All Free Biology MCQs with Answers

• A. Urease
• B. Lipase
• C. Maltase
• D. Protease

Explanation: Option A: Urease is an enzyme that catalyzes the hydrolysis of urea into ammonia and carbon dioxide. It is involved in the metabolism of nitrogen-containing compounds and is not directly related to the hydrolysis of fats. Option B: Lipase is the correct answer. Lipase is an enzyme that catalyzes the hydrolysis of fats, also known as lipids. It breaks down the ester bonds in triglycerides, the main components of dietary fats, into fatty acids and glycerol, allowing for their absorption and utilization by the body. Option C: Maltase is an enzyme that catalyzes the hydrolysis of maltose, a disaccharide formed by two glucose molecules. It breaks down maltose into individual glucose molecules, facilitating their absorption and metabolism. Option D: Protease is a general term for enzymes that catalyze the hydrolysis of proteins into smaller peptides or individual amino acids. Proteases are not directly involved in the hydrolysis of fats.

• A. Transport proteins
• B. Structural proteins
• C. Genetic proteins
• D. Regulatory proteins

Explanation: Option A: Hemoglobin falls under the category of transport proteins. These proteins are responsible for transporting various substances, such as oxygen, carbon dioxide, ions, and molecules, throughout the body. Hemoglobin, specifically found in red blood cells, carries oxygen from the lungs to the body tissues and assists in the transport of carbon dioxide from the tissues back to the lungs. Option B: Structural proteins provide support and shape to cells and tissues. Examples of structural proteins include collagen, keratin, and actin. These proteins contribute to the formation of various structures, such as connective tissues, hair, nails, and the cytoskeleton. Option C: Genetic proteins, also known as nucleoproteins, are involved in the storage, expression, and transmission of genetic information. They include DNA-binding proteins and histones, which play essential roles in DNA packaging and gene regulation. Option D: Regulatory proteins control and coordinate various cellular processes by interacting with other molecules, such as enzymes or DNA. They can regulate gene expression, cellular signaling pathways, and metabolic processes. Examples of regulatory proteins include transcription factors, hormones, and protein kinases.

• A. Coenzyme
• B. Co-factor
• C. Prosthetic group
• D. None

Explanation: Option A: Coenzymes are small organic molecules that assist enzymes in carrying out specific reactions. They often act as carriers of chemical groups or electrons during enzymatic reactions. While coenzymes are important for enzyme function, they are not considered the non-protein part of a conjugated protein. Option B: A Co-factor is a non-protein molecule or ion that is required for the proper functioning of an enzyme. Co-factors can be either inorganic ions, such as metal ions, or organic molecules. They help enzymes catalyze reactions by providing additional chemical groups or facilitating certain steps of the reaction. However, co-factors are not typically part of conjugated proteins. Option C: The prosthetic group refers to the non-protein component of a conjugated protein. It is a tightly bound molecule that is essential for the protein's structure and function. Prosthetic groups can be various types of molecules, such as metal ions or organic molecules like heme in hemoglobin. They play a crucial role in the protein's overall function and often participate directly in the protein's catalytic activity or ligand binding. Option D: This option indicates that none of the provided options is the correct answer. However, in this case, the correct answer is indeed option C, prosthetic group.

• A. Rickets
• B. Anaemia
• C. Heart disorders
• D. Stroke

Explanation: LDH-1 (lactate dehydrogenase-1) is an enzyme found in various tissues, including the heart, liver, kidneys, and red blood cells. It is an important diagnostic marker used in the assessment of certain medical conditions.In particular, elevated levels of LDH-1 are commonly associated with heart disorders, such as myocardial infarction (heart attack), congestive heart failure, and other forms of cardiac injury or damage. When the heart muscle is injured or stressed, it releases LDH-1 into the bloodstream, leading to an increase in its levels.Therefore, an increase in LDH-1 is often observed in patients with heart disorders, making it a useful indicator for assessing heart health and diagnosing related conditions.

