Quick recall · 239 cards
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Identify the amino acids containing nonpolar, aliphatic R groups.
C · All of the mentioned
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Which of the following is responsible for specifying the 3D shape of proteins?
A · Primary structure
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How many amino acids make up a protein?
B · 20
There are 20 standard amino acids that polymerize via peptide bonds to form proteins. These include 9 essential ones. Option B (20) is correct.
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Which of the following molecules is a typical fatty acid?
C · A long straight-chain hydrocarbon with a carboxylic acid group at one end.
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The fatty acid represented by the formula CH3(CH2)2CH=CH(CH2)3CH=CH(CH2)9COOH is:
C · Linoleic acid (18:2 Δ9,12)
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Comparing an unsaturated fatty acid to a saturated fatty acid, you would expect:
B · The unsaturated fatty acid to have a lower melting point.
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The total number of essential vitamins required for the proper functioning of the human body is ______________.
(a) 12
(b) 13
(c) 15
(d) 22
B · 13
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Which vitamins are fat soluble vitamins?
B · A, D, E, K
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All of the following My Plate food groups are good sources of vitamin B12 except for:
C · Grains
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Fermentation microorganisms produce ____ and growth factors in the food.
(a) minerals
(b) vitamins
(c) calories
(d) energy
B · vitamins
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Compound X increases the rate of the reaction below. What is Compound X most likely to be?
A. An enzyme
B. A lipid molecule
C. An indicator
D. An ADP molecule
A · An enzyme
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True or False: Enzyme A is an allosteric enzyme inhibited by galactose. This means that galactose molecules bind permanently to the active site and prevent all substrate binding.
A. True
B. False
B · False
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Which of the following correctly describes the primary structure of a protein?
A · The sequence of amino acids in a polypeptide chain
The primary structure of a protein refers to the linear sequence of amino acids linked by peptide bonds in a polypeptide chain.
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Proteins classified as fibrous proteins have which of the following characteristics?
B · Long, insoluble, and structural in function
Fibrous proteins are typically long, insoluble proteins that serve structural roles like collagen and keratin.
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Which type of protein structure is stabilized primarily by hydrogen bonds between backbone atoms?
B · Secondary structure
Secondary structure involves alpha-helices and beta-pleated sheets stabilized mainly by hydrogen bonds between the peptide backbone atoms.
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Globular proteins typically differ from fibrous proteins in which of the following ways?
B · They are often soluble and involved in metabolic functions
Globular proteins are usually water-soluble and perform metabolic functions such as enzymes and transport molecules.
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Which one of the following protein classifications is based on the presence of prosthetic groups?
B · Conjugated proteins
Conjugated proteins contain prosthetic groups such as metal ions, carbohydrates, or lipids attached to the polypeptide chain.
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Which property of proteins is responsible for their ability to buffer changes in pH?
A · Their amphoteric nature
Proteins can act as buffers because their amino acid residues have both acidic and basic groups, allowing them to accept or donate protons.
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Isoelectric point (pI) of a protein is defined as the pH at which the protein:
D · Has no net electrical charge
The isoelectric point is the pH at which the protein's positive and negative charges balance, resulting in zero net charge.
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Which of the following is a characteristic of proteins that contributes to their emulsifying properties in food systems?
A · Presence of hydrophobic and hydrophilic groups within the molecule
Proteins contain both hydrophobic and hydrophilic regions enabling them to stabilize emulsions by interfacing with water and oil phases.
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How does the presence of disulfide bonds impact the properties of a protein?
B · Stabilizes tertiary and quaternary structures
Disulfide bonds form covalent links that stabilize the tertiary and quaternary protein structures, enhancing stability.
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Which part of an amino acid distinguishes it from other amino acids?
C · Side chain (R group)
The side chain (R group) varies among amino acids and determines their unique chemical properties.
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Which of the following amino acids is classified as essential in the human diet?
C · Leucine
Leucine is an essential amino acid that cannot be synthesized by the human body and must be obtained through diet.
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Which amino acid contains a sulfur atom in its side chain?
A · Methionine
Methionine contains sulfur in its side chain, which is important for protein structure and function.
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The amino acid proline is unique because its side chain:
B · Forms a ring structure with the amino group
Proline's side chain is bonded to the amino group, forming a ring that restricts polypeptide flexibility.
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One important biological function of proteins is to act as enzymes. Which feature enables proteins to perform this function?
B · The specificity of their three-dimensional active sites
Proteins function as enzymes due to their specific three-dimensional structures that form active sites for substrates.
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Which protein function is primarily involved in transport across cell membranes?
C · Transport proteins
Transport proteins facilitate the movement of molecules across cell membranes, such as hemoglobin carrying oxygen.
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Which of the following best explains why protein denaturation leads to loss of biological activity?
B · The three-dimensional structure is disrupted
Denaturation disrupts the protein's tertiary and secondary structures, destroying the active conformation needed for biological activity.
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Which factor does NOT typically cause protein denaturation?
D · Low salt concentration
Low salt concentration usually does not cause denaturation, while high temperature, extreme pH, and heavy metals disrupt protein structure.
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In an experiment, a protein loses its biological function after heating and cannot regain it upon cooling. This loss is due to:
B · Irreversible denaturation
Irreversible denaturation occurs when structural changes are permanent and the protein cannot refold into its native structure after heating.
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Which of the following methods is most suitable for determining the molecular weight of a protein?
B · SDS-PAGE electrophoresis
SDS-PAGE electrophoresis separates proteins based on molecular weight, allowing estimation of protein size.
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In the Biuret test for proteins, the violet color develops due to the reaction of copper ions with:
B · Peptide bonds
The Biuret test detects peptide bonds by forming a violet-colored complex with copper ions in alkaline solution.
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Which analytical method uses antibodies to detect and quantify specific proteins?
A · Western blotting
Western blotting uses specific antibodies to detect proteins separated by electrophoresis, enabling quantification and identification.
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Which digestive enzyme primarily acts on proteins in the stomach by cleaving peptide bonds?
