All Free Biology MCQs with Answers

4621. Sugar found in genetic material is :

• A. Hexose sugar
• B. Tetrose sugar
• C. Pentose sugar
• D. Triose sugar

Explanation: C is correct. DNA and RNA consists of a pentose sugar (ribose). Pentose sugar is a fundamental component of genetic material, as it is found in both DNA and RNA. The pentose sugar in DNA is called deoxyribose, while the pentose sugar in RNA is called ribose. Role in genetic material: Pentose sugars form the backbone of the nucleic acid strands, linking nucleotides together through phosphodiester bonds

4622. The total number of amino acids the alpha chain of insulin are:

• A. 20
• B. 21
• C. 30
• D. 51

Explanation: The correct answer is B: 21. The alpha chain of insulin is composed of 21 amino acids, while the beta chain contains 30 amino acids. Together, they make up the total of 51 amino acids in the insulin molecule. The other options incorrectly identify either the number of amino acids in the alpha chain or confuse it with the beta chain or the total number of amino acids in insulin.

4623. Which one is found only in RNA?

• A. Cytosine
• B. Uracil
• C. Adenine
• D. Guanine

Explanation: The correct answer is B: Uracil. Uracil is a unique nitrogenous base found only in RNA. In contrast, DNA contains thymine instead of uracil. The other options, cytosine, adenine, and guanine, are present in both RNA and DNA, making them incorrect choices for this question.

4624. The most common carbohydrate monomer is:

• A. Maltose
• B. Glucose
• C. Lactose
• D. Galactose

Explanation: Glucose is the most common carbohydrate monomer, known as a monosaccharide. It plays a crucial role in providing energy to the body as it is readily used in cellular respiration. Maltose and lactose are disaccharides, composed of two monosaccharide units, and therefore do not qualify as monomers. Although galactose is also a monosaccharide, it is less prevalent than glucose in the context of common carbohydrate monomers.

4625. Which forms nails, hair and feathers?

• A. Fibrin
• B. Collagen
• C. Keratin
• D. Elastin

Explanation: The correct answer is Keratin. It is the major protein found in the epidermis of the skin, hair, wool, feathers, horn, and nails, providing structure and protection. Fibrin is involved in blood clotting, Collagen is found in connective tissues, and Elastin provides elasticity, none of which are responsible for forming nails, hair, or feathers.

4626. The most important type of RNA in cells is:

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

Explanation: The most important type of RNA in cells is messenger RNA (mRNA). mRNA is essential because it carries the genetic code from the DNA in the nucleus to the ribosomes in the cytoplasm. This code is presented in the form of codons-three-nucleotide sequences-each specifying a particular amino acid. During protein synthesis, mRNA serves as a template for assembling a sequence of amino acids to form a protein. While ribosomal RNA (rRNA) and transfer RNA (tRNA) are also crucial for protein synthesis, rRNA as part of the ribosome's structure and tRNA in transporting amino acids, they do not convey genetic information like mRNA does. cRNA is not a standard type of RNA involved in cellular processes.

4627. Which of the following statement is not true for compounds like glycoproteins and glycolipids?

• A. Both are conjugated molecules
• B. Both are synthesized in the endoplasmic reticulum
• C. Component of biological membrane
• D. Both are components of the extracellular matrix of animal cell membrane

Explanation: Glycoproteins and glycolipids are synthesized in golgi apparatus.Glycoproteins are synthesized in the Golgi apparatus through the modification of existing proteins, a process that involves trimming sugar residues and adding new ones. Proteins arrive from the endoplasmic reticulum (ER) with an initial carbohydrate chain, which is then further processed by enzymes called glycosyltransferases and glycosidases within the Golgi's compartments to create the final, mature glycoprotein.

4628. The number of oxygen atoms in lipid molecules is always _ as compared several carbon atoms.

• A. Less
• B. Equal
• C. More
• D. Double

Explanation: Lipids are organic molecules primarily composed of carbon and hydrogen atoms, forming long hydrocarbon chains. Oxygen atoms are present in smaller quantities, typically in functional groups like carboxyl groups in fatty acids. This results in a lower number of oxygen atoms compared to carbon atoms in lipid molecules. Therefore, the correct answer is 'Less'. Other options such as 'Equal', 'More', and 'Double' are incorrect because they do not accurately represent the elemental composition of lipids.

4629. Unsaturated fats are made saturated by:

• A. Polymerization
• B. Dehydrogenation
• C. Hydrogenation
• D. Hybridization

Explanation: The correct answer is Hydrogenation. This process involves the addition of hydrogen to unsaturated fats, breaking the double bonds (C=C) and forming single bonds (C-C), thus converting them into saturated fats. Polymerization is unrelated as it deals with forming polymers. Dehydrogenation removes hydrogen, which is contrary to what is needed. Hybridization is a concept in molecular chemistry dealing with orbitals, not with the saturation of fats.

4630. A peptide chain attains secondary structure through the formation of:

• A. Peptide bond
• B. Hydrogen bond
• C. Ionic bond
• D. Disulphide bond

Explanation: The secondary structure of proteins is primarily stabilized by hydrogen bonds. These bonds occur between the carbonyl oxygen and the amide hydrogen of the peptide backbone, leading to formations such as alpha-helices and beta-sheets. In contrast, peptide bonds create the linear sequence of amino acids and define the primary structure. Ionic bonds and disulphide bonds are more relevant to the tertiary structure, where they contribute to the protein's overall three-dimensional shape.