All Free Biology MCQs with Answers

4411. The specific gravity of fats and oils is:

• A. 0.08
• B. 0.8
• C. 0.008
• D. 8.0

Explanation: Fats are lighter than water specific gravity less than 1.0 i.e. 0.8.

4412. They are non-crystalline but some can be crystallized under specific conditions:

• A. Carbohydrates
• B. Monosaccharides
• C. Fats and oils
• D. Sucrose

Explanation: Fats and oils are not crystalline but some can be crystallized under speciic conditions.

4413. All the amino acids invariably have following components, EXCEPT:

• A. NH2
• B. H
• C. COOH
• D. CH3

Explanation: Amino acids differ from each other with respect to the R group only, the rest of the components are constant.

4414. Amino acids mainly differ due to the type or nature of:

• A. Carboxyl group
• B. R-group
• C. Amino group
• D. Methyl group

Explanation: Amino acids differ from each other on the basis of R group or side chain, rest of the components are constant e.g. when 'R' is hydrogen it will be glycine and if 'R' is methyl it will be alanine.

4415. If R-group is a hydrogen atom, the amino acid will be:

• A. Alanine
• B. Glycine
• C. Leucine
• D. Tyrosine

Explanation: Glycine is the simplest amino acid of nature having hydrogen as the 'R' group.

4416. Each protein has specific properties which are determined by the:

• A. Number of amino acids
• B. Specific sequence of the amino acids
• C. Shape of the amino acids
• D. Number and specific sequence of amino acids

Explanation: At primary structural level any change in the number and sequence of amino acids changes shape and properties of protein as well. Sickle cell hemoglobin is its best example where only glutamic acid have been replaced by valine and as a consequence its O2 carrying capacity is affected.

4417. A dipeptide glycylalanine consists of:

• A. Glycine and Glycine
• B. Glycine and Alanine
• C. Alanine and Alanine
• D. Glycine and Valine

Explanation: A dipeptide glycylalanine consists of the amino acids glycine and alanine. The amino acids are linked together by a peptide bond, which is an amide bond formed between the amino group of glycine and the carboxyl group of alanine. The name of the dipeptide is derived from the names of the amino acids, with the suffix "-yl" being added to the name of the first amino acid and the prefix "-yl" being added to the name of the second amino acid. In this case, the dipeptide is named glycylalanine because the glycine is linked to the alanine.

4418. One chain of insulin consists of _ amino acids and the other has _ amino acids.

• A. 21, 30
• B. 20, 31
• C. 31, 20
• D. 22, 29

Explanation: Short chain of insulin consists of 21 amino acids whereas long chain consists of 30 amino acids.

4419. Both chains of insulin are held together by:

• A. Peptide bonds
• B. Hydrogen bonds
• C. Disulphide bond
• D. Glycosidic bonds

Explanation: Disulphide bonds hold together the two chains of amino acids.

4420. The primary structure of proteins is stabilized by:

• A. Disulphide bonds
• B. Hydrogen bonds
• C. Hydrophobic interaction
• D. Peptide bonds

Explanation: The primary structure of proteins is stabilized by peptide bonds. Peptide bonds are the bonds that link amino acids together to form a polypeptide chain. Peptide bonds are formed when the carboxyl group of one amino acid reacts with the amino group of another amino acid. The reaction releases a molecule of water and forms a covalent bond between the two amino acids.