B · Pepsin
Pepsin is the main proteolytic enzyme in the stomach that breaks peptide bonds under acidic conditions.
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In protein metabolism, which process converts amino acids into keto acids by removal of the amino group?
B · Deamination
Deamination removes the amino group from amino acids, producing keto acids important for energy production.
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Which of the following best describes the primary structure of a protein?
A · A linear sequence of amino acids linked by peptide bonds
The primary structure is the unique linear sequence of amino acids connected by peptide bonds in a protein.
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Proteins are classified based on their composition. Which category includes proteins composed of amino acids only?
B · Simple proteins
Simple proteins are made only of amino acids without any prosthetic groups, unlike conjugated proteins which contain non-protein components.
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Which of the following is a correct classification of proteins based on their shape?
A · Globular and Fibrous
Proteins are mainly classified into globular (spherical) and fibrous (elongated) shapes based on their physical structure.
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Which of the following amino acids is classified as acidic due to its side chain?
A · Glutamic acid
Glutamic acid contains a carboxyl group in its side chain, giving it acidic properties at physiological pH.
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Which amino acid is considered essential and cannot be synthesized by the human body?
A · Leucine
Leucine is an essential amino acid which humans must obtain from the diet because it cannot be synthesized internally.
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Which property of amino acids primarily allows proteins to act as buffers in food systems?
A · Presence of ionizable side chains
Ionizable side chains allow amino acids to accept or donate protons, enabling proteins to buffer pH changes effectively.
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Which amino acid is unique because its side chain forms a cyclic structure that restricts the flexibility of the protein chain?
A · Proline
Proline’s side chain bonds back to the amino group, producing a ring structure that restricts conformational freedom of polypeptides.
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Peptide bonds in proteins are formed between which functional groups of amino acids?
A · Carboxyl group and amino group
A peptide bond forms between the carboxyl group of one amino acid and the amino group of another, releasing a molecule of water.
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Which level of protein structure is characterized by local folding into alpha-helices and beta-sheets stabilized by hydrogen bonds?
A · Secondary structure
Secondary structure involves local folded structures such as alpha-helices and beta-sheets stabilized mainly by hydrogen bonds.
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Which of the following best defines the quaternary structure of a protein?
A · Arrangement of multiple polypeptide chains into a functional protein
Quaternary structure refers to the association of two or more polypeptide subunits to form a functional protein complex.
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The disruption of which bond type primarily leads to protein denaturation without breaking the primary structure?
A · Hydrogen bonds
Hydrogen bonds maintaining secondary and tertiary structures are broken during denaturation; peptide bonds (primary structure) remain intact.
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Which of the following is NOT a functional property of proteins in food systems?
B · Thermal conductivity
Thermal conductivity is a physical property unrelated to the functional roles of proteins in foods, unlike water binding, emulsification, and gelation.
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Which factor most influences protein solubility in food formulations?
A · pH relative to the protein's isoelectric point
Proteins have minimum solubility at their isoelectric point where net charge is zero; pH changes influence solubility accordingly.
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Which functional property of proteins allows them to stabilize oil-in-water emulsions in foods like mayonnaise?
A · Emulsification
Proteins act as emulsifiers by adsorbing at oil-water interfaces, stabilizing emulsions like mayonnaise.
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Which of the following external factors is most likely to cause protein denaturation during food processing?
A · High temperature
High temperatures disrupt hydrogen bonds and hydrophobic interactions, causing protein denaturation during cooking or pasteurization.
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Which of the following factors does NOT significantly contribute to protein denaturation?
A · Mild stirring at room temperature
Mild agitation at room temperature usually does not disrupt protein folding or denature proteins significantly.
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Which of the following chemical agents can cause irreversible denaturation of proteins by breaking disulfide bonds?
A · Mercaptoethanol
Mercaptoethanol reduces disulfide bonds (-S-S-), causing irreversible unfolding of the protein structure.
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Which essential amino acid is often limiting in cereal-based diets, thereby affecting nutritional quality?
A · Lysine
Lysine is typically the limiting amino acid in cereal proteins, making it a key focus in nutritional evaluation.
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What is the protein efficiency ratio (PER) used to assess in food science?
A · The effectiveness of protein to support growth
PER measures the ability of a protein to support body weight gain, reflecting its nutritional quality.
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Which amino acid is considered conditionally essential, becoming essential only under certain metabolic conditions?
A · Arginine
Arginine is conditionally essential, especially during growth phases or illness when endogenous synthesis is insufficient.
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Which method is commonly used to measure protein concentration by detecting peptide bonds via ultraviolet absorption?
A · UV spectrophotometry
UV spectrophotometry detects absorption primarily at 280 nm due to aromatic amino acids and peptide bonds, allowing protein quantification.
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SDS-PAGE is a technique used to analyze proteins based on which property?
A · Molecular weight
SDS-PAGE separates proteins by their molecular weight by denaturing them and imparting uniform negative charge.
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Which method involves nitrogen determination to estimate protein content in food samples?
A · Kjeldahl method
The Kjeldahl method estimates total protein by measuring nitrogen content and converting it using a factor.
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Which of the following best defines lipids?
B · Water-insoluble organic compounds including fats, oils, and waxes
Lipids are a group of organic compounds that are insoluble in water but soluble in organic solvents. They include fats, oils, waxes, and related compounds.
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Lipids are generally classified as simple lipids, compound lipids, and derived lipids. Which among the following is a compound lipid?
B · Phospholipids
Compound lipids contain additional groups like phosphate or sugars along with fatty acids and glycerol. Phospholipids have a phosphate group and are examples of compound lipids.
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Which class of lipids is characterized by esters of fatty acids and long-chain alcohols?
C · Waxes
Waxes are esters formed from long-chain fatty acids and long-chain alcohols, distinguishing them from other lipid classes.
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Refer to the chemical structure diagram below. What functional group is characteristic of all fatty acids?
B · Carboxyl group (-COOH)
All fatty acids have a carboxyl group (-COOH) attached to a hydrocarbon chain, which is responsible for their acidic properties.
