All Free Biology MCQs with Answers

4581. The 5 carbon sugar present in the heart muscle is:

• A. Lyxose
• B. Ribose
• C. Xylose
• D. Glucose

Explanation: Ribose is a 5-carbon sugar that is an essential component of RNA, which is abundant in heart muscle due to its high energy demands. (Heart Muscles has high RNA content).

4582. Cellulose on hydrolysis yields:

• A. α D-Glucose
• B. α L-Glucose
• C. β D-Glucose
• D. β L-Glucose

Explanation: Cellulose is a polymer of β-D-Glucose units linked by β-1,4- glycosidic bonds.

4583. In living organisms, the lubricant that provides protection against damage resulting from friction is?

• A. Water
• B. Carbohydrate
• C. Lipid
• D. Protein

Explanation: Lipids, such as oils and fats, act as natural lubricants in the body. They reduce friction between tissues, protect organs, and help in smooth movement of joints and membranes. Water, carbohydrates, and proteins play other vital roles but do not serve as primary lubricants.

4584. The exoskeleton of arthropods is formed by the polymerisation of:

• A. Lipoglycans
• B. D-glucosamine
• C. Keratin sulphate and chondroitin sulphate
• D. N-acetyl glucosamine

Explanation: The exoskeleton of arthropods is made of chitin, a polysaccharide formed by the polymerisation of N-acetyl glucosamine. This gives the exoskeleton strength and rigidity while still allowing flexibility for movement.

4585. The percentage of water in bacterial cell is about:

• A. 15%
• B. 18%
• C. 50%
• D. 70%

Explanation: Like most living cells, bacterial cells contain a high amount of water, making up about 70% of their total composition. This water is essential for biochemical reactions, nutrient transport, and maintaining cell structure.

4586. The diagram depicts the primary structure of a protein. The bonds connecting the individual units are:

• A. Glycosidic bonds
• B. Peptide bonds
• C. Hydrogen bonds
• D. Disulphide bonds

Explanation: A peptide bond is a covalent chemical bond formed between two amino acid molecules. A chain of amino acids linked by peptide bonds forms the primary structure of a protein.

4587. The number of carbon atoms present in ribulose:

• A. 6
• B. 4
• C. 5
• D. 3

Explanation: Ribulose is known as a pentose sugar, indicating it contains 5 carbon atoms.

4588. The number of water-soluble vitamins is:

• A. A: 3
• B. B: 6
• C. C: 9
• D. D: 12

Explanation: There are 9 water-soluble vitamins.1.Vitamin C2.Vitamin B1 (Thiamine)3.Vitamin B2 (Riboflavin)4.Vitamin B3 (Niacin)5.Vitamin B5 (Pantothenic Acid)6.Vitamin B6 (Pyridoxine)7.Vitamin B7 (Biotin)8.Vitamin B9 (Folate)9.Vitamin B12 (Cobalamin)

4589. HDL is synthesized in:

• A. Intestine
• B. Liver
• C. Macrophages
• D. Both A and B

Explanation: Both the liver and intestines are involved in the synthesis of HDL. The liver produces HDL particles which are secreted into the bloodstream, while the intestines contribute to HDL production by synthesizing HDL in the enterocytes.

4590. RNA does not contain:

• A. Adenine
• B. Cytosine
• C. Phosphate
• D. Thymine

Explanation: Thymine is a nitrogenous base found in DNA but not in RNA. In RNA, Thymine is replaced by Uracil.