• A. Peptide bond
• B. Phosphodiester linkage
• C. H-bonding
• D. Ether linkage

Explanation: The amino acids in proteins are held together by covalent peptide bonds, which are formed through a condensation reaction between the carboxyl group (-COOH) of one amino acid and the amino group (-NH2) of another amino acid, with the elimination of a water molecule. Phosphodiester linkage refers to the covalent bond that connects the 3' carbon atom of one nucleotide to the 5' carbon atom of another nucleotide in DNA and RNA molecules. Hydrogen bonding is a type of noncovalent bond that occurs between a hydrogen atom covalently bonded to an electronegative atom (usually nitrogen, oxygen, or fluorine) and another electronegative atom in a different molecule or within the same molecule An ether linkage refers to the covalent bond that connects an oxygen atom to two alkyl or aryl groups in an ether molecule. The oxygen atom is covalently bonded to each alkyl or aryl group via a single bond, resulting in an oxygen atom with two unshared pairs of electrons.

• A. Acid halides
• B. Binary compounds
• C. Esters
• D. Alkanes

Explanation: Fatty acids occur as esters of alcohols, rather than as alcohols themselves. Specifically, fatty acids are typically found as esters of glycerol in triglycerides, which are the main constituents of natural fats and oils

• A. Simple protein
• B. Derived proteins
• C. Conjugated proteins
• D. All of these

Explanation: Simple proteins are composed of only amino acid residues linked together by peptide bonds. Examples of simple proteins include albumins and globulins Proteoses, enzymes, and peptones are all types of derived proteins. Derived proteins are formed by the partial hydrolysis of a protein molecule. Proteins can be hydrolyzed by either acids or enzymes to yield smaller peptides and amino acids. Conjugated proteins, on the other hand, are proteins that contain non-protein components, such as lipids, carbohydrates, or metals, in addition to amino acid residues. Examples of conjugated proteins include hemoglobin, which contains an iron-containing heme group, and glycoproteins, which contain carbohydrate groups. This option is incorrect

• A. Lyases
• B. Hydrolases
• C. Ligases
• D. Transferases

Explanation: Lyases, also known as lyases, are a class of enzymes that catalyze the breaking of various chemical bonds in organic molecules, without the addition of water. They typically act on C-C, C-O, C-N, and other bonds, and are involved in various metabolic pathways, including the synthesis and degradation of carbohydrates, amino acids, and nucleotides. Hydrolases are a class of enzymes that catalyze the hydrolysis of various chemical bonds in organic molecules, using water as a co-substrate. Ligases are a class of enzymes that catalyze the joining of two molecules by forming a new chemical bond between them, often utilizing ATP as a source of energy. Transferases are a class of enzymes that catalyze the transfer of a chemical group from one molecule to another molecule.

• A. Animals
• B. Plants
• C. Human beings
• D. None

Explanation: Globulin proteins are found in animals, including humans. Globulins are a class of proteins commonly found in the blood plasma and serve various functions, such as transporting lipids, ions, and antibodies, among others. These proteins are an essential component of the immune system and play crucial roles in maintaining overall health in animals, including humans. Examples of globulins include immunoglobulins (antibodies), which are produced by the immune system to recognize and neutralize foreign substances in the body, and transport globulins, which bind to and transport molecules such as hormones, vitamins, and metals.

• A. Oxidoreductase
• B. Hydrolases
• C. Ligases
• D. Transferases

Explanation: Enzymes that bring about exchange of functional group are called Transferases. Transferases are a class of enzymes that catalyze the transfer of a functional group from one molecule to another. The functional group can be an atom, a group of atoms, or a molecule. Some examples of transferases include: Kinases: These enzymes transfer a phosphate group from ATP to another molecule. Glycosidases: These enzymes transfer a sugar group from one molecule to another. Aminotransferases: These enzymes transfer an amino group from one molecule to another. Transferases play an important role in many biological processes, including metabolism, cell signaling, and DNA repair.