6001 to 6050 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 6001 to 6050
Which one of the following is not a phospholipid?
- a) Lecithin
- b) Plasmalogen
- c) Lysolecithin
- d) Gangliosides
Explanation:
Gangliosides are a class of glycosphingolipids (glycolipids) containing one or more sialic acid residues. Unlike phospholipids, they contain a sugar component instead of a phosphate group.
Why other options are incorrect:
Why other options are incorrect:
- • Lecithin: A common name for Phosphatidylcholine, which is a major phospholipid in cell membranes.
- • Plasmalogen: A type of ether phospholipid found in heart and brain tissue.
- • Lysolecithin: A derivative of lecithin produced by the removal of a fatty acid; it is classified as a lysophospholipid.
A fatty acid which is not synthesized in the human body and has to be supplied in the diet:
- a) Palmitic acid
- b) Oleic acid
- c) Linoleic acid
- d) Stearic acid
Explanation:
Linoleic acid is an essential fatty acid because humans lack the specific enzymes (desaturases) required to introduce double bonds at certain positions (beyond carbon-9), making dietary intake necessary.
Why other options are incorrect:
Why other options are incorrect:
- • Palmitic acid: A saturated fatty acid that is commonly synthesized by the body via the fatty acid synthase complex.
- • Oleic acid: A monounsaturated omega-9 fatty acid that the human body can readily synthesize from stearic acid.
- • Stearic acid: A long-chain saturated fatty acid that can be synthesized in the body or obtained from various animal and vegetable fats.
In cephalin, choline is replaced by:
- a) Serine
- b) Ethanolamine
- c) Betaine
- d) Sphingosine
Explanation:
Cephalin (Phosphatidylethanolamine) is a phospholipid similar to lecithin (Phosphatidylcholine), but in cephalin, the choline moiety found in lecithin is replaced by ethanolamine.
Why other options are incorrect:
Why other options are incorrect:
- • Serine: Phosphatidylserine is a different type of phospholipid where the serine amino acid replaces choline.
- • Betaine: This is a modified amino acid (N,N,N-trimethylglycine) and is not the structural component replacing choline in cephalin.
- • Sphingosine: This is an amino alcohol that serves as the backbone for sphingolipids, not the head group substituent in glycerophospholipids like cephalin.
The triacylglycerols present in plasma lipoproteins are hydrolyzed by:
- a) Lingual lipase
- b) Pancreatic lipase
- c) Colipase
- d) Lipoprotein lipase
Explanation:
Lipoprotein lipase (LPL) is an enzyme found on the surface of capillary endothelial cells that hydrolyzes triacylglycerols circulating in the blood (in chylomicrons and VLDL) into free fatty acids and glycerol.
Why other options are incorrect:
Why other options are incorrect:
- • Lingual lipase: Secreted in the mouth, this enzyme acts on dietary fats in the stomach during initial digestion.
- • Pancreatic lipase: The primary enzyme for digesting dietary triglycerides in the lumen of the small intestine.
- • Colipase: A protein cofactor that assists pancreatic lipase in binding to lipid droplets; it does not have lipase activity itself.
Amphipathic lipids are:
- a) Hydrophilic
- b) Hydrophobic
- c) Both (Hydrophilic) and (Hydrophobic)
- d) Lipophilic
Explanation:
Amphipathic lipids possess both a hydrophilic (water-loving) polar head group and a hydrophobic (water-fearing) non-polar tail (fatty acid chains). This dual nature is essential for the formation of biological membranes.
Why other options are incorrect:
Why other options are incorrect:
- • Hydrophilic: Refers to substances that are only water-soluble, which is only one part of an amphipathic lipid.
- • Hydrophobic: Refers to substances that repel water; amphipathic lipids contain these regions but are not defined by them alone.
- • Lipophilic: Means “fat-loving.” While amphipathic lipids have lipophilic tails, this term fails to account for the hydrophilic head, which is the defining characteristic of “amphipathic.”
Which of the following is not an essential fatty acid?
- a) Oleic acid
- b) Linoleic acid
- c) Arachidonic acid
- d) Linolenic acid
Explanation:
Oleic acid is a monounsaturated omega-9 fatty acid that the human body can synthesize endogenously from stearic acid; therefore, it is considered non-essential.
Why other options are incorrect:
Why other options are incorrect:
- • Linoleic acid: An essential omega-6 fatty acid that humans cannot synthesize.
- • Arachidonic acid: Often classified as conditionally essential because it can be synthesized from linoleic acid, but it is required in the diet if linoleic acid is deficient.
- • Linolenic acid: An essential omega-3 fatty acid that must be obtained through the diet.
The calorific value of lipid is:
- a) 4.0 Kcal/gm
- b) 6.0 Kcal/gm
- c) 9.0 Kcal/gm
- d) 15 Kcal/gm
Explanation:
Lipids are highly energy-dense, providing approximately 9 kcal/gram upon oxidation. This is significantly higher than carbohydrates or proteins, which both yield approximately 4 kcal/gram.
