All Free Biology MCQs with Answers

4541. The percentage of water in human bone cells is

• A. 18%
• B. 19%
• C. 20%
• D. 25%

Explanation: Human bone cells contain about 20% water, which is lower compared to other body tissues like muscles and brain that have a much higher water content.

4542. The attraction between water molecules and cell wall of xylem is termed as:

• A. Cohesion
• B. Tension
• C. Adhesion
• D. Imbibition

Explanation: Adhesion is the attraction between different kinds of molecules, such as water molecules and the cell wall of xylem.

4543. Sugar with a five-cornered ring structure is called

• A. Pyranose
• B. Furanose
• C. Dextrorotatory
• D. Levorotatory

Explanation: "Furanose" is the term used for sugars with a five-membered ring structure, resembling the compound furan.

4544. Which is not a polysaccharide?

• A. Chitin
• B. Cutin
• C. Pectin
• D. Dextrin

Explanation: Cutin is a waxy polymer found in the cuticle of plants, primarily composed of fatty acids, not sugars.

4545. Monosaccharides, which are rare in nature and occur in some bacteria, are:

• A. Trioses
• B. Tetroses
• C. Pentoses
• D. Hexoses

Explanation: Tetroses are four-carbon monosaccharides and are indeed rare in nature, occurring in some bacteria.

4546. Which of the following gives a blue color with iodine?

• A. Starch
• B. Glycogen
• C. Cellulose
• D. All of these

Explanation: Starch reacts with iodine to produce a blue-black color due to the formation of a polyiodide complex within the helical structure of amylose.

4547. The molecular basis of sickle cell anemia was found by:

• A. F. Sanger
• B. Beadle
• C. Tatum
• D. Ingram

Explanation: Vernon Ingram discovered that sickle cell anemia was caused by a specific mutation in the hemoglobin molecule, marking the first time a disease was linked to a molecular defect.

4548. What are most of the cellular secretions in nature?

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

Explanation: Glycoproteins are proteins that have carbohydrate groups attached to them and are commonly found in cellular secretions.

4549. Antibodies play important role against microorganisms and other antigen. So which type of proteins do they belong?

• A. Globular
• B. Fibrous
• C. Enzymes
• D. Both A & B

Explanation: Globular proteins are spherical and soluble in water. They play dynamic roles in biological processes, such as enzymatic activity and immune response, which includes antibodies.

4550. In the α helix protein structure, each turn has amino acids:

• A. 3.6
• B. 4.6
• C. 5.6
• D. 6.6

Explanation: In the α-helix structure of proteins, each complete turn of the helix contains 3.6 amino acid residues. This arrangement allows the formation of hydrogen bonds that stabilize the helical structure.