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Which of the following correctly describes the difference between saturated and unsaturated fatty acids?
C · Saturated fatty acids have no double bonds; unsaturated fatty acids have one or more double bonds
Saturated fatty acids have all single bonds between carbon atoms, while unsaturated fatty acids have one or more double bonds.
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Which characteristic of fatty acids directly influences the melting point of lipids?
B · Degree of unsaturation and chain length
Fatty acids with longer chains and fewer double bonds (more saturated) have higher melting points than short chain or unsaturated fatty acids.
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The cis configuration in unsaturated fatty acids causes which of the following effects on its structure?
B · Kinked shape causing less efficient packing
The cis double bond introduces a kink in the fatty acid chain, preventing tight packing and thus lowering melting points.
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Which physical property of lipids is primarily responsible for their solubility characteristics in water?
C · Their hydrophobic hydrocarbon chains
Lipids are generally hydrophobic due to their long hydrocarbon chains, making them insoluble in water.
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Which of the following explains why the iodine value of a lipid is a measure of its unsaturation?
A · Iodine reacts with double bonds in fatty acids
Iodine reacts with the carbon-carbon double bonds in unsaturated fatty acids, and the quantity of iodine absorbed indicates the degree of unsaturation.
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Refer to the chart below showing melting points of various fatty acids with different chain lengths and saturation. Which fatty acid is likely to have the lowest melting point?
B · Oleic acid (C18:1 cis)
Oleic acid is a monounsaturated cis fatty acid, which reduces close packing and lowers melting point compared to saturated fatty acids.
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Which fatty acid type is considered essential because humans cannot synthesize it?
C · Polyunsaturated fatty acids like linoleic acid
Essential fatty acids, such as linoleic acid (an omega-6 PUFA), cannot be synthesized by humans and must be obtained from diet.
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Which of the following is a characteristic of saturated fatty acids?
C · Have no double bonds and are fully saturated with hydrogen
Saturated fatty acids have no double bonds and are fully saturated with hydrogen atoms, typically solid at room temperature.
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Which of the following fatty acid types is most susceptible to lipid oxidation leading to rancidity?
C · Polyunsaturated fatty acids
Polyunsaturated fatty acids have multiple double bonds that are prone to oxidation, causing rancidity.
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Which of the following is NOT a primary function of lipids in food?
C · Acting as enzymes for digestion
Lipids do not act as enzymes; enzymes are proteins. Lipids provide energy, essential fatty acids, and influence flavor and texture.
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Which of these roles is uniquely attributed to lipids in food systems compared to carbohydrates and proteins?
B · Emulsification and moisture retention
Lipids contribute to emulsification, aiding in mixing water and oil phases, and help retain moisture, influencing food texture.
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Which process initiates lipid rancidity primarily through reaction with oxygen?
B · Autooxidation
Autooxidation is the free radical reaction of unsaturated lipids with oxygen leading to rancidity.
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Which of the following factors accelerates lipid oxidation in food products?
C · Exposure to light and metal ions
Light and trace metal ions act as pro-oxidants accelerating lipid oxidation and rancidity.
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Which method is commonly used to determine the acid value indicating the extent of hydrolytic rancidity in lipids?
B · Titration with potassium hydroxide (KOH)
Acid value is determined by titrating lipid samples with KOH to measure free fatty acid content due to hydrolysis.
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Refer to the classification chart below. Which method is specifically used to separate and quantify individual fatty acids in a lipid sample?
B · Gas chromatography (GC)
Gas chromatography is used to separate fatty acid methyl esters to quantify individual fatty acids present in lipids.
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Which of the following methods measures the degree of unsaturation in lipids by measuring the amount of halogen absorbed?
C · Iodine value
Iodine value measures the amount of iodine absorbed by unsaturated bonds, indicating the degree of unsaturation in lipids.
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Which of the following is a simple lipid?
A · Triglycerides
Simple lipids are esters of fatty acids with alcohols. Triglycerides consist of glycerol esterified with three fatty acids, making them simple lipids.
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Which class of lipids contains a phosphate group in their structure?
B · Phospholipids
Phospholipids contain a phosphate group attached to the glycerol backbone, differentiating them from other lipid classes.
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Refer to the classification chart below. Which category includes lipids formed by a long-chain alcohol and fatty acid?
D · Waxes
Waxes are esters formed from long-chain fatty acids and long-chain alcohols, as indicated in the diagram.
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Which of the following is a characteristic feature of saturated fatty acids?
A · They contain only single bonds between carbon atoms
Saturated fatty acids have no double bonds between their carbon atoms, only single bonds, resulting in a straight chain structure.
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Which of the following fatty acids is polyunsaturated?
C · Linoleic acid
Linoleic acid contains two double bonds, making it a polyunsaturated fatty acid.
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Refer to the molecular structure below. Identify the type of fatty acid depicted.
A · Monounsaturated fatty acid
The diagram shows one double bond in the hydrocarbon chain, indicating a monounsaturated fatty acid.
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Which property of lipids is primarily responsible for their insolubility in water?
C · Hydrophobic hydrocarbon chains
The long hydrophobic hydrocarbon chains of lipids repel water, making them insoluble in aqueous environments.
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Which of the following chemical tests is used to detect unsaturation in lipids?
B · Bromine test
The bromine test detects double bonds in unsaturated lipids by decolorization of bromine water.
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Refer to the reaction mechanism below. What type of reaction is illustrated in the lipid oxidation process?
A · Free radical chain reaction
Lipid oxidation proceeds through a free radical chain mechanism, which initiates, propagates, and terminates with radicals.
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What does the fatty acid nomenclature 18:1(Δ9) indicate?
A · 18 carbons, 1 double bond at carbon 9
The notation 18:1(Δ9) means the fatty acid has 18 carbon atoms, one double bond located between carbon 9 and 10.
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Which fatty acid is classified as omega-3 based on its nomenclature?
