lack of insulin leads to increased fatty acid mobilization and ketogenesis.
- • Synthesized in mitochondria: Ketogenesis occurs strictly within the mitochondrial matrix of liver cells.
- • Deplete alkali reserve: Ketone bodies are acidic; their accumulation (ketoacidosis) uses up bicarbonate buffers, depleting the alkali reserve.
All the following statements about carnitine are true except:
- a) It can be synthesised in the human body
- b) It can be synthesized from methionine and lysine
- c) It is required for transport of short chain fatty acids into mitochondria
- d) Its deficiency can occur due to haemodialysis
Correct Answer: c) It is required for transport of short chain fatty acids into mitochondria
Explanation: Carnitine is essential for the transport of **long-chain fatty acids** into the mitochondria. Short-chain and medium-chain fatty acids can diffuse through the mitochondrial membrane independently of the carnitine transport system.
Why other options are correct:
Explanation: Carnitine is essential for the transport of **long-chain fatty acids** into the mitochondria. Short-chain and medium-chain fatty acids can diffuse through the mitochondrial membrane independently of the carnitine transport system.
Why other options are correct:
- • Synthesised in the human body: Yes, it is synthesized primarily in the liver and kidneys.
- • Synthesized from methionine and lysine: These two amino acids are the essential precursors for the biosynthesis of carnitine.
- • Deficiency due to haemodialysis: Carnitine is a small molecule that can be removed from the blood during dialysis, potentially leading to secondary deficiency.
Which of the following can be synthesized in the human body if precursors are available?
- a) Oleic acid
- b) Palmitoleic acid
- c) Arachidonic acid
- d) All of these
Explanation:
Humans can synthesize oleic acid and palmitoleic acid from saturated fatty acids. Arachidonic acid can also be synthesized from linoleic acid when the necessary precursor is available. Therefore, all of these fatty acids can be synthesized in the human body if appropriate precursors are available.
Why other options are incorrect:
Why other options are incorrect:
- • Oleic acid: Can be synthesized from stearic acid by desaturation.
- • Palmitoleic acid: Can be synthesized from palmitic acid by desaturation.
- • Arachidonic acid: Can be synthesized from linoleic acid through desaturation and elongation reactions.
All the following can be oxidized by β-oxidation except:
- a) Palmitic acid
- b) Phytanic acid
- c) Linoleic acid
- d) Fatty acids having an odd number of carbon atoms
Correct Answer: b) Phytanic acid
Explanation: Phytanic acid is a branched-chain fatty acid. The presence of a methyl group at the beta-carbon atom blocks the normal β-oxidation process. Therefore, it must first undergo α-oxidation to remove the methyl group before it can subsequently undergo β-oxidation.
Why other options are incorrect :
Explanation: Phytanic acid is a branched-chain fatty acid. The presence of a methyl group at the beta-carbon atom blocks the normal β-oxidation process. Therefore, it must first undergo α-oxidation to remove the methyl group before it can subsequently undergo β-oxidation.
Why other options are incorrect :
- • Palmitic acid: A straight-chain saturated fatty acid that is the classic substrate for β-oxidation.
- • Linoleic acid: An unsaturated fatty acid that undergoes β-oxidation after specific auxiliary enzymes handle the double bonds.
- • Odd-chain fatty acids: These undergo β-oxidation until the final three-carbon unit (propionyl-CoA) remains, which is then processed further.
Anti-inflammatory corticosteroids inhibit the synthesis of
- a) Leukotrienes
- b) Prostaglandins
- c) Thromboxanes
- d) All of these
Explanation:
Anti-inflammatory corticosteroids inhibit phospholipase A₂ activity by inducing lipocortin (annexin-1). This reduces the release of arachidonic acid and consequently inhibits the synthesis of prostaglandins, thromboxanes, and leukotrienes.
Why other options are incorrect:
Why other options are incorrect:
- • Leukotrienes: Their synthesis is reduced because corticosteroids inhibit arachidonic acid release.
- • Prostaglandins: Their synthesis is reduced due to decreased availability of arachidonic acid.
- • Thromboxanes: Their synthesis is also reduced through inhibition of the arachidonic acid pathway.
Diets having a high ratio of polyunsaturated: saturated fatty acids can cause:
- a) Increase in serum triglycerides
- b) Decrease in serum cholesterol
- c) Decrease in serum HDL
- d) Skin lesions
Correct Answer: b) Decrease in serum cholesterol
Explanation: Polyunsaturated fatty acids (PUFAs) have a hypocholesterolemic effect. When they replace saturated fatty acids in the diet, they help lower total serum cholesterol levels by increasing the excretion of bile acids and cholesterol, as well as modulating the expression of LDL receptors.
Why other options are incorrect:
Explanation: Polyunsaturated fatty acids (PUFAs) have a hypocholesterolemic effect. When they replace saturated fatty acids in the diet, they help lower total serum cholesterol levels by increasing the excretion of bile acids and cholesterol, as well as modulating the expression of LDL receptors.
Why other options are incorrect:
- • Increase in serum triglycerides: High PUFA intake generally does not increase triglycerides; in fact, omega-3 PUFAs are known to lower them.
- • Decrease in serum HDL: While excessive intake might slightly lower HDL, the primary and most significant clinical effect is the reduction of total and LDL cholesterol.
- • Skin lesions: Skin lesions (like phrynoderma) are actually a clinical sign of deficiency of essential fatty acids, not of a diet high in PUFAs.
Thromboxanes cause:
- a) Vasodilation
- b) Bronchoconstriction
- c) Platelet aggregation
- d) All of these
Correct Answer: c) Platelet aggregation
Explanation: Thromboxane A2 (TXA2) is primarily produced by platelets. Its main physiological functions include being a potent vasoconstrictor and a powerful promoter of platelet aggregation (thrombosis).
Why other options are incorrect:
Explanation: Thromboxane A2 (TXA2) is primarily produced by platelets. Its main physiological functions include being a potent vasoconstrictor and a powerful promoter of platelet aggregation (thrombosis).
Why other options are incorrect:
- • Vasodilation: Thromboxanes act as vasoconstrictors, not vasodilators (Prostacyclin/PGI2 is the potent vasodilator).
- • Bronchoconstriction: While leukotrienes are potent bronchoconstrictors, thromboxanes are primarily associated with vascular and platelet activity rather than significant respiratory airway constriction.
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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