Biomolecules Class 11 MCQ

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

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

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

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

Correct Answer: 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.

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

Correct Answer: A. Carbohydrates. Carbohydrates are primary metabolites, not secondary metabolites.

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

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

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

Correct Answer: B. Rubber. Rubber is a terpenoid and is considered a secondary metabolite.

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

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

Correct Answer: C. Ricin. Ricin is a toxic lectin found in castor beans.

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

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

Correct Answer: B. They have a low molecular weight. Macromolecules have a high molecular weight.

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

Correct Answer: B. Glucose. Glucose is a simple sugar with a low molecular weight.

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

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

Correct Answer: 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.

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

Correct Answer: A. Collagen. Collagen is a structural protein found in connective tissues.

Correct Answer: B. RuBisCO. RuBisCO is an enzyme involved in photosynthesis.

Correct Answer: B. Insulin. Insulin is a hormone that regulates blood sugar levels.

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

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

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

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

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

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

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

Correct Answer: 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.

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

Correct Answer: B. Chitin. Chitin is a complex polysaccharide that provides structural support.

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

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

Correct Answer: D. Inulin. Inulin is a polysaccharide composed of fructose units.

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

Correct Answer: B. Nucleotides. Nucleic acids are polymers of nucleotides.

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

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

Correct Answer: B. Deoxyribose. Deoxyribose lacks an oxygen atom compared to ribose.

Correct Answer: D. Uracil. Uracil replaces thymine in RNA.

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

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

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

Correct Answer: A. Ribose. Ribose is a pentose sugar.

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

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

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

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

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

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

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

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

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

Correct Answer: C. 4. Hemoglobin consists of two alpha subunits and two beta subunits.

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

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

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

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

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

Correct Answer: A. An enzyme made of RNA. Ribozymes are catalytic RNA molecules.

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

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

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

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

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

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

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

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

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

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

Correct Answer: A. Optimal pH. Different enzymes have different optimal pH values.

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

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

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

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

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

Correct Answer: C. Oxidoreductases. Oxidoreductases catalyze the transfer of electrons between molecules.

Correct Answer: A. Transferases. Transferases move functional groups between molecules.

Correct Answer: B. Hydrolases. Hydrolases use water to break chemical bonds.

Correct Answer: A. Ligases. Ligases form new bonds between molecules.

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

Correct Answer: B. Apoenzyme. The apoenzyme is inactive without the cofactor.

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

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

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

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

Correct Answer: C. Niacin. Niacin is a precursor for NAD and NADP.

Correct Answer: A. Holoenzyme. The holoenzyme is the complete, active enzyme.

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

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

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

Correct Answer: B. NAD. NAD is a coenzyme involved in redox reactions.

Correct Answer: C. Zinc. Zinc is a cofactor for carboxypeptidase, a protease enzyme.

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

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