Biomolecules Class 11 MCQ

C. Carbon. The text states that living organisms have a higher relative abundance of carbon and hydrogen compared to the Earth’s crust.

A. Proteins. The acid-insoluble fraction primarily consists of proteins.

D. Elemental analysis. The text mentions that elemental analysis is performed to determine the elemental composition of a sample.

C. Biomolecules. Living organisms are primarily composed of organic compounds called biomolecules.

B. Presence of unique elements in living tissues not found in the Earth’s crust. The text states that all elements found in living tissues are also present in the Earth’s crust, but their relative abundance differs.

C. Essential for normal physiological processes. Primary metabolites are involved in essential functions like growth, development, and reproduction.

A. Carbohydrates. Carbohydrates are primary metabolites, not secondary metabolites.

B. Defense against herbivores. Many secondary metabolites, like toxins and lectins, help protect plants from herbivores.

B. Morphine. Morphine is an alkaloid derived from the opium poppy and is used as a pain reliever.

C. By acting as drugs, pigments, and flavoring agents. Secondary metabolites have various applications in medicine, industry, and food.

B. Rubber. Rubber is a terpenoid and is considered a secondary metabolite.

C. Imparting color to flowers and fruits. Pigments like carotenoids and anthocyanins give color to various plant parts.

A. By attracting pollinators. Essential oils often have strong fragrances that attract insects for pollination.

C. Ricin. Ricin is a toxic lectin found in castor beans.

C. They are not directly involved in essential physiological processes. Toxins are often produced for defense or competition, not for basic metabolic functions.

C. Their molecular weight. Macromolecules have a high molecular weight, typically over 1000 daltons.

B. They have a low molecular weight. Macromolecules have a high molecular weight.

A. They form large aggregates. Lipids aggregate to form larger structures, making them functionally similar to other macromolecules.

B. Glucose. Glucose is a simple sugar with a low molecular weight.

B. By the polymerization of monomers. Macromolecules are formed by joining repeating subunits called monomers.

D. Peptide bond. Peptide bonds link the carboxyl group of one amino acid to the amino group of another.

B. Essential amino acids cannot be synthesized by the body and must be obtained from the diet. Essential amino acids cannot be synthesized by the body and must be obtained from the diet.

A. Energy storage. While proteins can be metabolized for energy, their primary functions are not related to energy storage.

A. Collagen. Collagen is a structural protein found in connective tissues.

B. RuBisCO. RuBisCO is an enzyme involved in photosynthesis.

B. Insulin. Insulin is a hormone that regulates blood sugar levels.

B. By forming antibodies. Antibodies are proteins that recognize and neutralize foreign invaders.

B. To move molecules across cell membranes. Transport proteins facilitate the movement of molecules across cell membranes.

C. Collagen. Collagen is a major component of connective tissues, providing structural support.

B. Hemoglobin. Hemoglobin binds to oxygen in the lungs and carries it to the tissues.

B. Glucose. Glucose is a monosaccharide, the basic building block of polysaccharides.

B. Structural component of plant cell walls. Cellulose provides rigidity and strength to plant cells.

C. Glycogen. Glycogen is stored in the liver and muscles of animals.

B. The reducing end has a free anomeric carbon while the non-reducing end does not. The anomeric carbon is involved in forming glycosidic bonds.

B. Starch. The helical structure of starch allows it to trap iodine molecules, resulting in a blue color.

B. Chitin. Chitin is a complex polysaccharide that provides structural support.

D. All of the above. Homopolysaccharides are composed of a single type of monosaccharide.

A. Energy storage in plants. Starch is stored in granules within plant cells.

D. Inulin. Inulin is a polysaccharide composed of fructose units.

A. It does not have a helical structure. The lack of a helical structure prevents cellulose from trapping iodine molecules.

B. Nucleotides. Nucleic acids are polymers of nucleotides.

C. Amino acid. Amino acids are the building blocks of proteins, not nucleic acids.

A. Adenine and guanine. Purines have a double-ring structure.

B. Deoxyribose. Deoxyribose lacks an oxygen atom compared to ribose.

D. Uracil. Uracil replaces thymine in RNA.

D. Storage of genetic information. DNA and RNA carry the instructions for building and maintaining an organism.

C. Phosphodiester bond. Phosphodiester bonds link the phosphate group of one nucleotide to the sugar of another.

B. Cytosine and thymine. Pyrimidines have a single-ring structure.

A. Ribose. Ribose is a pentose sugar.

B. Nucleotides contain a phosphate group while nucleosides do not. Nucleosides consist of a nitrogenous base and a sugar.

