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Card 1
Which of the following elements is NOT among the most common atoms present in the large macromolecules of living organisms?
D. Sulfur. The most common atoms present in these molecules are carbon (C), hydrogen (H), oxygen (O), and nitrogen (N). Sulfur (S) and phosphorus (P) are mentioned as biomolecules that some contain, but not among the most common.
Card 2
What is the maximum number of electrons that the second electron shell of an atom can hold, which is relevant to carbon's bonding properties?
C. Eight electrons. The first electron shell can hold up to two electrons, and the second shell can hold a maximum of eight electrons.
Card 3
Which statement accurately describes the stability and energy requirements of covalent bonds in biological molecules?
A. Covalent bonds are the strongest bonds in biological molecules, requiring the greatest energy input to break them. This provides great stability to biological molecules.
Card 4
What type of carbon structure is represented by a continuous line of carbon atoms without any branching?
A. Chain. Carbon atoms can form stable chains, branched chains, and cyclic structures (rings).
Card 5
What is the primary reason for the tetrahedral arrangement of carbon's four covalent bonds?
B. The four pairs of electrons repel each other, positioning themselves as far apart as possible. This causes the four covalent bonds to point to the corners of a regular tetrahedron.
Card 6
What term is used to describe carbon compounds that contain carbon=carbon double bonds?
D. Unsaturated. Carbon compounds with carbon=carbon double bonds are known as unsaturated, introducing more variety to organic molecules.
Card 7
Which functional group is characteristic of carbohydrates, as mentioned in the context of biological functional groups?
A. Hydroxyl group. Carbohydrates contain the hydroxyl group, fatty acids contain the carboxyl group, and lipids contain the ester group.
Card 8
What is the chemically active part of a member of a series of organic molecules, which gives them their characteristic chemical properties?
B. Functional group. Functional groups are the chemically active parts of organic molecules that make them reactive and determine their unique physical and chemical properties.
Card 9
Which of the following is considered an organic molecule according to the definition provided?
C. Proteins. Organic molecules are defined as those made of carbon and hydrogen, such as urea, proteins, sugars, and lipids, which are found in living organisms. Carbon dioxide, carbonic acid, and hydrogen carbonate ions are explicitly stated as not considered organic.
Card 10
What is the name of the process where a new covalent bond is formed between monomers, and a molecule of water is produced?
A. Condensation. During condensation, a new covalent bond is formed, and a molecule of water is produced, linking monomers to form a polymer.
Card 11
What is the reverse process of condensation, which involves water molecules acting as a reactant to break a covalent bond?
B. Hydrolysis. Hydrolysis is the reverse of condensation, involving water molecules splitting a covalent bond to produce monomers.
Card 12
When two monosaccharide molecules combine to form a disaccharide, what type of linkage is formed between them after the removal of H–O–H?
C. Glycosidic linkage. The linkage formed between monosaccharide residues after the removal of H–O–H during a condensation reaction is called a glycosidic linkage.
Card 13
What is the role of enzymes in condensation reactions that form disaccharides?
B. Enzymes catalyze the reaction, significantly increasing its rate. Condensation reactions can happen slowly in the absence of enzymes, but catalysis by an enzyme greatly increases the rate.
Card 14
What is the primary characteristic of carbon that allows for the formation of diverse compounds upon which life is based?
A. Its ability to form four strong, stable covalent bonds. Carbon has four electrons in its second shell, enabling it to form four strong covalent bonds, which is crucial for molecular diversity.
Card 15
Which of the following is an example of a macromolecule?
D. Polysaccharide. Macromolecules are defined as very large organic molecules, including proteins, nucleic acids, and polysaccharides.
Card 16
How do intermolecular forces compare to covalent bonds in biological molecules?
A. Intermolecular forces are much weaker and can be easily broken and reformed. Covalent bonds are strong and require significant energy to break, while intermolecular forces are much weaker.
Card 17
Which of the following best describes an 'asymmetric' carbon atom?
