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. Sucrose
- B. Starch
- C. Maltose
- D. Cellulose
Explanation: Option C is correct. Maltose is a reducing sugar because it has a free aldehyde group that can undergo oxidation, allowing it to act as a…
Correct answer: Maltose- A. Main nitrogenous bases of nucleic acids
- B. Main nitrogenous wastes of humans
- C. Main nitrogenous bases of phospholipids
- D. Main types of amino acids in proteins
Explanation: Option A is correct. Adenine and guanine are main nitrogenous bases of nucleic acids.Adenine (A) and guanine (G) are purines, which are a…
Correct answer: Main nitrogenous bases of nucleic acids- A. Starch
- B. Cellulose
- C. Glycogen
- D. Chitin
Explanation: Glycogen is stored in both bacteria and animals. It serves as a primary energy storage molecule, a glucose polymer, in both organisms…
Correct answer: Glycogen- A. Pepsin
- B. Collagen
- C. Haemoglobin
- D. Immunoglobulin
Explanation: The correct answer is Collagen. Collagen is a structural protein, which means it provides support and strength to various body tissues…
Correct answer: Collagen- 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…
Correct answer: Pentose sugar- 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.
Correct answer: 21- 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.
Correct answer: Uracil- A. Maltose
- B. Glucose
- C. Lactose
- D. Galactose
Explanation: Glucose is the most common carbohydrate monomer, known as a monosaccharide.
Correct answer: Glucose- 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…
Correct answer: Keratin- 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…
Correct answer: mRNA- 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…
Correct answer: Both are synthesized in the endoplasmic reticulum- A. Less
- B. Equal
- C. More
- D. Double
Explanation: Lipids are organic molecules primarily composed of carbon and hydrogen atoms, forming long hydrocarbon chains.
Correct answer: Less- 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)…
Correct answer: Hydrogenation- A. Peptide bond
- B. Hydrogen bond
- C. Ionic bond
- D. Disulphide bond
Explanation: The secondary structure of proteins is primarily stabilized by hydrogen bonds.
Correct answer: Hydrogen bond- A. Maintaining the structural integrity of cell membranes
- B. Regulating and stabilizing environmental temperatures
- C. Inducing a cooling effect
- D. Catalyzing chemical reactions
Explanation: The property of high specific heat capacity allows a substance to absorb considerable heat without a significant temperature increase.
Correct answer: Regulating and stabilizing environmental temperatures- A. Palmitic acid
- B. Stearic acid
- C. Linoleic acid
- D. Oleic acid
Explanation: Linoleic acid has the most liquid-like consistency of the options provided because it has the lowest melting point.
Correct answer: Linoleic acid- A. tRNA
- B. rRNA
- C. mRNA
- D. Ribozyme
Explanation: Option D (Ribozyme) is correct because ribozymes are RNA molecules capable of catalyzing biochemical reactions, akin to protein enzymes.
Correct answer: Ribozyme- A. Carbon, nitrogen and oxygen
- B. Carbon, hydrogen, oxygen and phosphorus
- C. Carbon, hydrogen, oxygen and nitrogen
- D. Carbon, hydrogen and oxygen
Explanation: Carbohydrates are organic compounds consisting of carbon, hydrogen, and oxygen.
Correct answer: Carbon, hydrogen and oxygen- A. Glucose
- B. Glyceraldehyde
- C. Dihydroxyacetone
- D. Ribose
Explanation: Dihydroxyacetone is the correct answer because it is a ketose sugar, meaning it contains a ketone functional group.
Correct answer: Dihydroxyacetone- A. Bacteria
- B. Green plants
- C. Protists
- D. Protozoans
Explanation: Green plants are the primary source of carbohydrates in the ecosystem due to their ability to perform photosynthesis.
Correct answer: Green plants