first chapter MCQS
EXERCISE
Question 1: Attraction Between Water Molecules
Concept: The attraction between the slight negative charge of one water molecule and the slight positive charge of another water molecule is called:
(a) Covalent bond
(b) Hydrogen bond
(c) Ionic bond
(d) Hydrophilic bond
Correct Answer: (b) Hydrogen bond
Question 2: Coalescing Oil Droplets
Concept: The tendency of water to cause oil drops to coalesce into a larger droplet is termed:
(a) Hydrophilic force
(b) Hydrophobic exclusion
(c) Hydrophilic exclusion
(d) Hydrogen bonding
Correct Answer: (b) Hydrophobic exclusion
Question 3: Covalent Bond Between Monosaccharides
Concept: The covalent bond that forms between two monosaccharides is known as:
(a) Peptide bond
(b) Glycosidic bond
(c) Phosphodiester bond
(d) Ester bond
Correct Answer: (b) Glycosidic bond
Question 4: Most Abundant Carbohydrate in Nature
Concept: The most abundant carbohydrate found in nature is:
(a) Glucose
(b) Maltose
(c) Cellulose
(d) Glycogen
Correct Answer: (c) Cellulose
Question 5: Most Important Organic Compound in Cells
Concept: The most important organic compound in a cell that carries out virtually all of the cell's activities is:
(a) Protein
(b) Carbohydrates
(c) Nucleic acid
(d) Lipids
Correct Answer: (a) Protein
Question 6: Unique Feature of Amino Acids
Concept: All amino acids share the same formula except for the:
(a) Alpha carbon
(b) Hydroxyl group
(c) Radical group
(d) Amino group
Correct Answer: (c) Radical group
Question 7: Trihydroxy Alcohol
Concept: A trihydroxy alcohol made of three carbon atoms is:
(a) Glucose
(b) Glycerol
(c) Maltose
(d) Ribose
Correct Answer: (b) Glycerol
Question 8: Class of Lipids from Isoprenoid Units
Concept: A large and important class of lipids made up of isoprenoid units is called:
(a) Phospholipid
(b) Terpenoids
(c) Waxes
(d) Acylglycerol
Correct Answer: (b) Terpenoids
Question 9: Hydrolysis of Polymers
Concept: To completely hydrolyze a polymer that is 21 monomers long, how many molecules of water are needed?
(a) 10
(b) 20
(c) 21
(d) 2
Correct Answer: (b) 20
Question 10: Comparison of Starch and Cellulose
Concept: Which of the following statements is true for both starch and cellulose?
(a) They are both polymers of glucose.
(b) They are geometric isomers of each other.
(c) They can both be digested by humans.
(d) They are both used for energy storage in plants.
Correct Answer: (a) They are both polymers of glucose.
Question 1: Attraction Between Water Molecules
Correct Answer: (b) Hydrogen bond
Explanation: A hydrogen bond is a weak bond that occurs between a slightly positive hydrogen atom of one water molecule and the slightly negative oxygen atom of another water molecule. This bond is essential for many properties of water, including its high surface tension and boiling point.
Question 2: Coalescing Oil Droplets
Correct Answer: (b) Hydrophobic exclusion
Explanation: Hydrophobic exclusion refers to the phenomenon in which non-polar substances, like oil, do not mix with polar substances, such as water. When in contact, water molecules prefer to associate with each other rather than with the oil. This leads to the oil droplets merging into larger ones.
Question 3: Covalent Bond Between Monosaccharides
Correct Answer: (b) Glycosidic bond
Explanation: A glycosidic bond is a type of covalent bond that forms between the hydroxyl group of one monosaccharide and the anomeric carbon of another, resulting in the formation of disaccharides or polysaccharides. This process occurs through a dehydration reaction.
Question 4: Most Abundant Carbohydrate in Nature
Correct Answer: (c) Cellulose
Explanation: Cellulose is a complex carbohydrate that forms the structural component of plant cell walls. It is the most abundant organic polymer on Earth, primarily composed of long chains of glucose molecules linked by β(1→4) glycosidic bonds, making it insoluble and supportive.
Question 5: Most Important Organic Compound in Cells
Correct Answer: (a) Protein
Explanation: Proteins are vital macromolecules that perform a vast array of functions within living organisms. They are responsible for catalyzing metabolic reactions, providing structural support, and regulating bodily functions, among many other roles.
Question 6: Unique Feature of Amino Acids
Correct Answer: (c) Radical group
Explanation: All amino acids share a common backbone structure, but they differ in their side chains, known as radical groups or R groups. These groups dictate the unique properties and functions of each amino acid.
Question 7: Trihydroxy Alcohol
Correct Answer: (b) Glycerol
Explanation: Glycerol is a trihydroxy alcohol with three carbon atoms, each of which has a hydroxyl (-OH) group attached. It serves as a backbone in the structure of triglycerides and phospholipids, which are essential components of cell membranes.
Question 8: Class of Lipids from Isoprenoid Units
Correct Answer: (b) Terpenoids
Explanation: Terpenoids, also known as isoprenoids, are a class of lipids constructed from isoprene units. They play various roles in biological systems, including serving as pigments, hormones, and structural components of membranes.
Question 9: Hydrolysis of Polymers
Correct Answer: (b) 20
Explanation: To completely hydrolyze a polymer made of 21 monomers, 20 water molecules are required. This is because hydrolysis involves breaking apart each bond between monomers, and every bond broken requires one molecule of water.
Question 10: Comparison of Starch and Cellulose
Correct Answer: (a) They are both polymers of glucose.
Explanation: Both starch and cellulose are polysaccharides made up of glucose molecules. However, they differ in the type of glycosidic bonds formed; starch consists of α(1→4) bonds (and branches), while cellulose consists of β(1→4) bonds, leading to different physical properties and biological roles.