C. A carbon atom with four different atoms or groups attached to its four bonds. This arrangement leads to molecules that can be mirror images of each other, contributing to variety.
Card 18
What is the definition of a 'double bond' in chemistry?
B. A chemical bond in which two pairs of electrons are shared between two atoms. This involves four bonding electrons, providing more variety to carbon compounds.
Card 19
Which of the following is NOT considered a fundamental quantity in the SI metric system?
D. Volume. Length (m), time (s), temperature (K), and mass (kg) are listed as fundamental quantities, while volume (m^3) is a derived quantity.
Card 20
What is the purpose of using metric multipliers (e.g., nano, micro, kilo) with SI units?
A. To express very large or very small numbers concisely. Metric multipliers are used to handle numbers encountered in ecology (large) and microscopy/biochemistry (small).
Card 21
In the context of organic molecules, what is the 'R-group'?
B. The remainder of the organic molecule, apart from the functional group, which has little effect on the functional group's chemical properties. The R-group is the part of the molecule that is not the functional group.
Card 22
What is the abbreviated unit for 'amount of substance' in the SI base units?
C. mol. The amount of substance is measured in moles, abbreviated as mol.
Card 23
Why is a measured quantity without units considered meaningless?
D. Units indicate what a given quantity is measured in, providing context and meaning. Without units, a numerical value lacks specific physical meaning.
Card 24
What is the significance of the fact that cell enzymes can distinguish between mirror-image forms of molecules like glyceraldehyde?
A. It highlights how the specific three-dimensional arrangement of atoms in organic molecules is crucial for biological recognition and function. Even with similar chemical properties, enzymes are highly specific to particular molecular forms.
Card 25
Which of the following statements about the formation and digestion of disaccharides is correct?
C. Disaccharides are formed by condensation reactions and digested by hydrolysis reactions, both typically catalyzed by different enzymes. Condensation forms the disaccharide with water as a product, and hydrolysis breaks it down with water as a reactant, each requiring specific enzymes.
Card 26
Which of the following describes the relationship between condensation and hydrolysis reactions in metabolism?
A. Condensation reactions form new covalent bonds and produce water, while hydrolysis reactions break covalent bonds by consuming water. They are essentially reverse processes, crucial for building and breaking down macromolecules.
Card 27
What is the primary role of enzymes in condensation and hydrolysis reactions?
D. Enzymes act as catalysts, significantly increasing the rate of both condensation and hydrolysis reactions. For example, amylase speeds up polysaccharide hydrolysis, and different enzymes catalyze the condensation and hydrolysis of disaccharides.
Card 28
Which of the following macromolecules are formed through condensation reactions?
C. Polysaccharides, polypeptides, and nucleic acids are all formed by condensation reactions. These reactions involve the joining of many monomer units, such as monosaccharides, amino acids, and nucleotides, respectively, with the removal of water.
Card 29
What is a glycosidic linkage?
B. A glycosidic linkage is a strong covalent bond formed between monosaccharide residues during condensation reactions to create disaccharides and polysaccharides. It is formed by the removal of a water molecule between two monosaccharide units.
Card 30
Which statement accurately describes the digestion of polymers in biological systems?
A. Polymers like starch, glycogen, and proteins are digested into their component monomers through hydrolysis reactions. These reactions involve the addition of water to break the covalent bonds linking the monomer units, often facilitated by specific enzymes.
Card 31
What is the general chemical formula for carbohydrates?
C. The general formula for carbohydrates is C x (H 2 O) y. This formula indicates that carbohydrates are composed of carbon, hydrogen, and oxygen, with hydrogen and oxygen typically in a 2:1 ratio, similar to water.
Card 32
Why is glucose considered an especially important monosaccharide in biology?
D. Glucose is vital because it is synthesized by green leaves, transported in the blood, used by all cells in respiration as a primary energy substrate, and serves as a building block for larger molecules like cellulose, starch, and glycogen.