A · Alpha-linolenic acid (18:3, n-3)
Omega-3 fatty acids have the first double bond at the third carbon from the methyl end; alpha-linolenic acid fits this classification.
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Refer to the diagram showing fatty acid chains with double bond positions. Which of these is a trans-fatty acid?
B · Trans-double bond between carbons 9 and 10
Trans-fatty acids have double bonds with hydrogen atoms on opposite sides of the carbon chain, as shown in the trans-double bond.
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Which is a major biological function of lipids?
C · Energy storage and insulation
Lipids serve as a major form of energy storage and provide thermal insulation in organisms.
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Which essential fatty acid must be obtained through diet due to its importance in human physiology?
B · Linoleic acid
Linoleic acid (an omega-6 fatty acid) is essential and must be obtained through dietary intake.
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Which lipid-related compound plays a key role in cell membrane fluidity?
B · Phospholipids with unsaturated fatty acids
Phospholipids containing unsaturated fatty acids increase membrane fluidity by disrupting tight packing.
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Which of the following factors accelerates lipid oxidation and rancidity?
C · Exposure to light and oxygen
Exposure to light and oxygen promotes free radical formation, accelerating lipid oxidation and rancidity.
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Which of the following is a common method used to inhibit lipid oxidation in food products?
B · Using antioxidants like BHT or BHA
Synthetic antioxidants such as BHT and BHA are added to food to prevent lipid oxidation and extend shelf life.
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Refer to the diagram depicting oxidative rancidity pathways. What is the primary reactive species initiating the oxidation?
D · Lipid radical
Lipid radicals initiate the chain reaction in oxidative rancidity by abstracting hydrogen atoms from fatty acids.
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Which solvent system is most commonly used for extraction of lipids from food samples?
B · Chloroform-methanol mixture
The chloroform-methanol solvent system (Folch method) effectively extracts a broad range of lipids from food samples.
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Which analytical method is used to determine the fatty acid composition after lipid extraction?
A · Gas chromatography
Gas chromatography analyzes fatty acid methyl esters, providing detailed information on fatty acid profiles.
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Which of the following vitamins is classified as water-soluble?
C · Vitamin C
Vitamin C is water-soluble, while vitamins A, D, and E are fat-soluble vitamins.
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Which vitamin belongs to the group of fat-soluble vitamins?
C · Vitamin K
Vitamin K is fat-soluble, while thiamine, riboflavin, and vitamin B12 are water-soluble vitamins.
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Which vitamin class is characterized by stability to heat and light but sensitivity to oxidation?
B · Fat-soluble vitamins
Fat-soluble vitamins like A, D, E, and K are generally more stable to heat and light but sensitive to oxidation compared to water-soluble vitamins.
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Which vitamin is a precursor of niacin and is often included in the vitamin B complex?
C · Niacin (Vitamin B3)
Niacin is Vitamin B3, part of the vitamin B complex; vitamins like pantothenic acid and pyridoxine are also B-complex vitamins but not precursors of niacin.
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Which vitamin's deficiency is associated with the disease beriberi?
A · Vitamin B1 (Thiamine)
Beriberi is caused by deficiency of Vitamin B1 (Thiamine), important in carbohydrate metabolism.
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Which of the following is NOT a fat-soluble vitamin?
B · Vitamin C
Vitamin C is water-soluble, while vitamins A, D, and E are fat-soluble.
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Which vitamin primarily aids in blood clotting and wound healing?
A · Vitamin K
Vitamin K is essential for synthesis of clotting factors and plays a key role in blood coagulation.
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Deficiency of which vitamin results in scurvy characterized by bleeding gums and poor wound healing?
A · Vitamin C
Vitamin C deficiency causes scurvy, which involves defective collagen synthesis leading to bleeding gums and delayed wound healing.
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Which vitamin plays a crucial role in calcium absorption and bone health?
A · Vitamin D
Vitamin D promotes calcium and phosphate absorption, essential for bone mineralization.
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Pyridoxine (Vitamin B6) is important for which of the following physiological functions?
B · Amino acid metabolism
Vitamin B6 acts as a coenzyme in amino acid metabolism and neurotransmitter synthesis.
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Excessive intake of which vitamin can lead to hypervitaminosis and toxicity symptoms?
A · Vitamin A
Vitamin A, being fat-soluble, can accumulate in the body causing toxicity, unlike most water-soluble vitamins.
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Which food is the best source of vitamin B12 (Cobalamin)?
C · Meat and animal products
Vitamin B12 is primarily found in animal-based foods such as meat, fish, and dairy products.
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Which disease is a direct result of niacin deficiency?
A · Pellagra
Pellagra is caused by niacin deficiency and is characterized by dermatitis, diarrhea, and dementia.
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Which vitamin is abundant in citrus fruits and important for collagen synthesis?
A · Vitamin C
Vitamin C is highly present in citrus fruits and is essential for collagen formation and antioxidant activity.
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Vitamin D deficiency primarily causes which of the following conditions?
A · Rickets
Vitamin D deficiency leads to rickets in children, characterized by defective bone mineralization.
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Which vitamin deficiency is linked with pernicious anemia?
A · Vitamin B12
Vitamin B12 deficiency leads to pernicious anemia due to impaired DNA synthesis in red blood cell precursors.
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Which mineral is classified as a macro-mineral essential for body functions?
C · Calcium
Calcium is a macro-mineral required in larger amounts compared to trace minerals like zinc, iron, and copper.
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Which of the following minerals is considered a trace mineral required in very small quantities?
C · Iron
Iron is a trace mineral needed in small quantities for oxygen transport and enzymatic reactions.
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Which mineral plays a critical role in thyroid hormone synthesis?
A · Iodine
Iodine is an essential component of thyroid hormones (T3 and T4).
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Which of the following minerals is stored primarily in bones and teeth, contributing to structural integrity?
B · Phosphorus
Phosphorus is a major mineral stored in bones and teeth, working closely with calcium to maintain bone structure.
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A deficiency of which mineral causes anemia due to impaired hemoglobin synthesis?
