Free Biological Molecules MCQs with Answers

• A. Air
• B. Water
• C. Land
• D. Gravity

Explanation: Gravity is a highly constant abiotic factor because its strength does not vary substantially across the ordinary habitats of an ecosystem…

• A. Hydrogen bonding
• B. Transpiration
• C. Adhesion
• D. Root prerssure

Explanation: Transpiration creates negative pressure in the leaf and pulls the continuous water column upward through xylem under the cohesion-tension…

• A. 10%
• B. 30%
• C. 75%
• D. 90%

Explanation: Approximately 71% of Earth's surface is covered by water, and this is conventionally rounded to about 75% in many biology texts.

• A. 65%
• B. 18%
• C. 10%
• D. 3%

Explanation: Oxygen is the most abundant element in the human body by mass, contributing about 65%, largely because it is present in body water and…

• A. 20%
• B. 65%
• C. 85%
• D. 89%

Explanation: Brain tissue contains a high proportion of water, commonly given in introductory biology as about 85%, because water forms the medium for…

• A. Iron
• B. Hydrogen
• C. Chlorine
• D. Copper

Explanation: Hydrogen is a macronutrient because plants require it in relatively large amounts, mainly as part of water and organic compounds.

• A. Water
• B. Glucose
• C. Oxygen
• D. Sodium chloride

Explanation: Glucose is an organic carbohydrate because it contains carbon and hydrogen bonded in a carbon-based molecular structure and serves as a…

• A. Calcium
• B. Iron
• C. Water
• D. Carbohydrates

Explanation: Carbohydrates are broken down into glucose and other simple sugars, which cells use in cellular respiration to release energy for vital…

• A. Protein
• B. carbohydrates
• C. Flavoprotein
• D. lipid

Explanation: Molisch's test is a general test for carbohydrates because carbohydrate dehydration products react with alpha-naphthol to produce a violet…

• A. Dextrose
• B. Sugar
• C. Glycogen
• D. Starch

Explanation: Glucose is also called dextrose, especially because naturally occurring glucose rotates plane-polarized light to the right.

• A. Claude Silbert Hudson
• B. Anselme Payen
• C. Jons jacob Berzeliis
• D. Justus von Liebig

Explanation: Claude Silbert Hudson is commonly described in older textbooks as a father of carbohydrate chemistry because of his work on sugar…

• A. Starch
• B. Glucose
• C. Fructose
• D. Cellulose

Explanation: Plants synthesize glucose during photosynthesis from carbon dioxide and water using light energy, and glucose is then used to form other…

• A. Aerial stem
• B. Root
• C. Scale leaves
• D. Bud

Explanation: An onion bulb is a modified underground stem whose fleshy scale leaves store carbohydrates and water.

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

Explanation: Green algae store photosynthetic carbohydrate mainly as starch, often in association with their chloroplasts.

• A. Heterotrophs
• B. Autotrophes
• C. Carnivores
• D. Saprotrophs

Explanation: Insectivorous plants carry out photosynthesis and make their own carbohydrates, so they remain autotrophs.

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

Explanation: Tetroses are four-carbon monosaccharides and are relatively rare, occurring in some bacteria and in a few metabolic pathways.

• A. 1 to 3 thousand
• B. 3 to many thousand
• C. 3 to 5 thousand
• D. 5 to 9 thousand

Explanation: In the general formula Cx(H2O)y for carbohydrates, x may begin at 3 in trioses and extend to many thousands in polysaccharides.

• A. CO
• B. C-COO-C
• C. HCOH
• D. HOH

Explanation: A keto group contains a carbonyl group within the carbon chain and is represented as C=O, commonly shortened in such options to CO.

• A. Glucose
• B. Starch
• C. Sucrose
• D. Glycogen

Explanation: Starch is the main carbohydrate obtained by animals from plant-based foods such as cereals, potatoes and legumes; digestion breaks it down…

• A. Silk
• B. Wool
• C. Cotton
• D. Paper

Explanation: Cotton fibres are composed almost entirely of cellulose, a polymer of beta-glucose units, making cotton the usual example of relatively…