Why other options are incorrect:
Why other options are incorrect:
- • 4.0 Kcal/gm: This is the approximate energy value for carbohydrates and proteins.
- • 6.0 Kcal/gm: This value does not correspond to the standard metabolic yield of any major macronutrient.
- • 15 Kcal/gm: This value is far too high; no dietary macronutrient provides this amount of energy.
Rancidity of butter is prevented by the addition of:
- a) Vitamin D
- b) Tocopherols
- c) Presence of priotin
- d) Presence of ‘Cu’
Explanation:
Tocopherols (Vitamin E) act as potent antioxidants. They prevent the oxidative rancidity of fats like butter by scavenging free radicals and terminating the chain reactions that lead to lipid peroxidation.
Why other options are incorrect:
Why other options are incorrect:
- • Vitamin D: This is a fat-soluble vitamin involved in calcium metabolism, not an antioxidant.
- • Presence of priotin: This is not a standard substance used for food preservation.
- • Presence of ‘Cu’ (Copper): Heavy metals like copper actually catalyze the oxidation of lipids, which would accelerate (not prevent) rancidity.
Sphingomyelins on hydrolysis yield:
- a) Glycerol, fatty acids, phosphoric acid and choline
- b) Glycerol, sphingosine, choline and fatty acids
- c) Sphingosine, phosphoric acid, Glycerol and inositol
- d) Sphingosine, fatty acids, phosphoric acid and choline
Explanation:
Sphingomyelin is a type of sphingolipid. Unlike glycerophospholipids, it contains a sphingosine backbone rather than glycerol. Upon complete hydrolysis, it yields one molecule each of sphingosine, a fatty acid, phosphoric acid, and choline.
Why other options are incorrect:
Why other options are incorrect:
- • Glycerol-containing options (a, b, c): These are incorrect because sphingomyelin lacks a glycerol backbone; it uses sphingosine.
- • Inositol: This is a component of phosphatidylinositol, not sphingomyelin.
Inherited deficiency of enzyme cerebrosidase produces:
- a) Fabry’s disease
- b) Niemann-Pick disease
- c) Gaucher’s disease
- d) Tay-Sachs disease
Explanation:
Gaucher’s disease is a lysosomal storage disorder caused by a deficiency of the enzyme glucocerebrosidase (also known as acid β-glucosidase), leading to the accumulation of glucocerebroside in cells.
Why other options are incorrect:
Why other options are incorrect:
- • Fabry’s disease: Caused by a deficiency of alpha-galactosidase A.
- • Niemann-Pick disease: Caused by a deficiency of sphingomyelinase.
- • Tay-Sachs disease: Caused by a deficiency of hexosaminidase A.
Phosphatidic acid on hydrolysis yields:
- a) Glycerol, fatty acids, phosphoric acid, choline
- b) Glycerol, fatty acids, phosphoric acid
- c) Glycerol, fatty acids, phosphoric acid, Glucose
- d) Sphingol, fatty acids, phosphoric acid
Explanation:
Phosphatidic acid is the simplest phospholipid. It consists of a glycerol backbone esterified to two fatty acids and one phosphoric acid group. It acts as the precursor for the synthesis of other glycerophospholipids.
Why other options are incorrect:
Why other options are incorrect:
- • Choline (a): This is a component of Phosphatidylcholine (Lecithin), not phosphatidic acid itself.
- • Glucose (c): Glucose is a component of glycolipids, not phosphatidic acid.
- • Sphingol (d): This is a structural component of sphingolipids, whereas phosphatidic acid is a glycerophospholipid.
The maximum number of double bonds present in essential fatty acids (including conditionally essential) is:
- a) 1
- b) 2
- c) 3
- d) 4
Explanation:
Among the fatty acids categorized as essential or conditionally essential, Arachidonic acid stands out as a polyunsaturated fatty acid with 20 carbons and 4 double bonds (20:4, Δ5,8,11,14).
Why other options are incorrect:
Why other options are incorrect:
- • 1: Monounsaturated fatty acids (like Oleic acid) are non-essential as the body can synthesize them.
- • 2: Linoleic acid has 2 double bonds, but it is not the maximum among the essential/conditionally essential group.
- • 3: Linolenic acid has 3 double bonds, but Arachidonic acid (4 double bonds) is also recognized in this biological context.
Cerebrosides are composed of:
- a) Sphingosine, fatty acids, glycerol and phosphoric acid
- b) Sphingosine, fatty acids, galactose
- c) Glycerol, fatty acids, galactose
- d) Glycerol, fatty acids, galactose, sphingol
Explanation:
Cerebrosides are the simplest glycosphingolipids. They consist of a ceramide backbone (sphingosine + fatty acid) linked to a single sugar residue, which is usually galactose in neural tissue.
Why other options are incorrect:
Why other options are incorrect:
- • Glycerol-containing options (a, c, d): Cerebrosides are sphingolipids, not glycerolipids; they do not contain glycerol.