B · Iron
Iron deficiency leads to iron deficiency anemia as iron is a key component of hemoglobin.
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Which mineral is involved in the activation of many enzymes and supports immune function?
A · Zinc
Zinc is important for enzyme activity, wound healing, and immune system maintenance.
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Potassium is important for which of the following functions in the human body?
B · Nerve impulse transmission and muscle contraction
Potassium helps maintain electrical gradients required for nerve impulses and muscle contractions.
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Sodium and potassium together maintain the balance of which physiological parameter?
B · Blood pressure and fluid balance
Sodium and potassium regulate osmotic balance and blood pressure via fluid balance control.
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Which of the following minerals is a cofactor for antioxidant enzymes such as glutathione peroxidase?
B · Selenium
Selenium acts as a cofactor for antioxidant enzymes protecting cells from oxidative damage.
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Which mineral deficiency results in goiter and impaired cognitive development?
A · Iodine
Iodine deficiency causes goiter and can impair brain development, especially in infants.
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Which dietary sources are rich in calcium?
B · Milk and dairy products
Milk and dairy products are major dietary sources of calcium required for bones and teeth.
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Iron deficiency is most common in which of the following population groups?
A · Infants and menstruating women
Infants and menstruating women have higher iron requirements and are prone to iron deficiency anemia.
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Which of the following symptoms is most indicative of magnesium deficiency?
A · Muscle cramps and weakness
Magnesium deficiency can cause neuromuscular symptoms such as muscle cramps and weakness.
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What is the effect of excessive heat during food processing on water-soluble vitamins?
B · Degradation and loss increase
Water-soluble vitamins like vitamin C and B complex are sensitive to heat and often degrade during food processing.
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Which mineral is most likely to be lost due to leaching during washing and boiling of vegetables?
C · Potassium
Potassium is water-soluble and easily leached into cooking water during boiling or washing.
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Which vitamin is most susceptible to destruction by exposure to light during storage?
B · Vitamin C
Vitamin C is highly sensitive to light, oxygen, and heat, leading to rapid degradation.
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During food processing, which factor can improve vitamin retention?
B · Minimal processing and shorter cooking times
Minimal processing and shorter cooking times help retain vitamins by reducing exposure to heat and oxygen.
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How does the interaction between vitamin C and iron affect iron absorption?
B · Vitamin C enhances non-heme iron absorption
Vitamin C reduces ferric iron to ferrous form, thereby increasing non-heme iron absorption in the intestine.
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Excessive intake of calcium supplements can impair the absorption of which vitamin?
A · Vitamin D
High calcium levels can interfere with vitamin D metabolism and absorption.
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Which vitamin deficiency can impair the absorption of dietary iron leading to anemia?
C · Vitamin C
Vitamin C enhances iron absorption; its deficiency can lead to impaired iron uptake and anemia.
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Which processing method results in the highest loss of water-soluble vitamins but minimal loss of minerals?
A · Boiling
Boiling causes leaching of water-soluble vitamins into the cooking water; minerals are less affected due to their stability.
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Which of the following is a fat-soluble vitamin?
C · Vitamin A
Vitamin A is a fat-soluble vitamin, whereas Vitamins B12, B6, and C are water-soluble.
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Which vitamin is classified as a water-soluble vitamin?
C · Vitamin C
Vitamin C is water-soluble, while Vitamins D, K, and E are fat-soluble.
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Which vitamin primarily acts as an antioxidant protecting cell membranes from oxidative damage?
B · Vitamin E
Vitamin E is a major fat-soluble antioxidant that protects cell membranes from oxidative damage.
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Which vitamin plays a crucial role in blood clotting by synthesizing prothrombin?
A · Vitamin K
Vitamin K is essential for blood clotting as it is required for the synthesis of prothrombin.
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A deficiency in which vitamin primarily results in the disruption of vision, particularly night blindness?
B · Vitamin A
Vitamin A deficiency is linked to night blindness and other vision impairments.
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Which vitamin is synthesized in the skin upon exposure to sunlight and helps regulate calcium metabolism?
B · Vitamin D
Vitamin D is synthesized in the skin when exposed to ultraviolet light and plays an essential role in calcium metabolism.
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Which of the following foods is the richest natural source of Vitamin C?
B · Oranges
Oranges and other citrus fruits provide a high amount of Vitamin C.
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Which vitamin is predominantly found in animal liver and dairy products?
B · Vitamin A
Vitamin A is abundantly present in animal liver and dairy products.
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Which of the following is NOT a significant source of vitamin B12?
C · Leafy green vegetables
Vitamin B12 is primarily found in animal-derived foods; leafy green vegetables do not contain significant amounts.
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Which vitamin deficiency causes beriberi, characterized by neurological and cardiovascular symptoms?
A · Vitamin B1
Thiamine (Vitamin B1) deficiency results in beriberi.
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Which of the following diseases is caused by Vitamin C deficiency?
A · Scurvy
Scurvy is caused by a lack of Vitamin C, leading to defective collagen synthesis.
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Which vitamin deficiency is commonly responsible for the development of pellagra, characterized by dermatitis, diarrhea, and dementia?
A · Vitamin B3
Niacin (Vitamin B3) deficiency causes pellagra.
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Which vitamin deficiency can lead to rickets, a disease characterized by bone deformities in children?
A · Vitamin D
Vitamin D deficiency affects calcium metabolism causing rickets.
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Minerals are primarily classified into which two categories based on their required amounts in the human diet?
B · Macro and micro minerals
Minerals are classified into macro (major) minerals and micro (trace) minerals depending on the required dietary amounts.
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Which of these is considered a trace mineral essential in very small amounts for human health?
B · Iron
Iron is a trace mineral required in micro quantities, whereas calcium, potassium, and magnesium are macro minerals.
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Which mineral is classified as a macro mineral and plays an essential role in maintaining osmotic balance and nerve function?
B · Potassium
Potassium is a macro mineral vital for osmotic balance and nerve impulse transmission.
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Which of the following minerals is primarily involved in oxygen transport in the human body?