Card 33
How does the structure of glucose contribute to its stability?
B. The carbon atoms in the glucose ring each have four covalent bonds, with an optimum angle of 109.5° between them. This angle results in a perfect tetrahedron, which is a very stable molecular structure.
Card 34
What is the definition of an isomer?
A. Isomers are compounds that possess the same component atoms in their molecules but differ in the arrangement of these atoms. This structural difference can lead to variations in their properties.
Card 35
What distinguishes D-glucose from E-glucose?
C. D-glucose and E-glucose are anomers, a type of geometric isomer where the positions of the –H and –OH groups attached to carbon atom 1 in the glucose ring interchange. These small structural differences are recognized by enzymes and can significantly impact polymer construction.
Card 36
Which of the following is an example of a disaccharide?
B. Maltose is a disaccharide, formed by the condensation reaction of two glucose molecules. Other examples include sucrose and lactose, which are also condensation products of two monosaccharides.
Card 37
What happens to a phosphodiester bond during the hydrolysis of a nucleic acid?
A. During the hydrolysis of a nucleic acid, the phosphodiester bond breaks. This bond links the 3' carbon of one sugar molecule to the 5' carbon of another sugar molecule, and its breakage with water forms 3 − OH − deoxyribose − 5 − PO 4 3 −.
Card 38
Why is glucose soluble in water and transportable in blood plasma?
D. Glucose is a polar molecule that dissolves in water due to the formation of hydrogen bonds with its slightly charged hydroxyl (–OH) groups. The attraction between water's oxygen ions and glucose's hydroxyl groups facilitates its solubility and transport.
Card 39
Which of the following is a characteristic of monosaccharides?
C. Monosaccharides are simple sugars with relatively small molecules. They typically taste sweet and are soluble in water, such as glucose and fructose.
Card 40
What is the significance of the prefix D- in carbohydrate names like D-fructose?
A. The prefix D- indicates that the molecule is an optical isomer. Optical isomers are mirror images of each other and rotate the plane of plane-polarized light in opposite directions; D- indicates rotation to the right.
Card 41
Which of the following describes the primary function of starch in plants?
A. Starch is the major storage carbohydrate in most plants, laid down as compact grains in plastids. Its usefulness comes from its compactness and insolubility, making it an ideal energy store that takes up little space and has no osmotic effects.
Card 42
What is the key difference in the structural composition between amylose and amylopectin?
D. Amylose is an unbranched chain of several thousand 1,4 linked α-glucose units, while amylopectin has shorter chains of 1,4 linked α-glucose units with additional branch points of α-1,6 glycosidic links.
Card 43
How does the structure of starch contribute to its effectiveness as an energy storage molecule in plants?
C. The bonds between glucose residues in starch bring the molecules together as a helix, stabilized by hydrogen bonds. This coiling and branching during polymerization make it compact and insoluble, allowing it to be stored efficiently without causing osmotic effects.
Card 44
Which of the following tests is used to identify the presence of starch?
B. Starch can be tested for with iodine, which forms a blue-black starch–polyiodide complex when iodine molecules fit into the center of the starch helix.
Card 45
What is the main characteristic that distinguishes glycogen from amylopectin?
A. Glycogen is chemically very similar to amylopectin, both being polymers of α-glucose, but glycogen is larger and more highly branched than amylopectin.
Card 46
Why is glycogen a useful store of energy in animal cells, particularly regarding its osmotic effects?
D. Glycogen is a useful store of energy because, like starch, it is insoluble. This insolubility means it has no osmotic effects, preventing water from being drawn into the cells, which would occur if individual glucose molecules were dissolved in the cytoplasm.
Card 47
How does the extensive branching in glycogen contribute to its function as an energy reserve?
C. The extensive branching in glycogen provides a compact structure for storing more glucose molecules in a small volume. Additionally, the many non-reducing ends resulting from branches allow for more rapid enzyme-controlled hydrolysis to release glucose when energy demand increases.
