All Free Biology MCQs with Answers

• A. Dextrose
• B. Lymph sugar
• C. Grape sugar
• D. Both A and C

Explanation: Glucose is also known as both dextrose and grape sugar, making Option D correct. Dextrose refers to glucose's property of rotating plane-polarized light to the right. Grape sugar is a term used because glucose is found in grapes. The term 'lymph sugar' is incorrect as it pertains to glucose's presence in lymph fluid, not as an alternate name for glucose.

• A. Monosaccharides
• B. Carbon atoms
• C. Amino acids
• D. Fatty acids

Explanation: The correct answer is that a glycosidic bond is present between monosaccharides. Glycosidic bonds are specific to carbohydrates, linking simple sugars together to form more complex carbohydrates. Carbon atoms form various types of covalent bonds, but glycosidic bonds specifically refer to the linkage between sugars. Amino acids are linked by peptide bonds, which are different from glycosidic bonds, and fatty acids form ester bonds when creating lipids, not glycosidic bonds.

• A. Mannose
• B. Galactose
• C. Maltose
• D. Raffinose

Explanation: The correct option is D. Raffinose is a trisaccharide, which means it is composed of three sugar units: glucose, galactose, and fructose. This structure differentiates it from monosaccharides like mannose and galactose, which each contain only one sugar unit. Maltose, on the other hand, is a disaccharide consisting of two glucose units, thus not fitting the definition of a trisaccharide.

• A. Glucose
• B. Galactose
• C. Fructose
• D. Ribose

Explanation: Glycogen is a storage form of energy in animals and is made up of repeating glucose units linked by a-1,4-glycosidic and a-1,6-glycosidic bonds. During hydrolysis, water is used to break these bonds, releasing glucose molecules. Therefore, the hydrolysis of glycogen yields glucose. The other sugars listed (galactose, fructose, and ribose) are not components of glycogen, thus they are not products of its hydrolysis.

• A. ATP
• B. Amino acid
• C. Glucose
• D. All of these

Explanation: Glucose is a simple sugar, a monosaccharide, and is a primary source of energy for cells. Glucose is broken down through cellular respiration to produce adenosine triphosphate (ATP), the energy currency of cells.Glucose is broken down through cellular respiration to produce adenosine triphosphate (ATP), the energy currency of cells.

• A. Lipids
• B. Carbohydrate
• C. Protein
• D. All of these

Explanation: Protein quaternary structure refers to the organization, number, and spatial arrangement of multiple folded protein subunits that assemble into a functional multi-subunit complex. This level of structure is crucial for the protein's biological activity, stability, and ability to interact with other molecules, as seen in hemoglobin, which consists of four subunits working together to transport oxygen efficiently.

• A. Cholesterol, Guanine
• B. Amino acid NH-2
• C. Nucleotide:Adenine
• D. Nucleoside: Uracil

Explanation: The given structure corresponds with the structure of ribose sugar. As it lacks a phosphoric acid it cannot be a nucleotide and is hence a nucleoside.

• A. Lactose
• B. Glycogen
• C. Starch
• D. Fructose

Explanation: Glycogen and starch are examples of polysaccharides while fructose is an example of monosaccharide.

• A. Primary structure
• B. Tertiary structure
• C. Secondary structure
• D. Quaternary structure

Explanation: The primary structure of a protein refers to the linear sequence of amino acids along the polypeptide chain. It is the specific order of amino acids that make up the protein. The primary structure serves as the foundation for the higher-order structures and overall function of the protein.

• A. tRNA
• B. rRNA
• C. mRNA
• D. Ribozyme

Explanation: Ribozyme is the only enzyme made of RNA.