B · Iron
Iron is a key component of hemoglobin which transports oxygen.
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Which mineral is essential for thyroid hormone synthesis and metabolic regulation?
A · Iodine
Iodine is required for the synthesis of thyroid hormones controlling metabolism.
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Excess intake of which mineral can cause a toxicity condition known as hyperkalemia, affecting cardiac function?
B · Potassium
High potassium levels (hyperkalemia) can disrupt cardiac rhythm and function.
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Which of the following foods is an excellent source of calcium?
B · Milk
Milk and dairy products are rich sources of calcium.
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Iron is most abundantly found in which of the following food sources?
B · Red meat
Red meat is a major source of highly bioavailable heme iron.
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Which of these is NOT a good dietary source of zinc?
D · Refined sugar
Refined sugar does not provide zinc or significant minerals.
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Which mineral deficiency is linked to anemia, characterized by low hemoglobin and fatigue?
B · Iron
Iron deficiency is the most common cause of anemia.
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Excessive intake of which mineral can lead to fluorosis, causing mottled enamel and bone problems?
B · Fluoride
Fluoride toxicity causes fluorosis affecting teeth and bones.
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Which of the following is a symptom of magnesium deficiency?
A · Muscle cramps
Muscle cramps and spasms are common symptoms of magnesium deficiency.
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Excessive sodium intake can lead to which of the following health problems?
A · Hypertension
High sodium intake is linked to increased blood pressure (hypertension).
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Which factor primarily affects the bioavailability of iron in plant-based foods?
A · Presence of phytic acid and polyphenols that inhibit absorption
Phytic acid and polyphenols in plant foods chelate iron and reduce its absorption.
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Which vitamin enhances the absorption of non-heme iron when consumed together?
B · Vitamin C
Vitamin C improves the absorption of non-heme (plant-based) iron by reducing it to a more absorbable form.
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Which of the following conditions may reduce the bioavailability of fat-soluble vitamins from food sources?
B · Low bile secretion and fat malabsorption
Low bile secretion impairs micelle formation necessary for the absorption of fat-soluble vitamins.
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Which mineral’s absorption is inhibited by excessive calcium intake due to competitive uptake in the intestine?
B · Zinc
High calcium intake can inhibit zinc absorption due to competition for intestinal transporters.
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Excessive intake of zinc supplements may lead to deficiency of which other trace mineral due to competitive absorption?
A · Copper
High zinc intake interferes with copper absorption leading to deficiency.
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Excessive vitamin E intake may interfere with the metabolism of which vitamin, potentially increasing bleeding risk?
B · Vitamin K
High doses of vitamin E can antagonize vitamin K activity, affecting blood clotting.
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Which preservation method helps retain maximum vitamin C content in fruits and vegetables during processing?
B · Blanching followed by quick freezing
Blanching inactivates enzymes and quick freezing preserves vitamin C by reducing degradation.
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Which mineral is most susceptible to leaching losses during cooking in water?
B · Potassium
Potassium is water-soluble and often lost in cooking water.
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Which of the following factors does NOT significantly affect the stability of vitamins during food processing?
D · Carbohydrate content
Carbohydrate content does not directly affect vitamin stability; heat, light, and oxygen do.
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In the context of vitamin A stability, which of the following factors collectively accelerate its degradation in fortified milk during storage, considering its chemical nature and interaction with minerals?
B · High oxygen levels, presence of copper, and acidic pH
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Which of the following vitamin-mineral pairs incorrectly matches the primary vitamin active form with its mineral cofactor used in enzymatic function?
C · Pyridoxal phosphate (Vitamin B6) - Zinc
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Considering the role of folate and iron in hemoglobin synthesis, which of the following scenarios best explains anemia development related to an imbalance of these nutrients and the biochemical mechanism involved?
A · Iron deficiency with adequate folate leads to hypochromic microcytic anemia due to impaired heme synthesis
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What is the correct definition of water activity (a\_w) in foods?
B · The ratio of the vapor pressure of water in the food to that of pure water at the same temperature
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Which of the following values represents pure distilled water's water activity at room temperature?
C · 1.0
Pure distilled water at room temperature has a water activity (a\_w) of 1.0 by definition, as it is the reference state for measuring water activity.
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Water activity (aW) in food is best described as which of the following?
B · Energy status of water available for microbial growth and chemical reactions
Water activity represents the energy status of water available in the food for microbial growth and chemical reactions, not the total moisture content or heat content.
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Which method is commonly used for measuring water activity in foods?
B · Psychrometric dew point method
The psychrometric dew point method measures water activity by determining the relative humidity of air in equilibrium with the food sample, which relates directly to water activity.
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Refer to the diagram below showing a schematic of a dew point hygrometer used to measure water activity. What is the principle behind this instrument?
B · Measuring the temperature at which water vapor condenses (dew point) in air equilibrated with the food
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Which of the following factors does NOT influence water activity in foods?
C · Atmospheric pressure variations at sea level
Atmospheric pressure variations at sea level have negligible effect on water activity. Water activity is mainly influenced by temperature, solutes, and food matrix structure.
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Which statement best describes the impact of solute concentration on water activity?
B · Increasing solutes decreases water activity by binding free water
Increasing solute concentration in food reduces water activity by binding free water molecules, making them unavailable for microbial growth and reactions.
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Consider a food sample stored at increasing temperature. What is the most likely effect on its water activity (a\_w)?
C · Water activity increases with temperature increase
Water activity generally increases with temperature because vapor pressure increases, raising the ratio of vapor pressures in the food system.
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Which factor contributes most to lowering water activity in dried foods?
C · Binding of water by solutes like sugar or salt
Solutes like sugar or salt bind water molecules, reducing free water, thereby significantly lowering water activity in dried foods.
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Refer to the graph below showing microbial growth rate at different water activity levels. Which water activity range is most conducive for the growth of most bacteria?
B · Between 0.85 and 0.99 a\_w
Most bacteria require water activity above 0.85 to grow and proliferate efficiently. Lower values inhibit their growth.