Card 48
Which of the following statements accurately describes the energy storage in brain cells?
A. Brain cells store virtually no energy reserves and instead require a constant supply of glucose directly from the blood circulation.
Card 49
What is the most abundant carbohydrate, making up over 50% of all organic carbon?
B. Cellulose is the most abundant carbohydrate, primarily found in the cell walls of green plants and plant debris in the soil.
Card 50
What type of glucose molecule is used in the synthesis of cellulose?
C. Cellulose molecules are a polymer of β-glucose molecules, combined together by glycosidic bonds between carbon-4 of one β-glucose molecule and carbon-1 of the next.
Card 51
How do β-glucose units arrange themselves in a cellulose molecule to form its characteristic structure?
A. In cellulose, successive β-glucose units are linked at 180º to each other, requiring one of the two β-glucoses to rotate relative to the other to ensure adjacent –OH groups point in the same direction for glycosidic bond formation.
Card 52
What structural features contribute to the extreme strength and durability of cellulose?
D. Cellulose molecules are straight and uncoiled, with hydrogen bonds stabilizing and strengthening adjacent glucose units within the same strand, between fibrils, and between parallel strands. In plant cell walls, additional strength comes from cellulose fibers being laid down in layers that run in different directions.
Card 53
Which of the following is a primary industrial use of cellulose fibers?
B. Cellulose fibers are used in various industrial applications, including as cotton, in the manufacture of paper, rayon fibers for clothes, nitrocellulose for explosives, cellulose acetate for fibers, and cellophane for packaging.
Card 54
What is the fundamental difference in function between starch/glycogen and cellulose, despite both being made of glucose?
A. Starch and glycogen are primarily used for energy storage, while cellulose is used for structural support and mechanical strength in plant cell walls, a difference stemming from the distinct orientation of their glucose isomers (α-glucose for starch/glycogen and β-glucose for cellulose).
Card 55
What is the glycocalyx and where is it found?
C. The glycocalyx refers to the carbohydrate components, specifically glycoproteins and glycolipids, found only on the outer surface of the plasma membrane, forming a 'sugar coating'.
Card 56
How do glycoproteins and glycolipids contribute to cell–cell recognition?
B. Glycoproteins and glycolipids, along with peripheral proteins, allow cells to recognize each other due to their unique shapes. This recognition function is crucial for the immune system to differentiate between 'self' and 'non-self' cells or tissues.
Card 57
Which statement best describes the role of hydrogen bonds in the stability of glucose's ring structure?
D. The provided text does not explicitly state that hydrogen bonds stabilize the glucose ring structure itself, but rather mentions that hydrogen bonds stabilize the whole starch molecule and cellulose structures. The stability of the glucose ring is attributed to the optimum 109.5° angle between covalent bonds, forming a perfect tetrahedron.
Card 58
What is the significance of glucose being a 'hexose'?
A. The term 'hexose' indicates that glucose is a 6-carbon sugar, as implied by its chemical formula C6H12O6, which specifies the number of carbon atoms in the molecule.
Card 59
How does the cyclic form of glucose relate to its linear form in solution?
B. Glucose can be folded into a ring (cyclic) form, and in solution, it can exist in equilibrium with its linear structural form, as depicted in structural formulas.
Card 60
What is an 'isomer' in the context of organic compounds like glucose?
C. Isomers are compounds that have the same component atoms and chemical formula but differ in the arrangement of these atoms, leading to variations in their structural formulae.
Card 61
What are anomers, and what is their significance in carbohydrate molecules?
A. Anomers are a type of geometric variation found at specific atoms in carbohydrate molecules, such as the alpha and beta forms of glucose, which arise from the interchange of –H and –OH groups attached to carbon atom 1. These minor structural differences are recognized by enzymes and can significantly affect polymer construction.
Card 62
What distinguishes optical isomers from other types of isomers?
D. Optical isomers are organic compounds that are mirror images of each other, possessing the same chemical properties but rotating the plane of plane-polarized light in opposite directions (D- form rotates right, L- form rotates left).
