All Free Biology MCQs with Answers

4551. The most abundant protein in the whole biosphere is.

• A. Rubisco
• B. Collagen
• C. Haemoglobin
• D. Albumin

Explanation: Rubisco, short for Ribulose-1,5-bisphosphate carboxylase/oxygenase, is the enzyme responsible for fixing carbon dioxide during the Calvin cycle of photosynthesis. It is the most abundant protein on Earth due to its central role in photosynthetic organisms.

4552. Which of the following is not an amino acid?

• A. Histidine
• B. Lactic acid
• C. Glutamic acid
• D. Glycine

Explanation: Lactic acid is an organic acid involved in metabolic processes, but it is not an amino acid. It is produced during anaerobic respiration in muscles.

4553. Keratinized epithelium is present in:

• A. Hair
• B. Skin
• C. Bone
• D. Muscle

Explanation: The skin, particularly the outermost layer called the epidermis, is composed of keratinized epithelium. This keratinization provides a tough, protective layer.

4554. Two amino acids are attached due to _ bonds in different polypeptide chains:

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

Explanation: Peptide bonds are covalent bonds that link the carboxyl group of one amino acid to the amino group of another, forming the backbone of polypeptide chains.

4555. The sequence of atoms in a peptide bond is.

• A. -C-N-N-C-
• B. -C-O-N-C-
• C. -C-C-C-N-
• D. -N-C-C-C-

Explanation: This is the correct sequence representing the typical order of atoms in a peptide bond, with carbon atoms flanking a nitrogen atom.

4556. Glycosphingolipid are made up of:

• A. Sphingolipids
• B. Alcohol and fatty acids
• C. Carbohydrate and sphingolipids
• D. Carbohydrates and fatty acids

Explanation: Glycosphingolipids are composed of carbohydrate groups attached to sphingolipids.

4557. A compound produced as a result of a chemical reaction of an alcohol with an acid in which water molecule is released is called_.

• A. Monosaccharide
• B. Fatty acid
• C. Nucleic acid
• D. Neutral lipid

Explanation: Neutral lipids, such as triglycerides, are formed when an alcohol (glycerol) reacts with fatty acids, releasing water molecules in a process called esterification.

4558. Lipoproteins rich in cholesterol are:

• A. Chylomicrons
• B. VLDL
• C. LDL
• D. HDL

Explanation: LDL (Low-Density Lipoprotein) is rich in cholesterol and is often referred to as "bad cholesterol" because high levels can lead to plaque formation in arteries.

4559. In water, hydrophobic interactions of phospholipids are:

• A. In heads
• B. In tails
• C. Both A and B
• D. None of these

Explanation: The tails of phospholipids are hydrophobic, meaning they avoid water, leading to the formation of bilayers.

4560. A triglyceride is:

• A. Protein
• B. Nucleic acid
• C. A simple sugar
• D. Lipid

Explanation: Triglycerides are a type of lipid, which is a category ofbiological molecules that includes fats, oils, and waxes. Theyare composed of glycerol and three fatty acids.