- • Phosphoric acid (a): Cerebrosides are non-phosphorus-containing lipids (unlike phospholipids); they only contain a sugar moiety.
Acetoacetic acid and β-hydroxybutyric acid are formed in the:
- a) Kidneys
- b) Heart
- c) Liver
- d) Intestine
Explanation:
The liver is the primary site for ketogenesis. It converts excess acetyl-CoA (derived from fatty acid oxidation) into ketone bodies like acetoacetate and β-hydroxybutyrate, which are then exported to peripheral tissues for energy.
Why other options are incorrect:
Why other options are incorrect:
- • Kidneys/Intestine: While these tissues have many metabolic functions, they are not the site of ketogenesis.
- • Heart: The heart (along with the brain and skeletal muscle) is a major *consumer* of ketone bodies for energy, especially during fasting, but it does not synthesize them.
Which amino acid is a lipotropic factor?
- a) Lysine
- b) Leucine
- c) Tryptophan
- d) Methionine
Explanation:
Methionine is a lipotropic factor because it acts as a methyl donor for the synthesis of choline. Choline is essential for the formation of lecithin, which helps mobilize fats out of the liver, thus preventing fatty liver.
Why other options are incorrect:
Why other options are incorrect:
- • Lysine: An essential amino acid involved in protein synthesis and carnitine production, but not primarily classified as a lipotropic agent.
- • Leucine: A branched-chain amino acid primarily involved in muscle protein synthesis and energy metabolism.
- • Tryptophan: A precursor for serotonin and niacin; it does not possess significant lipotropic activity.
The class of lipoproteins having a beneficial effect in atherosclerosis is:
- a) Low density lipoproteins (LDL)
- b) Very low density lipoproteins (VLDL)
- c) High density lipoproteins (HDL)
- d) Chylomicrons
Explanation:
High-density lipoproteins (HDL) are known as “good cholesterol” because they participate in reverse cholesterol transport, where they carry excess cholesterol from peripheral tissues and arteries back to the liver for excretion or recycling, thereby protecting against atherosclerosis.
Why other options are incorrect:
Why other options are incorrect:
- • LDL: Known as “bad cholesterol,” high levels contribute to the buildup of plaque in the arteries.
- • VLDL: These carry triglycerides to tissues; high levels are associated with an increased risk of cardiovascular disease.
- • Chylomicrons: These transport dietary lipids; they are not typically associated with protection against atherosclerosis.
Cholesterol is the precursor for the biosynthesis of:
- a) Fatty acids
- b) Prostaglandins
- c) Bile acids
- d) Sphingomyelin
Explanation:
Cholesterol serves as the vital precursor for the synthesis of bile acids (and bile salts), steroid hormones (such as cortisol, estrogen, and testosterone), and Vitamin D.
Why other options are incorrect:
Why other options are incorrect:
- • Fatty acids: These are synthesized from Acetyl-CoA, not cholesterol.
- • Prostaglandins: These are synthesized from essential polyunsaturated fatty acids, specifically Arachidonic acid.
- • Sphingomyelin: This is a sphingolipid synthesized from sphingosine and fatty acids; cholesterol is not a precursor for its backbone.
Which of the following conditions is characterized by ketonuria but without glycosuria?
- a) Diabetes mellitus
- b) Diabetes insipidus
- c) Prolonged starvation
- d) Addison’s disease
Explanation:
In prolonged starvation, the body exhausts glycogen stores and shifts to fat oxidation, leading to the production of ketone bodies (ketonuria). However, blood glucose levels remain normal or low, so there is no glucose in the urine (no glycosuria).
Why other options are incorrect:
Why other options are incorrect:
- • Diabetes mellitus: Characterized by both ketonuria and glycosuria due to high blood sugar levels.
- • Diabetes insipidus: A hormonal disorder related to vasopressin (ADH); it does not involve ketone or glucose metabolism.
- • Addison’s disease: An adrenal insufficiency; while it may cause metabolic changes, it does not typically present with this combination of findings.
Ketone bodies are formed in:
- a) Kidney
- b) Liver
- c) Heart
- d) Intestines
Explanation:
The liver is the exclusive site for the synthesis of ketone bodies (ketogenesis). During periods of fasting or low carbohydrate intake, the liver converts acetyl-CoA from fatty acid oxidation into ketone bodies for use by other tissues.
Why other options are incorrect:
Why other options are incorrect:
- • Kidney: While the kidney can utilize ketone bodies, it does not possess the necessary enzymes for their production.
- • Heart: The heart is a major consumer of ketone bodies for energy but cannot synthesize them.
- • Intestines: The intestines do not play a role in the pathway of ketogenesis.
Changes in serum high-density lipoproteins (HDL) are more truly reflected by those of:
- a) HDL-1
- b) HDL-2
- c) HDL-3
- d) HDL-C
Explanation:
Changes in serum HDL are more truly reflected by changes in HDL-2, the larger and more buoyant HDL subfraction. HDL-2 levels are particularly associated with variations in HDL concentration and are considered an important indicator of HDL metabolism.