A. The sequence of amino acids. The primary structure is simply the order of amino acids in the polypeptide chain.

C. Both A and B. Alpha-helices and beta-sheets are common secondary structures stabilized by hydrogen bonds.

C. Tertiary. The tertiary structure is the overall 3D shape of the polypeptide chain.

D. All of the above. Various interactions, including hydrogen bonds, disulfide bonds, and ionic interactions, contribute to the stability of the tertiary structure.

D. Quaternary. Some proteins consist of multiple polypeptide chains interacting with each other.

B. N-terminal amino acid. The N-terminal amino acid has a free amino group.

A. C-terminal amino acid. The C-terminal amino acid has a free carboxyl group.

D. All of the above. The tertiary structure is crucial for the protein’s activity and interactions.

C. 4. Hemoglobin consists of two alpha subunits and two beta subunits.

C. It determines the sequence of amino acids. The sequence of amino acids is the primary structure.

D. To catalyze biochemical reactions. Enzymes speed up chemical reactions within cells.

B. Active site. The active site is where the substrate interacts with the enzyme.

C. They increase the activation energy of a reaction. Enzymes lower the activation energy, making the reaction easier to start.

B. Enzyme catalysts are more specific. Enzymes typically catalyze only one or a few specific reactions.

A. An enzyme made of RNA. Ribozymes are catalytic RNA molecules.

A. Physical changes are reversible, while chemical changes are not. In a chemical change, the composition of matter is altered.

A. Increasing temperature increases the rate of reaction. Higher temperatures increase the kinetic energy of molecules, leading to more collisions.

A. A series of chemical reactions that occur in a specific sequence. Metabolic pathways involve a series of interconnected reactions.

C. End product. The end product is the final molecule produced in a metabolic pathway.

C. They always require enzymes to occur. While enzymes speed up reactions, many reactions can occur spontaneously, albeit at a slower rate.

C. Binding of the substrate to the enzyme’s active site. The substrate must first bind to the enzyme before the reaction can proceed.

B. Transition state. The transition state is a high-energy state that the substrate must reach to be converted into product.

B. By decreasing the activation energy. Enzymes lower the energy barrier that the substrate must overcome.

D. Activation energy. Activation energy is the energy needed to initiate a chemical reaction.

C. It is formed after the product is released. The enzyme-substrate complex is formed before the product is released.

A. Optimal pH. Different enzymes have different optimal pH values.

B. Increasing temperature can increase enzyme activity up to a certain point, after which activity declines. High temperatures can denature enzymes.

B. Enzyme activity reaches a maximum velocity (Vmax). At high substrate concentrations, all enzyme active sites become saturated.

C. Inhibitor. Inhibitors can bind to the active site or an allosteric site.

A. An inhibitor that binds to the active site and competes with the substrate. Competitive inhibitors resemble the substrate in structure.

C. 6. Enzymes are classified into six major classes based on the type of reaction they catalyze.

C. Oxidoreductases. Oxidoreductases catalyze the transfer of electrons between molecules.

A. Transferases. Transferases move functional groups between molecules.

B. Hydrolases. Hydrolases use water to break chemical bonds.

A. Ligases. Ligases form new bonds between molecules.

A. A non-protein component required for enzyme activity. Cofactors can be organic or inorganic molecules.

B. Apoenzyme. The apoenzyme is inactive without the cofactor.

B. A tightly bound cofactor. Prosthetic groups are usually permanently associated with the enzyme.

A. A loosely bound cofactor. Coenzymes often act as carriers of electrons or functional groups.

D. Activator. Activators are molecules that increase enzyme activity but are not considered cofactors.

D. All of the above. Metal ions can play various roles in enzyme activity.

C. Niacin. Niacin is a precursor for NAD and NADP.

A. Holoenzyme. The holoenzyme is the complete, active enzyme.

A. Heme. Heme is a prosthetic group found in enzymes like catalase and peroxidase.

B. They are tightly bound to the enzyme. Coenzymes are loosely bound and can be released after the reaction.

D. All of the above. Cofactors play various essential roles in enzyme function.

B. NAD. NAD is a coenzyme involved in redox reactions.

C. Zinc. Zinc is a cofactor for carboxypeptidase, a protease enzyme.

B. Its activity decreases. The cofactor is essential for the enzyme’s catalytic activity.

D. Increasing activation energy. Prosthetic groups, like all cofactors, help decrease activation energy.