Card 63
Which of the following correctly describes a 'reducing sugar' in the context of the Benedict's test?
B. Reducing sugars, which include all monosaccharides and most disaccharides (except sucrose), reduce copper(II) sulfate in Benedict's reagent upon heating, producing an orange/red precipitate of copper(I) oxide.
Card 64
What information can be gathered from the color and density of the precipitate in a Benedict's test?
A. The color and density of the precipitate formed during a Benedict's test provide a semi-quantitative indication of the approximate amount of reducing sugar present in a sample.
Card 65
Why is the numbering of carbon atoms in organic molecules like glucose important?
C. Numbering carbon atoms allows for the identification of which specific atoms are affected when the molecule reacts and changes shape, such as when the oxygen on carbon-5 attaches to carbon-1 during glucose ring formation.
Card 66
Which of the following best describes the structural difference between starch and cellulose?
C. Starch is made from D-glucose molecules, while cellulose is made from E-glucose molecules, leading to different orientations of monomers and distinct overall structures. This difference in glucose isomer and orientation dictates their distinct functions.
Card 67
What is the primary function of cellulose in plants, and how does its structure contribute to this function?
A. Cellulose provides structural support and mechanical strength in plant cell walls. Its structure, with E-glucose molecules rotated 180° relative to each other and stabilized by hydrogen bonds between adjacent glucose units and parallel strands, forms strong, unbranched chains that contribute to its toughness.
Card 68
Which of the following is NOT a characteristic of cellulose due to its unique structure?
D. Cellulose is not primarily used for energy storage. Instead, it is an extremely strong, insoluble, tough, durable, and slightly elastic material, primarily serving structural roles in plants, unlike starch and glycogen which are for energy storage.
Card 69
In the context of cellulose formation, what is the significance of the 180° rotation of adjacent β-glucose molecules?
B. The 180° rotation of adjacent β-glucose molecules ensures that the -OH groups are pointing in the same direction, which facilitates the formation of hydrogen bonds within the same strand and between parallel strands. This arrangement stabilizes and strengthens the cellulose structure.
Card 70
Which of the following statements accurately describes the composition and location of the glycocalyx?
C. The glycocalyx is composed of short-chain polysaccharides attached to proteins (glycoproteins) and lipids (glycolipids) on the outer surface of the plasma membrane. It forms a 'sugar coating' on the cell's exterior.
Card 71
What is the primary role of the glycocalyx in cell-cell interactions?
A. The glycocalyx is crucial for cell-cell recognition, allowing cells to identify each other due to the unique shapes of its carbohydrate macromolecules. This function is vital for the immune system to distinguish 'self' from 'non-self' cells.
Card 72
Which of the following is a function of the glycocalyx related to chemical signaling?
B. The glycocalyx acts as receptor sites for chemical signals, such as hormone messengers. Its specific carbohydrate structures allow it to bind to these signals, initiating cellular responses.
Card 73
How does the glycocalyx contribute to the immune system's ability to differentiate between 'self' and 'non-self'?
C. The glycocalyx's carbohydrate formation is genetically determined, creating unique macromolecular shapes on the membrane surface. These specific shapes act as antigens, allowing the immune system to recognize and distinguish body cells from foreign cells or tissues.
Card 74
What is the definition of an antigen, as described in the context of the glycocalyx and immune response?
D. An antigen is a substance, often a glycoprotein or other protein, that can induce an immune response. It is recognized by the body as foreign ('non-self') and stimulates the immune system.
Card 75
Which of the following statements correctly distinguishes between antigens and antibodies?
A. Antigens are substances that can induce an immune response and can originate within or externally to the body, while antibodies are proteins produced within the body by lymphocytes that recognize and bind to specific antigens to aid in their removal.
Card 76
In the ABO blood group system, why is blood group O considered the universal donor?