Why other options are incorrect:
Why other options are incorrect:
- • HDL-1: This is a minor HDL subfraction and does not primarily reflect changes in serum HDL.
- • HDL-3: HDL-3 is a smaller, denser HDL subfraction and is less reflective of overall changes in serum HDL.
- • HDL-C: HDL-C represents the cholesterol content carried by HDL particles rather than a specific HDL subfraction.
Mitochondrial lipogenesis requires
- a) Bicarbonate
- b) Biotin
- c) Acetyl CoA carboxylase
- d) NADPH
Explanation:
Mitochondrial lipogenesis requires NADPH as a source of reducing equivalents for the reductive steps involved in fatty acid synthesis. NADPH is essential for the reduction reactions during lipogenesis.
Why other options are incorrect:
Why other options are incorrect:
- • Bicarbonate: Used in acetyl CoA carboxylation, mainly in the cytosolic fatty acid synthesis pathway.
- • Biotin: A cofactor for acetyl CoA carboxylase in cytosolic fatty acid synthesis.
- • Acetyl CoA carboxylase: The classic enzyme of de novo fatty acid synthesis is primarily cytosolic, not mitochondrial.
Fatty acids having chain length of 10 carbon atoms enter the
- a) Portal circulation
- b) Lacteals
- c) Systemic circulation
- d) Colon
Explanation:
Fatty acids are categorized by chain length. Short-chain and medium-chain fatty acids (typically those with 12 carbons or fewer, like 10-carbon atoms) are water-soluble enough to be absorbed directly into the portal circulation via the intestinal capillaries and transported to the liver bound to albumin.
Why other options are incorrect:
Why other options are incorrect:
- • Lacteals: These are lymphatic capillaries that absorb long-chain fatty acids (which are re-esterified into triglycerides and packaged into chylomicrons).
- • Systemic circulation: This is where lipids from the thoracic duct eventually enter, but it is not the primary site of initial absorption for medium-chain fatty acids.
- • Colon: The majority of fat absorption occurs in the small intestine (jejunum), not the colon.
A soluble system for synthesis of fatty acids have been isolated from avian liver, required for the formation of long chain fatty acids by this system is
- a) ATP
- b) Acetyl CoA
- c) NADPH
- d) All of these
Explanation:
The soluble fatty acid synthesis system in avian liver requires ATP, acetyl CoA, and NADPH. ATP provides energy, acetyl CoA supplies the carbon units, and NADPH provides reducing power for the synthesis of long-chain fatty acids.
Why other options are incorrect:
Why other options are incorrect:
- • ATP: Required for the ATP-dependent carboxylation of acetyl CoA during fatty acid synthesis, but it is not the only requirement.
- • Acetyl CoA: Provides the carbon source for fatty acid synthesis, but other components are also required.
- • NADPH: Supplies reducing equivalents for the reduction reactions during fatty acid synthesis, but it is not sufficient alone.
Most animal tissues contain appreciable amounts of lipid, when in the form of depot fat it consists largely of
- a) Cholesterol ester
- b) Phosphatides
- c) Chylomicrons
- d) Triacylglycerol
Explanation:
Depot fat (stored fat in adipose tissue) serves primarily as an energy reservoir for the body. It consists almost entirely (more than 90%) of triacylglycerols (also known as triglycerides), which are highly efficient, energy-dense molecules for long-term storage.
Why other options are incorrect:
Why other options are incorrect:
- • Cholesterol ester: Primarily found in cell membranes and as a precursor for steroid hormones, not as a primary energy depot.
- • Phosphatides: Also known as phospholipids; these are structural components of cell membranes.
- • Chylomicrons: These are transport vehicles (lipoproteins) used to carry dietary lipids through the blood and lymph, not a form of stored depot fat.
A fatty acid not synthesized in man is
- a) Oleic
- b) Palmitic
- c) Linoleic
- d) Stearic
Explanation:
Humans lack the specific desaturase enzymes (delta-12 and delta-15 desaturases) required to introduce double bonds at certain positions beyond carbon-9. Therefore, Linoleic acid (an omega-6 fatty acid) cannot be synthesized by the human body and must be obtained through the diet; it is classified as an “essential fatty acid.”
Why other options are incorrect:
Why other options are incorrect:
- • Oleic: A non-essential monounsaturated fatty acid that the human body can synthesize.
- • Palmitic: A saturated fatty acid that is the primary product of the fatty acid synthase complex in humans.
- • Stearic: A long-chain saturated fatty acid that can be synthesized by elongating palmitic acid.
The ‘free fatty acids’ (FFA) of plasma:
- a) metabolically inert
- b) mainly bound to β-lipoproteins
- c) stored in the fat
- d) mainly bound to serum albumin
Explanation:
Free fatty acids (also known as non-esterified fatty acids or NEFA) are hydrophobic molecules that circulate in the bloodstream. Because they are not soluble in plasma, they are mainly bound to serum albumin, which acts as a carrier protein to transport them from adipose tissue to various peripheral tissues for energy production.
