Free Conjugated Molecules MCQs with Answers

1. A conjugated molecule such as a glycoprotein consists of

• A. two identical monomers joined together
• B. a protein combined with a non-protein group
• C. a lipid combined with another lipid
• D. a polysaccharide broken into monosaccharides

Explanation: Conjugated molecules are built from two different classes of biological molecule joined together, so a glycoprotein is protein plus carbohydrate and a lipoprotein is protein plus lipid. The cell surface is coated with such molecules, and they are what allow cells to recognise one another. Two identical monomers joined together would simply be a dimer of a single class.

2. Haemoglobin is classified as a conjugated protein because it

• A. consists of four identical polypeptide chains
• B. contains only amino acids joined by peptide bonds
• C. is made in the bone marrow rather than the liver
• D. contains a non protein haem group attached to its polypeptide chains

Explanation: A conjugated protein is a protein permanently joined to a non protein prosthetic group, and in haemoglobin each of the four chains carries an iron containing haem that actually binds the oxygen. Without the haem the globin protein alone could carry nothing. Glycoproteins and lipoproteins are conjugated in the same sense, with a carbohydrate or lipid group instead.

3. Glycoproteins are formed as a result of the combination of:

• A. Lipids and proteins
• B. Carbohydrates and proteins
• C. Nucleic acid and proteins
• D. Fatty acids and carbohydrates

Explanation: The prefix glyco means sugar, so a glycoprotein is protein joined to a carbohydrate group, and such molecules coat the cell surface where they act in recognition and as receptors. Lipid with protein gives a lipoprotein and nucleic acid with protein a nucleoprotein, both of which are conjugated molecules of other kinds. Reading the prefix identifies the non protein partner every time.