Free Proteins MCQs with Answers

• A. two amino groups
• B. the carboxyl group of one amino acid and the amino group of the next
• C. two R groups
• D. the carboxyl group of one amino acid and the R group of the next

Explanation: A peptide bond is a condensation between the carboxyl group of one amino acid and the alpha amino group of the next, releasing water.

• A. primary structure
• B. secondary structure
• C. tertiary structure
• D. quaternary structure

Explanation: Secondary structure is the regular local folding held together by hydrogen bonds between the backbone carbonyl and amide groups, giving…

• A. primary structure only
• B. secondary structure only
• C. tertiary structure only
• D. quaternary structure

Explanation: Quaternary structure exists whenever a functional protein is built from more than one polypeptide chain.

• A. its peptide bonds are hydrolysed and amino acids are released
• B. its tertiary structure is destroyed but its primary structure remains intact
• C. its amino acid sequence is rearranged
• D. it becomes more soluble and more active

Explanation: Heat breaks the relatively weak hydrogen, ionic and hydrophobic interactions that hold the chain in its three dimensional shape, so the…

• A. are found in every protein
• B. cannot be synthesised by the body and must be supplied in the diet
• C. are needed only during childhood
• D. make up the active site of every enzyme

Explanation: About nine of the twenty amino acids cannot be made by the human body at a useful rate, so they have to come from food, and a protein…

• A. hydrogen bonds between R groups
• B. ionic bonds between charged R groups
• C. disulphide bridges between cysteine residues
• D. peptide bonds between R groups

Explanation: Peptide bonds join the amino group of one residue to the carboxyl group of the next along the backbone, so they build the primary…

• A. Benedict's test
• B. Iodine test
• C. Biuret test
• D. Emulsion test

Explanation: Biuret test uses NaOH and CuSO4 to detect peptide bonds, giving a purple/violet color with proteins.

• A. α-helix and β-pleated sheet
• B. Quaternary folding
• C. Amino acid sequence
• D. Disulfide bridges

Explanation: Secondary structure involves local folding into α-helix or β-pleated sheet, stabilized by hydrogen bonds between backbone atoms.

• A. Ionic bonds
• B. Hydrogen bonds
• C. Disulfide bridges
• D. Hydrophobic exclusion

Explanation: Regular hydrogen bonding between backbone carbonyl and amide groups coils the chain into an alpha helix or folds it into a beta pleated…

• A. Keratin
• B. Collagen
• C. Hemoglobin
• D. Histone

Explanation: Haemoglobin folds into a compact soluble ball with hydrophilic residues outside, which is what lets it dissolve in the cytoplasm of a red…

• A. Affect solubility
• B. Hold R-groups
• C. Link amino acid
• D. Help in releasing oxygen

Explanation: A peptide bond forms by condensation between the carboxyl group of one amino acid and the amino group of the next, so it is what creates…

• A. carbohydrates
• B. proteins
• C. lipids
• D. carbonates

Explanation: Proteins contain nitrogen because their amino acids have amino groups, written as -NH2, in addition to carbon, hydrogen, and oxygen.

• A. Hydrolysis
• B. Pinocytosis
• C. Dehydration synthesis
• D. Active transport

Explanation: Amino acids join by peptide bonds through dehydration synthesis, in which a molecule of water is removed as the bond forms.

• A. Carbohydrates
• B. Proteins
• C. Nucleic Acid
• D. Fats

Explanation: Most enzymes are globular proteins whose specific three-dimensional shapes form active sites for binding substrates and catalysing…

• A. Pellagra
• B. Marasmus
• C. Beri-Beri
• D. Rickets

Explanation: Marasmus results from severe deficiency of total calories and protein, producing marked wasting in children.

• A. Lipids
• B. Carbohydrates
• C. Amino acids
• D. Protein and amino acids

Explanation: Henna contains lawsone, which reacts with proteins and amino groups in keratin of the skin and hair to produce an orange-red stain.

• A. Gene
• B. Protein
• C. Glucose
• D. Diabetes

Explanation: Insulin is a peptide hormone made of amino acids, so it is a protein that regulates blood glucose concentration.

• A. alanine
• B. glycine
• C. valine
• D. phenylalanine

Explanation: Glycine is the simplest amino acid because its side chain is only a hydrogen atom, giving it the smallest possible amino-acid structure.

• A. Antibodies.
• B. Interferons
• C. Antitoxins
• D. All of these

Explanation: Antibodies, interferons and antitoxins are protein molecules involved in defence, signalling or neutralising toxins.

• A. H bonds
• B. Disulphide Bond
• C. Ionic bond
• D. Hydrophobic bonds

Explanation: An alpha helix is stabilized by hydrogen bonds between the carbonyl oxygen of one peptide bond and the hydrogen of another peptide bond in…