Why other options are incorrect:
Why other options are incorrect:
- • Metabolically inert: On the contrary, plasma FFAs are highly metabolically active and represent a major energy source for the body.
- • Bound to β-lipoproteins: Lipoproteins primarily transport esterified lipids (like triglycerides and cholesterol), not free fatty acids.
- • Stored in the fat: FFAs in the plasma are the result of lipolysis occurring in adipose tissue; they are *released* from fat storage, not stored while in the plasma.
Adipose tissue which is a store house for triacyl glycerol synthesis the same using
- a) The glycerol released by hydrolysis of triacyl glycerol
- b) The glycerol-3-phosphate obtained in the metabolism of glucose
- c) 2-phosphoglycerate
- d) 3-phosphoglycerate
Explanation:
Adipose tissue lacks the enzyme glycerol kinase, meaning it cannot utilize free glycerol for triacylglycerol synthesis. Instead, it relies on glycerol-3-phosphate derived from the glycolytic intermediate dihydroxyacetone phosphate (DHAP) during glucose metabolism.
Why other options are incorrect:
Why other options are incorrect:
- • Glycerol released by hydrolysis: Because adipose tissue lacks glycerol kinase, it cannot phosphorylate free glycerol to reuse it.
- • 2-phosphoglycerate & 3-phosphoglycerate: These are intermediates of glycolysis that are further downstream and are not the direct precursor for the glycerol backbone of triacylglycerols.
Increase in blood of this class of lipoproteins is beneficial to ward off coronary heart disease:
- a) HDL
- b) LDL
- c) VLDL
- d) IDL
Explanation:
HDL (High-Density Lipoprotein) is often referred to as “good cholesterol.” It is beneficial because it performs “reverse cholesterol transport,” where it scavenges excess cholesterol from peripheral tissues and arteries and transports it back to the liver for excretion or recycling, thereby reducing the risk of plaque formation in the arteries.
Why other options are incorrect:
Why other options are incorrect:
- • LDL: Known as “bad cholesterol,” high levels contribute to atherosclerosis.
- • VLDL & IDL: These are also associated with the transport of triglycerides and cholesterol, and elevated levels are generally linked to a higher risk of cardiovascular complications.
In the extra mitochondrial synthesis of fatty acids, CO2 is utilized
- a) To keep the system anaerobic and prevent regeneration of acetyl CoA
- b) In the conversion of malonyl to CoA hydroxybutyryl CoA
- c) In the conversion of acetyl CoA to malonyl CoA
- d) In the formation of acetyl CoA from 1 carbon intermediates
Explanation:
In extra mitochondrial fatty acid synthesis, CO2 is utilized during the carboxylation of acetyl CoA to form malonyl CoA. This reaction is catalyzed by acetyl CoA carboxylase and requires ATP and biotin.
Why other options are incorrect:
Why other options are incorrect:
- • Anaerobic system: CO2 is not used to keep fatty acid synthesis anaerobic.
- • Malonyl CoA conversion: CO2 is released during the condensation steps of fatty acid synthesis rather than being utilized to form hydroxybutyryl CoA.
- • Acetyl CoA from 1-carbon intermediates: CO2 is not utilized for the formation of acetyl CoA from one-carbon intermediates.
Current concepts concerning the intestinal absorption of triacylglycerols are that
- a) They must be completely hydrolysed before the constituent fatty acids can be absorbed
- b) They are hydrolysed partially and the material absorbed consists of free fatty acids, mono and diacyl glycerols and unchanged triacyl glycerols
- c) Fatty acids with less than 10 carbon atoms are absorbed about equally via lymph and via portal blood
- d) In the absence of bile the hydrolysis of triacyl glycerols is absorbed
Explanation:
The current understanding of lipid digestion (the “partial hydrolysis” theory) indicates that pancreatic lipase does not hydrolyze triacylglycerols completely to glycerol and fatty acids. Instead, it produces a mixture consisting of 2-monoacylglycerols, free fatty acids, diacylglycerols, and some remaining triacylglycerols, all of which are incorporated into mixed micelles for absorption by the intestinal mucosa.
Why other options are incorrect:
Why other options are incorrect:
- • Option A: Total hydrolysis is not required; the enterocytes can absorb monoacylglycerols and resynthesize triglycerides.
- • Option C: Short- and medium-chain fatty acids (less than 10-12 carbons) are absorbed primarily via the portal blood, not equally via the lymph.
- • Option D: Bile is essential for emulsification; in the absence of bile, lipid digestion and absorption are significantly impaired, not “absorbed.”