B. Blood group O red blood cells have neither A nor B antigens on their surface. This absence of A and B antigens means they will not trigger an agglutination reaction when transfused into recipients with anti-A or anti-B antibodies, making them compatible with all blood types.
Card 77
A person with blood group A accidentally receives a transfusion of group B blood. What immediate reaction is likely to occur?
C. The anti-B antibodies naturally present in the recipient's (Group A) plasma will recognize the B antigens on the transfused red blood cells, causing the 'foreign' B cells to clump together, a process known as agglutination.
Card 78
What is the term for the process where red blood cells are clumped together by an antibody, as seen in incompatible blood transfusions?
A. The process in which red blood cells are clumped together by an antibody is called agglutination. This occurs when specific antibodies in the recipient's plasma bind to corresponding antigens on the donor's red blood cells.
Card 79
Which of the following is a key characteristic of lipids that describes their interaction with water?
B. Lipids are poorly soluble in water and generally behave as 'water-repelling' molecules, a property described as hydrophobic. They can, however, be dissolved in less-polar organic solvents.
Card 80
What are the primary building blocks of triglycerides?
C. Triglycerides are formed from the reaction between a trihydric alcohol called glycerol and three fatty acids. Fatty acids are long-chain carboxylic acids with long hydrocarbon 'tails'.
Card 81
What is the difference between saturated and unsaturated fatty acids?
A. Saturated fatty acids have no carbon-carbon double bonds in their hydrocarbon tail, meaning they are fully hydrogenated. Unsaturated fatty acids, in contrast, have one or more carbon-carbon double bonds in their hydrocarbon tail.
Card 82
Why are fatty acid molecules described as 'acids'?
D. Fatty acid molecules are described as 'acids' because their functional group (-COOH) tends to ionize slightly in aqueous solution, producing hydrogen ions (H+). This property is characteristic of an acid.
Card 83
Which of the following correctly identifies the type of bond formed when fatty acids react with glycerol to form a triglyceride?
B. When the carboxyl functional group of fatty acids reacts with the hydroxyl functional groups of glycerol to form a triglyceride, the bonds formed are known as ester bonds. This is a condensation reaction where water is removed.
Card 84
What is the main reason why triglyceride molecules aggregate into huge globules in the presence of water?
A. The hydrophobic properties of the long hydrocarbon tails present in triglycerides cause them to clump together (aggregate) into huge globules when in the presence of water. This is due to their insolubility in water.
Card 85
Which of the following statements about glycerol is correct?
C. Glycerol is a trihydric alcohol with three hydroxyl groups. It is not a fatty acid or a sugar, and it belongs to the alcohol family of organic compounds, acting as a component of triglycerides.
Card 86
How do fats and oils differ at room temperature (approximately 20 °C)?
B. At room temperature, oils are liquid, while fats are solid. This is the only difference between them, despite both being types of lipids.
Card 87
What is the typical length of the hydrocarbon tails found in fats and oils?
A. The long hydrocarbon tails present in fats and oils are typically about 16-18 carbon atoms long, although they can be any even number between 14 and 22.
Card 88
Why is it important for the match of antigens and antibodies to be perfect in a large blood transfusion?
D. For a large transfusion, a perfect match of antigens and antibodies is crucial to prevent agglutination. If incompatible blood is transfused, the recipient's antibodies will cause the donor's red blood cells to clump, blocking vessels and potentially being fatal.
Card 89
Which of the following industrial uses is directly derived from cellulose fibers?
A. Cellulose fibers are used as cotton and manufactured into paper. They are also used to make rayon fibers for clothes, nitrocellulose for explosives, cellulose acetate for various fibers, and cellophane for packaging.
Card 90
What is the 'common mistake' highlighted when discussing glucose isomers for starch, glycogen, and cellulose synthesis?
B. The common mistake is confusing D-glucose, used in the synthesis of starch and glycogen, with E-glucose, which is used in the synthesis of cellulose. It is important to refer to the correct specific isomer for each polysaccharide.
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