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Which of the following microorganisms can grow at the lowest water activity?
B · Molds
Molds can grow at lower water activities (as low as 0.6) compared to most bacteria, which require higher water activities.
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Which water activity value generally inhibits the growth of most pathogenic bacteria in food?
B · Below 0.91
Pathogenic bacteria usually do not grow well below a water activity of 0.91, making this a critical control point in food preservation.
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Why does lowering water activity increase the shelf life of food products?
B · It reduces free water available for microbial growth and chemical reactions
Lowering water activity decreases free water availability, thus inhibiting microbial growth and slowing down spoilage and deterioration reactions, prolonging shelf life.
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Refer to the graph below showing relationship between water activity and shelf life for a dried food product. What happens to shelf life as water activity approaches 0.6?
C · Shelf life increases significantly
As water activity decreases (for example toward 0.6), the shelf life of dried food significantly increases due to less microbial growth and slower chemical deterioration.
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Which of the following chemical changes in food is most likely to be slowed by reducing water activity?
B · Maillard browning reaction
Reducing water activity limits Maillard browning reaction since it depends on the availability of water for reactant mobility and interaction.
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What water activity range is typically targeted to maximize shelf life without freezing in dried food products?
C · 0.60 - 0.70
Water activity between 0.60 and 0.70 is optimal for many dried foods to minimize microbial growth but maintain product texture and avoid freezing.
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How does water activity primarily affect the texture of dry crisp foods like crackers?
B · Higher water activity causes them to lose crispiness by moisture uptake
Higher water activity causes moisture absorption, leading to loss of crispness and texture degradation in dry foods like crackers.
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Which of the following quality attributes in fruits is most influenced by water activity levels?
B · Firmness and juiciness
Water activity affects texture-related quality parameters like firmness and juiciness in fruits by controlling the water available in tissues.
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Which of the following effects occur when water activity in meat products is lowered?
A · Tougher texture and reduced microbial spoilage
Reducing water activity in meat leads to tougher texture due to less free water and enhances preservation by reducing microbial spoilage.
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How does controlled water activity modification improve the shelf life of bakery products?
B · By reducing water activity to prevent mold growth and staling
Reducing water activity in bakery items limits mold growth and staling reactions, thereby extending shelf life while maintaining acceptable texture.
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Which processing method is used to control water activity by physically removing water from foods?
B · Drying
Drying physically removes water, reducing moisture and water activity, which controls spoilage and extends shelf life.
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Refer to the flow diagram below depicting water activity control methods in food processing. Which stage is responsible for adding solutes to lower a\_w?
B · Sugar/Salt addition
Adding sugar or salt binds free water reducing water activity, which is a common method to preserve foods.
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Which of the following is NOT an effective approach to reduce water activity in foods during processing?
C · Adding excess free water
Adding excess free water increases water activity rather than reducing it; thus, it is not effective for water activity control.
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Why is vacuum packaging useful for controlling water activity in food products?
B · It prevents moisture migration and reduces oxygen exposure, indirectly controlling a\_w
Vacuum packaging reduces oxygen and moisture movement, which helps maintain water activity and improve shelf life.
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If two food samples have identical moisture content but different water activities, what can be inferred?
A · They have different amounts of free water available for microbial growth
Different water activities despite identical moisture content imply different free water availability, which influences microbial growth and shelf life.
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Which parameter is more critical to control microbial growth in food preservation?
B · Water activity
Water activity is directly related to microbial growth potential and is more critical to control in food preservation than moisture content alone.
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Refer to the schematic below illustrating a sorption isotherm graph for a food product. Which region indicates a high water activity with relatively low moisture content?
C · Capillary condensation region (high a\_w, moderate moisture)
The capillary condensation region shows relatively low moisture content but high water activity due to physical state of water, indicating a critical region for stability.
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Which preservation technique relies primarily on reducing water activity to inhibit microbial growth?
C · Drying and dehydration
Drying and dehydration remove free water and thus lower water activity, inhibiting microbial growth and improving preservation.
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How does adding solutes like salt or sugar aid in food preservation with respect to water activity?
B · By lowering the water activity through binding free water
Salt and sugar lower water activity by binding free water molecules, reducing water available for microbial metabolism.
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Refer to the graph below showing a\_w levels of various foods and their corresponding preservation methods. Which method is best for foods with a water activity above 0.9?
A · Freezing
Foods with water activity above 0.9 are best preserved by freezing to inhibit microbial growth as drying or humectants are less effective at those levels.
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Which type of food preservation method involves lowering water activity by fermentative conversion of sugars?
B · Fermentation (e.g., pickling)
Fermentation reduces available sugars and water activity by converting sugars to organic acids, enhancing preservation.
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How does refrigeration affect water activity in most foods?
B · It has little effect on water activity but slows microbial growth
Refrigeration slows microbial growth by lowering temperature but usually does not significantly change water activity, unless freezing occurs.
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Which of the following best defines food enzymes?
A · Proteins that catalyze chemical reactions in food systems
Food enzymes are proteins that act as biological catalysts, speeding up chemical reactions without being consumed.
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Food enzymes are primarily classified based on which criterion?
B · The type of reaction they catalyze
Enzymes are classified by the type of biochemical reaction they catalyze, such as oxidoreductases, hydrolases, lyases, etc.
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Which class of enzymes primarily catalyzes the breakdown of starch in food?
B · Amylases
Amylases hydrolyze starch molecules into sugars, facilitating starch breakdown during food processing.
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Which of the following statements is TRUE regarding the classification of food enzymes?
B · Lyases break chemical bonds by means other than hydrolysis or oxidation
Lyases catalyze the cleavage of bonds by means other than hydrolysis and oxidation, often forming double bonds or rings.
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Which of the following is the most appropriate classification for an enzyme that catalyzes the oxidation of phenolic compounds in food browning reactions?
B · Oxidoreductase
Oxidoreductases catalyze oxidation-reduction reactions; polyphenol oxidase is an oxidoreductase involved in browning.