Main metabolic end product of cholesterol:
- a) Coprosterol
- b) 5-pregnenolone
- c) Bile acid
- d) Glycine
Explanation:
The liver is the primary site for cholesterol catabolism. The major metabolic pathway for the excretion of cholesterol is its conversion into bile acids (such as cholic acid and chenodeoxycholic acid). These bile acids are then conjugated with glycine or taurine to form bile salts, which are essential for the digestion and absorption of dietary fats.
Why other options are incorrect:
Why other options are incorrect:
- • Coprosterol: This is a bacterial reduction product of cholesterol formed in the intestine, not a primary metabolic product synthesized by the body.
- • 5-pregnenolone: This is a precursor for steroid hormone synthesis, not the end-product of metabolic degradation.
- • Glycine: This is an amino acid used to conjugate bile acids, not a metabolic product of cholesterol itself.
In the type II (a) hyper lipoproteinemia there is increase in
- a) Chylomicron
- b) β-lipoprotein (LDL)
- c) Pre-β-lipoprotein (VLDL)
- d) α-lipoprotein (HDL)
Explanation:
Type IIa hyperlipoproteinemia (Familial Hypercholesterolemia) is characterized by an elevated concentration of β-lipoproteins, which correspond to LDL (Low-Density Lipoproteins). This condition is primarily due to a deficiency or dysfunction of LDL receptors, leading to high levels of plasma cholesterol.
Why other options are incorrect:
Why other options are incorrect:
- • Chylomicron: Elevated in Type I and Type V hyperlipoproteinemia.
- • Pre-β (VLDL): Elevated in Type IV hyperlipoproteinemia.
- • α-lipoprotein (HDL): This is the “good” cholesterol; an increase in this is generally protective, not a diagnostic marker for this specific hyperlipoproteinemia.
Normal fat content of liver is about _ gms %.
- a) 5
- b) 8
- c) 10
- d) 15
Explanation:
The normal fat content in a healthy human liver is approximately 5% by weight. When the fat content exceeds this limit, it is referred to as hepatic steatosis (fatty liver).
Why other options are incorrect:
Why other options are incorrect:
- • 8%, 10%, & 15%: These levels represent increased fat accumulation in the liver, which can lead to metabolic issues and inflammation if not addressed.
Obesity is accumulation of _ in the body.
- a) Water
- b) NaCl
- c) Fat
- d) Proteins
Explanation:
Obesity is defined as a medical condition in which excess body fat has accumulated to the extent that it may have a negative effect on health. It occurs when energy intake (calories from food) consistently exceeds energy expenditure.
Why other options are incorrect:
Why other options are incorrect:
- • Water & NaCl: Their retention leads to edema or fluid overload, not obesity.
- • Proteins: The body does not store excess protein as protein; instead, if consumed in excess, it is deaminated and the carbon skeletons are converted into fat for storage.
The first lipoprotein to be secreted by the liver is
- a) VLDL
- b) nascent VLDL
- c) LDL
- d) IDL
Explanation:
The liver secretes nascent VLDL into the bloodstream. These are considered “nascent” because they lack certain apolipoproteins (like Apo C and Apo E) in the blood, which they acquire later from circulating HDL to become “mature” VLDL.
Why other options are incorrect:
Why other options are incorrect:
- • VLDL: While correct in a broad sense, “nascent VLDL” is the more specific and scientifically accurate term for the particle immediately upon secretion.
- • LDL & IDL: These are derived from VLDL in the peripheral circulation through the action of lipoprotein lipase, not secreted directly by the liver.
This lipoprotein removes cholesterol from the body
- a) HDL
- b) VLDL
- c) IDL
- d) Chylomicrons
Explanation:
HDL (High-Density Lipoprotein) is responsible for “reverse cholesterol transport.” It picks up excess cholesterol from peripheral tissues (such as the walls of arteries) and transports it back to the liver, where it can be converted into bile acids and excreted from the body.
Why other options are incorrect:
Why other options are incorrect:
- • VLDL & IDL: These lipoproteins primarily transport triglycerides and cholesterol *to* the peripheral tissues.
- • Chylomicrons: These are responsible for transporting dietary lipids (triglycerides) from the intestines to the rest of the body.
When the stored triacylglycerol is lipolysed in the adipose tissue blood levels of _ increased.
- a) FFA only
- b) Glycerol only
- c) Free fatty acids (FFA) and Glycerol
- d) Triacylglycerol
Explanation:
Lipolysis of stored triacylglycerol in adipose tissue releases free fatty acids (FFA) and glycerol into the blood. FFA are transported mainly bound to albumin and used by tissues as an energy source, while glycerol is transported to the liver.
Why other options are incorrect:
Why other options are incorrect:
- • FFA only: Lipolysis also produces glycerol from the triacylglycerol molecule.
- • Glycerol only: Free fatty acids are also released during triacylglycerol breakdown.
- • Triacylglycerol: Triacylglycerol is broken down during lipolysis rather than being increased in the blood.
All long chain fatty acids with even number of carbon atoms are oxidized to a pool of _ by β-oxidation.
