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. Starch
- B. Cellulose
- C. Glycogen
- D. All of these
Explanation: Cellulose gives no color with iodine. Glycogen gives red color with iodine while starch gives blue color with iodine.
Correct answer: Starch- A. C-N
- B. C-O
- C. C-H
- D. H-O
Explanation: Carbon-oxygen association in glycosidic linkages provides stability to the complex carbohydrate molecules, Carbon combines with nitrogen…
Correct answer: C-H- A. Lignin
- B. Starch
- C. Chitin
- D. Cellulose
Explanation: Starch is an example of functional carbohydrate and it is less resistant to decay because it can be easily digested in the human body.
Correct answer: Starch- A. Secondary Structure
- B. Primary Structure
- C. Quaternary Structure
- D. Tertiary Structure
Explanation: Haemoglobin consists of four polypeptide chains and exhibits quaternary structure.
Correct answer: Quaternary Structure- A. Globular proteins
- B. Glycoproteins
- C. Fibrous proteins
- D. Both Options A and B are correct
Explanation: An antibody, also known as an immunoglobulin, is a large Y-shaped globular protein produced mainly by plasma cells and is used by the…
Correct answer: Both Options A and B are correct- A. Alanine
- B. Glycine
- C. Leucine
- D. Valine
Explanation: R-group in amino acid may be a hydrogen atom as in glycine, or CH3, as in alanine, or any other group.
Correct answer: Glycine427. Fatty acids are the organic compounds containing hydrogen, oxygen and one of the following are:
- A. -COOH
- B. -NH
- C. Acyl
- D. Sucrose
Explanation: Generally, a fatty acid consists of a straight chain of an even number of carbon atoms with hydrogen atoms along the length of the chain…
Correct answer: -COOH- A. Nucleotide
- B. Nucleoside
- C. Nucleic Acid
- D. Polynucleotide
Explanation: The compound formed by a combination of a base and a pentose sugar is called nucleoside,A nucleoside and a phosphoric acid combine to form…
Correct answer: Nucleoside- A. Uracil
- B. Thymine
- C. Cytosine
- D. Adenine
Explanation: Adenine, guanine, and cytosine are the N2 containing bases present in both DNA and RNA.
Correct answer: Uracil- A. Carbon, water and oxygen
- B. Carbon, Sulphur and hydrogen
- C. Carbon, calcium and hydrogen
- D. Carbon, hydrogen and oxygen
Explanation: The word carbohydrate literally means hydrated carbons. They are composed of carbon, hydrogen, and oxygen and the ratio of hydrogen and…
Correct answer: Carbon, hydrogen and oxygen- A. Ribose and Heptulose
- B. Phosphoglyceraldehyde and Dihydroxyacetone phosphate
- C. Glucose and Galactose
- D. Fructose and Ribulose
Explanation: Phosphoglyceraldehyde and Dihydroxyacetone phosphate are isomers. They are formed during glycolysis in photosynthesis when Fructose 1,6…
Correct answer: Phosphoglyceraldehyde and Dihydroxyacetone phosphate- A. Cellulose
- B. Chitin
- C. Proteins
- D. Glycerol
Explanation: Chitin is a structural polysaccharide found in cell walls of fungi and made up of N-acetyl glucosamine subunits, while cell walls of…
Correct answer: Chitin- A. Acetic Acid
- B. Butyric acid
- C. Oleic acid
- D. Palmitic acid
Explanation: Fatty acid may contain no double bond (saturated fatty acids) or up to 6 double bonds (unsaturated fatty acids).
Correct answer: Oleic acid- A. A-T
- B. C-G
- C. A-U
- D. T-A
Explanation: In RNA, nitrogenous bases form the usual complementary pairing, via cytosine (C) with guanine (G) and uracil (U) with adenine (A).
Correct answer: A-U- A. Waxes
- B. Glycerol
- C. Starch
- D. Cellulose
Explanation: A type of carbohydrate, cellulose contains chains of glucose rings, providing strength and rigidity.
Correct answer: Cellulose- A. Glyceraldehyde
- B. Dihydroxyacetone
- C. Ribose
- D. Glucose
Explanation: Glyceraldehyde, ribose and glucose are examples of aldose sugars while dihydroxyacetone is an example of keto sugar.
Correct answer: Dihydroxyacetone- A. Glycine
- B. Alanine
- C. Leucine
- D. Valine
Explanation: Amino acids mainly differ due to the type or nature of R group. R may be a hydrogen atom as in glycine, or CH3 as in alanine, or any other…
Correct answer: Glycine- A. Guanine
- B. Cytosine
- C. Thymine
- D. Uracil
Explanation: Nitrogenous bases are of two types, single ringed pyrimidines and double ringed purines.
Correct answer: Guanine- A. Glyceraldehyde
- B. Dihydroxyacetone
- C. Glucose
- D. Ribose
Explanation: Glyceraldehyde, ribose, and glucose are aldose sugars while dihydroxyacetone is the simplest three-carbon keto sugar.
Correct answer: Dihydroxyacetone- A. DNA, ATP, Ribulose bisphosphate and Cysteine
- B. DNA, NAD and Insulin
- C. DNA, NADP, ATP and Ribulose bisphosphate
- D. DNA, RNA and Myosin
Explanation: Ribose is a five carbon sugar and a monosaccharide. It is a major component of nucleosides/ nucleotides, dinucleotides, nucleic acid and…
Correct answer: DNA, NADP, ATP and Ribulose bisphosphate