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Which source is NOT a common origin of food enzymes used in the food industry?
D · Synthetic polymers
Food enzymes are derived from microbial, plant, or animal sources; synthetic polymers are not enzyme sources.
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Which characteristic is common to microbial enzymes that make them advantageous in food processing?
B · They have high stability and specificity
Microbial enzymes often have high activity, stability, and specificity and can be produced in large quantities.
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Which of the following enzyme sources is best suited for industrial-scale enzyme production due to rapid growth and ease of manipulation?
B · Fungal cultures
Fungal cultures like Aspergillus species grow rapidly and can be easily manipulated, facilitating large scale enzyme production.
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Which statement about characteristics of food enzymes is FALSE?
C · Enzymes are consumed in the reactions they catalyze
Enzymes are catalysts and are not consumed or permanently changed during the reaction.
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Refer to the diagram below showing an enzyme-substrate complex. Which step correctly represents the formation of the enzyme-substrate complex?
A · Substrate binds to enzyme's active site
The initial step in the mechanism is substrate binding the enzyme's active site forming the enzyme-substrate complex.
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Which step in enzyme action involves the conversion of substrate to product within the enzyme-substrate complex?
B · Catalytic action
Catalytic action is the step where the enzyme facilitates substrate conversion to product while in the complex.
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Which theory best explains the specificity of enzyme-substrate interaction?
A · Lock and Key model
The Lock and Key model suggests the substrate fits exactly into the enzyme's active site like a key into a lock, explaining specificity.
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Which of the following best describes the induced fit model of enzyme action?
A · Enzyme active site changes shape upon substrate binding
The induced fit model describes enzyme's active site reshaping to fit the substrate for better catalysis.
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Which factor does NOT significantly affect enzyme activity in food systems?
D · Color of the enzyme solution
Color of enzyme solution does not influence enzyme activity; temperature, pH, and substrate concentration do.
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Refer to the graph below showing enzyme activity versus temperature. What does the peak of the curve represent?
A · Optimal temperature for maximum enzyme activity
The peak corresponds to the optimal temperature at which enzyme activity is highest before denaturation occurs.
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Which of the following is NOT a factor affecting enzyme activity?
D · Color of the food product
Color of food product does not affect enzyme activity, whereas substrate concentration, pH, and activators do.
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How does pH affect enzyme activity in food processing?
A · Enzymes function optimally at a specific pH and denature outside this range
Enzymes have an optimal pH range for activity, with deviation causing denaturation or decreased function.
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Increasing substrate concentration generally causes enzyme activity to:
C · Increase until enzyme saturation is reached
Enzyme activity increases with substrate concentration until all active sites are occupied at saturation level.
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Which of the following usually describes the effect of temperature beyond the enzyme's optimum?
B · Enzyme denaturation occurs reducing activity
Temperatures above optimum cause enzyme denaturation, leading to loss of structure and activity.
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Which of these is NOT an application of enzymes in the food industry?
C · Preservation of food by addition of antibiotics
Antibiotic addition is not an enzymatic application; enzymes help in quality improvement and processing.
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Which enzyme is commonly used in cheese production to coagulate milk proteins?
B · Rennet (chymosin)
Rennet contains chymosin, a protease that coagulates casein proteins in milk, essential for cheese making.
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Enzymes like pectinases are used in juice clarification mainly because they:
B · Break down pectin substances causing turbidity
Pectinases hydrolyze pectin, reducing turbidity and improving juice clarity.
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Which pair of enzyme application and its primary function in the food industry is INCORRECT?
D · Cellulases - Increase sweetness of fruit juice
Cellulases break down cellulose but do not directly increase sweetness; amylases hydrolyze starch to sugars for sweetness.
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What is the main industrial use of invertase in the food sector?
A · Converting sucrose into glucose and fructose to enhance sweetness
Invertase hydrolyzes sucrose into glucose and fructose, which are sweeter and improve product consistency.
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Which of the following is a common method to inhibit enzyme activity in foods?
A · Heating above optimum temperature (pasteurization)
Heating can denature enzymes, inhibiting their activity and preventing spoilage reactions.
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Which type of enzyme inhibitor binds to the enzyme's active site and directly competes with the substrate?
B · Competitive inhibitor
Competitive inhibitors resemble substrate molecules and bind reversibly to the enzyme active site, blocking substrate binding.
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Which enzyme inhibition method would be considered irreversible in food processing?
A · Binding of heavy metals like mercury to enzyme sulfhydryl groups
Heavy metals can bind covalently and irreversibly to critical enzyme groups, permanently inhibiting activity.
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Which method is NOT a typical control strategy to inhibit undesirable enzyme activity in foods?
C · Increasing enzyme concentration
Increasing enzyme concentration would increase activity, not inhibit it; other options reduce enzyme activity.
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Which inhibitor type binds to a site other than the active site and changes enzyme conformation?
C · Non-competitive inhibitor
Non-competitive inhibitors bind allosterically and alter enzyme shape, reducing activity regardless of substrate presence.
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Which of the following best describes enzyme denaturation?
A · Permanent loss of enzyme’s tertiary and quaternary structure, abolishing activity
Denaturation disrupts the enzyme’s native conformation leading to permanent loss of activity.
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Which factor generally increases enzyme stability in food processing?
A · Low storage temperature
Low temperatures slow down enzyme denaturation and preserve stability over longer periods.
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Refer to the flowchart below depicting enzyme action and denaturation processes. Which step indicates irreversible loss of enzyme activity due to heat?
A · Denaturation
Denaturation corresponds to irreversible unfolding of enzyme structure, leading to loss of function.
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Which statement correctly describes enzyme stability in relation to temperature?
A · Stability decreases at temperatures above enzyme’s optimum
Elevated temperatures above optimum cause unfolding and decreased stability of enzymes.
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Which factor often leads to reversible enzyme denaturation rather than permanent inactivation?
A · Mild heat treatment below optimum
Mild heat denaturation may be reversible upon cooling, while extreme conditions cause permanent damage.