- a) CO2
- b) Propionic acid
- c) Acetic acid
- d) Acetyl CoA
Explanation:
The process of β-oxidation involves the sequential removal of two-carbon units from the carboxyl end of a fatty acid chain. For fatty acids with an even number of carbon atoms, these successive cleavages result in the formation of Acetyl-CoA units, which enter the citric acid cycle for energy production.
Why other options are incorrect:
Why other options are incorrect:
- • CO2: This is an end-product of the Citric Acid Cycle, not β-oxidation itself.
- • Propionic acid: This is produced during the oxidation of odd-chain fatty acids, not even-chain fatty acids.
- • Acetic acid: While Acetyl-CoA contains an acetyl group, the actual product released from the enzyme complex is the high-energy thioester Acetyl-CoA, not free acetic acid.
The level of free fatty acids in plasma is increased by
- a) Insulin
- b) Caffeine
- c) Glucose
- d) Niacin
Explanation:
Caffeine stimulates the mobilization of fatty acids from adipose tissue. It does this by inhibiting phosphodiesterase, which leads to increased levels of intracellular cyclic AMP (cAMP). This activates hormone-sensitive lipase (HSL), resulting in increased lipolysis and a subsequent rise in plasma free fatty acids.
Why other options are incorrect:
Why other options are incorrect:
- • Insulin: Inhibits lipolysis; it is a potent anti-lipolytic hormone.
- • Glucose: Promotes insulin secretion, which in turn suppresses lipolysis.
- • Niacin: Known to inhibit adipose tissue lipolysis, often used therapeutically to lower plasma FFA levels.
Cholesterol is excreted as such into __.
- a) Urine
- b) Faeces
- c) Bile
- d) Tears
Explanation:
Cholesterol is not catabolized to CO2 and water by the body. Instead, it is eliminated from the body by excretion into the bile as free cholesterol or as bile salts. Once in the intestine, a portion of this cholesterol is excreted from the body via the faeces.
Why other options are incorrect:
Why other options are incorrect:
- • Bile: While cholesterol is secreted *into* bile (it is the transit vehicle), the final excretion point from the human body is the faeces.
- • Urine: Cholesterol is not excreted in the urine under normal physiological conditions.
- • Tears: Not a route for cholesterol excretion.
LCAT is
- a) Lactose choline alamine transferse
- b) Lecithin cholesterol acyl transferase
- c) Lecithin carnitine acyl transferase
- d) Lanoleate carbamoyl acyl transferase
Explanation:
LCAT stands for Lecithin:cholesterol acyltransferase. It is an enzyme synthesized by the liver that circulates in the blood associated with HDL. Its primary function is to catalyze the transfer of a fatty acid from phosphatidylcholine (lecithin) to free cholesterol, forming cholesterol esters. This process is crucial for the maturation of HDL and the reverse cholesterol transport pathway.
Why other options are incorrect:
Why other options are incorrect:
- The other options are nonsensical combinations of biochemistry terms designed to distract from the correct enzymatic name.
Cholesterol molecule has _ carbon atoms.
- a) 27
- b) 21
- c) 15
- d) 12
Explanation:
Cholesterol is a sterol containing 27 carbon atoms. It has a four-ring steroid nucleus, a hydroxyl group, and a hydrocarbon side chain.
Why other options are incorrect:
Why other options are incorrect:
- • 21: This corresponds to the carbon skeleton of many C21 steroid hormones, not cholesterol.
- • 15: This is not the total carbon number of cholesterol.
- • 12: This is not the total carbon number of cholesterol.
A hydrocarbon formed in cholesterol synthesis is
- a) Mevalonate
- b) HMG CoA
- c) Squalene
- d) Zymosterol
Explanation:
Squalene is a long-chain hydrocarbon (C30H50) that serves as the immediate precursor for the cyclization process that forms the steroid nucleus. It is formed by the condensation of six isoprene units (farnesyl pyrophosphate).
Why other options are incorrect:
Why other options are incorrect:
- • HMG-CoA & Mevalonate: These are early stage intermediates in the cholesterol biosynthetic pathway, but they are not hydrocarbons.
- • Zymosterol: This is a sterol intermediate that appears much later in the pathway, after the cyclization of squalene has already occurred.
While citrate is converted to isocitrate in the mitochondria, it is converted to _ in the cytosol.
- a) Acetyl CoA + oxaloacetate
- b) Acetyl CoA + malonyl CoA
- c) Acetyl CoA + Pyruvate
- d) Acetyl CoA + acetoacetyl CoA
Explanation:
In the cytosol, citrate is cleaved by ATP-citrate lyase to produce Acetyl CoA and oxaloacetate. Acetyl CoA is then used mainly for fatty acid and cholesterol synthesis.
Why other options are incorrect:
Why other options are incorrect:
- • Acetyl CoA + malonyl CoA: Malonyl CoA is formed from Acetyl CoA by acetyl-CoA carboxylase; it is not a direct product of citrate cleavage.
