Free Biological Molecules MCQs with Answers
1,790 Biological Molecules MCQs from Biology, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
The chapter covers water's polarity and biological roles, carbohydrates, lipids, proteins and nucleic acids, including their monomers, bonds, structures and functions. It also distinguishes RNA from DNA and explains conjugated molecules such as glycoproteins, glycolipids and nucleoproteins, which combine organic molecules with a non-protein component.
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- A. Metabolic reactions
- B. Catabolic reactions
- C. Anabolic reactions
- D. Both B and C
Explanation: Reactions in which simple substances are combined to form complex substances are called anabolic reactions.
Correct answer: Anabolic reactions1462. The number of calories required to raise the temperature of 1g of water from 15 to 16°C is called?
- A. Specific Heat of Vaporization
- B. Caloric heat
- C. Specific heat capacity
- D. Both a and b
Explanation: It is defined as the amount of heat required to raise the temperature of 1 gram of a substance by 1°C.
Correct answer: Specific heat capacity- A. Primary structure
- B. Secondary structure
- C. Tertiary structure
- D. Quaternary structure
Explanation: Tertiary structure refers to the overall 3D shape of a single polypeptide chain, including the arrangement of secondary structures and…
Correct answer: Tertiary structure- A. Egg
- B. Grains
- C. Pulses
- D. Both B and C
Explanation: Vegetative sources of protein come from plants. Grains (like wheat, rice, maize) and pulses (like beans, lentils, peas) are rich sources…
Correct answer: Both B and C- A. Structural and Regulatory
- B. Structural only
- C. Regulatory only
- D. Transport proteins
Explanation: Conjugated histone proteins play both structural and regulatory roles in the cell.
Correct answer: Structural and Regulatory- A. Uracil is a pyrimidine
- B. Glycine is a sulfur-containing amino acid
- C. Sucrose is a disaccharide
- D. Cellulose is a polysaccharide
Explanation: Option A: Uracil is a pyrimidine: This statement is correct. Uracil is one of the four nitrogenous bases found in RNA.
Correct answer: Glycine is a sulfur-containing amino acid- A. Carbon and Sulfur
- B. Phosphorus and Calcium
- C. Sulfur and Magnesium
- D. Magnesium and Sodium
Explanation: The correct answer is Phosphorus and Calcium. In the context of biological molecules, the six elements that make up about 98% of the mass…
Correct answer: Phosphorus and Calcium- A. Coiled around a common axis
- B. Coiled around each other
- C. Coiled differently
- D. Coiled over protein sheath
- E. Both A and B
Explanation: According to the Watson-Crick model, the DNA molecule consists of two long, parallel chains which are joined together by short crossbars…
Correct answer: Both A and B- A. Hormones
- B. Cofactors
- C. Antibodies
- D. Vitamins
Explanation: Many coenzymes are derived from vitamins, which are essential nutrients that organisms need in small amounts.
Correct answer: Vitamins- A. Heat capacity
- B. Heat of vaporization
- C. Dipole nature
- D. Ionization of water
Explanation: The correct answer is Heat of vaporization. Water's high heat of vaporization allows it to absorb large amounts of heat energy as it…
Correct answer: Heat of vaporization1471. Usually a polypeptide chain bends and folds upon itself to form a globular shape. This is protein's:
- A. Primary structure
- B. Tertiary structure
- C. Secondary structure
- D. Quaternary structure
Explanation: The correct answer is the tertiary structure because it represents the complete three-dimensional folding of a single polypeptide chain…
Correct answer: Tertiary structure- A. Cluster
- B. Spherical or curled up ball
- C. Flat uncoiled chains
- D. Long strands or fibrils
Explanation: Fibrous proteins are distinguished by their long, thread-like strands or fibrils.
Correct answer: Long strands or fibrils- A. Ionic bond
- B. Peptide bond
- C. Glycosidic linkage
- D. Ester linkage
Explanation: Option D is correct. When an alcohol and an acid react, they undergo an esterification reaction to form an ester bond or linkage.
Correct answer: Ester linkage- A. C18H32O16
- B. C57H110O6
- C. C300H500O250
- D. C42H45O23N17S
Explanation: Option B is correct. The molecular formula C57H110O6 corresponds to triacylglycerol, a lipid composed of three fatty acids linked to a…
Correct answer: C57H110O6- A. tRNA
- B. rRNA
- C. mRNA
- D. RNA Primers
Explanation: Option D is correct. The type of RNA that initiates the process of replication in prokaryotic cells is RNA primase, which synthesizes…
Correct answer: RNA Primers- A. Glycolipids
- B. Nucleoproteins
- C. Glycoproteins
- D. Simple proteins
Explanation: The correct answer is Option D: Simple proteins. Simple proteins do not have any non-protein prosthetic groups and are composed entirely…
Correct answer: Simple proteins- A. They are insoluble
- B. They contain carboxyl and amino groups
- C. They have a low molecular mass
- D. They possess only secondary structure
Explanation: Option B is correct. Proteins act as pH buffers due to their amphoteric nature, meaning they can function as both acids and bases.
Correct answer: They contain carboxyl and amino groups- A. Cellulose
- B. Starch
- C. Glycogen
- D. Chitin
Explanation: Option B is correct. The given diagram shows an α-glucose ring structure, identifiable by the downward orientation of the hydroxyl (OH)…
Correct answer: Starch- A. They store a high amount of energy
- B. They are polymers of fatty acids
- C. They play an important role in insulation
- D. They are mostly hydrophobic
Explanation: Option B is correct. Lipids are not polymers of fatty acids because they do not consist of repeating units.
Correct answer: They are polymers of fatty acids- A. Energy currency of the cell
- B. Contains ribose sugar
- C. Contains three high-energy bonds
- D. Contains three phosphate groups
Explanation: Option C is correct because ATP contains only two high-energy bonds, not three.
Correct answer: Contains three high-energy bonds