- • Acetyl CoA + Pyruvate: Pyruvate is not produced when cytosolic citrate is cleaved.
- • Acetyl CoA + acetoacetyl CoA: Acetoacetyl CoA is involved in ketogenesis and cholesterol synthesis, but is not produced directly from citrate in the cytosol.
Avidin is antagonistic to
- a) Niacin
- b) PABA
- c) Biotin
- d) Pantothenic acid
Explanation:
Avidin is a protein present in raw egg white that binds strongly to biotin (vitamin B7), preventing its absorption in the intestine. Thus, avidin is antagonistic to biotin.
Why other options are incorrect:
Why other options are incorrect:
- • Niacin: Avidin does not specifically bind or inhibit niacin.
- • PABA: PABA is a precursor involved in folate synthesis in microorganisms and is not the target of avidin.
- • Pantothenic acid: Avidin does not interfere with the absorption or function of pantothenic acid.
CTP is required for the synthesis of
- a) Fatty acids
- b) Proteins
- c) Phospholipids
- d) Cholesterol
Explanation:
Cytidine triphosphate (CTP) is a high-energy nucleotide specifically required for the synthesis of glycerophospholipids (e.g., phosphatidylcholine and phosphatidylethanolamine). In the CDP-choline or CDP-ethanolamine pathways, CTP is used to activate the polar head group, forming a CDP-derivative (like CDP-choline) which is then reacted with diacylglycerol to form the phospholipid.
Why other options are incorrect:
Why other options are incorrect:
- • Fatty acids: Require ATP and NADPH.
- • Proteins: Require ATP and GTP.
- • Cholesterol: Requires ATP and NADPH.
Lysolecithin is formed from lecithin by the action of
- a) Phospholipase A1
- b) Phospholipase A2
- c) Phospholipase C
- d) Phospholipase D
Explanation:
Phospholipase A2 is an enzyme that specifically hydrolyzes the fatty acid ester bond at the sn-2 position of phospholipids (like lecithin/phosphatidylcholine). When this fatty acid is removed, the remaining molecule is called lysolecithin (or lysophosphatidylcholine).
Why other options are incorrect:
Why other options are incorrect:
- • Phospholipase A1: Removes the fatty acid at the sn-1 position.
- • Phospholipase C: Cleaves the bond between the glycerol and the phosphate group.
- • Phospholipase D: Cleaves the bond between the phosphate and the polar head group.
Fatty acids can not be converted into carbohydrates in the body, as the following reaction is not possible:
- a) Conversion of glucose-6-phosphate into glucose
- b) Fructose 1, 6 diphosphate to fructose-6-phosphate
- c) Transformation of acetyl CoA to pyruvate
- d) Formation of acetyl CoA from fatty acids
Explanation:
The primary reason fatty acids cannot be used for gluconeogenesis (conversion to glucose) in humans is that the reaction catalyzed by the Pyruvate Dehydrogenase complex—the conversion of pyruvate to acetyl CoA—is irreversible. Since acetyl CoA cannot be converted back into pyruvate, the carbon atoms from fatty acids (which enter as acetyl CoA) cannot be incorporated into the gluconeogenic pathway.
Why other options are incorrect:
Why other options are incorrect:
- • Option A & B: These are standard, reversible (or bypass) reactions that occur normally during glucose metabolism/gluconeogenesis.
- • Option D: This is the fundamental step of β-oxidation and occurs readily in the mitochondria.
Cholesterol circulates in blood stream chiefly as
- a) Free cholesterol
- b) Ester cholesterol
- c) Low density lipoproteins
- d) Low density lipoproteins and high density lipoproteins
Explanation:
Cholesterol circulates in the bloodstream mainly as part of lipoproteins, particularly LDL and HDL. LDL transports cholesterol from the liver to peripheral tissues, while HDL transports cholesterol from peripheral tissues back to the liver.
Why other options are incorrect:
Why other options are incorrect:
- • Free cholesterol: Only a smaller proportion of circulating cholesterol is present in the free form.
- • Ester cholesterol: Cholesteryl esters are a major form of cholesterol carried within lipoproteins, but the question asks about the lipoprotein carriers.
- • Low density lipoproteins: LDL is a major carrier of cholesterol, but HDL also carries cholesterol in the bloodstream.
What is the sub cellular site for the β-oxidation of fatty acids?
- a) Nucleus
- b) Mitochondria
- c) Lysosome
- d) Cytosol
Explanation:
The primary site for the β-oxidation of fatty acids is the mitochondria. After fatty acids are activated to acyl-CoA in the cytosol, they are transported into the mitochondrial matrix (via the carnitine shuttle) where they undergo the cycles of oxidation to produce Acetyl-CoA, NADH, and FADH2.
Why other options are incorrect:
Why other options are incorrect:
- • Cytosol: This is the site for fatty acid *synthesis*, not oxidation.
- • Nucleus & Lysosome: These organelles are not involved in the pathway of fatty acid β-oxidation.
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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